Publications by authors named "Jamie F S Mann"

23 Publications

  • Page 1 of 1

Deep Gene Sequence Cluster Analyses of Multi-Virus-Infected Mucosal Tissue Reveal Enhanced Transmission of Acute HIV-1.

J Virol 2021 01 13;95(3). Epub 2021 Jan 13.

Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada

Exposure of the genital mucosa to a genetically diverse viral swarm from the donor HIV-1 can result in breakthrough and systemic infection by a single transmitted/founder (TF) virus in the recipient. The highly diverse HIV-1 envelope (Env) in this inoculating viral swarm may have a critical role in transmission and subsequent immune response. Thus, chronic (Env) and acute (Env) Env chimeric HIV-1 were tested using multivirus competition assays in human mucosal penile and cervical tissues. Viral competition analysis revealed that Env viruses resided and replicated mainly in the tissue, while Env viruses penetrated the human tissue and established infection of CD4 T cells more efficiently. Analysis of the replication fitness, as tested in peripheral blood mononuclear cells (PBMCs), showed similar replication fitness of Env and Env viruses, which did not correlate with transmission fitness in penile tissue. Further, we observed that chimeric Env viruses with higher replication in genital mucosal tissue (chronic Env viruses) had higher binding affinity to C-type lectins. Data presented herein suggest that the inoculating HIV-1 may be sequestered in the genital mucosal tissue (represented by chronic Env HIV-1) but that a single HIV-1 clone (e.g., acute Env HIV-1) can escape this trapped replication for systemic infection. During heterosexual HIV-1 transmission, a genetic bottleneck occurs in the newly infected individual as the virus passes from the mucosa, leading to systemic infection with a single transmitted HIV-1 clone in the recipient. This bottleneck in the recipient has just been described (K. Klein et al., PLoS Pathog 14:e1006754, https://doi.org/10.1371/journal.ppat.1006754), and the mechanisms involved in this selection process have not been elucidated. However, understanding mucosal restriction is of the utmost importance for understanding dynamics of infections and for designing focused vaccines. Using our human penile and cervical mucosal tissue models for mixed HIV infections, we provide evidence that HIV-1 from acute/early infection, compared to that from chronic infection, can more efficiently traverse the mucosal epithelium and be transmitted to T cells, suggesting higher transmission fitness. This study focused on the role of the HIV-1 envelope in transmission and provides strong evidence that HIV transmission may involve breaking the mucosal lectin trap.
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http://dx.doi.org/10.1128/JVI.01737-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7925087PMC
January 2021

A targeted reactivation of latent HIV-1 using an activator vector in patient samples from acute infection.

EBioMedicine 2020 Sep 9;59:102853. Epub 2020 Jul 9.

Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, Canada; Division of Infectious Diseases, Department of Medicine, Case Western Reserve University, Cleveland, OH 44106, United States. Electronic address:

Background: During combined anti-retroviral treatment, a latent HIV reservoir persists within resting memory CD4 T cells that initiates viral recrudescence upon treatment interruption. Strategies for HIV-1 cure have largely focused on latency reversing agents (LRAs) capable of reactivating and eliminating this viral reservoir. Previously investigated LRAs have largely failed to achieve a robust latency reversal sufficient for reduction of latent HIV pool or the potential of virus-free remission in the absence of treatment.

Methods: We utilize a polyvalent virus-like particle (VLP) formulation called Activator Vector (ACT-VEC) to 'shock' provirus into transcriptional activity. Ex vivo co-culture experiments were used to evaluate the efficacy of ACT-VEC in relation to other LRAs in individuals diagnosed and treated during the acute stage of infection. IFN-γ ELISpot, qRT-PCR and Illumina MiSeq were used to evaluate antigenicity, latency reversal, and diversity of induced virus respectively.

Findings: Using samples from HIV patients diagnosed and treated at acute/early infection, we demonstrate that ACT-VEC can reverse latency in HIV infected CD4 T cells to a greater extent than other major recall antigens as stimuli or even mitogens such as PMA/Iono. Furthermore, ACT-VEC activates more latent HIV-1 than clinically tested HDAC inhibitors or protein kinase C agonists.

Interpretation: Taken together, these results show that ACT-VEC can induce HIV reactivation from latently infected CD4 T cells collected from participants on first line combined antiretroviral therapy for at least two years after being diagnosed and treated at acute/early stage of infection. These findings could provide guidance to possible targeted cure strategies and treatments.

Funding: NIH and CIHR.
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http://dx.doi.org/10.1016/j.ebiom.2020.102853DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7502668PMC
September 2020

Advances in HIV-1 Vaccine Development.

Viruses 2018 04 1;10(4). Epub 2018 Apr 1.

Department of Microbiology and Immunology, University of Western Ontario, London, ON, N6A 5C1, Canada.

