Publications by authors named "David J Nolan"

31 Publications

Emergence of an early SARS-CoV-2 epidemic in the United States.

medRxiv 2021 Feb 8. Epub 2021 Feb 8.

The emergence of the early COVID-19 epidemic in the United States (U.S.) went largely undetected, due to a lack of adequate testing and mitigation efforts. The city of New Orleans, Louisiana experienced one of the earliest and fastest accelerating outbreaks, coinciding with the annual Mardi Gras festival, which went ahead without precautions. To gain insight into the emergence of SARS-CoV-2 in the U.S. and how large, crowded events may have accelerated early transmission, we sequenced SARS-CoV-2 genomes during the first wave of the COVID-19 epidemic in Louisiana. We show that SARS-CoV-2 in Louisiana initially had limited sequence diversity compared to other U.S. states, and that one successful introduction of SARS-CoV-2 led to almost all of the early SARS-CoV-2 transmission in Louisiana. By analyzing mobility and genomic data, we show that SARS-CoV-2 was already present in New Orleans before Mardi Gras and that the festival dramatically accelerated transmission, eventually leading to secondary localized COVID-19 epidemics throughout the Southern U.S.. Our study provides an understanding of how superspreading during large-scale events played a key role during the early outbreak in the U.S. and can greatly accelerate COVID-19 epidemics on a local and regional scale.
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http://dx.doi.org/10.1101/2021.02.05.21251235DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7872376PMC
February 2021

Brain tissue transcriptomic analysis of SIV-infected macaques identifies several altered metabolic pathways linked to neuropathogenesis and poly (ADP-ribose) polymerases (PARPs) as potential therapeutic targets.

J Neurovirol 2021 Feb 6;27(1):101-115. Epub 2021 Jan 6.

Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL, USA.

Despite improvements in antiretroviral therapy, human immunodeficiency virus type 1 (HIV-1)-associated neurocognitive disorders (HAND) remain prevalent in subjects undergoing therapy. HAND significantly affects individuals' quality of life, as well as adherence to therapy, and, despite the increasing understanding of neuropathogenesis, no definitive diagnostic or prognostic marker has been identified. We investigated transcriptomic profiles in frontal cortex tissues of Simian immunodeficiency virus (SIV)-infected Rhesus macaques sacrificed at different stages of infection. Gene expression was compared among SIV-infected animals (n = 11), with or without CD8+ lymphocyte depletion, based on detectable (n = 6) or non-detectable (n = 5) presence of the virus in frontal cortex tissues. Significant enrichment in activation of monocyte and macrophage cellular pathways was found in animals with detectable brain infection, independently from CD8+ lymphocyte depletion. In addition, transcripts of four poly (ADP-ribose) polymerases (PARPs) were up-regulated in the frontal cortex, which was confirmed by real-time polymerase chain reaction. Our results shed light on involvement of PARPs in SIV infection of the brain and their role in SIV-associated neurodegenerative processes. Inhibition of PARPs may provide an effective novel therapeutic target for HIV-related neuropathology.
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http://dx.doi.org/10.1007/s13365-020-00927-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7786889PMC
February 2021

Molecular surveillance of methicillin-resistant Staphylococcus aureus genomes in hospital unexpectedly reveals discordance between temporal and genetic clustering.

Am J Infect Control 2021 01 18;49(1):59-64. Epub 2020 Jun 18.

BioInfoExperts, LLC, Thibodaux, LA.

Background: The objective of this study was to identify sources and linkages among methicillin-resistant Staphylococcus aureus infections using whole-genome sequencing (WGS).

Methods: A total of 56 samples were obtained from all patients with a confirmed MRSA infection over 6 months at University of Florida-Health Jacksonville. Samples were cultured and sequenced; data was analyzed on an automated cloud-based platform. Genetic Clusters were defined as <40 single nucleotide polymorphisms. Temporal Clusters were defined as ≥5 MRSA cases over 3 days.

Results: We found 7 Genetic Clusters comprising 15 samples. Four Genetic Clusters contained patients with non-overlapping stays (3-10 weeks apart), 3 of which contained patients who shared the same Unit. We also found 5 Temporal Clusters comprising 23 samples, although none of the samples were genetically related.

Discussion: Results showed that temporal clustering may be a poor indicator of genetic linkage. Shared epidemiological characteristics between patients in Genetic Clusters may point toward previously unidentified hospital sources. Repeated observation of related strains is also consistent with ongoing MRSA transmission within the surrounding high-risk community.

Conclusions: WGS is a valuable tool for hospital infection prevention and control.
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http://dx.doi.org/10.1016/j.ajic.2020.06.180DOI Listing
January 2021

Delayed Expression of PD-1 and TIGIT on HIV-Specific CD8 T Cells in Untreated HLA-B*57:01 Individuals Followed from Early Infection.

J Virol 2020 07 1;94(14). Epub 2020 Jul 1.

Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden

While the relationship of protective human leukocyte antigen (HLA) class I alleles and HIV progression is well defined, the interaction of HLA-mediated protection and CD8 T-cell exhaustion is less well characterized. To gain insight into the influence of HLA-B*57:01 on the deterioration of CD8 T-cell responses during HIV infection in the absence of antiretroviral treatment, we compared HLA-B*57:01-restricted HIV-specific CD8 T-cell responses to responses restricted by other HLA class I alleles longitudinally after control of peak viremia. Detailed characterization of polyfunctionality, differentiation phenotypes, transcription factor, and inhibitory receptor expression revealed progression of CD8 T-cell exhaustion over the course of the infection in both patient groups. However, early effects on the phenotype of the total CD8 T-cell population were apparent only in HLA-B*57-negative patients. The HLA-B*57:01-restricted, HIV epitope-specific CD8 T-cell responses showed beneficial functional patterns and significantly lower frequencies of inhibitory receptor expression, i.e., PD-1 and coexpression of PD-1 and TIGIT, within the first year of infection. Coexpression of PD-1 and TIGIT was correlated with clinical markers of disease progression and declining percentages of the T-bet Eomes CD8 T-cell population. In accordance with clinical and immunological deterioration in the HLA-B*57:01 group, the difference in PD-1 and TIGIT receptor expression did not persist to later stages of the disease. Given the synergistic nature of TIGIT and PD-1, the coexpression of those inhibitory receptors should be considered when evaluating T-cell pathogenesis, developing immunomodulatory therapies or vaccines for HIV, and when using immunotherapy or vaccination for other causes in HIV-infected patients. HIV-mediated T-cell exhaustion influences the patient´s disease progression, immune system and subsequently non-AIDS complications, and efficacy of vaccinations against other pathogens. Consequently, the possibilities of interfering with exhaustion are numerous. Expanding the use of immunomodulatory therapies to include HIV treatment depends on information about possible targets and their role in the deterioration of the immune system. Furthermore, the rise of immunotherapies against cancer and elevated cancer incidence in HIV-infected patients together increase the need for detailed knowledge of T-cell exhaustion and possible interactions. A broader approach to counteract immune exhaustion to alleviate complications and improve efficacy of other vaccines also promises to increase patients' health and quality of life.
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http://dx.doi.org/10.1128/JVI.02128-19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7343205PMC
July 2020

