Publications by authors named "Victor C Huber"

39 Publications

Combinatorial liposomal peptide vaccine induces IgA and confers protection against influenza virus and bacterial super-infection.

Clin Transl Immunology 2021 10;10(9):e1337. Epub 2021 Sep 10.

Institute for Glycomics Griffith University Gold Coast QLD Australia.

Objectives: The upper respiratory tract is the major entry site for and influenza virus. Vaccine strategies that activate mucosal immunity could significantly reduce morbidity and mortality because of these pathogens. The severity of influenza is significantly greater if a streptococcal infection occurs during the viraemic period and generally viral infections complicated by a subsequent bacterial infection are known as super-infections. We describe an innovative vaccine strategy against influenza virus:.  super-infection. Moreover, we provide the first description of a liposomal multi-pathogen-based platform that enables the incorporation of both viral and bacterial antigens into a vaccine and constitutes a transformative development.

Methods: Specifically, we have explored a vaccination strategy with biocompatible liposomes that express conserved streptococcal and influenza A virus B-cell epitopes on their surface and contain encapsulated diphtheria toxoid as a source of T-cell help. The vaccine is adjuvanted by inclusion of the synthetic analogue of monophosphoryl lipid A, 3D-PHAD.

Results: We observe that this vaccine construct induces an Immunoglobulin A (IgA) response in both mice and ferrets. Vaccination reduces viral load in ferrets from influenza challenge and protects mice from both pathogens. Notably, vaccination significantly reduces both mortality and morbidity associated with a super-infection.

Conclusion: The vaccine design is modular and could be adapted to include B-cell epitopes from other mucosal pathogens where an IgA response is required for protection.
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http://dx.doi.org/10.1002/cti2.1337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8432089PMC
September 2021

A chimeric influenza hemagglutinin delivered by parainfluenza virus 5 vector induces broadly protective immunity against genetically divergent influenza a H1 viruses in swine.

Vet Microbiol 2020 Nov 18;250:108859. Epub 2020 Sep 18.

Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, United States. Electronic address:

Pigs are an important reservoir for human influenza viruses, and influenza causes significant economic loss to the swine industry. As demonstrated during the 2009 H1N1 pandemic, control of swine influenza virus infection is a critical step toward blocking emergence of human influenza virus. An effective vaccine that can induce broadly protective immunity against heterologous influenza virus strains is critically needed. In our previous studies [McCormick et al., 2015; PLoS One, 10(6):e0127649], we used molecular breeding (DNA shuffling) strategies to increase the breadth of the variable and conserved epitopes expressed within a single influenza A virus chimeric hemagglutinin (HA) protein. Chimeric HAs were constructed using parental HAs from the 2009 pandemic virus and swine influenza viruses that had a history of zoonotic transmission to humans. In the current study, we used parainfluenza virus 5 (PIV-5) as a vector to express one of these chimeric HA antigens, HA-113. Recombinant PIV-5 expressing HA-113 (PIV5-113) were rescued, and immunogenicity and protective efficacy were tested in both mouse and pig models. The results showed that PIV5-113 can protect mice and pigs against challenge with viruses expressing parental HAs. The protective immunity was extended against other genetically diversified influenza H1-expressing viruses. Our work demonstrates that PIV5-based influenza vaccines are efficacious as vaccines for pigs. The PIV5 vaccine vector and chimeric HA-113 antigen are discussed in the context of the development of universal influenza vaccines and the potential contribution of PIV5-113 as a candidate universal vaccine.
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http://dx.doi.org/10.1016/j.vetmic.2020.108859DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7500346PMC
November 2020

Human Monoclonal Antibody Derived from Transchromosomic Cattle Neutralizes Multiple H1 Clades of Influenza A Virus by Recognizing a Novel Conformational Epitope in the Hemagglutinin Head Domain.

J Virol 2020 10 27;94(22). Epub 2020 Oct 27.

Department of Biology and Microbiology, South Dakota State University, Brookings, South Dakota, USA

Influenza remains a global health risk and challenge. Currently, neuraminidase (NA) inhibitors are extensively used to treat influenza, but their efficacy is compromised by the emergence of drug-resistant variants. Neutralizing antibodies targeting influenza A virus surface glycoproteins are critical components of influenza therapeutic agents and may provide alternative strategies to the existing countermeasures. However, the major hurdle for the extensive application of antibody therapies lies in the difficulty of generating nonimmunogenic antibodies in large quantities rapidly. Here, we report that one human monoclonal antibody (MAb), 53C10, isolated from transchromosomic (Tc) cattle exhibits potent neutralization and hemagglutination inhibition titers against different clades of H1N1 subtype influenza A viruses. selection of antibody escape mutants revealed that 53C10 recognizes a novel noncontinuous epitope in the hemagglutinin (HA) head domain involving three amino acid residues, glycine (G), serine (S), and glutamic acid (E) at positions 172, 207, and 212, respectively. The results of our experiments supported a critical role for substitution of arginine at position 207 (S207R) in mediating resistance to 53C10, while substitutions at either G172E or E212A did not alter antibody recognition and neutralization. The E212A mutation may provide structural stability for the epitope, while the substitution G172E probably compensates for loss of fitness introduced by S207R. Our results offer novel insights into the mechanism of action of MAb 53C10 and indicate its potential role in therapeutic treatment of H1 influenza virus infection in humans. Respiratory diseases caused by influenza viruses still pose a serious concern to global health, and neutralizing antibodies constitute a promising area of antiviral therapeutics. However, the potential application of antibodies is often hampered by the challenge in generating nonimmunogenic antibodies in large scale. In the present study, transchromosomic (Tc) cattle were used for the generation of nonimmunogenic monoclonal antibodies (MAbs), and characterization of such MAbs revealed one monoclonal antibody, 53C10, exhibiting a potent neutralization activity against H1N1 influenza viruses. Further characterization of the neutralization escape mutant generated using this MAb showed that three amino acid substitutions in the HA head domain contributed to the resistance. These findings emphasize the importance of Tc cattle in the production of nonimmunogenic MAbs and highlight the potential of MAb 53C10 in the therapeutic application against H1 influenza virus infection in humans.
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http://dx.doi.org/10.1128/JVI.00945-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7592206PMC
October 2020

Immunotherapy targeting the Streptococcus pyogenes M protein or streptolysin O to treat or prevent influenza A superinfection.