An efficacious HIV-1 vaccine is regarded as the best way to halt the ongoing HIV-1 epidemic. However, despite significant efforts to develop a safe and effective vaccine, the modestly protective RV144 trial remains the only efficacy trial to provide some level of protection against HIV-1 acquisition. This review will outline the history of HIV vaccine development, novel technologies being applied to HIV vaccinology and immunogen design, as well as the studies that are ongoing to advance our understanding of vaccine-induced immune correlates of protection.
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http://dx.doi.org/10.3390/v10040167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5923461PMC
April 2018

Virus-Like Particle, Liposome, and Polymeric Particle-Based Vaccines against HIV-1.

Front Immunol 2018 28;9:345. Epub 2018 Feb 28.

Department of Microbiology and Immunology, University of Western Ontario, London, ON, Canada.

It is acknowledged that vaccines remain the best hope for eliminating the HIV-1 epidemic. However, the failure to produce effective vaccine immunogens and the inability of conventional delivery strategies to elicit the desired immune responses remains a central theme and has ultimately led to a significant roadblock in HIV vaccine development. Consequently, significant efforts have been applied to generate novel vaccine antigens and delivery agents, which mimic viral structures for optimal immune induction. Here, we review the latest developments that have occurred in the nanoparticle vaccine field, with special emphasis on strategies that are being utilized to attain highly immunogenic, systemic, and mucosal anti-HIV humoral and cellular immune responses. This includes the design of novel immunogens, the central role of antigen-presenting cells, delivery routes, and biodistribution of nanoparticles to lymph nodes. In particular, we will focus on virus-like-particle formulations and their preclinical uses within the HIV prophylactic vaccine setting.
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http://dx.doi.org/10.3389/fimmu.2018.00345DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5835502PMC
March 2019

A heterogeneous human immunodeficiency virus-like particle (VLP) formulation produced by a novel vector system.

NPJ Vaccines 2018 19;3. Epub 2018 Jan 19.

1Department of Microbiology and Immunology, University of Western Ontario, London, ON N6A 5C1 Canada.

First identified as the etiological agent behind Acquired Immunodeficiency Syndrome (AIDS) in the early 1980s, HIV-1 has continued to spread into a global pandemic and major public health concern. Despite the success of antiretroviral therapy at reducing HIV-1 viremia and preventing the dramatic CD4 T-cell collapse, infected individuals remain HIV positive for life. Unfortunately, it is increasingly clear that natural immunity is not, and may never be, protective against this pathogen. Therefore, efficacious vaccine interventions, which can either prevent infection or eradicate the latent viral reservoir and effect cure, are a major medical priority. Here we describe the development of a safe vaccine platform, currently being utilized in on-going prophylactic and therapeutic preclinical studies and consisting of highly heterogeneous virus-like particle formulations that represent the virus diversity within infected individuals. These VLPs contain no 5'LTR, no functional integrase, and have a severely mutated stem loop 1-thereby preventing any potential reverse transcription, integration, and RNA packaging. Furthermore, we demonstrate that these VLPs are morphologically identical to wild-type virus with polyvalent Env in a functional form. Finally, we show that the VLPs are antigenic and capable of generating strong immune recall responses.
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http://dx.doi.org/10.1038/s41541-017-0040-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5775397PMC
January 2018

Eradication of HIV-1 latent reservoirs through therapeutic vaccination.

AIDS Res Ther 2017 Sep 12;14(1):45. Epub 2017 Sep 12.

Department of Microbiology and Immunology, University of Western Ontario, London, ON, N6A 5C1, Canada.

Despite the significant success of combination anti-retroviral therapy to reduce HIV viremia and save lives, HIV-1 infection remains a lifelong infection that must be appropriately managed. Advances in the understanding of the HIV infection process and insights from vaccine development in other biomedical fields such as cancer, imaging, and genetic engineering have fueled rapid advancements in HIV cure research. In the last few years, several studies have focused on the development of "Kick and Kill" therapies to reverse HIV latency and kick start viral translational activity. This has been done with the aim that concomitant anti-retroviral treatment and the elicited immune responses will prevent de novo infections while eradicating productively infected cells. In this review, we describe our perspective on HIV cure and the new approaches we are undertaking to eradicate the established pro-viral reservoir.
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http://dx.doi.org/10.1186/s12981-017-0177-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5594457PMC
September 2017

An in vitro Model to Mimic Selection of Replication-Competent HIV-1 Intersubtype Recombination in Dual or Superinfected Patients.

J Mol Biol 2017 07 1;429(14):2246-2264. Epub 2017 May 1.

