A J Paramyxovirus-vectored HIV vaccine induces humoral and cellular responses in mice

Human immunodeficiency virus (HIV) infects and depletes CD4+ T-cells, resulting in Acquired Immunodeficiency Syndrome (AIDS) and death. Despite numerous clinical trials, there is no licensed HIV vaccine. The HIV envelope glycoprotein (env) is a major target for vaccine development, especially for the development of antibody-mediated protection. In this study, we used J paramyxovirus (JPV) as a viral vector to express HIV-env. We replaced the JPV small hydrophobic (SH) gene with HIV-env (rJPV-env). Intranasal rJPV-env immunization induced anti-HIV-gp120 IgG antibodies in mice. Furthermore, we examined the immunogenicity of homologous and heterologous prime/boost regimens with rJPV-env, parainfluenza virus 5 (rPIV5)-vectored HIV-env, and HIV-Gag-Env virus-like particles (VLPs). The rJPV-env/rPIV5-env heterologous prime/boost regimen induced the strongest humoral and cellular responses. Introducing a third dose of immunization, mice that received a viral-vectored prime had high levels of HIV-env-specific cellular responses, with group rJPV-env/rPIV5-env/VLP having the highest. Together, this work indicates that a heterologous combination of viral-vectored HIV-env vaccines and a HIV-Gag-Env VLP induces high levels of humoral and cellular responses against HIV in mice.

Combined intranasal and intramuscular parainfluenza 5-, simian adenovirus ChAdOx1- and poxvirus MVA-vectored vaccines induce synergistically HIV-1-specific T cells in the mucosa

Introduction

The primary goal of this work is to broaden and enhance the options for induction of protective CD8⁺ T cells against HIV-1 and respiratory pathogens.

Methods

We explored the advantages of the parainfluenza virus 5 (PIV5) vector for delivery of pathogen-derived transgenes alone and in combination with the in-human potent regimen of simian adenovirus ChAdOx1 prime-poxvirus MVA boost delivering bi-valent mosaic of HIV-1 conserved regions designated HIVconsvX.

Results

We showed in BALB/c mice that the PIV5 vector expressing the HIVconsvX immunogens could be readily incorporated with the other two vaccine modalities into a single regimen and that for specific vector combinations, mucosal CD8⁺ T-cell induction was enhanced synergistically by a combination of the intranasal and intramuscular routes of administration.

Discussion

Encouraging safety and immunogenicity data from phase 1 human trials of ChAdOx1- and MVA-vectored vaccines for HIV-1, and PIV5-vectored vaccines for SARS-CoV-2 and respiratory syncytial virus pave the way for combining these vectors for HIV-1 and other indications in humans.

Efficacy of Parainfluenza Virus 5 (PIV5)-vectored Intranasal COVID-19 Vaccine as a Single Dose Vaccine and as a Booster against SARS-CoV-2 Variants

Immunization with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines has greatly reduced coronavirus disease 2019 (COVID-19)-related deaths and hospitalizations, but waning immunity and the emergence of variants capable of immune escape indicate the need for novel SARS-CoV-2 vaccines. An intranasal parainfluenza virus 5 (PIV5)-vectored COVID-19 vaccine CVXGA1 has been proven efficacious in animal models and blocks contact transmission of SARS-CoV-2 in ferrets. CVXGA1 vaccine is currently in human clinical trials in the United States. This work investigates the immunogenicity and efficacy of CVXGA1 and other PIV5-vectored vaccines expressing additional antigen SARS-CoV-2 nucleoprotein (N) or SARS-CoV-2 variant spike (S) proteins of beta, delta, gamma, and omicron variants against homologous and heterologous challenges in hamsters. A single intranasal dose of CVXGA1 induces neutralizing antibodies against SARS-CoV-2 WA1 (ancestral), delta variant, and omicron variant and protects against both homologous and heterologous virus challenges. Compared to mRNA COVID-19 vaccine, neutralizing antibody titers induced by CVXGA1 were well-maintained over time. When administered as a boost following two doses of a mRNA COVID-19 vaccine, PIV5-vectored vaccines expressing the S protein from WA1 (CVXGA1), delta, or omicron variants generate higher levels of cross-reactive neutralizing antibodies compared to three doses of a mRNA vaccine. In addition to the S protein, the N protein provides added protection as assessed by the highest body weight gain post-challenge infection. Our data indicates that PIV5-vectored COVID-19 vaccines, such as CVXGA1, can serve as booster vaccines against emerging variants.

Protection of K18-hACE2 mice and ferrets against SARS-CoV-2 challenge by a single-dose mucosal immunization with a parainfluenza virus 5-based COVID-19 vaccine

Transmission-blocking vaccines are urgently needed to reduce transmission of SARS-CoV 2, the cause of the COVID-19 pandemic. The upper respiratory tract is an initial site of SARS-CoV-2 infection and, for many individuals, remains the primary site of virus replication. An ideal COVID-19 vaccine should reduce upper respiratory tract virus replication and block transmission as well as protect against severe disease. Here, we optimized a vaccine candidate, parainfluenza virus 5 (PIV5) expressing the SARS-CoV-2 S protein (CVXGA1), and then demonstrated that a single-dose intranasal immunization with CVXGA1 protects against lethal infection of K18-hACE2 mice, a severe disease model. CVXGA1 immunization also prevented virus infection of ferrets and blocked contact transmission. This mucosal vaccine strategy inhibited SARS-CoV-2 replication in the upper respiratory tract, thus preventing disease progression to the lower respiratory tract. A PIV5-based mucosal vaccine provides a strategy to induce protective innate and cellular immune responses and reduce SARS-CoV-2 infection and transmission in populations.