PLoS One 2020 23;15(6):e0235139. Epub 2020 Jun 23.

Division of Basic Biomedical Sciences, The Sanford School of Medicine of the University of South Dakota, Vermillion, SD, United States of America.

Viral infections complicated by a bacterial infection are typically referred to as coinfections or superinfections. Streptococcus pyogenes, the group A streptococcus (GAS), is not the most common bacteria associated with influenza A virus (IAV) superinfections but did cause significant mortality during the 2009 influenza pandemic even though all isolates are susceptible to penicillin. One approach to improve the outcome of these infections is to use passive immunization targeting GAS. To test this idea, we assessed the efficacy of passive immunotherapy using antisera against either the streptococcal M protein or streptolysin O (SLO) in a murine model of IAV-GAS superinfection. Prophylactic treatment of mice with antiserum to either SLO or the M protein decreased morbidity compared to mice treated with non-immune sera; however, neither significantly decreased mortality. Therapeutic use of antisera to SLO decreased morbidity compared to mice treated with non-immune sera but neither antisera significantly reduced mortality. Overall, the results suggest that further development of antibodies targeting the M protein or SLO may be a useful adjunct in the treatment of invasive GAS diseases, including IAV-GAS superinfections, which may be particularly important during influenza pandemics.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0235139PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7310742PMC
September 2020

Contribution of Host Immune Responses Against Influenza D Virus Infection Toward Secondary Bacterial Infection in a Mouse Model.

Viruses 2019 10 29;11(11). Epub 2019 Oct 29.

Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA.

Influenza D viruses (IDV) are known to co-circulate with viral and bacterial pathogens in cattle and other ruminants. Currently, there is limited knowledge regarding host responses to IDV infection and whether IDV infection affects host susceptibility to secondary bacterial infections. To begin to address this gap in knowledge, the current study utilized a combination of and approaches to evaluate host cellular responses against primary IDV infection and secondary bacterial infection with . Primary IDV infection in mice did not result in clinical signs of disease and it did not enhance the susceptibility to secondary infection. Rather, IDV infection appeared to protect mice from the usual clinical features of secondary bacterial infection, as demonstrated by improved weight loss, survival, and recovery when compared to infection alone. We found a notable increase in IFN-β expression following IDV infection while utilizing human alveolar epithelial A549 cells to analyze early anti-viral responses to IDV infection. These results demonstrate for the first time that IDV infection does not increase the susceptibility to secondary bacterial infection with , with evidence that anti-viral immune responses during IDV infection might protect the host against these potentially deadly outcomes.
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http://dx.doi.org/10.3390/v11110994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893757PMC
October 2019

Development of a multiplex real-time RT-PCR assay for simultaneous detection and differentiation of influenza A, B, C, and D viruses.

Diagn Microbiol Infect Dis 2019 Sep 29;95(1):59-66. Epub 2019 Apr 29.

Kansas State Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA; Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA. Electronic address:

Influenza is a common and contagious respiratory disease caused by influenza A, B, C, and D viruses (IAV, IBV, ICV, and IDV). A multiplex real-time RT-PCR assay was developed for simultaneous detection of IAV, IBV, ICV, and IDV. The assay was designed to target unique sequences in the matrix gene of IBV and ICV, the RNA polymerase subunit PB1 of IDV, and combined with USDA and CDC IAV assays, both target the matrix gene. The host 18S rRNA gene was included as an internal control. In silico analyses indicated high strain coverages: 97.9% for IBV, 99.5% for ICV, and 100% for IDV. Transcribed RNA, viral isolates and clinical samples were used for validation. The assay specifically detected target viruses without cross-reactivity, nor detection of other common pathogens. The limit of detection was approximately 30 copies for each viral RNA template, which was equivalent to a threshold cycle value of ~37.
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http://dx.doi.org/10.1016/j.diagmicrobio.2019.04.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6697560PMC
September 2019

A Novel Role for PDZ-Binding Motif of Influenza A Virus Nonstructural Protein 1 in Regulation of Host Susceptibility to Postinfluenza Bacterial Superinfections.

Viral Immunol 2019 04 1;32(3):131-143. Epub 2019 Mar 1.