Department of Molecular Biology and Microbiology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Division of Infectious Diseases, Department of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA; Department of Microbiology and Immunology, Western University, London, Ontario N6A 5C1, Canada. Electronic address:

The low frequency of HIV-1 recombinants within entire viral populations in both individual patients and culture-based infection models impedes investigation of the underlying factors contributing to either the occurrence of recombinants or the survival of recombinants once they are formed. So far, most of the related studies have no consideration of recombinants' functionality. Here, we established a functional recombinant production (FRP) system to produce pure and functional HIV-1 intersubtype Env recombinants and utilized 454 pyrosequencing to investigate the distribution of over 4000 functional and non-functional recombination breakpoints from either the FRP system or dual infection cultures. The results revealed that most of the breakpoints converged in gp41 (62%) and C1 (25.3%) domains of gp120, which has strong correlation with the similarity between the two recombining sequences. Yet, the breakpoints also appeared in C2 (5.2%) and C5 (4.6%) domains not correlated with the recombining sequence similarity. Interestingly, none of the intersubtype gp120 recombinants recombined between C1 and gp41 regions either from the FRP system or from the dual infection culture, and very few from the HIV epidemic were functional. The present study suggests that the selection of functional Env recombinants is one of the reasons for the predominance of C1 and gp41 Env recombinants in the HIV epidemic, and it provides an in vitro model to mimic the selection of replication-competent HIV-1 intersubtype recombination in dual or superinfected patients.
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http://dx.doi.org/10.1016/j.jmb.2017.04.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6202033PMC
July 2017

Intravaginal immunisation using a novel antigen-releasing ring device elicits robust vaccine antigen-specific systemic and mucosal humoral immune responses.

J Control Release 2017 03 21;249:74-83. Epub 2017 Jan 21.

Imperial College London, Department of Medicine, Division of Infectious Diseases, Section of Virology, Norfolk Place, London W2 1PG, UK.

The generation of effective levels of antigen-specific immunity at the mucosal sites of pathogen entry is a key goal for vaccinologists. We explored topical vaginal application as an approach to initiate local antigen-specific immunity, enhance previously existing systemic immunity or re-target responses to the mucosae. To deliver a protein vaccine formulation to the vaginal mucosal surface, we used a novel vaginal ring device comprising a silicone elastomer body into which three freeze-dried, rod-shaped, hydroxypropylmethylcellulose inserts were incorporated. Each rod contained recombinant HIV-1 CN54gp140 protein (167μg)±R848 (167μg) adjuvant. The inserts were loaded into cavities within each ring such that only the ends of the inserts were initially exposed. Sheep received a prime-boost vaccination regime comprising intramuscular injection of 100μg CN54gp140+200μg R848 followed by three successive ring applications of one week duration and separated by one month intervals. Other sheep received only the ring devices without intramuscular priming. Serum and vaginal mucosal fluids were sampled every two weeks and analysed by CN54gp140 ELISA and antigen-specific B cells were measured by flow cytometry at necropsy. Vaccine antigen-specific serum antibody responses were detected in both the intramuscularly-primed and vaginal mucosally-primed groups. Those animals that received only vaginal vaccinations had identical IgG but superior IgA responses. Analysis revealed that all animals exhibited mucosal antigen-specific IgG and IgA with the IgA responses 30-fold greater than systemic levels. Importantly, very high numbers of antigen-specific B cells were detected in local genital draining lymph nodes. We have elicited local genital antigen-specific immune responses after topical application of an adjuvanted antigen formulation within a novel vaginal ring vaccine release device. This regimen and delivery method elicited high levels of antigen-specific mucosal IgA and large numbers of local antigen-reactive B cells, both likely essential for effective mucosal protection.
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http://dx.doi.org/10.1016/j.jconrel.2017.01.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5333785PMC
March 2017

First Phase I human clinical trial of a killed whole-HIV-1 vaccine: demonstration of its safety and enhancement of anti-HIV antibody responses.

Retrovirology 2016 Nov 28;13(1):82. Epub 2016 Nov 28.

Department of Microbiology and Immunology, Schulich School of Medicine and Dentistry, The University of Western Ontario, 1400 Western Road, London, ON, N6G 2V4, Canada.

Background: Vaccination with inactivated (killed) whole-virus particles has been used to prevent a wide range of viral diseases. However, for an HIV vaccine this approach has been largely negated due to inherent safety concerns, despite the ability of killed whole-virus vaccines to generate a strong, predominantly antibody-mediated immune response in vivo. HIV-1 Clade B NL4-3 was genetically modified by deleting the nef and vpu genes and substituting the coding sequence for the Env signal peptide with that of honeybee melittin signal peptide to produce a less virulent and more replication efficient virus. This genetically modified virus (gmHIV-1) was inactivated and formulated as a killed whole-HIV vaccine, and then used for a Phase I human clinical trial (Trial Registration: Clinical Trials NCT01546818). The gmHIV-1 was propagated in the A3.01 human T cell line followed by virus purification and inactivation with aldrithiol-2 and γ-irradiation. Thirty-three HIV-1 positive volunteers receiving cART were recruited for this observer-blinded, placebo-controlled Phase I human clinical trial to assess the safety and immunogenicity.