Emerging Patterns in HIV-1 gp120 Variable Domains in Anatomical Tissues in the Absence of a Plasma Viral Load.

AIDS Res Hum Retroviruses 2019 06 10;35(6):588-596. Epub 2019 Apr 10.

6 Departments of Laboratory Medicine, Pathology and Medicine, The University of California at San Francisco, San Francisco, California.

The HIV envelope protein contains five hypervariable domains (V1-V5) that are fundamental for cell entry. We contrasted modifications in the variable domains derived from a panel of 24 tissues from 7 subjects with no measurable plasma viral load (NPVL) to variable domains from 76 tissues from 15 subjects who had a detectable plasma viral load (PVL) at death. NPVL subject's V1 and V2 domains were usually highly length variable, whereas length variation in PVL sequences was more conserved. Longer V1s contained more charged residues, whereas longer V2s were more glycosylated. Structural analysis demonstrated V1/V2 charge, and N-site additions/subtractions were localized to the CD4 binding pocket. Diversified envelopes in tissues during therapy may represent a mechanism for HIV persistence in tissues, as binding pocket complexity is associated with HIV that may escape neutralization, whereas shorter envelopes are associated with increased infectivity. Further analysis of tissue-derived envelope sequences may enable better understanding of potential immunological approaches targeting the persistent HIV reservoir.
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http://dx.doi.org/10.1089/AID.2018.0267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6588100PMC
June 2019

Genomic Investigation of a Outbreak Involving Prison and Community Cases in Florida, United States.

Am J Trop Med Hyg 2018 10;99(4):867-874

Division of Infectious Diseases and Global Medicine, College of Medicine, University of Florida, Gainesville, Florida.

We used whole-genome sequencing to investigate a tuberculosis outbreak involving U.S.-born persons in the prison system and both U.S.- and foreign-born persons in the community in Florida over a 7-year period (2009-2015). Genotyping by spacer oligonucleotide typing and 24-locus mycobacterial interspersed repetitive unit-variable number tandem repeat suggested that the outbreak might be clonal in origin. However, contact tracing could not link the two populations. Through a multidisciplinary approach, we showed that the cluster involved distinct bacterial transmission networks segregated by country of birth. The source strain is of foreign origin and circulated in the local Florida community for more than 20 years before introduction into the prison system. We also identified novel transmission links involving foreign and U.S.-born cases not discovered during contact investigation. Our data highlight the potential for spread of strains originating from outside the United States into U.S. "high-risk" populations, such as prisoners, with subsequent movement back to the general community.
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http://dx.doi.org/10.4269/ajtmh.17-0700DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6159577PMC
October 2018

Ultradeep single-molecule real-time sequencing of HIV envelope reveals complete compartmentalization of highly macrophage-tropic R5 proviral variants in brain and CXCR4-using variants in immune and peripheral tissues.

J Neurovirol 2018 08 23;24(4):439-453. Epub 2018 Apr 23.

Bioinfoexperts, LLC, 718 Bayou Ln, Thibodaux, LA, 70301, USA.

Despite combined antiretroviral therapy (cART), HIV+ patients still develop neurological disorders, which may be due to persistent HIV infection and selective evolution in brain tissues. Single-molecule real-time (SMRT) sequencing technology offers an improved opportunity to study the relationship among HIV isolates in the brain and lymphoid tissues because it is capable of generating thousands of long sequence reads in a single run. Here, we used SMRT sequencing to generate ~ 50,000 high-quality full-length HIV envelope sequences (> 2200 bp) from seven autopsy tissues from an HIV+/cART+ subject, including three brain and four non-brain sites. Sanger sequencing was used for comparison with SMRT data and to clone functional pseudoviruses for in vitro tropism assays. Phylogenetic analysis demonstrated that brain-derived HIV was compartmentalized from HIV outside the brain and that the variants from each of the three brain tissues grouped independently. Variants from all peripheral tissues were intermixed on the tree but independent of the brain clades. Due to the large number of sequences, a clustering analysis at three similarity thresholds (99, 99.5, and 99.9%) was also performed. All brain sequences clustered exclusive of any non-brain sequences at all thresholds; however, frontal lobe sequences clustered independently of occipital and parietal lobes. Translated sequences revealed potentially functional differences between brain and non-brain sequences in the location of putative N-linked glycosylation sites (N-sites), V1 length, V3 charge, and the number of V4 N-sites. All brain sequences were predicted to use the CCR5 co-receptor, while most non-brain sequences were predicted to use CXCR4 co-receptor. Tropism results were confirmed by in vitro infection assays. The study is the first to use a SMRT sequencing approach to study HIV compartmentalization in tissues and supports other reports of limited trafficking between brain and non-brain sequences during cART. Due to the long sequence length, we could observe changes along the entire envelope gene, likely caused by differential selective pressure in the brain that may contribute to neurological disease.
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http://dx.doi.org/10.1007/s13365-018-0633-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281851PMC
August 2018

Evidence for Mother-to-Child Transmission of Zika Virus Through Breast Milk.

Clin Infect Dis 2018 03;66(7):1120-1121

Infectious Diseases Research Incubator and the Zoonosis and Emerging Pathogens Regional Collaborative Network, Universidad Centroccidental Lisandro Alvarado, Lara, Venezuela.