1 Department of Microbiology and Immunology, Montana State University, Bozeman, Montana.

Influenza A viruses (IAVs) have multiple mechanisms for altering the host immune response to aid in virus survival and propagation. While both type I and II interferons (IFNs) have been associated with increased bacterial superinfection (BSI) susceptibility, we found that in some cases type I IFNs can be beneficial for BSI outcome. Specifically, we have shown that antagonism of the type I IFN response during infection by some IAVs can lead to the development of deadly BSI. The nonstructural protein 1 (NS1) from IAV is well known for manipulating host type I IFN responses, but the viral proteins mediating BSI severity remain unknown. In this study, we demonstrate that the PDZ-binding motif (PDZ-bm) of the NS1 C-terminal region from mouse-adapted A/Puerto Rico/8/34-H1N1 (PR8) IAV dictates BSI susceptibility through regulation of IFN-α/β production. Deletion of the NS1 PDZ-bm from PR8 IAV (PR8-TRUNC) resulted in 100% survival and decreased bacterial burden in superinfected mice compared with 0% survival in mice superinfected after PR8 infection. This reduction in BSI susceptibility after infection with PR8-TRUNC was due to the presence of IFN-β, as protection from BSI was lost in Ifn-β mice, resembling BSI during PR8 infection. PDZ-bm in PR8-infected mice inhibited the production of IFN-β posttranscriptionally, and both delayed and reduced expression of the tunable interferon-stimulated genes. Finally, a similar lack of BSI susceptibility, due to the presence of IFN-β on day 7 post-IAV infection, was also observed after infection of mice with A/TX98-H3N2 virus that naturally lacks a PDZ-bm in NS1, indicating that this mechanism of BSI regulation by NS1 PDZ-bm may not be restricted to PR8 IAV. These results demonstrate that the NS1 C-terminal PDZ-bm, like the one present in PR8 IAV, is involved in controlling susceptibility to BSI through the regulation of IFN-β, providing new mechanisms for NS1-mediated manipulation of host immunity and BSI severity.
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http://dx.doi.org/10.1089/vim.2018.0118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6479245PMC
April 2019

The Streptococcus pyogenes fibronectin/tenascin-binding protein PrtF.2 contributes to virulence in an influenza superinfection.

Sci Rep 2018 08 14;8(1):12126. Epub 2018 Aug 14.

Division of Basic Biomedical Sciences, The Sanford School of Medicine of the University of South Dakota, Vermillion, South Dakota, USA.

Influenza A virus (IAV) and Streptococcus pyogenes (the group A Streptococcus; GAS) are important contributors to viral-bacterial superinfections, which result from incompletely defined mechanisms. We identified changes in gene expression following IAV infection of A549 cells. Changes included an increase in transcripts encoding proteins with fibronectin-type III (FnIII) domains, such as fibronectin (Fn), tenascin N (TNN), and tenascin C (TNC). We tested the idea that increased expression of TNC may affect the outcome of an IAV-GAS superinfection. To do so, we created a GAS strain that lacked the Fn-binding protein PrtF.2. We found that the wild-type GAS strain, but not the mutant, co-localized with TNC and bound to purified TNC. In addition, adherence of the wild-type strain to IAV-infected A549 cells was greater compared to the prtF.2 mutant. The wild-type strain was also more abundant in the lungs of mice 24 hours after superinfection compared to the mutant strain. Finally, all mice infected with IAV and the prtF.2 mutant strain survived superinfection compared to only 42% infected with IAV and the parental GAS strain, indicating that PrtF.2 contributes to virulence in a murine model of IAV-GAS superinfection.
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http://dx.doi.org/10.1038/s41598-018-29714-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6092322PMC
August 2018

Contributions of Influenza Virus Hemagglutinin and Host Immune Responses Toward the Severity of Influenza Virus: Streptococcus pyogenes Superinfections.

Viral Immunol 2018 Jul/Aug;31(6):457-469. Epub 2018 Jun 5.

1 Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota , Vermillion, South Dakota.

Influenza virus infections can be complicated by bacterial superinfections, which are medically relevant because of a complex interaction between the host, the virus, and the bacteria. Studies to date have implicated several influenza virus genes, varied host immune responses, and bacterial virulence factors, however, the host-pathogen interactions that predict survival versus lethal outcomes remain undefined. Previous work by our group showed that certain influenza viruses could yield a survival phenotype (A/swine/Texas/4199-2/98-H3N2, TX98), whereas others were associated with a lethal phenotype (A/Puerto Rico/8/34-H1N1, PR8). Based on this observation, we developed the hypothesis that individual influenza virus genes could contribute to a superinfection, and that the host response after influenza virus infection could influence superinfection severity. The present study analyzes individual influenza virus gene contributions to superinfection severity using reassortant viruses created using TX98 and PR8 viral genes. Host and pathogen interactions, relevant to survival and lethal phenotypes, were studied with a focus on pathogen clearance, host cellular infiltrates, and cytokine levels after infection. Specifically, we found that the hemagglutinin gene expressed by an influenza virus can contribute to the severity of a secondary bacterial infection, likely through modulation of host proinflammatory responses. Altogether, these results advance our understanding of molecular mechanisms underlying influenza virus-bacteria superinfections and identify viral and corresponding host factors that may contribute to morbidity and mortality.
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http://dx.doi.org/10.1089/vim.2017.0193DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6043403PMC
October 2018

The Unexpected Impact of Vaccines on Secondary Bacterial Infections Following Influenza.

Viral Immunol 2018 03 17;31(2):159-173. Epub 2017 Nov 17.

2 Division of Basic Biomedical Sciences, University of South Dakota , Vermillion, South Dakota.

Influenza virus infections remain a significant health burden worldwide, despite available vaccines. Factors that contribute to this include a lack of broad coverage by current vaccines and continual emergence of novel virus strains. Further complicating matters, when influenza viruses infect a host, severe infections can develop when bacterial pathogens invade. Secondary bacterial infections (SBIs) contribute to a significant proportion of influenza-related mortality, with Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes, and Haemophilus influenzae as major coinfecting pathogens. Vaccines against bacterial pathogens can reduce coinfection incidence and severity, but few vaccines are available and those that are, may have decreased efficacy in influenza virus-infected hosts. While some studies indicate a benefit of vaccine-induced immunity in providing protection against SBIs, a comprehensive understanding is lacking. In this review, we discuss the current knowledge of viral and bacterial vaccine availability, the generation of protective immunity from these vaccines, and the effectiveness in limiting influenza-associated bacterial infections.
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http://dx.doi.org/10.1089/vim.2017.0138DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5863092PMC
March 2018

Binding host proteins to the M protein contributes to the mortality associated with influenza- superinfections.

Microbiology (Reading) 2017 Oct;163(10):1445-1456

Division of Basic Biomedical Sciences, The Sanford School of Medicine of the University of South Dakota, Vermillion, South Dakota, USA.