Results: Genetically modified and killed whole-HIV-1 vaccine, SAV001, was well tolerated with no serious adverse events. HIV-1-specific PCR showed neither evidence of vaccine virus replication in the vaccine virus-infected human T lymphocytes in vitro nor in the participating volunteers receiving SAV001 vaccine. Furthermore, SAV001 with adjuvant significantly increased the pre-existing antibody response to HIV-1 proteins. Antibodies in the plasma of vaccinees were also found to recognize HIV-1 envelope protein on the surface of infected cells as well as showing an enhancement of broadly neutralizing antibodies inhibiting tier I and II of HIV-1 B, D, and A subtypes.

Conclusion: The killed whole-HIV vaccine, SAV001, is safe and triggers anti-HIV immune responses. It remains to be determined through an appropriate trial whether this immune response prevents HIV infection.
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http://dx.doi.org/10.1186/s12977-016-0317-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5126836PMC
November 2016

CD71 targeting boosts immunogenicity of sublingually delivered influenza haemagglutinin antigen and protects against viral challenge in mice.

J Control Release 2016 06 16;232:75-82. Epub 2016 Apr 16.

Imperial College London, Mucosal Infection and Immunity, Section of Virology, St Mary's Campus, London W2 1PG, United Kingdom. Electronic address:

The delivery of vaccines to the sublingual mucosa is an attractive prospect due to the ease and acceptability of such an approach. However, novel adjuvant and delivery approaches are required to optimally vaccinate at this site. We have previously shown that conjugation of protein antigen to the iron transport molecule, transferrin, can significantly enhance mucosal immune responses. We tested whether conjugating influenza haemagglutinin to transferrin could improve the immune response to sublingually delivered antigen. Transferrin conjugated haemagglutinin induced a significant antibody and T cell response in both naïve animals and previously immunized animals. The immune response generated was able to protect mice against influenza virus challenge. Sublingually administered antigen dispersed more widely through the gastro-intestinal tract than intranasally delivered antigen and transferrin conjugation had a more marked effect on sublingually delivered antigen than intranasal immunisation. From these studies we conclude that transferrin conjugation of antigen is effective at boosting immune responses to sublingually delivered antigen and may be an attractive approach for influenza vaccines, particularly when mass campaigns are required.
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http://dx.doi.org/10.1016/j.jconrel.2016.04.022DOI Listing
June 2016

TLR4 and TLR7/8 Adjuvant Combinations Generate Different Vaccine Antigen-Specific Immune Outcomes in Minipigs when Administered via the ID or IN Routes.

PLoS One 2016 10;11(2):e0148984. Epub 2016 Feb 10.

Imperial College London, Department of Infectious Diseases, Division of Medicine, Norfolk Place, London, W2 1PG, United Kingdom.

The induction of high levels of systemic and mucosal humoral immunity is a key goal for many prophylactic vaccines. However, adjuvant strategies developed in mice have often performed poorly in the clinic. Due to their closer similarity to humans, minipigs may provide a more accurate picture of adjuvant performance. Based on their complementary signalling pathways, we assessed humoral immune responses to model antigens after co-administration with the toll-like receptor 4 (TLR4) stimulator glucopyranosyl lipid adjuvant (GLA-AF) or the TLR7/8 agonist resiquimod (R848) (alone and in combination) via the intradermal (ID), intranasal (IN) or combined routes in the Gottingen minipig animal model. Surprisingly, we discovered that while GLA-AF additively enhanced the adjuvant effect of R848 when injected ID, it abrogated the adjuvant activity of R848 after IN inoculation. We then performed a route comparison study using a CN54 gp140 HIV Envelope model antigen adjuvanted with R848 + GLA-AF (ID) or R848 alone (IN). Animals receiving priming inoculations via one route were then boosted by the alternate route. Although differences were observed in the priming phase (IN or ID), responses converged upon boosting by the alternative route with no observable impact resultant from the order of administration (ID/IN vs IN/ID). Specific IgG responses were measured at a distal mucosal site (vaginal), although there was no evidence of mucosal linkage as these closely reflected serum antibody levels. These data indicate that the complex in vivo cross-talk between innate pathways are likely tissue specific and cannot be predicted by simple in vitro models.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0148984PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4749393PMC
July 2016

Plasmid DNA Vaccine Co-Immunisation Modulates Cellular and Humoral Immune Responses Induced by Intranasal Inoculation in Mice.

PLoS One 2015 6;10(11):e0141557. Epub 2015 Nov 6.

Mucosal Infection and Immunity Group, Department of Infectious Diseases, Division of Medicine, Imperial College, London, United Kingdom.