Zikavirus (ZIKV) is an emerging viral pathogen that continues to spread throughout different regions of the world. Herein we report a case that provides further evidence that ZIKV transmission can occur through breastfeeding by providing a detailed clinical, genomic, and virological case-based description.
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http://dx.doi.org/10.1093/cid/cix968DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6019007PMC
March 2018

The Spleen Is an HIV-1 Sanctuary During Combined Antiretroviral Therapy.

AIDS Res Hum Retroviruses 2018 01 30;34(1):123-125. Epub 2017 Nov 30.

5 The AIDS and Cancer Specimen Resource, University of California San Francisco , San Francisco, California.

Combined antiretroviral therapy (cART) does not eradicate HIV, which persists for years and can re-establish replication if treatment is stopped. The current challenge is identifying those tissues harboring virus through cART. Here, we used HIV env-nef single genome sequencing and HIV gag droplet digital PCR (ddPCR) to survey 50 tissues from five subjects on cART with no detectable plasma viral load at death. The spleen most consistently contained multiple proviral and expressed sequences (4/5 participants). Spleen-derived HIV demonstrated two distinct phylogenetic patterns: multiple identical sequences, often from different tissues, as well as diverse viral sequences on long terminal branches. Our results suggested that ddPCR may overestimate the size of the tissue-based viral reservoir. The spleen, a lymphatic organ at the intersection of the immune and circulatory systems, may play a key role in viral persistence.
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http://dx.doi.org/10.1089/AID.2017.0254DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771542PMC
January 2018

Brain-specific HIV Nef identified in multiple patients with neurological disease.

J Neurovirol 2018 02 23;24(1):1-15. Epub 2017 Oct 23.

The University of California, San Francisco, CA, USA.

HIV-1 Nef is a flexible, multifunctional protein with several cellular targets that is required for pathogenicity of the virus. This protein maintains a high degree of genetic variation among intra- and inter-host isolates. HIV Nef is relevant to HIV-associated neurological diseases (HAND) in patients treated with combined antiretroviral therapy because of the protein's role in promoting survival and migration of infected brain macrophages. In this study, we analyzed 2020 HIV Nef sequences derived from 22 different tissues and 31 subjects using a novel computational approach. This approach combines statistical regression and evolved neural networks (ENNs) to classify brain sequences based on the physical and chemical characteristics of functional Nef domains. Based on training, testing, and validation data, the method successfully classified brain Nef sequences at 84.5% and provided informative features for further examination. These included physicochemical features associated with the Src-homology-3 binding domain, the Nef loop (including the AP-2 Binding region), and a cytokine-binding domain. Non-brain sequences from patients with HIV-associated neurological disease were frequently classified as brain, suggesting that the approach could indicate neurological risk using blood-derived virus or for the development of biomarkers for use in assay systems aimed at drug efficacy studies for the treatment of HIV-associated neurological diseases.
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http://dx.doi.org/10.1007/s13365-017-0586-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5792318PMC
February 2018

Insights into the Impact of CD8 Immune Modulation on Human Immunodeficiency Virus Evolutionary Dynamics in Distinct Anatomical Compartments by Using Simian Immunodeficiency Virus-Infected Macaque Models of AIDS Progression.

J Virol 2017 12 14;91(23). Epub 2017 Nov 14.

Emerging Pathogens Institute and Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, USA

A thorough understanding of the role of human immunodeficiency virus (HIV) intrahost evolution in AIDS pathogenesis has been limited by the need for longitudinally sampled viral sequences from the vast target space within the host, which are often difficult to obtain from human subjects. CD8 lymphocyte-depleted macaques infected with simian immunodeficiency virus (SIV) provide an increasingly utilized model of pathogenesis due to clinical manifestations similar to those for HIV-1 infection and AIDS progression, as well as a characteristic rapid disease onset. Comparison of this model with SIV-infected non-CD8 lymphocyte-depleted macaques also provides a unique opportunity to investigate the role of CD8 cells in viral evolution and population dynamics throughout the duration of infection. Using several different phylogenetic methods, we analyzed viral sequences obtained from extensive longitudinal sampling of multiple tissues and enriched leukocyte populations from SIVmac251-infected macaques with or without CD8 lymphocyte depletion. SIV evolutionary and selection patterns in non-CD8 lymphocyte-depleted animals were characterized by sequential population turnover and continual viral adaptation, a scenario readily comparable to intrahost evolutionary patterns during human HIV infection in the absence of antiretroviral therapy. Alternatively, animals that were depleted of CD8 lymphocytes exhibited greater variation in population dynamics among tissues and cell populations over the course of infection. Our findings highlight the major role for CD8 lymphocytes in prolonging disease progression through continual control of SIV subpopulations from various anatomical compartments and the potential for greater independent viral evolutionary behavior among these compartments in response to immune modulation. Although developments in combined antiretroviral therapy (cART) strategies have successfully prolonged the time to AIDS onset in HIV-1-infected individuals, a functional cure has yet to be found. Improvement of drug interventions for a virus that is able to infect a wide range of tissues and cell types requires a thorough understanding of viral adaptation and infection dynamics within this target milieu. Although it is difficult to accomplish in the human host, longitudinal sampling of multiple anatomical locations is readily accessible in the SIV-infected macaque models of neuro-AIDS. The significance of our research is in identifying the impact of immune modulation, through differing immune selective pressures, on viral evolutionary behavior in a multitude of anatomical compartments. The results provide evidence encouraging the development of a more sophisticated model that considers a network of individual viral subpopulations within the host, with differing infection and transmission dynamics, which is necessary for more effective treatment strategies.
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http://dx.doi.org/10.1128/JVI.01162-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5686727PMC
December 2017

Eradication of HIV from Tissue Reservoirs: Challenges for the Cure.

AIDS Res Hum Retroviruses 2018 01 7;34(1):3-8. Epub 2017 Aug 7.