The mortality associated with influenza A virus (IAV) is often due to the development of secondary bacterial infections known as superinfections. The group A streptococcus (GAS) is a relatively uncommon cause of IAV superinfections, but the mortality of these infections is high. We used a murine model to determine whether the surface-localized GAS M protein contributes to the outcome of IAV-GAS superinfections. A comparison between wild-type GAS and an M protein mutant strain (emm3) showed that the M3 protein was essential to virulence. To determine whether the binding, or recruitment, of host proteins to the bacterial surface contributed to virulence, GAS was suspended with BALF collected from mice that had recovered from a sub-lethal infection with IAV. Following intranasal inoculation of naïve mice, the mortality associated with the wild-type strain, but not the emm3 mutant strain, was greater compared to mice inoculated with GAS suspended with either BALF from uninfected mice or PBS. Further analyses showed that both albumin and fibrinogen (Fg) were more abundant in the respiratory tract 8 days after IAV infection, that M3 bound both proteins to the bacterial surface, and that suspension of GAS with either protein increased GAS virulence in the absence of antecedent IAV infection. Overall, the results showed that M3 is essential to the virulence of GAS in an IAV superinfection and suggested that increased abundance of albumin and Fg in the respiratory tract following IAV infection enhanced host susceptibility to secondary GAS infection.
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http://dx.doi.org/10.1099/mic.0.000532DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5845574PMC
October 2017

So You Want To Be A Reviewer.

S D Med 2017 Mar;70(3):127-133

Sanford Health Fertility and Reproductive Medicine, Sioux Falls, South Dakota.

Peer review is a process for evaluating the quality of "work" of a scientist or professional as judged by others in the same or related field. In the context of the biomedical and health sciences, it primarily pertains to review of manuscripts submitted to journals for consideration of publication, abstracts for proposed presentations at professional meetings, and competitive research grant applications. Serving as a reviewer is a scholarly pursuit and a worthwhile endeavor, assuming it is approached in a conscientious, responsible manner. The purpose of this article is to define peer review and its various forms, suggest reasons for serving as a manuscript reviewer, discuss considerations prior to accepting a review assignment, and provide guidelines for the process.
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March 2017

Establishment of memory CD8+ T cells with live attenuated influenza virus across different vaccination doses.

J Gen Virol 2016 Dec 2;97(12):3205-3214. Epub 2016 Nov 2.

Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Parkville, VIC 3010, Australia.

FluMist has been used in children and adults for more than 10 years. As pre-existing CD8+ T cell memory pools can provide heterologous immunity against distinct influenza viruses, it is important to understand influenza-specific CD8+ T cell responses elicited by different live attenuated influenza virus (LAIV) regimens. In this study, we immunized mice intranasally with two different doses of live-attenuated PR8 virus (PR8 ts, H1N1), low and high, and then assessed protective efficacy by challenging animals with heterosubtypic X31-H3N2 virus at 6 weeks post-vaccination. Different LAIV doses elicited influenza-specific CD8+ T cell responses in lungs and spleen, but unexpectedly not in bronchoalveolar lavage. Interestingly, the immunodominance hierarchy at the acute phase after immunization varied depending on the LAIV dose; however, these differences disappeared at 6 weeks post-vaccination, resulting in generation of comparable CD8+ T cell memory pools. After vaccination with either dose, sufficient numbers of specific CD8+ T cells were generated for recall and protection of mice against heterosubtypic H1N1→H3N2 challenge. As a result, immunized mice displayed reduced weight loss, diminished inflammatory responses and lower viral titres in lungs, when compared to unvaccinated animals. Interestingly, the higher dose led to enhanced viral clearance on day 5 post-challenge, though this was not associated with increased CD8+ T cell responses, but with higher levels of non-neutralizing antibodies against the priming virus. Our study suggests that, while different LAIV doses result in distinct immune profiles, even a low dose produces sufficient protective CD8+ T cell memory against challenge infection, though the high dose results in more rapid viral clearance and reduced inflammation.
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http://dx.doi.org/10.1099/jgv.0.000651DOI Listing
December 2016

So You Want to be an Author: A Primer on Writing for Publication in the Medical Literature Part I: Manuscript Preparation.

S D Med 2016 Apr;69(4):172-5

Writing a manuscript on a topic in the medical sciences that gets accepted for publication is not always a guaranteed process. The goal of this article is to provide a description of some key points associated with preparing a manuscript. It has been written primarily for less experienced or aspiring authors, but it addresses points that are important for even well-established authors to consider. Although there may not be a direct path from scientific observation to published work, possessing the desire to publish and persevering throughout the process can ultimately lead to one's findings being both preserved in and contributing to the scientific literature. Although challenging, and at times frustrating, it is a rewarding endeavor.
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April 2016

Differential Type I Interferon Signaling Is a Master Regulator of Susceptibility to Postinfluenza Bacterial Superinfection.

mBio 2016 05 3;7(3). Epub 2016 May 3.

Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, USA

Unlabelled: Bacterial superinfections are a primary cause of death during influenza pandemics and epidemics. Type I interferon (IFN) signaling contributes to increased susceptibility of mice to bacterial superinfection around day 7 post-influenza A virus (IAV) infection. Here we demonstrate that the reduced susceptibility to methicillin-resistant Staphylococcus aureus (MRSA) at day 3 post-IAV infection, which we previously reported was due to interleukin-13 (IL-13)/IFN-γ responses, is also dependent on type I IFN signaling and its subsequent requirement for protective IL-13 production. We found, through utilization of blocking antibodies, that reduced susceptibility to MRSA at day 3 post-IAV infection was IFN-β dependent, whereas the increased susceptibility at day 7 was IFN-α dependent. IFN-β signaling early in IAV infection was required for MRSA clearance, whereas IFN-α signaling late in infection was not, though it did mediate increased susceptibility to MRSA at that time. Type I IFN receptor (IFNAR) signaling in CD11c(+) and Ly6G(+) cells was required for the observed reduced susceptibility at day 3 post-IAV infection. Depletion of Ly6G(+) cells in mice in which IFNAR signaling was either blocked or deleted indicated that Ly6G(+) cells were responsible for the IFNAR signaling-dependent susceptibility to MRSA superinfection at day 7 post-IAV infection. Thus, during IAV infection, the temporal differences in type I IFN signaling increased bactericidal activity of both CD11c(+) and Ly6G(+) cells at day 3 and reduced effector function of Ly6G(+) cells at day 7. The temporal differential outcomes induced by IFN-β (day 3) and IFN-α (day 7) signaling through the same IFNAR resulted in differential susceptibility to MRSA at 3 and 7 days post-IAV infection.

Importance: Approximately 114,000 hospitalizations and 40,000 annual deaths in the United States are associated with influenza A virus (IAV) infections. Frequently, these deaths are due to community-acquired Gram-positive bacterial species, many of which show increasing resistance to antibiotic therapy. Severe complications, including parapneumonic empyema and necrotizing pneumonia, can arise, depending on virulence factors expressed by either the virus or bacteria. Unfortunately, we are unable to control the expression of these virulence factors, making host responses a logical target for therapeutic interventions. Moreover, interactions between virus, host, and bacteria that exacerbate IAV-related morbidities and mortalities are largely unknown. Here, we show that type I interferon (IFN) expression can modulate susceptibility to methicillin-resistant Staphylococcus aureus (MRSA) infection, with IFN-β reducing host susceptibility to MRSA infection while IFN-α increases susceptibility. Our data indicate that treatments designed to augment IFN-β and/or inhibit IFN-α production around day 7 post-IAV infection could reduce susceptibility to deadly superinfections.
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http://dx.doi.org/10.1128/mBio.00506-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4959663PMC
May 2016

So You Want To Be An Author: A Primer On Writing For Publication In The Medical Literature Part II: Manuscript Submission.

S D Med 2016 May;69(5):221-223

Department of Family Medicine, University of South Dakota Sanford School of Medicine.

Completing a draft of a manuscript that demonstrates the impact of your research within the current literature is the first step toward publication. The next step involves a review process that will allow your peers to provide feedback on the written document, with the goal of improving the presentation of your work. To complete this process, an author will have to be willing to accept constructive criticism of his or her work, as presented, and to modify the manuscript based on the feedback received. This peer-review process will ultimately shape the final draft of your manuscript, and here we provide some points to consider as you navigate the submission and review process.
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May 2016

The Association between Invasive Group A Streptococcal Diseases and Viral Respiratory Tract Infections.

Front Microbiol 2016 21;7:342. Epub 2016 Mar 21.

Division of Basic Biomedical Sciences, The Sanford School of Medicine of the University of South Dakota Vermillion, SD, USA.

Viral infections of the upper respiratory tract are associated with a variety of invasive diseases caused by Streptococcus pyogenes, the group A streptococcus, including pneumonia, necrotizing fasciitis, toxic shock syndrome, and bacteremia. While these polymicrobial infections, or superinfections, are complex, progress has been made in understanding the molecular basis of disease. Areas of investigation have included the characterization of virus-induced changes in innate immunity, differences in bacterial adherence and internalization following viral infection, and the efficacy of vaccines in mitigating the morbidity and mortality of superinfections. Here, we briefly summarize viral-S. pyogenes superinfections with an emphasis on those affiliated with influenza viruses.
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http://dx.doi.org/10.3389/fmicb.2016.00342DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4800185PMC
April 2016

Construction and Immunogenicity Evaluation of Recombinant Influenza A Viruses Containing Chimeric Hemagglutinin Genes Derived from Genetically Divergent Influenza A H1N1 Subtype Viruses.

PLoS One 2015 10;10(6):e0127649. Epub 2015 Jun 10.

Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, United States of America.

Background And Objectives: Influenza A viruses cause highly contagious diseases in a variety of hosts, including humans and pigs. To develop a vaccine that can be broadly effective against genetically divergent strains of the virus, in this study we employed molecular breeding (DNA shuffling) technology to create a panel of chimeric HA genes.

Methods And Results: Each chimeric HA gene contained genetic elements from parental swine influenza A viruses that had a history of zoonotic transmission, and also from a 2009 pandemic virus. Each parental virus represents a major phylogenetic clade of influenza A H1N1 viruses. Nine shuffled HA constructs were initially screened for immunogenicity in mice by DNA immunization, and one chimeric HA (HA-129) was expressed on both a A/Puerto Rico/8/34 backbone with mutations associated with a live, attenuated phenotype (PR8LAIV-129) and a A/swine/Texas/4199-2/98 backbone (TX98-129). When delivered to mice, the PR8LAIV-129 induced antibodies against all four parental viruses, which was similar to the breadth of immunity observed when HA-129 was delivered as a DNA vaccine. This chimeric HA was then tested as a candidate vaccine in a nursery pig model, using inactivated TX98-129 virus as the backbone. The results demonstrate that pigs immunized with HA-129 developed antibodies against all four parental viruses, as well as additional primary swine H1N1 influenza virus field isolates.

Conclusion: This study established a platform for creating novel genes of influenza viruses using a molecular breeding approach, which will have important applications toward future development of broadly protective influenza virus vaccines.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0127649PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4465703PMC
June 2016

Vaccination against the M protein of Streptococcus pyogenes prevents death after influenza virus: S. pyogenes super-infection.

Vaccine 2014 Sep 29;32(40):5241-9. Epub 2014 Jul 29.

Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD, United States. Electronic address:

Influenza virus infections are associated with a significant number of illnesses and deaths on an annual basis. Many of the deaths are due to complications from secondary bacterial invaders, including Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pyogenes. The β-hemolytic bacteria S. pyogenes colonizes both skin and respiratory surfaces, and frequently presents clinically as strep throat or impetigo. However, when these bacteria gain access to normally sterile sites, they can cause deadly diseases including sepsis, necrotizing fasciitis, and pneumonia. We previously developed a model of influenza virus:S. pyogenes super-infection, which we used to demonstrate that vaccination against influenza virus can limit deaths associated with a secondary bacterial infection, but this protection was not complete. In the current study, we evaluated the efficacy of a vaccine that targets the M protein of S. pyogenes to determine whether immunity toward the bacteria alone would allow the host to survive an influenza virus:S. pyogenes super-infection. Our data demonstrate that vaccination against the M protein induces IgG antibodies, in particular those of the IgG1 and IgG2a isotypes, and that these antibodies can interact with macrophages. Ultimately, this vaccine-induced immunity eliminated death within our influenza virus:S. pyogenes super-infection model, despite the fact that all M protein-vaccinated mice showed signs of illness following influenza virus inoculation. These findings identify immunity against bacteria as an important component of protection against influenza virus:bacteria super-infection.
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http://dx.doi.org/10.1016/j.vaccine.2014.06.093DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4146501PMC
September 2014

Enhanced response to pulmonary Streptococcus pneumoniae infection is associated with primary ciliary dyskinesia in mice lacking Pcdp1 and Spef2.

Cilia 2013 Dec 20;2(1):18. Epub 2013 Dec 20.

Sanford Children's Health Research Center, Sanford Research/USD, 2301 E, 60th St, N, Sioux Falls, SD 57104, USA.

Background: Lower airway abnormalities are common in patients with primary ciliary dyskinesia (PCD), a pediatric syndrome that results from structural or functional defects in motile cilia. Patients can suffer from recurrent bacterial infection in the lung, bronchiectasis, and respiratory distress in addition to chronic sinusitis, otitis media, infertility, and laterality defects. However, surprisingly little is known about the pulmonary phenotype of mouse models of this disorder.

Results: The pulmonary phenotype of two mouse models of PCD, nm1054 and bgh, which lack Pcdp1 and Spef2, respectively, was investigated by histological and immunohistochemical analysis. In addition, both models were challenged with Streptococcus pneumoniae, a common respiratory pathogen found in the lungs of PCD patients. Histopathological analyses reveal no detectable cellular, developmental, or inflammatory abnormalities in the lower airway of either PCD model. However, exposure to S. pneumoniae results in a markedly enhanced inflammatory response in both models. Based on analysis of inflammatory cells in bronchoalveolar lavage fluid and flow cytometric analysis of cytokines in the lung, the bgh model shows a particularly dramatic lymphocytic response by 3 days post-infection compared to the nm1054 model or wild type animals.

Conclusions: Defects in ciliary motility result in a severe response to pulmonary infection. The PCD models nm1054 and bgh are distinct and clinically relevant models for future studies investigating the role of mucociliary clearance in host defense.
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http://dx.doi.org/10.1186/2046-2530-2-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3878133PMC
December 2013

Influenza vaccines: from whole virus preparations to recombinant protein technology.

Authors:
Victor C Huber

Expert Rev Vaccines 2014 Jan;13(1):31-42

Division of Basic Biomedical Sciences, University of South Dakota, 414 E Clark Street, Vermillion, SD 57069, USA.

Vaccination against influenza represents our most effective form of prevention. Historical approaches toward vaccine creation and production have yielded highly effective vaccines that are safe and immunogenic. Despite their effectiveness, these historical approaches do not allow for the incorporation of changes into the vaccine in a timely manner. In 2013, a recombinant protein-based vaccine that induces immunity toward the influenza virus hemagglutinin was approved for use in the USA. This vaccine represents the first approved vaccine formulation that does not require an influenza virus intermediate for production. This review presents a brief history of influenza vaccines, with insight into the potential future application of vaccines generated using recombinant technology.
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http://dx.doi.org/10.1586/14760584.2014.852476DOI Listing
January 2014

Construction and immunogenicity evaluation of an epitope-based antigen against swine influenza A virus using Escherichia coli heat-labile toxin B subunit as a carrier-adjuvant.

Vet Microbiol 2013 Jun 26;164(3-4):229-38. Epub 2013 Feb 26.

Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007, USA.

Influenza A virus causes a highly contagious respiratory disease in a variety of avian and mammalian hosts, including humans and pigs. The primary means for preventing influenza epidemics is vaccination. Epitope-based vaccine represents a new approach to achieve protective immunity. The objective of this study was to construct and evaluate the immunogenicity of an epitope-based antigen for its potential application in future influenza vaccine development. The antigen, comprised of a set of consensus influenza A virus epitopes (IAVe), was genetically linked to a subunit of the bacterial heat-labile enterotoxin (LTB) as an adjuvant. Immunogenicity of this LTB-IAVe antigen was evaluated in a pig model. Despite an inability to detect neutralizing antibodies directed toward the whole virus, humoral immunity against the IAVe was demonstrated in both serum (IgA and IgG) and mucosal secretions (IgG) of immunized pigs. Specific cellular immunity was also induced after LTB-IAVe immunization, as evidenced by up-regulating of IL-1β, IL-8, and IL-4 expression in peripheral blood mononuclear cells (PBMCs) of vaccinated pigs. In comparison to the non-immunized pigs, pigs immunized with the LTB-IAVe showed improved protection against a pathogenic H1N1 swine influenza virus challenge, with about 50% decrease of pneumonic lesions and 10-fold reduction of the viral load in lung and nasal secretion at five days post challenge. This study establishes a platform for future construction of epitope-based vaccines against influenza A virus infection.
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http://dx.doi.org/10.1016/j.vetmic.2013.02.010DOI Listing
June 2013

Can surveillance of the influenza virus PB1-F2 gene be used to predict the severity of secondary bacterial infections?