Background: An effective HIV vaccine will likely require induction of both mucosal and systemic cellular and humoral immune responses. We investigated whether intramuscular (IM) delivery of electroporated plasmid DNA vaccine and simultaneous protein vaccinations by intranasal (IN) and IM routes could be combined to induce mucosal and systemic cellular and humoral immune responses to a model HIV-1 CN54 gp140 antigen in mice.

Results: Co-immunisation of DNA with intranasal protein successfully elicited both serum and vaginal IgG and IgA responses, whereas DNA and IM protein co-delivery did not induce systemic or mucosal IgA responses. Cellular IFNγ responses were preserved in co-immunisation protocols compared to protein-only vaccination groups. The addition of DNA to IN protein vaccination reduced the strong Th2 bias observed with IN protein vaccination alone. Luminex analysis also revealed that co-immunisation with DNA and IN protein induced expression of cytokines that promote B-cell function, generation of TFH cells and CCR5 ligands that can reduce HIV infectivity.

Significance: These data suggest that while IN inoculation alone elicits both cellular and humoral responses, co-administration with homologous DNA vaccination can tailor these towards a more balanced Th1/Th2 phenotype modulating the cellular cytokine profile while eliciting high-levels of antigen-specific antibody. This work provides insights on how to generate differential immune responses within the same vaccination visit, and supports co-immunisation with DNA and protein by a mucosal route as a potential delivery strategy for HIV vaccines.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0141557PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4636430PMC
June 2016

Enhanced immunogenicity of an HIV-1 DNA vaccine delivered with electroporation via combined intramuscular and intradermal routes.

J Virol 2014 Jun 9;88(12):6959-69. Epub 2014 Apr 9.

Mucosal Infection & Immunity Group, Section of Infectious Diseases, Imperial College London, St Mary's Campus, London, United Kingdom

Unlabelled: It is accepted that an effective prophylactic HIV-1 vaccine is likely to have the greatest impact on viral transmission rates. As previous reports have implicated DNA-priming, protein boost regimens to be efficient activators of humoral responses, we sought to optimize this regimen to further augment vaccine immunogenicity. Here we evaluated single versus concurrent intradermal (i.d.) and intramuscular (i.m.) vaccinations as a DNA-priming strategy for their abilities to elicit humoral and cellular responses against a model HIV-1 vaccine antigen, CN54-gp140. To further augment vaccine-elicited T and B cell responses, we enhanced cellular transfection with electroporation and then boosted the DNA-primed responses with homologous protein delivered subcutaneously (s.c.), intranasally (i.n.), i.m., or transcutaneously (t.c.). In mice, the concurrent priming regimen resulted in significantly elevated gamma interferon T cell responses and high-avidity antigen-specific IgG B cell responses, a hallmark of B cell maturation. Protein boosting of the concurrent DNA strategy further enhanced IgG concentrations but had little impact on T cell reactivity. Interestingly protein boosting by the subcutaneous route increased antibody avidity to a greater extent than protein boosting by either the i.m., i.n., or t.c. route, suggesting that this route may be preferential for driving B cell maturation. Using an alternative and larger animal model, the rabbit, we found the concurrent DNA-priming strategy followed by s.c. protein boosting to again be capable of eliciting high-avidity humoral responses and to also be able to neutralize HIV-1 pseudoviruses from diverse clades (clades A, B, and C). Taken together, we show that concurrent multiple-route DNA vaccinations induce strong cellular immunity, in addition to potent and high-avidity humoral immune responses.

Importance: The route of vaccination has profound effects on prevailing immune responses. Due to the insufficient immunogenicity and protection of current DNA delivery strategies, we evaluated concurrent DNA delivery via simultaneous administration of plasmid DNA by the i.m. and i.d. routes. The rationale behind this study was to provide clear evidence of the utility of concurrent vaccinations for an upcoming human clinical trial. Furthermore, this work will guide future preclinical studies by evaluating the use of model antigens and plasmids for prime-boost strategies. This paper will be of interest not only to virologists and vaccinologists working in the HIV field but also to researchers working in other viral vaccine settings and, critically, to the wider field of vaccine delivery.
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http://dx.doi.org/10.1128/JVI.00183-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4054344PMC
June 2014

Polymeric penetration enhancers promote humoral immune responses to mucosal vaccines.

J Control Release 2014 Jun 20;183:43-50. Epub 2014 Mar 20.

