Selected Grantee Publications
Deciphering the Role of Mucosal Immune Responses and the Cervicovaginal Microbiome in Resistance to HIV Infection in HIV-Exposed Seronegative Women
Ponnan et al., Microbiology Spectrum. 2021.
https://journals.asm.org/doi/10.1128/Spectrum.00470-21
Identifying correlates of protection in HIV-exposed seronegative (HESN) individuals requires identification of HIV-specific local immune responses. Researchers performed a comprehensive investigation of the vaginal mucosa and cervicovaginal microbiome in HESN women. They found elevated antiviral cytokines, soluble immunoglobulins, activated NK cells, CXCR5+ CD8+ T cells, and T follicular helper cells in HESN women compared to HIV-unexposed healthy women. They also found greater bacterial diversity and increased abundance of Gardnerella species in the mucosa of HESN women. These findings suggest that the genital tract of HESN women contains innate immune factors, antiviral mediators, and T cell subsets that protect against HIV. Supported by ORIP (P51OD011132) and NIAID.
CD4+ T Cells Are Dispensable for Induction of Broad Heterologous HIV Neutralizing Antibodies in Rhesus Macaques
Sarkar et al., Frontiers in Immunology. 2021.
https://www.frontiersin.org/articles/10.3389/fimmu.2021.757811/full
Researchers investigated the humoral response in vaccinated rhesus macaques with CD4+ T cell depletion, using the VC10014 DNA protein co-immunization vaccine platform (with gp160 plasmids and gp140 trimeric proteins derived from an HIV-1 infected subject). Both CD4+-depleted and non-depleted animals developed comparable Tier 1 and 2 heterologous HIV-1 neutralizing plasma antibody titers. Thus, primates generate HIV neutralizing antibodies in the absence of robust CD4+ T cell help, which has important implications for vaccine development. Supported by ORIP (P51OD011092, P40OD028116, U42OD023038, U42OD010426), NIAID, and NIDCR.
A Large Repertoire of B Cell Lineages Targeting One Cluster of Epitopes in a Vaccinated Rhesus Macaque
Li et al., Vaccine. 2021.
https://www.sciencedirect.com/science/article/pii/S0264410X21010355?via%3Dihub=
A rhesus macaque that was serially immunized six times with the 8-mer epitope for human monoclonal antibody (mAb) 447-52D—specific to the V3 region of gp120 HIV-1—provided a rare opportunity to study the repertoire of antibodies produced upon vaccination against a particular antigenic site. From a blood sample taken 3 weeks after the last immunization, researchers produced 41 V3-specific recombinant mAbs by single B cell isolation and cloning. Sequence analysis revealed 21 B cell lineages (single and clonally related). The broad repertoire of Abs directed to a small antigenic site shows the targeting potency of a vaccine-elicited immune response in rhesus macaques. Supported by ORIP (P51OD011092, U42OD010246) and NIAID.
PD-1 Blockade and Vaccination Provide Therapeutic Benefit Against SIV by Inducing Broad and Functional CD8+ T Cells in Lymphoid Tissue
Rahman et al., Science Immunology. 2021.
https://doi.org/10.1126/sciimmunol.abh3034
Effective HIV therapies must induce functional CD8+ T cells and clear latent viral reservoirs during antiretroviral therapy (ART). Using a rhesus macaque model, researchers showed that therapeutic vaccination under ART using a CD40L plus TLR7 agonist-adjuvanted DNA/modified vaccinia Ankara vaccine regimen induced robust SIV-specific CD4+ and CD8+ T cell responses. Addition of an anti-PD-1 antibody to the SIV vaccine increased cytotoxic CD8+ T cells in lymph nodes after ART interruption, correlating to the control of virus and prolonged survival compared with the vaccine alone. Thus, combining immune checkpoint blockade with vaccination may be a promising avenue toward an HIV cure. Supported by ORIP (P51OD011132) and NIAID.
Blocking α4β7 Integrin Delays Viral Rebound in SHIVSF162P3-Infected Macaques Treated with Anti-HIV Broadly Neutralizing Antibodies
Frank et al., Science Translational Medicine. 2021.
https://doi.org/10.1126/scitranslmed.abf7201
To explore therapeutic potentials of combining anti-HIV broadly neutralizing antibodies (bNAbs) with α4β7 integrin blockade using the monoclonal antibody Rh-α4β7, investigators treated SHIVSF162P3-infected, viremic macaques with bNAbs only or bNAbs and Rh-α4β7. Treatment with bNAbs alone decreased viremia below 200 copies/ml in eight out of eight macaques, but seven of the monkeys rebounded within 3 weeks. In contrast, three of six macaques treated with both Rh-α4β7 and bNAbs maintained viremia below 200 copies/ml for 21 weeks, whereas three of those monkeys rebounded after 6 weeks. These findings suggest that α4β7 integrin blockade may prolong virologic control by bNAbs in SHIVSF162P3-infected macaques. Supported by ORIP (P51OD011104, U42OD010568, U42OD024282, P40OD028116), NIAID, and NCI.