5 The AIDS and Cancer Specimen Resource , San Francisco, California.

The persistence of HIV infection, even after lengthy and successful combined antiretroviral therapy (cART), has precluded an effective cure. The anatomical locations and biological mechanisms through which the viral population is maintained remain unknown. Much research has focused nearly exclusively on circulating resting T cells as the predominant source of persistent HIV, a strategy with limited success in developing an effective cure strategy. In this study, we review research supporting the importance of anatomical tissues and other immune cells for HIV maintenance and expansion, including the central nervous system, lymph nodes, and macrophages. We present accumulated research that clearly demonstrates the limitations of using blood-derived cells as a proxy for tissue reservoirs and sanctuaries throughout the body. We cite recent studies that have successfully used deep-sequencing strategies to uncover the complexity of HIV infection and the ability of the virus to evolve despite undetectable plasma viral loads. Finally, we suggest new strategies and highlight the importance of tissue banks for future research.
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http://dx.doi.org/10.1089/AID.2017.0072DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771544PMC
January 2018

Complete Genome Sequences of Identical Isolates in a Nursing Mother and Her Infant.

Genome Announc 2017 Apr 27;5(17). Epub 2017 Apr 27.

Department of Pathology and Laboratory Medicine, Hospital Internacional Barquisimeto, Lara, Barquisimeto, Venezuela

Complete genome sequences were obtained for Zika viruses isolated from the breast milk of a Venezuelan patient and her child, who was exclusively breastfeeding at the time. These sequences are the first to be reported from a presumptive autochthonous postnatal transmission case from mother to child in Venezuela.
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http://dx.doi.org/10.1128/genomeA.00231-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5408108PMC
April 2017

A method for obtaining simian immunodeficiency virus RNA sequences from laser capture microdissected and immune captured CD68+ and CD163+ macrophages from frozen tissue sections of bone marrow and brain.

J Immunol Methods 2017 03 14;442:59-63. Epub 2017 Jan 14.

Department of Biology, Boston College, Chestnut Hill, MA, USA. Electronic address:

Laser capture microdissection (LCM) is used to extract cells or tissue regions for analysis of RNA, DNA or protein. Several methods of LCM are established for different applications, but a protocol for consistently obtaining lentiviral RNA from LCM captured immune cell populations is not described. Obtaining optimal viral RNA for analysis of viral genes from immune-captured cells using immunohistochemistry (IHC) and LCM is challenging. IHC protocols have long antibody incubation times that increase risk of RNA degradation. But, immune capture of specific cell populations like macrophages without staining for virus cannot result in obtaining only a fraction of cells which are productively lentivirally infected. In this study we sought to obtain simian immunodeficiency virus (SIV) RNA from SIV gp120+ and CD68+ monocyte/macrophages in bone marrow (BM) and CD163+ perivascular macrophages in brain of SIV-infected rhesus macaques. Here, we report an IHC protocol with RNase inhibitors that consistently results in optimal quantity and yield of lentiviral RNA from LCM-captured immune cells.
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http://dx.doi.org/10.1016/j.jim.2017.01.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5338743PMC
March 2017

Non-toxigenic environmental Vibrio cholerae O1 strain from Haiti provides evidence of pre-pandemic cholera in Hispaniola.

Sci Rep 2016 10 27;6:36115. Epub 2016 Oct 27.

Emerging Pathogens Institute, University of Florida, Gainesville, USA.

Vibrio cholerae is ubiquitous in aquatic environments, with environmental toxigenic V. cholerae O1 strains serving as a source for recurrent cholera epidemics and pandemic disease. However, a number of questions remain about long-term survival and evolution of V. cholerae strains within these aquatic environmental reservoirs. Through monitoring of the Haitian aquatic environment following the 2010 cholera epidemic, we isolated two novel non-toxigenic (ctxA/B-negative) Vibrio cholerae O1. These two isolates underwent whole-genome sequencing and were investigated through comparative genomics and Bayesian coalescent analysis. These isolates cluster in the evolutionary tree with strains responsible for clinical cholera, possessing genomic components of 6 and 7 pandemic lineages, and diverge from "modern" cholera strains around 1548 C.E. [95% HPD: 1532-1555]. Vibrio Pathogenicity Island (VPI)-1 was present; however, SXT/R391-family ICE and VPI-2 were absent. Rugose phenotype conversion and vibriophage resistance evidenced adaption for persistence in aquatic environments. The identification of V. cholerae O1 strains in the Haitian environment, which predate the first reported cholera pandemic in 1817, broadens our understanding of the history of pandemics. It also raises the possibility that these and similar environmental strains could acquire virulence genes from the 2010 Haitian epidemic clone, including the cholera toxin producing CTXϕ.
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http://dx.doi.org/10.1038/srep36115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5081557PMC
October 2016

HIV-1 Evolutionary Patterns Associated with Metastatic Kaposi's Sarcoma during AIDS.

Sarcoma 2016 29;2016:4510483. Epub 2016 Aug 29.

The AIDS and Cancer Specimen Resource, University of California at San Francisco and the Department of Laboratory Medicine, Pathology, and Medicine, University of California at San Francisco, 1001 Poterero Ave, Bldg 3, Rm 207, UCSF Box 1317, San Francisco, CA 94110, USA.

Kaposi's sarcoma (KS) in HIV-infected individuals can have a wide range of clinical outcomes, from indolent skin tumors to a life-threatening visceral cancer. KS tumors contain endothelial-related cells and inflammatory cells that may be HIV-infected. In this study we tested if HIV evolutionary patterns distinguish KS tumor relatedness and progression. Multisite autopsies from participants who died from HIV-AIDS with KS prior to the availability of antiretroviral therapy were identified at the AIDS and Cancer Specimen Resource (ACSR). Two patients (KS1 and KS2) died predominantly from non-KS-associated disease and KS3 died due to aggressive and metastatic KS within one month of diagnosis. Skin and visceral tumor and nontumor autopsy tissues were obtained (n = 12). Single genome sequencing was used to amplify HIV RNA and DNA, which was present in all tumors. Independent HIV tumor clades in phylogenies differentiated KS1 and KS2 from KS3, whose sequences were interrelated by both phylogeny and selection. HIV compartmentalization was confirmed in KS1 and KS2 tumors; however, in KS3, no compartmentalization was observed among sampled tissues. While the sample size is small, the HIV evolutionary patterns observed in all patients suggest an interplay between tumor cells and HIV-infected cells which provides a selective advantage and could promote KS progression.
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http://dx.doi.org/10.1155/2016/4510483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5019946PMC
September 2016

HIV DNA Is Frequently Present within Pathologic Tissues Evaluated at Autopsy from Combined Antiretroviral Therapy-Treated Patients with Undetectable Viral Loads.