Imperial College London, Department of Infectious Diseases, Division of Medicine, Norfolk Place, London W2 1PG, UK. Electronic address:

Protective mucosal immune responses are thought best induced by trans-mucosal vaccination, providing greater potential to generate potent local immune responses than conventional parenteral vaccination. However, poor trans-mucosal permeability of large macromolecular antigens limits bioavailability to local inductive immune cells. This study explores the utility of polymeric penetration enhancers to promote trans-mucosal bioavailability of insulin, as a biomarker of mucosal absorption, and two vaccine candidates: recombinant HIV-1 envelope glycoprotein (CN54gp140) and tetanus toxoid (TT). Responses to vaccinating antigens were assessed by measurement of serum and the vaginal humoral responses. Polyethyleneimine (PEI), Dimethyl-β-cyclodextrin (DM-β-CD) and Chitosan enhanced the bioavailability of insulin following intranasal (IN), sublingual (SL), intravaginal (I.Vag) and intrarectal (IR) administration. The same penetration enhancers also increased antigen-specific IgG and IgA antibody responses to the model vaccine antigens in serum and vaginal secretions following IN and SL application. Co-delivery of both antigens with PEI or Chitosan showed the highest increase in systemic IgG and IgA responses following IN or SL administration. However the highest IgA titres in vaginal secretions were achieved after IN immunisations with PEI and Chitosan. None of the penetration enhancers were able to increase antibody responses to gp140 after I.Vag immunisations, while in contrast PEI and Chitosan were able to induce TT-specific systemic IgG levels following I.Vag administration. In summary, we present supporting data that suggest appropriate co-formulation of vaccine antigens with excipients known to influence mucosal barrier functions can increase the bioavailability of mucosally applied antigens promoting the induction of mucosal and systemic antibody responses.
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http://dx.doi.org/10.1016/j.jconrel.2014.03.018DOI Listing
June 2014

Glucopyranosyl lipid A adjuvant significantly enhances HIV specific T and B cell responses elicited by a DNA-MVA-protein vaccine regimen.

PLoS One 2014 23;9(1):e84707. Epub 2014 Jan 23.

Imperial College London, Department of Infectious Diseases, Division of Medicine, Norfolk Place, London, United Kingdom.

Using a unique vaccine antigen matched and single HIV Clade C approach we have assessed the immunogenicity of a DNA-poxvirus-protein strategy in mice and rabbits, administering MVA and protein immunizations either sequentially or simultaneously and in the presence of a novel TLR4 adjuvant, GLA-AF. Mice were vaccinated with combinations of HIV env/gag-pol-nef plasmid DNA followed by MVA-C (HIV env/gag-pol-nef) with HIV CN54gp140 protein (+/-GLA-AF adjuvant) and either co-administered in different muscles of the same animal with MVA-C or given sequentially at 3-week intervals. The DNA prime established a population of B cells that were able to mount a statistically significant anamnestic response to the boost vaccines. The greatest antigen-specific antibody response was observed in animals that received all vaccine components. Moreover, a high proportion of the total mucosal IgG (20 - 50%) present in the vaginal vault of these vaccinated animals was vaccine antigen-specific. The potent elicitation of antigen-specific immune responses to this vaccine modality was also confirmed in rabbits. Importantly, co-administration of MVA-C with the GLA-AF adjuvanted HIV CN54gp140 protein significantly augmented the antigen-specific T cell responses to the Gag antigen, a transgene product expressed by the MVA-C vector in a separate quadriceps muscle. We have demonstrated that co-administration of MVA and GLA-AF adjuvanted HIV CN54gp140 protein was equally effective in the generation of humoral responses as a sequential vaccination modality thus shortening and simplifying the immunization schedule. In addition, a significant further benefit of the condensed vaccination regime was that T cell responses to proteins expressed by the MVA-C were potently enhanced, an effect that was likely due to enhanced immunostimulation in the presence of systemic GLA-AF.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0084707PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900398PMC
November 2014

Mucosal application of gp140 encoding DNA polyplexes to different tissues results in altered immunological outcomes in mice.

PLoS One 2013 24;8(6):e67412. Epub 2013 Jun 24.

Section of Infectious Diseases, Department of Medicine, Imperial College London, London, United Kingdom.

Increasing evidence suggests that mucosally targeted vaccines will enhance local humoral and cellular responses whilst still eliciting systemic immunity. We therefore investigated the capacity of nasal, sublingual or vaginal delivery of DNA-PEI polyplexes to prime immune responses prior to mucosal protein boost vaccination. Using a plasmid expressing the model antigen HIV CN54gp140 we show that each of these mucosal surfaces were permissive for DNA priming and production of antigen-specific antibody responses. The elicitation of systemic immune responses using nasally delivered polyplexed DNA followed by recombinant protein boost vaccination was equivalent to a systemic prime-boost regimen, but the mucosally applied modality had the advantage in that significant levels of antigen-specific IgA were detected in vaginal mucosal secretions. Moreover, mucosal vaccination elicited both local and systemic antigen-specific IgG(+) and IgA(+) antibody secreting cells. Finally, using an Influenza challenge model we found that a nasal or sublingual, but not vaginal, DNA prime/protein boost regimen protected against infectious challenge. These data demonstrate that mucosally applied plasmid DNA complexed to PEI followed by a mucosal protein boost generates sufficient antigen-specific humoral antibody production to protect from mucosal viral challenge.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067412PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3691144PMC
February 2014

Pulmonary delivery of DNA vaccine constructs using deacylated PEI elicits immune responses and protects against viral challenge infection.