Authors:
Victor C Huber

Virulence 2012 Oct 1;3(6):523-4. Epub 2012 Oct 1.

Division of Basic Biomedical Sciencesm, University of South Dakota, Vermillion, SD, USA.

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http://dx.doi.org/10.4161/viru.21811DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3524154PMC
October 2012

Characterization of a porcine intestinal epithelial cell line for influenza virus production.

J Gen Virol 2012 Sep 27;93(Pt 9):2008-2016. Epub 2012 Jun 27.

Department of Biology/Microbiology, South Dakota State University, Brookings, SD 57007, USA.

We have developed a porcine intestine epithelial cell line, designated SD-PJEC for the propagation of influenza viruses. The SD-PJEC cell line is a subclone of the IPEC-J2 cell line, which was originally derived from newborn piglet jejunum. Our results demonstrate that SD-PJEC is a cell line of epithelial origin that preferentially expresses receptors of oligosaccharides with Sia2-6Gal modification. This cell line is permissive to infection with human and swine influenza A viruses and some avian influenza viruses, but poorly support the growth of human-origin influenza B viruses. Propagation of swine-origin influenza viruses in these cells results in a rapid growth rate within the first 24 h post-infection and the titres ranged from 4 to 8 log(10) TCID(50) ml(-1). The SD-PJEC cell line was further tested as a potential alternative cell line to Madin-Darby canine kidney (MDCK) cells in conjunction with 293T cells for rescue of swine-origin influenza viruses using the reverse genetics system. The recombinant viruses A/swine/North Carolina/18161/02 (H1N1) and A/swine/Texas/4199-2/98 (H3N2) were rescued with virus titres of 7 and 8.25 log(10) TCID(50) ml(-1), respectively. The availability of this swine-specific cell line represents a more relevant substrate for studies and growth of swine-origin influenza viruses.
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http://dx.doi.org/10.1099/vir.0.044388-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3542131PMC
September 2012

Naturally occurring swine influenza A virus PB1-F2 phenotypes that contribute to superinfection with Gram-positive respiratory pathogens.

J Virol 2012 Sep 6;86(17):9035-43. Epub 2012 Jun 6.

Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.

A combination of viral, bacterial, and host factors contributes to the severity and overall mortality associated with influenza virus-bacterium superinfections. To date, the virulence associated with the recently identified influenza virus protein PB1-F2 has been largely defined using models of primary influenza virus infection, with only limited assessment in models of Streptococcus pneumoniae superinfection. Specifically, these studies have incorporated isogenic viruses that differ in the PB1-F2 expressed, but there is still knowledge to be gained from evaluation of natural variants derived from a nonhuman host species (swine). Using this rationale, we developed the hypothesis that naturally occurring viruses expressing variants of genes, like the PB1-F2 gene, can be associated with the severity of secondary bacterial infections. To test this hypothesis, we selected viruses expressing variants in PB1-F2 and evaluated outcomes from superinfection with three distinct Gram-positive respiratory pathogens: Streptococcus pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes. Our results demonstrate that the amino acid residues 62L, 66S, 75R, 79R, and 82L, previously proposed as molecular signatures of PB1-F2 virulence for influenza viruses in the setting of bacterial superinfection, are broadly associated with enhanced pathogenicity in swine in a bacterium-specific manner. Furthermore, truncated PB1-F2 proteins can preferentially increase mortality when associated with Streptococcus pyogenes superinfection. These findings support efforts to increase influenza virus surveillance to consider viral genotypes that could be used to predict increased severity of superinfections with specific Gram-positive respiratory pathogens.
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http://dx.doi.org/10.1128/JVI.00369-12DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3416121PMC
September 2012

Correlates of vaccine protection from influenza and its complications.

Hum Vaccin Immunother 2012 Jan 1;8(1):34-44. Epub 2012 Jan 1.

Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, USA.

Despite use of influenza vaccines for more than 65 y, influenza and its complications are a major cause of morbidity and mortality worldwide. Most deaths during influenza virus infections are due to underlying co-morbidities or secondary bacterial pneumonia. The measures of immune response currently used for licensure of influenza vaccines are relevant mainly for protection from viral infection in healthy adults. Development of new or improved influenza vaccines will require a definition of novel, and specific correlates of protection. These correlates should associate immune responses with outcomes that are relevant to specific risk groups, such as asthma exacerbation, hospitalization or disruptions to care or daily activities. Assessment of vaccine effectiveness for both viral and bacterial vaccines should include measures of impact on secondary bacterial pneumonia.
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http://dx.doi.org/10.4161/hv.8.1.18214DOI Listing
January 2012

Contribution of murine innate serum inhibitors toward interference within influenza virus immune assays.

Influenza Other Respir Viruses 2012 Mar 29;6(2):127-35. Epub 2011 Aug 29.

Division of Basic Biomedical Sciences, University of South Dakota, Vermillion, SD 57069-2390, USA.

Background: Prior to detection of an antibody response toward influenza viruses using the hemagglutination inhibition assay (HAI), sera are routinely treated to inactivate innate inhibitors using both heat inactivation (56°C) and recombinant neuraminidase [receptor-destroying enzyme (RDE)].

Objectives: We revisited the contributions of innate serum inhibitors toward interference with influenza viruses in immune assays, using murine sera, with emphasis on the interactions with influenza A viruses of the H3N2 subtype.

Methods: We used individual serum treatments: 56°C alone, RDE alone, or RDE + 56°C, to treat sera prior to evaluation within HAI, microneutralization, and macrophage uptake assays.