J Virol 2016 10 29;90(20):8968-83. Epub 2016 Sep 29.

National Neurological AIDS Bank, Department of Neurology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA David Geffen School of Medicine and Olive View-UCLA Medical Center, Department of Neurology, Los Angeles, California, USA.

Unlabelled: HIV infection treatment strategies have historically defined effectiveness through measuring patient plasma HIV RNA. While combined antiretroviral therapy (cART) can reduce plasma viral load (pVL) to undetectable levels, the degree that HIV is eliminated from other anatomical sites remains unclear. We investigated the HIV DNA levels in 229 varied autopsy tissues from 20 HIV-positive (HIV(+)) cART-treated study participants with low or undetectable plasma VL and cerebrospinal fluid (CSF) VL prior to death who were enrolled in the National Neurological AIDS Bank (NNAB) longitudinal study and autopsy cohort. Extensive medical histories were obtained for each participant. Autopsy specimens, including at least six brain and nonbrain tissues per participant, were reviewed by study pathologists. HIV DNA, measured in tissues by quantitative and droplet digital PCR, was identified in 48/87 brain tissues and 82/142 nonbrain tissues at levels >200 HIV copies/million cell equivalents. No participant was found to be completely free of tissue HIV. Parallel sequencing studies from some tissues recovered intact HIV DNA and RNA. Abnormal histological findings were identified in all participants, especially in brain, spleen, lung, lymph node, liver, aorta, and kidney. All brain tissues demonstrated some degree of pathology. Ninety-five percent of participants had some degree of atherosclerosis, and 75% of participants died with cancer. This study assists in characterizing the anatomical locations of HIV, in particular, macrophage-rich tissues, such as the central nervous system (CNS) and testis. Additional studies are needed to determine if the HIV recovered from tissues promotes the pathogenesis of inflammatory diseases, such as HIV-associated neurocognitive disorders, cancer, and atherosclerosis.

Importance: It is well-known that combined antiretroviral therapy (cART) can reduce plasma HIV to undetectable levels; however, cART cannot completely clear HIV infection. An ongoing question is, "Where is HIV hiding?" A well-studied HIV reservoir is "resting" T cells, which can be isolated from blood products and succumb to cART once activated. Less-studied reservoirs are anatomical tissue samples, which have unknown cART penetration, contain a comparably diverse spectrum of potentially HIV-infected immune cells, and are important since <2% of body lymphocytes actually reside in blood. We examined 229 varied autopsy specimens from 20 HIV(+) participants who died while on cART and identified that >50% of tissues were HIV infected. Additionally, we identified considerable pathology in participants' tissues, especially in brain, spleen, lung, lymph node, liver, aorta, and kidney. This study substantiates that tissue-associated HIV is present despite cART and can inform future studies into HIV persistence.
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http://dx.doi.org/10.1128/JVI.00674-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5044815PMC
October 2016

HIV Maintains an Evolving and Dispersed Population in Multiple Tissues during Suppressive Combined Antiretroviral Therapy in Individuals with Cancer.

J Virol 2016 10 29;90(20):8984-93. Epub 2016 Sep 29.

The AIDS and Cancer Specimen Resource, University of California at San Francisco, San Francisco, California, USA Departments of Laboratory Medicine, Pathology, and Medicine, University of California at San Francisco, San Francisco, California, USA

Unlabelled: While combined antiretroviral therapy (cART) can result in undetectable plasma viral loads, it does not eradicate HIV infection. Furthermore, HIV-infected individuals while on cART remain at an increased risk of developing serious comorbidities, such as cancer, neurological disease, and atherosclerosis, suggesting that during cART, tissue-based HIV may contribute to such pathologies. We obtained DNA and RNA env, nef, and pol sequences using single-genome sequencing from postmortem tissues of three HIV(+) cART-treated (cART(+)) individuals with undetectable viral load and metastatic cancer at death and performed time-scaled Bayesian evolutionary analyses. We used a sensitive in situ hybridization technique to visualize HIV gag-pol mRNA transcripts in cerebellum and lymph node tissues from one patient. Tissue-associated virus evolved at similar rates in cART(+) and cART-naive (cART(-)) patients. Phylogenetic trees were characterized by two distinct features: (i) branching patterns consistent with constant viral evolution and dispersal among tissues and (ii) very recently derived clades containing both DNA and RNA sequences from multiple tissues. Rapid expansion of virus near death corresponded to wide-spread metastasis. HIV RNA(+) cells clustered in cerebellum tissue but were dispersed in lymph node tissue, mirroring the evolutionary patterns observed for that patient. Activated, infiltrating macrophages were associated with HIV RNA. Our data provide evidence that tissues serve as a sanctuary for wild-type HIV during cART and suggest the importance of macrophages as an alternative reservoir and mechanism of virus spread.

Importance: Combined antiretroviral therapy (cART) reduces plasma HIV to undetectable levels; however, removal of cART results in plasma HIV rebound, thus highlighting its inability to entirely rid the body of infection. Additionally, HIV-infected individuals on cART remain at high risk of serious diseases, which suggests a contribution from residual HIV. In this study, we isolated and sequenced HIV from postmortem tissues from three HIV(+) cART(+) individuals who died with metastatic cancer and had no detectable plasma viral load. Using high-resolution evolutionary analyses, we found that tissue-based HIV continues to replicate, evolve, and migrate among tissues during cART. Furthermore, cancer onset and metastasis coincided with increased HIV expansion, suggesting a linked mechanism. HIV-expressing cells were associated with tissue macrophages, a target of HIV infection. Our results suggest the importance of tissues, and macrophages in particular, as a target for novel anti-HIV therapies.
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http://dx.doi.org/10.1128/JVI.00684-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5044847PMC
October 2016

Evolution of Neuroadaptation in the Periphery and Purifying Selection in the Brain Contribute to Compartmentalization of Simian Immunodeficiency Virus (SIV) in the Brains of Rhesus Macaques with SIV-Associated Encephalitis.

J Virol 2016 07 10;90(13):6112-6126. Epub 2016 Jun 10.

Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, USA

Unlabelled: The emergence of a distinct subpopulation of human or simian immunodeficiency virus (HIV/SIV) sequences within the brain (compartmentalization) during infection is hypothesized to be linked to AIDS-related central nervous system (CNS) neuropathology. However, the exact evolutionary mechanism responsible for HIV/SIV brain compartmentalization has not been thoroughly investigated. Using extensive viral sampling from several different peripheral tissues and cell types and from three distinct regions within the brain from two well-characterized rhesus macaque models of the neurological complications of HIV infection (neuroAIDS), we have been able to perform in-depth evolutionary analyses that have been unattainable in HIV-infected subjects. The results indicate that, despite multiple introductions of virus into the brain over the course of infection, brain sequence compartmentalization in macaques with SIV-associated CNS neuropathology likely results from late viral entry of virus that has acquired through evolution in the periphery sufficient adaptation for the distinct microenvironment of the CNS.

Importance: HIV-associated neurocognitive disorders remain prevalent among HIV type 1-infected individuals, whereas our understanding of the critical components of disease pathogenesis, such as virus evolution and adaptation, remains limited. Building upon earlier findings of specific viral subpopulations in the brain, we present novel yet fundamental results concerning the evolutionary patterns driving this phenomenon in two well-characterized animal models of neuroAIDS and provide insight into the timing of entry of virus into the brain and selective pressure associated with viral adaptation to this particular microenvironment. Such knowledge is invaluable for therapeutic strategies designed to slow or even prevent neurocognitive impairment associated with AIDS.
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http://dx.doi.org/10.1128/JVI.00137-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4907235PMC
July 2016

The meningeal lymphatic system: a route for HIV brain migration?

J Neurovirol 2016 06 16;22(3):275-81. Epub 2015 Nov 16.

University of California and the AIDS and Cancer Specimen Resource, San Francisco, CA, USA.

Two innovative studies recently identified functional lymphatic structures in the meninges that may influence the development of HIV-associated neurological disorders (HAND). Until now, blood vessels were assumed to be the sole transport system by which HIV-infected monocytes entered the brain by bypassing a potentially hostile blood-brain barrier through inflammatory-mediated semi-permeability. A cascade of specific chemokine signals promote monocyte migration from blood vessels to surrounding brain tissues via a well-supported endothelium, where the cells differentiate into tissue macrophages capable of productive HIV infection. Lymphatic vessels on the other hand are more loosely organized than blood vessels. They absorb interstitial fluid from bodily tissues where HIV may persist and exchange a variety of immune cells (CD4(+) T cells, monocytes, macrophages, and dendritic cells) with surrounding tissues through discontinuous endothelial junctions. We propose that the newly discovered meningeal lymphatics are key to HIV migration among viral reservoirs and brain tissue during periods of undetectable plasma viral loads due to suppressive combinational antiretroviral therapy, thus redefining the migration process in terms of a blood-lymphatic transport system.
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http://dx.doi.org/10.1007/s13365-015-0399-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4868798PMC
June 2016

Tracking the Emergence of Host-Specific Simian Immunodeficiency Virus env and nef Populations Reveals nef Early Adaptation and Convergent Evolution in Brain of Naturally Progressing Rhesus Macaques.

J Virol 2015 Aug 3;89(16):8484-96. Epub 2015 Jun 3.

Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, USA Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA

Unlabelled: While a clear understanding of the events leading to successful establishment of host-specific viral populations and productive infection in the central nervous system (CNS) has not yet been reached, the simian immunodeficiency virus (SIV)-infected rhesus macaque provides a powerful model for the study of human immunodeficiency virus (HIV) intrahost evolution and neuropathogenesis. The evolution of the gp120 and nef genes, which encode two key proteins required for the establishment and maintenance of infection, was assessed in macaques that were intravenously inoculated with the same viral swarm and allowed to naturally progress to simian AIDS and potential SIV-associated encephalitis (SIVE). Longitudinal plasma samples and immune markers were monitored until terminal illness. Single-genome sequencing was employed to amplify full-length env through nef transcripts from plasma over time and from brain tissues at necropsy. nef sequences diverged from the founder virus faster than gp120 diverged. Host-specific sequence populations were detected in nef (~92 days) before they were detected in gp120 (~182 days). At necropsy, similar brain nef sequences were found in different macaques, indicating convergent evolution, while gp120 brain sequences remained largely host specific. Molecular clock and selection analyses showed weaker clock-like behavior and stronger selection pressure in nef than in gp120, with the strongest nef selection in the macaque with SIVE. Rapid nef diversification, occurring prior to gp120 diversification, indicates that early adaptation of nef in the new host is essential for successful infection. Moreover, the convergent evolution of nef sequences in the CNS suggests a significant role for nef in establishing neurotropic strains.

Importance: The SIV-infected rhesus macaque model closely resembles HIV-1 immunopathogenesis, neuropathogenesis, and disease progression in humans. Macaques were intravenously infected with identical viral swarms to investigate evolutionary patterns in the gp120 and nef genes leading to the emergence of host-specific viral populations and potentially linked to disease progression. Although each macaque exhibited unique immune profiles, macaque-specific nef sequences evolving under selection were consistently detected in plasma samples at 3 months postinfection, significantly earlier than in gp120 macaque-specific sequences. On the other hand, nef sequences in brain tissues, collected at necropsy of two animals with detectable infection in the central nervous system (CNS), revealed convergent evolution. The results not only indicate that early adaptation of nef in the new host may be essential for successful infection, but also suggest that specific nef variants may be required for SIV to efficiently invade CNS macrophages and/or enhance macrophage migration, resulting in HIV neuropathology.
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http://dx.doi.org/10.1128/JVI.01010-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4524235PMC
August 2015

Anti-α4 antibody treatment blocks virus traffic to the brain and gut early, and stabilizes CNS injury late in infection.

PLoS Pathog 2014 Dec 11;10(12):e1004533. Epub 2014 Dec 11.

Department of Biology, Boston College, Chestnut Hill, Massachusetts, United States of America.