J Control Release 2013 Sep 14;170(3):452-9. Epub 2013 Jun 14.

Imperial College London, Department of Infectious Diseases, Division of Medicine, Norfolk Place, London W2 1PG, UK.

Vaccination through mucosal surfaces has been shown to elicit antiviral immune responses against a number of mucosal pathogens. Here we demonstrate that both mucosal and systemic immune responses can be elicited against a model HIV-1 CN54gp140 antigen when cation-complexed plasmid DNA vaccines are applied topically to the murine pulmonary mucosa as an immune priming strategy. Furthermore, using an influenza challenge model we show that a plasmid DNA vaccine complexed to a less toxic form of PEI called dPEI (a nearly fully hydrolysed linear PEI with 11% additional free protonatable nitrogen atoms) can provide significant protection against a respiratory challenge infection in mice. Furthermore, we show that dPEI polyplexes have the potential to transfect not only mucosal epithelium, but also to enter deeper into tissues through the modulation of tight junction integrity. Taken together, these results demonstrate that less toxic forms of PEI can be effective delivery vehicles for plasmid DNAs to elicit cellular and humoral protective responses in vivo. Moreover, our observations suggest that these less toxic derivatives of PEI could be utilised for topical plasmid DNA vaccine delivery to human mucosal tissue surfaces, and that this application may permit dissemination of the immune responses through the linked mucosal network thus providing protective immunity at distal portals of pathogen entry.
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http://dx.doi.org/10.1016/j.jconrel.2013.06.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3767111PMC
September 2013

Generation of self-renewing immature dendritic cells from mouse spleen that can take up mycobacteria and present antigens to T cells.

APMIS 2010 Oct;118(10):729-38

Department for Cellular and Molecular Medicine, St George's University of London, London, UK.

Dendritic cells (DC) play a key role in driving the adaptive immune response to Mycobacterium tuberculosis (MTB), the causative pathogen of tuberculosis (TB). However, studying these important yet very sparse immune cells in the context of MTB pathogenesis is severely restricted by the lack of suitable cell lines and the complexity of culturing of DC progenitors, usually obtained from the bone marrow. However, significant advances have been made towards generating long-term DC cultures from various lymphoid tissues. Here, we report the evidence for generating a long-term, self-renewing DC culture from the Balb/c mouse spleen. We demonstrate that these cells, termed IDC-3, have a myeloid DC origin, i.e. they are CD11c(+) CD11b(++) CD8-α(-) F4/80(+/-) and that they also display a phenotype MHC-II(+) CD16/32(++) CD80(+/-) CD86(+) , indicating that they are immature DC. Following incubation with Mycobacterium bovis BCG (Bacillus Calmette Guerin), the IDC-3 efficiently took up bacteria and acquired the morphology of mature DC. Importantly though, when IDC-3 were pre-stimulated with a mycobacterial antigen in vitro, they were able to induce proliferation of T lymphocytes from mice immunized with the same antigen. The T-cell stimulatory potential of IDC-3 was further enhanced when the cells were co-stimulated with an anti-CD40 mAb. We therefore suggest that the IDC-3 culture system could be a useful tool for studying the interaction of DC with mycobacteria.
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http://dx.doi.org/10.1111/j.1600-0463.2010.02650.xDOI Listing
October 2010

Lipid vesicle size of an oral influenza vaccine delivery vehicle influences the Th1/Th2 bias in the immune response and protection against infection.

Vaccine 2009 Jun 5;27(27):3643-9. Epub 2009 Apr 5.

Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, Scotland, UK.

Previous studies, using parenteral administration of antigen in lipid vesicles, have indicated a possible role for vesicle size in determining the Th1/Th2 bias of the resulting immune response. We have also demonstrated that the incorporation of bile salts into lipid vesicles (bilosomes) allows successful induction of mucosal and systemic immunity via the oral route. The following study was therefore carried out to determine whether size could also influence the Th1/Th2 bias in the immune response to bilosome entrapped influenza A antigen containing haemagglutinin administered by the oral route in the mouse and whether this could influence the disease process in the classical ferret model of disease. Consequently we produced two formulations of influenza A antigen entrapped in bilosomes: BV3 which contained a single population (range 10-100 nm, Z-average diameter 250 nm) and BV which had two populations (60-350 and 400-2,500 nm, Z-average 980 nm). Following oral vaccination of BALB/c mice, BV was found to generate an immune response that had a significantly greater Th1 bias than BV3 as measured by serum IgG2a production and antigen-induced spleen cell IFN-gamma production. In the traditional infection challenge model (ferrets) vaccination with BV (large) vesicles resulted in greater protection in terms of symptom-score and a higher responder number. However, both oral vaccine formulations were an improvement on intramuscular administration in terms of higher antibody production, lower temperatures, and reduced symptoms over time, post-infection. The results presented here demonstrate that oral vaccine formulations can be physically modified to manipulate resultant immune responses following vaccination and consequently can be designed to enhance the effectiveness of candidate vaccine antigens.
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http://dx.doi.org/10.1016/j.vaccine.2009.03.040DOI Listing
June 2009

Delivery systems: a vaccine strategy for overcoming mucosal tolerance?

