Selected Grantee Publications
Vpr Attenuates Antiviral Immune Responses and Is Critical for Full Pathogenicity of SIVmac239 in Rhesus Macaques
Laliberté et al., iScience. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10679897/
The accessory viral protein R (Vpr) exhibits multilayered functions, and more work is needed to understand its roles in viral replication, immune evasion, and pathogenicity in vivo. Using male and female rhesus macaques, researchers examined how deletion of vpr affects simian immunodeficiency virus (SIV) replication kinetics, innate immune activation, B- and T-cell responses, and neutralizing activity. They found that lack of Vpr delays and attenuates viral replication during acute infection, allowing most animals to mount efficient and persisting immune responses and higher levels of neutralizing antibodies. Overall, these results suggest that Vpr promotes viral replication and innate immune evasion during acute SIV infection. Supported by ORIP (P51OD011133, P51OD011132, S10OD026799).
Deep Analysis of CD4 T Cells in the Rhesus CNS During SIV Infection
Elizaldi et al., PLOS Pathogens. 2023.
https://pubmed.ncbi.nlm.nih.gov/38060615/
Systemic HIV infection results in chronic inflammation that causes lasting damage to the central nervous system (CNS), despite long-term antiretroviral therapy (ART). Researchers studied neurocognitive outcomes in male and female rhesus macaques infected with simian immunodeficiency virus (SIV) using an ART regimen simulating suboptimal adherence; one group received no ART, and the other received ART with periodic interruptions. Using single-cell transcriptomic profiling, the researchers also identified molecular programs induced in the brain upon infection. They found that acute infection led to marked imbalance in the CNS CD4/CD8 T‑cell ratio, which persisted into the chronic phase. The studies provide insight into the role of CD4 T cells in the CNS during HIV infection. Supported by ORIP (P51OD011107, K01OD023034), NIA, NIAID, and NCI.
Cholera Toxin B Scaffolded, Focused SIV V2 Epitope Elicits Antibodies That Influence the Risk of SIVmac251 Acquisition in Macaques
Rahman et al., Frontiers in Immunology. 2023.
https://pubmed.ncbi.nlm.nih.gov/37153584/
Previous work has indicated that the production of antibodies against epitopes in the V2 loop of gp120—a protein component of the viral spikes used to infiltrate host cells—correlates with protection from viral acquisition. Researchers assessed the efficacy of a simian immunodeficiency virus (SIV) vaccine consisting of a V2c epitope scaffolded onto cholera toxin B in rhesus macaques of both sexes. Immunized animals generated V2c-specific antibody responses, and differences in the functional antibody and immune cell responses were observed and compared with responses in a historically protective vaccine regimen. Different responses also were observed when varying adjuvants were administered with the vaccines. Thus, full protection against SIV infection might require vaccines against multiple spike epitopes. Supported by ORIP (P51OD011104, R24OD010976) and NIAID.
Simian Immunodeficiency Virus and Storage Buffer: Field-Friendly Preservation Methods for RNA Viral Detection in Primate Feces
Wilde et al., mSphere. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10732032/
Simian immunodeficiency virus (SIV) infects more than 40 nonhuman primate (NHP) species in sub-Saharan Africa, but testing in wild NHP populations can be challenging. Researchers compared methods for SIV RNA preservation and recovery from NHP fecal samples stored in four different buffers. The goal of this work was to identify a robust “field-friendly” method (i.e., without freezing or refrigeration) for this effort, and the samples were collected from a mantled guereza colobus housed at the Columbus Zoo and Aquarium. The authors reported that the DNA/RNA shield is an optimal buffer for preserving SIV RNA in fecal samples in the field. Their findings will inform future fieldwork and facilitate improved approaches for studies of SIV and other RNA viruses. Supported by ORIP (P51OD011132) and NIAID.
Lymphoid Tissues Contribute to Plasma Viral Clonotypes Early After Antiretroviral Therapy Interruption in SIV-Infected Rhesus Macaques
Solis-Leal et al., Science Translational Medicine. 2023.
https://pubmed.ncbi.nlm.nih.gov/38091409/
Researchers are interested in better understanding the sources, timing, and mechanisms of HIV rebound that occurs after interruption of antiretroviral therapy (ART). Using rhesus macaques (sex not specified), investigators tracked barcoded simian immunodeficiency virus (SIV) clonotypes over time and among tissues. Among the tissues studied, mesenteric lymph nodes, inguinal lymph nodes, and spleen contained viral barcodes detected in plasma. Additionally, the authors reported that CD4+ T cells harbored the most viral RNA after ART interruption. These tissues are likely to contribute to viral reactivation and rebound after ART interruption, but further studies are needed to evaluate the relative potential contributions from other tissues and organs. Supported by ORIP (P51OD011104, P51OD011133, S10OD028732, S10OD028653), NCI, NIMH, and NINDS.