Four SIV-infected monkeys with high plasma virus and CNS injury were treated with an anti-α4 blocking antibody (natalizumab) once a week for three weeks beginning on 28 days post-infection (late). Infection in the brain and gut were quantified, and neuronal injury in the CNS was assessed by MR spectroscopy, and compared to controls with AIDS and SIV encephalitis. Treatment resulted in stabilization of ongoing neuronal injury (NAA/Cr by 1H MRS), and decreased numbers of monocytes/macrophages and productive infection (SIV p28+, RNA+) in brain and gut. Antibody treatment of six SIV infected monkeys at the time of infection (early) for 3 weeks blocked monocyte/macrophage traffic and infection in the CNS, and significantly decreased leukocyte traffic and infection in the gut. SIV - RNA and p28 was absent in the CNS and the gut. SIV DNA was undetectable in brains of five of six early treated macaques, but proviral DNA in guts of treated and control animals was equivalent. Early treated animals had low-to-no plasma LPS and sCD163. These results support the notion that monocyte/macrophage traffic late in infection drives neuronal injury and maintains CNS viral reservoirs and lesions. Leukocyte traffic early in infection seeds the CNS with virus and contributes to productive infection in the gut. Leukocyte traffic early contributes to gut pathology, bacterial translocation, and activation of innate immunity.
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http://dx.doi.org/10.1371/journal.ppat.1004533DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4263764PMC
December 2014

Spatiotemporal dynamics of simian immunodeficiency virus brain infection in CD8+ lymphocyte-depleted rhesus macaques with neuroAIDS.

J Gen Virol 2014 Dec 9;95(Pt 12):2784-2795. Epub 2014 Sep 9.

Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.

Despite the success of combined antiretroviral therapy in controlling viral replication in human immunodeficiency virus (HIV)-infected individuals, HIV-associated neurocognitive disorders, commonly referred to as neuroAIDS, remain a frequent and poorly understood complication. Infection of CD8(+) lymphocyte-depleted rhesus macaques with the SIVmac251 viral swarm is a well-established rapid disease model of neuroAIDS that has provided critical insight into HIV-1-associated neurocognitive disorder onset and progression. However, no studies so far have characterized in depth the relationship between intra-host viral evolution and pathogenesis in this model. Simian immunodeficiency virus (SIV) env gp120 sequences were obtained from six infected animals. Sequences were sampled longitudinally from several lymphoid and non-lymphoid tissues, including individual lobes within the brain at necropsy, for four macaques; two animals were sacrificed at 21 days post-infection (p.i.) to evaluate early viral seeding of the brain. Bayesian phylodynamic and phylogeographic analyses of the sequence data were used to ascertain viral population dynamics and gene flow between peripheral and brain tissues, respectively. A steady increase in viral effective population size, with a peak occurring at ~50-80 days p.i., was observed across all longitudinally monitored macaques. Phylogeographic analysis indicated continual viral seeding of the brain from several peripheral tissues throughout infection, with the last migration event before terminal illness occurring in all macaques from cells within the bone marrow. The results strongly supported the role of infected bone marrow cells in HIV/SIV neuropathogenesis. In addition, our work demonstrated the applicability of Bayesian phylogeography to intra-host studies in order to assess the interplay between viral evolution and pathogenesis.
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http://dx.doi.org/10.1099/vir.0.070318-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4233634PMC
December 2014

HIV-associated neuropathogenesis: a systems biology perspective for modeling and therapy.

Biosystems 2014 May 13;119:53-61. Epub 2014 Apr 13.

University of Florida, 2055 Mowry Road, Department of Pathology and Laboratory Medicine, Gainesville, FL 32610, USA. Electronic address:

Despite the development of powerful antiretroviral drugs, HIV-1 associated neurological disorders (HAND) will affect approximately half of those infected with HIV-1. Combined anti-retroviral therapy (cART) targets viral replication and increases T-cell counts, but it does not always control macrophage polarization, brain infection or inflammation. Moreover, it remains difficult to identify those at risk for HAND. New therapies that focus on modulating host immune response by making use of biological pathways could prove to be more effective than cART for the treatment of neuroAIDS. Additionally, while numerous HAND biomarkers have been suggested, they are of little use without methods for appropriate data integration and a systems-level interpretation. Machine learning, could be used to develop multifactorial computational models that provide clinicians and researchers with the ability to identify which factors (in what combination and relative importance) are considered important to outcome.
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http://dx.doi.org/10.1016/j.biosystems.2014.04.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4112533PMC
May 2014

Empirical validation of viral quasispecies assembly algorithms: state-of-the-art and challenges.

Sci Rep 2013 Oct 3;3:2837. Epub 2013 Oct 3.

1] University of Manchester, Faculty of Medical and Human Sciences, Northwest Institute of Bio-Health Informatics, Centre for Health Informatics, Institute of Population Health, Manchester, UK [2] University of Florida, College of Medicine, Department of Pathology, Immunology and Laboratory Medicine, Gainesville, Florida, USA.

Next generation sequencing (NGS) is superseding Sanger technology for analysing intra-host viral populations, in terms of genome length and resolution. We introduce two new empirical validation data sets and test the available viral population assembly software. Two intra-host viral population 'quasispecies' samples (type-1 human immunodeficiency and hepatitis C virus) were Sanger-sequenced, and plasmid clone mixtures at controlled proportions were shotgun-sequenced using Roche's 454 sequencing platform. The performance of different assemblers was compared in terms of phylogenetic clustering and recombination with the Sanger clones. Phylogenetic clustering showed that all assemblers captured a proportion of the most divergent lineages, but none were able to provide a high precision/recall tradeoff. Estimated variant frequencies mildly correlated with the original. Given the limitations of currently available algorithms identified by our empirical validation, the development and exploitation of additional data sets is needed, in order to establish an efficient framework for viral population reconstruction using NGS.
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http://dx.doi.org/10.1038/srep02837DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3789152PMC
October 2013

Longitudinal analysis of intra-host simian immunodeficiency virus recombination in varied tissues of the rhesus macaque model for neuroAIDS.

J Gen Virol 2013 Nov 20;94(Pt 11):2469-2479. Epub 2013 Aug 20.

Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.