Expert Rev Vaccines 2009 Jan;8(1):103-12

University of London, St George's, London SW170RE, UK.

Antigens administered via the oral and, to a lesser extent, the nasal route are potentially able to invoke tolerance, resulting in a nonreactive immune response. This has been a hurdle for mucosal vaccine development and yet the desire to induce protective local and systemic responses, with pain-free and more convenient products, has been the impetus driving mucosal vaccine R&D. Nevertheless, few mucosal vaccines have reached the marketplace and products are still treated with caution, particularly where live organisms are utilized. In this review, we examine the use of delivery systems with adjuvant properties as key components in a vaccine strategy that does not require the use of live vectors to overcome tolerance and have exemplified their success in mucosal vaccines, concentrating on the nasal and oral routes of administration.
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http://dx.doi.org/10.1586/14760584.8.1.103DOI Listing
January 2009

Oral delivery of tetanus toxoid using vesicles containing bile salts (bilosomes) induces significant systemic and mucosal immunity.

Methods 2006 Feb;38(2):90-5

Department of Immunology, Strathclyde Institute for Biomedical Sciences, John Arbuthnott Building, University of Strathclyde, Glasgow G4 0NR, UK.

Protein antigens administered via the oral route are exposed to a hostile environment in the gastrointestinal tract, consisting of digestive enzymes and a range of pH (1-7.5). Using a delivery system can afford protection to entrapped components against degradation and permit delivery of antigen to the cells responsible for generating local and systemic immune responses. In this comparative study, mice were immunised orally with tetanus toxoid (40 or 200 microg dose/mouse, four doses in total) entrapped in non-ionic surfactant vesicles formulated with bile salts (bilosomes). The higher entrapped dose (BV-TT, 200 microg) induced IgG1 by study week 3 to similar levels to those observed with subcutaneous un-entrapped TT at the lower (<50 microg) dose. However, both bilosome formulations (BV-TT, low, and high doses), though not un-entrapped TT, caused a rise in the numbers of IgA positive plasma cells observed in the small intestine, primarily in the first 15 cm of the small intestine.
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http://dx.doi.org/10.1016/j.ymeth.2005.11.002DOI Listing
February 2006

Optimisation of a lipid based oral delivery system containing A/Panama influenza haemagglutinin.

Vaccine 2004 Jun;22(19):2425-9

Department of Immunology, University of Strathclyde, Arbuthnott Building, SIBS, 27 Taylor Street, Glasgow, G4 0NR, Scotland, UK.

Vaccine antigens administered by the oral route are often degraded by gastric secretions during gastrointestinal transit. This necessitates larger and more frequent doses of antigen for vaccination. A delivery system, which overcomes this, is a lipid vesicle containing bile salts (bilosome), which prevents antigen degradation and enhances mucosal penetration. The effect of bilosome formulation modification on vaccine transit efficacy across the mucosa was determined. Specific antibody levels were assessed by end-point titre ELISA and the subclasses determined. Significant IgG1 titres were induced when the protein loading was doubled from 15 to 30 microg (P=0.009) and was equivalent to antigen administration by the subcutaneous route. No IgG2a was induced, indicating the generation of a TH2 response. Significant mucosal IgA levels were also observed with this treatment group (P=0.05).
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http://dx.doi.org/10.1016/j.vaccine.2003.11.067DOI Listing
June 2004

Immune responses to a GnRH-based anti-fertility immunogen, induced by different adjuvants and subsequent effect on vaccine efficacy.

Vaccine 2004 Feb;22(8):1024-31

Department of Immunology, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, Scotland, UK.

A modified GnRH peptide (CHWSYGLRPG-NH2) was conjugated to tetanus toxoid and formulated with different adjuvants (non-ionic surfactant vesicles, aluminium hydroxide, Quil A, PLGA (poly(lactide-co-glycolide)/triacetin), and Quil A/PLGA). A comparison of the anti-fertility efficacy of the formulations was made by examining specific antibody levels, antibody subclasses, endocrine ablation and gonadal atrophy. The production of IgG2b antibody provided the best correlation for castration. PLGA was considered the most effective adjuvant as it produced a consistent anti-fertility response in all the treated animals.
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http://dx.doi.org/10.1016/j.vaccine.2003.08.043DOI Listing
February 2004