Intradermal but Not Intramuscular Modified Vaccinia Ankara Immunizations Protect Against Intravaginal Tier2 Simian–Human Immunodeficiency Virus Challenges in Female Macaques
Bollimpelli et al., Nature Communications. 2023.
https://www.doi.org/10.1038/s41467-023-40430-7
Researchers have been exploring multiple strategies to develop an HIV vaccine. In this study, the investigators determined the immunogenicity and efficacy of intradermal and intramuscular routes of modified vaccinia Ankara (MVA) vaccination in female rhesus macaques. They found that both routes of MVA vaccination enabled control of viral replication, but only the intradermal vaccination was effective in protection against viral acquisition. Their findings suggest that the intradermal MVA vaccinations provide protection by modulating the innate and T helper responses. Taken together, this work underscores the importance of testing the influence of the route of immunization for HIV vaccines in humans. Supported by ORIP (P51OD011132, R24OD010976) and NIAID.
Host Immunity Associated With Spontaneous Suppression of Viremia in Therapy-Naïve Young Rhesus Macaques Following Neonatal SHIV Infection
Evangelous et al., Journal of Virology. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10688376/
Previously, investigators developed a pediatric rhesus macaque model for simian–human immunodeficiency virus infection that can be exploited to identify host immunity associated with viremia suppression. In the present study, they used the model (with male and female animals) to characterize humoral and cellular immunity and plasma biomarkers associated with spontaneous viremia suppression. They identified CD8-expressing cells and varied T-cell subsets that were associated with viremia suppression. Additionally, the authors observed intermediate monocytes with upregulation of inhibitory genes that previously had been reported only in cytotoxic cells. These findings suggest a complex immunologic milieu of viremia suppression in pediatric populations. Supported by ORIP (P51OD011092, U42OD010426) and NIAID.
Conjugation of HIV-1 Envelope to Hepatitis B Surface Antigen Alters Vaccine Responses in Rhesus Macaques
Nettere et al., NPJ Vaccines. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10673864/
Researchers are interested in developing an HIV-1 vaccine that improves upon the regimen used in the RV144 clinical trial. The authors tested the hypothesis that a conjugate vaccine based on the learned response to immunization with hepatitis B virus could be utilized to expand T-cell help and improve antibody production against HIV-1. Using juvenile rhesus macaques of both sexes, they evaluated the immunogenicity of their conjugate regimen. Their findings suggest that conjugate vaccination can engage both HIV-1 Env– and hepatitis B surface antigen–specific Tcell help and modify antibody responses at early time points. This work may help inform future efforts to improve the durability and efficacy of next-generation HIV vaccines. Supported by ORIP (P51OD011107, K01OD024877) and NIAID.
The Impact of SIV-Induced Immunodeficiency on Clinical Manifestation, Immune Response, and Viral Dynamics in SARS-CoV-2 Coinfection
Melton et al., bioRxiv. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10680717/
The effects of immunodeficiency caused by chronic HIV infection on COVID-19 have not been directly addressed in a controlled setting. Investigators conducted a pilot study in which two pigtail macaques (PTMs) chronically infected with SIVmac239 were exposed to SARS-CoV-2 and compared with SIV-naive PTMs infected with SARS-CoV-2. Despite the marked decrease in CD4+ T cells in the SIV-positive animals prior to exposure to SARS-CoV-2, investigators found that disease progression, viral persistence, and evolution of SARS-CoV-2 were comparable to the control group. These findings suggest that SIV-induced immunodeficiency alters the immune response to SARS-CoV-2 infection, leading to impaired cellular and humoral immunity. However, this impairment does not significantly alter the course of infection. Supported by ORIP (P51OD011104, U42OD013117, S10OD026800, S10OD030347) and NIAID.
A Combined Adjuvant Approach Primes Robust Germinal Center Responses and Humoral Immunity in Non-Human Primates
Phung et al., Nature Communications. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10625619/
Protein antigens require adjuvants for high immunogenicity, and delivery kinetics are a critical component of rational HIV vaccine design. Investigators employed a combined adjuvant approach (i.e., short phosphoserine peptide linkers that promote tight binding to aluminum hydroxide, plus saponin/MPLA nanoparticles) with slow antigen delivery and potent immune-stimulating complexes in rhesus macaques of both sexes. They reported that pSer-modified antigen shifts immunodominance to allow subdominant epitope-targeting of rare B cells. These findings indicate that a combined adjuvant approach can augment humoral immunity by modulating immunodominance, and this work can be applied for the development of clinical therapeutics. Supported by ORIP (P51OD011104) and NIAID.