Results: Our data demonstrate that inhibitors present within untreated murine sera interfere with the HAI assay in a manner that is different from that seen for the microneutralization assay. Specifically, the γ class inhibitor α(2) -Macroglobulin (A2-M) can inhibit H3N2 viruses within the HAI assay, but not in the microneutralization assay. Based on these findings, we used a macrophage uptake assay to demonstrate that these inhibitors can increase uptake by macrophages when the influenza viruses express an HA from a 1968 H3N2 virus isolate, but not a 1997 H3N2 isolate.

Conclusions: The practice of treating sera to inactivate innate inhibitors of influenza viruses prior to evaluation within immune assays has allowed us to effectively detect influenza virus-specific antibodies for decades. However, this practice has yielded an under-appreciation for the contribution of innate serum inhibitors toward host immune responses against these viruses, including contributions toward neutralization and macrophage uptake.
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http://dx.doi.org/10.1111/j.1750-2659.2011.00283.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3235232PMC
March 2012

Safety of live attenuated influenza vaccine in mild to moderately immunocompromised children with cancer.

Vaccine 2011 May 13;29(24):4110-5. Epub 2011 Apr 13.

Vanderbilt University Medical Center, 1161 21st Ave South, Nashville, TN 37232, USA.

Background: The safety of intranasal live-attenuated influenza vaccine (LAIV) in immunocompromised children with cancer is unknown. The objective of this study was to describe the safety and immunogenicity of LAIV in mild to moderately immunocompromised children with cancer.

Methods: We conducted a multicenter, randomized, double-blind study of LAIV versus placebo in children aged 5-17 years with cancer. LAIV (frozen formulation) or allantoic fluid/buffer was administered intranasally. Reactogenicity, adverse events, blood for immune assays, and nasal swabs for viral shedding were obtained during 5 visits over the first 42 days postvaccination; information concerning serious adverse events (SAEs) was collected for 180 days.

Results: 20 subjects were enrolled (LAIV, n=10; placebo, n=10) with a mean age of 12.2 years. Ten subjects had hematologic malignancy (LAIV, n=4; placebo, n=6); 10 subjects had solid tumors (LAIV, n=6; placebo, n=4). One subject was excluded from immunogenicity analysis for not receiving a full dose of LAIV. LAIV resulted in an increased incidence of runny nose/nasal congestion occurring in all LAIV recipients; no related SAEs were observed. Four of 10 LAIV recipients shed vaccine virus, with none exceeding 7-10 days duration. LAIV demonstrated modest immunogenicity by hemagglutination inhibition (≥ 4 fold rise for any strain, 33%) and microneutralization assays (≥ 4 fold rise for any strain, 44%).

Conclusion: In this small pilot study conducted in mild to moderately immunocompromised children with cancer, runny nose/nasal congestion was increased in LAIV recipients, no related SAEs occurred, and prolonged viral shedding was not detected. Moderate immunogenicity was demonstrated in this small group of individuals.
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http://dx.doi.org/10.1016/j.vaccine.2011.03.097DOI Listing
May 2011

Inactivated and live, attenuated influenza vaccines protect mice against influenza: Streptococcus pyogenes super-infections.

Vaccine 2011 May 8;29(21):3773-81. Epub 2011 Apr 8.

Division of Basic Biomedical Sciences, University of South Dakota, Vermillion, SD, United States.

Mortality associated with influenza virus super-infections is frequently due to secondary bacterial complications. To date, super-infections with Streptococcus pyogenes have been studied less extensively than those associated with Streptococcus pneumoniae. This is significant because a vaccine for S. pyogenes is not clinically available, leaving vaccination against influenza virus as our only means for preventing these super-infections. In this study, we directly compared immunity induced by two types of influenza vaccine, either inactivated influenza virus (IIV) or live, attenuated influenza virus (LAIV), for the ability to prevent super-infections. Our data demonstrate that both IIV and LAIV vaccines induce similar levels of serum antibodies, and that LAIV alone induces IgA expression at mucosal surfaces. Upon super-infection, both vaccines have the ability to limit the induction of pro-inflammatory cytokines within the lung, including IFN-γ which has been shown to contribute to mortality in previous models of super-infection. Limiting expression of these pro-inflammatory cytokines within the lungs subsequently limits recruitment of macrophages and neutrophils to pulmonary surfaces, and ultimately protects both IIV- and LAIV-vaccinated mice from mortality. Despite their overall survival, both IIV- and LAIV-vaccinated mice demonstrated levels of bacteria within the lung tissue that are similar to those seen in unvaccinated mice. Thus, influenza virus:bacteria super-infections can be limited by vaccine-induced immunity against influenza virus, but the ability to prevent morbidity is not complete.
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http://dx.doi.org/10.1016/j.vaccine.2011.03.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3084433PMC
May 2011

Contribution of vaccine-induced immunity toward either the HA or the NA component of influenza viruses limits secondary bacterial complications.

J Virol 2010 Apr 3;84(8):4105-8. Epub 2010 Feb 3.

Division of Basic Biomedical Sciences, University of South Dakota, 414 E. Clark St., Vermillion, SD 57069, USA.

Secondary bacterial infections contribute to morbidity and mortality from influenza. Vaccine effectiveness is typically assessed using prevention of influenza, not secondary infections, as an endpoint. We vaccinated mice with formalin-inactivated influenza virus vaccine preparations containing disparate HA and NA proteins and demonstrated an ability to induce the appropriate anti-HA and anti-NA immune profiles. Protection from both primary viral and secondary bacterial infection was demonstrated with vaccine-induced immunity directed toward either the HA or the NA. This finding suggests that immunity toward the NA component of the virion is desirable and should be considered in generation of influenza vaccines.
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http://dx.doi.org/10.1128/JVI.02621-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2849504PMC
April 2010
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