Parainfluenza Virus 5 Priming Followed by SIV/HIV Virus-Like-Particle Boosting Induces Potent and Durable Immune Responses in Nonhuman Primates

The search for a preventive vaccine against HIV infection remains an ongoing challenge, indicating the need for novel approaches. Parainfluenza virus 5 (PIV5) is a paramyxovirus replicating in the upper airways that is not associated with any animal or human pathology. In animal models, PIV5-vectored vaccines have shown protection against influenza, RSV, and other human pathogens. Here, we generated PIV5 vaccines expressing HIV envelope (Env) and SIV Gag and administered them intranasally to macaques, followed by boosting with virus-like particles (VLPs) containing trimeric HIV Env. Moreover, we compared the immune responses generated by PIV5-SHIV prime/VLPs boost regimen in naïve vs a control group in which pre-existing immunity to the PIV5 vector was established. We demonstrate for the first time that intranasal administration of PIV5-based HIV vaccines is safe, well-tolerated and immunogenic, and that boosting with adjuvanted trimeric Env VLPs enhances humoral and cellular immune responses. The PIV5 prime/VLPs boost regimen induced robust and durable systemic and mucosal Env-specific antibody titers with functional activities including ADCC and neutralization. This regimen also induced highly polyfunctional antigen-specific T cell responses. Importantly, we show that diminished responses due to PIV5 pre-existing immunity can be overcome in part with VLP protein boosts. Overall, these results establish that PIV5-based HIV vaccine candidates are promising and warrant further investigation including moving on to primate challenge studies.

Cessation from smoking improves innate host defense and clearance of experimentally inoculated nasal S. aureus

Staphylococcus aureus (SA) nasal carriage is transient in most humans and usually benign, but dissemination of SA to extranasal sites causes the majority of clinical infections, and SA is a major cause of serious infections in the U.S. A better understanding of innate nasal decolonization mechanisms is urgently needed, as are relevant models for studying SA clearance. Here, we screened a population of healthy smokers for nasal SA carriage, and compared participants’ abilities to clear experimentally applied nasal SA before and after completion of a smoking cessation program. We determined that cigarette smoking increases mean nasal SA load (2.6×104 CFU/swab) compared to healthy non-smokers (1.7×103 CFU/swab) and might increase the rate of SA nasal carriage in otherwise healthy adults: 22 of 99 smokers carried SA at the screening visit, while only 4 of 30 non-smokers screened positive during the same time period. Only 6 of 19 experimental inoculation studies in active smokers resulted in SA clearance within the month of follow-up, while in the cessation group, 6 of 9 subjects cleared nasal SA and carriage duration averaged 21±4 days. Smoking cessation associated with enhanced expression of SA-associated IL-1β and G-CSF in nasal fluids. Participants who failed to clear SA exhibited higher nasal SA load and elevated nasal interleukin-1 receptor antagonist (IL-1RA) expression at the pre-experiment study visits. We conclude that smokers exhibit higher SA load than non-smokers, and that innate immune pathways including G-CSF expression and signaling through the IL-1 axis are important mediators of nasal SA clearance.

Evaluation of the pig-tailed macaque (Macaca nemestrina) as a model of human Staphylococcus aureus nasal carriage

Staphylococcus aureus (SA) nasal carriage is a common condition effecting both healthy and immunocompromised populations, and provides a reservoir for dissemination of potentially infectious strains by casual contact. Factors regulating the onset and duration of nasal SA colonization are mostly unknown, and a human-relevant animal model is needed. Here, we screened 17 pig-tailed macaques (Macaca nemestrina) for SA carriage, and 14 of 17 animals tested positive in the nose at one or both screening sessions (8 weeks apart), while the other three animals were negative in the nose but positive in the pharynx at least once. Similar to humans, SA colonization was densest in the nose, and treatment of the nostrils with mupirocin ointment effectively cleared the nostrils and 6 extra-nasal body sites. Experimental nasal SA colonization was established with 104 CFU/nostril, and both autologous and non-autologous strains survived over 40 days without any apparent adverse effects. A human nasal SA isolate (D579/ST398) was carried in 4 of 6 animals for over three weeks. Nostrils that did eradicate experimentally applied SA exhibited neutrophilic innate immunity marked by elevated nasal IL-1β, IL-8, and MCP-1, and a 10-fold decreased IL-1RA:IL-1β ratio within 7 days post-inoculation, analogous to the human condition. Taken together, pig-tailed macaques represent a physiological model of human SA nasal carriage with utility for testing natural colonization and decolonization mechanisms, and novel classes of anti-SA therapeutics.