Interleukin-15 Response Signature Predicts RhCMV/SIV Vaccine Efficacy
Barrenäs et al., PLOS Pathogens. 2021.
https://doi.org/10.1371/journal.ppat.1009278
Standard immunogenicity measures do not predict efficacy of a vaccine based on strain 68-1 rhesus cytomegalovirus (RhCMV) vectors expressing SIV proteins (RhCMV/SIV). This vaccine robustly protects just over half of immunized monkeys. Using functional genomics, researchers found that RhCMV/SIV efficacy is correlated with a vaccine-induced response to interleukin-15 (IL-15) that includes modulation of immune cell, inflammation, toll-like receptor signaling, and cell death programming pathways. RhCMV/SIV imparts a coordinated and persistent induction of innate and adaptive immune pathways featuring IL-15, a known regulator of CD8+ T cell function, that support the ability of vaccine-elicited CD8+ T cells to mediate protection against SIV. Supported by ORIP (P51OD010425, P51OD011092), NIAID, and NCI.
Recrudescence of Natural Coccidioidomycosis During Combination Antiretroviral Therapy in a Pigtail Macaque Experimentally Infected with Simian Immunodeficiency Virus
Guerriero et al., AIDS Research and Human Retroviruses. 2021.
https://doi.org/10.1089/AID.2020.0228
Coccidioidomycosis is a common fungal infection in people living with HIV, particularly in regions where Coccidioides is endemic, such as the U.S. Southwest. Researchers diagnosed a recrudescent case of previously treated, naturally occurring coccidioidomycosis in a pigtail macaque experimentally infected with simian immunodeficiency virus (SIV) and virally suppressed on combination antiretroviral therapy (cART). Coccidioides IgG antibody titer became detectable before discontinuation of cART, but symptomatic coccidioidomycosis developed after cART withdrawal. This animal was screened and treated in accordance with the guidelines for coccidioidomycosis prevention and treatment. The researchers conclude that macaques with coccidioidomycosis history should be excluded from HIV studies. Supported by ORIP (P51OD010425), NIAID, and NIMH.
Protection of Newborn Macaques by Plant-Derived HIV Broadly Neutralizing Antibodies: A Model for Passive Immunotherapy During Breastfeeding
Rosenberg et al., Journal of Virology. 2021.
https://doi.org/10.1128/JVI.00268-21
Preventing vertical transmission of HIV to newborns is an unmet medical need in resource poor countries. Using a breastfeeding macaque model with multiple simian-human immunodeficiency virus challenge, researchers assessed the protective efficacy of two human broadly neutralizing antibodies (bnAbs) against HIV, PGT121 and VRC07-523, which are produced by a plant expression system. Despite the transient presence of plasma viral RNA, the bnAbs prevented productive infection in all newborns with no sustained plasma viremia, compared to viral loads ranging from 103 to 5x108 in four untreated controls. Thus, plant-expressed antibodies show promise as passive immunoprophylaxis in a breastfeeding model in newborns. Supported by ORIP (U42OD023038, P51OD011092) and NIAID.
Tissue-Specific Transcriptional Profiling of Plasmacytoid Dendritic Cells Reveals a Hyperactivated State in Chronic SIV Infection
Lee et al., PLOS Pathogens. 2021.
https://doi.org/10.1371/journal.ppat.1009674
Persistent immune activation is an obstacle to optimal health for people living with HIV. Using RNA sequencing, researchers investigated the immunostimulatory potential of plasmacytoid dendritic cells (pDCs) in chronic SIV infection in rhesus macaques. They observed that pDCs have highly activated profiles in these animals. In contrast, pDCs from SIV-infected sooty mangabeys (natural hosts for SIV) had expression profiles similar to uninfected animals. In chronically infected rhesus macaques, interferon alpha transcripts were readily detected in lymph node-homing pDCs, but not those from blood. Therefore, pDCs are a major producer of type-I interferon in chronic SIV infection and could be a useful immunotherapy target. Supported by ORIP (R24OD010445, P51OD011132, P51OD011092, S10OD026799) and NIAID.
Immune Inactivation of Anti-Simian Immunodeficiency Virus Chimeric Antigen Receptor T Cells in Rhesus Macaques
Haeseleer et al., Molecular Therapy–Methods & Clinical Development. 2021.
https://doi.org/10.1016/j.omtm.2021.06.008
Chimeric antigen receptor (CAR) T cell therapies are under development as potential HIV cures. Researchers found that CAR T cells expressing a single-chain variable fragment (scFv) that recognizes V1 or V3 of the SIV envelope eliminated SIV-infected T cells in vitro. However, in vivo infusion of these CAR T cells in rhesus macaques resulted in no detectable antiviral activity. Anti-SIV IgG antibodies in the SIV-infected animals were associated with inhibited CAR T cell effector functions. Thus, lack of in vivo efficacy of CAR T cells might be due to antibodies blocking the interaction between the CAR scFv and its epitope. Supported by ORIP (P51OD011092) and NIAID.