Human immunodeficiency virus intra-host recombination has never been studied in vivo both during early infection and throughout disease progression. The CD8-depleted rhesus macaque model of neuroAIDS was used to investigate the impact of recombination from early infection up to the onset of neuropathology in animals inoculated with a simian immunodeficiency virus (SIV) swarm. Several lymphoid and non-lymphoid tissues were collected longitudinally at 21 days post-infection (p.i.), 61 days p.i. and necropsy (75-118 days p.i.) from four macaques that developed SIV-encephalitis or meningitis, as well as from two animals euthanized at 21 days p.i. The number of recombinant sequences and breakpoints in different tissues and over time from each primate were compared. Breakpoint locations were mapped onto predicted RNA and protein secondary structures. Recombinants were found at each time point and in each primate as early as 21 days p.i. No association was found between recombination rates and specific tissue of origin. Several identical breakpoints were identified in sequences derived from different tissues in the same primate and among different primates. Breakpoints predominantly mapped to unpaired nucleotides or pseudoknots in RNA secondary structures, and proximal to glycosylation sites and cysteine residues in protein sequences, suggesting selective advantage in the emergence of specific recombinant sequences. Results indicate that recombinant sequences can become fixed very early after infection with a heterogeneous viral swarm. Features of RNA and protein secondary structure appear to play a role in driving the production of recombinants and their selection in the rapid disease model of neuroAIDS.
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http://dx.doi.org/10.1099/vir.0.055335-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3809109PMC
November 2013

HIV-1 Nef in macrophage-mediated disease pathogenesis.

Int Rev Immunol 2012 Dec;31(6):432-50

BioInfoExperts, Thibodaux, LA, USA.

Combined anti-retroviral therapy (cART) has significantly reduced the number of AIDS-associated illnesses and changed the course of HIV-1 disease in developed countries. Despite the ability of cART to maintain high CD4+ T-cell counts, a number of macrophage-mediated diseases can still occur in HIV-infected subjects. These diseases include lymphoma, metabolic diseases, and HIV-associated neurological disorders. Within macrophages, the HIV-1 regulatory protein "Nef" can modulate surface receptors, interact with signaling pathways, and promote specific environments that contribute to each of these pathologies. Moreover, genetic variation in Nef may also guide the macrophage response. Herein, we review findings relating to the Nef-macrophage interaction and how this relationship contributes to disease pathogenesis.
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http://dx.doi.org/10.3109/08830185.2012.737073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3544535PMC
December 2012

Assessment of annular distensibility in the aortic valve.

Interact Cardiovasc Thorac Surg 2012 Sep 13;15(3):361-3. Epub 2012 Jun 13.

School of Engineering and Informatics, National University of Ireland, Galway, Ireland.

OBJECTIVES The recent introduction of transcatheter aortic heart valves into clinical practice has driven the need to develop methodologies to size such valves without access to the annulus in the manner hitherto possible with open heart surgery. To date, sizing has largely been done according to manufacturer-supplied guidelines based on transoesophageal echocardiography or multidetector computed tomography. We sought to examine how the diameter of the aortic valve annulus stretches under typical pressures encountered in normal and diseased states. In particular, we sought to measure how the area-derived diameter, Dcsa, i.e. the diameter derived from a cross-sectional area, varies with distending pressure. METHODS We conducted testing on 14 explanted pig hearts. Placing each heart in a 37 °C bath, an EndoFLIP EF-325 catheter (Crospon, Galway, Ireland) was introduced into the aortic valve transapically. The catheter allows intra-balloon pressure and up to 16 area-derived diameters to be measured simultaneously, thus permitting the shape of a lumen to be observed. By dividing the minimum area-derived diameter by distending pressure, a measure of distensibility (mm/mmHg) could be determined. Once the balloon was centred, balloon pressure was ramped between 100 and 200 mmHg, and the area-derived diameter was calculated at each pressure. RESULTS Between 100 and 200 mmHg, the mean (SD) increase in diameter was found to be 3.0 (1.5) mm. Distensibility in the different hearts ranged from 0 to 0.05 mm/mmHg. In some cases, the diameter change over the pressure range was negligible, whereas in one case, the diameter change over the range was 5 mm. Whereas different nominal values of diameter are to be expected, a significant variation in the degree of distensibility was observed. CONCLUSIONS Distensibility of the aortic valve annulus is highly variable. Measurement of this parameter in addition to nominal annulus diameter may suggest occasions where a larger transcatheter aortic-valve implantation valve than would be suggested by annulus diameter measurement alone, could be deployed safely with an objective of reducing regurgitation where the annulus is sufficiently distensible.
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http://dx.doi.org/10.1093/icvts/ivs273DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3422965PMC
September 2012

Efficient transmission and persistence of low-frequency SIVmac251 variants in CD8-depleted rhesus macaques with different neuropathology.

J Gen Virol 2012 May 1;93(Pt 5):925-938. Epub 2012 Feb 1.

Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA.

Infection of CD8-depleted rhesus macaques with the genetically heterogeneous simian immunodeficiency virus (SIV)mac251 viral swarm provides a rapid-disease model for simian acquired immune deficiency syndrome and SIV-encephalitis (SIVE). The objective was to evaluate how the diversity of the swarm influences the initial seeding of the infection that may potentially affect disease progression. Plasma, lymphoid and non-lymphoid (brain and lung) tissues were collected from two infected macaques euthanized at 21 days post-infection (p.i.), as well as longitudinal specimens and post-mortem tissues from four macaques followed throughout the infection. About 1300 gp120 viral sequences were obtained from the infecting SIVmac251 swarm and the macaques longitudinal and post-mortem samples. Phylogenetic and amino acid signature pattern analyses were carried out to assess frequency, transmission dynamics and persistence of specific viral clusters. Although no significant reduction in viral heterogeneity was found early in infection (21 days p.i.), transmission and replication of SIV variants was not entirely random. In particular, two distinct motifs under-represented (<4 %) in the infecting swarm were found at high frequencies (up to 14 %) in all six macaques as early as 21 days p.i. Moreover, a macrophage tropic variant not detected in the viral swarm (<0.3 %) was present at high frequency (29-100 %) in sequences derived from the brain of two macaques with meningitis or severe SIVE. This study demonstrates the highly efficient transmission and persistence in vivo of multiple low frequency SIVmac251 founder variants, characterized by specific gp120 motifs that may be linked to pathogenesis in the rapid-disease model of neuroAIDS.
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http://dx.doi.org/10.1099/vir.0.039586-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3541805PMC
May 2012