Antibody-Mediated Depletion of Viral Reservoirs is Limited in SIV-Infected Macaques Treated Early With Antiretroviral Therapy
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Virus-specific strategies to target the latent HIV reservoir in individuals on combination antiretroviral therapy (cART) have been limited by inefficient induction of viral protein expression. Researchers used rhesus macaques to investigate an antibody-mediated reservoir targeting strategy, targeting the CD4 molecule rather than a viral protein, to deplete potential viral target cells irrespective of infection status.
Recombinant Simian Varicella Virus–Simian Immunodeficiency Virus Vaccine Induces T and B Cell Functions and Provides Partial Protection Against Repeated Mucosal SIV Challenges in Rhesus Macaques
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An effective vaccine is needed urgently to control the global HIV epidemic completely by 2030. Recombinant simian varicella virus (rSVV) vaccines expressing SIV antigens offer a potential new approach in the evaluation of HIV vaccine candidates. Building on their previous findings, the investigators induced systemic and mucosal immune responses with live, attenuated rSVV vaccinations followed by SIV group–specific antigen and SIV envelope protein boosts in female rhesus macaques treated with repeated intravaginal SIV challenges.
Transient T Cell Expansion, Activation, and Proliferation in Therapeutically Vaccinated Simian Immunodeficiency Virus–Positive Macaques Treated with N-803
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Many HIV vaccine strategies induce neutralizing antibodies and CD8+ T cells, but more information on these protective immune responses is needed. Researchers hypothesized that CD8+ T cells elicited by vaccination during antiretroviral therapy (ART) would be recalled and boosted by treatment with N-803 after ART discontinuation. They tested this approach in male Mauritian cynomolgus macaques infected with simian immunodeficiency virus.
Long-Term Evolutionary Adaptation of SIVcpz toward HIV-1 Using a Humanized Mouse Model
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Chimpanzee-derived simian immunodeficiency viruses (SIVcpz) are thought to have evolved into the highly pathogenic HIV-1 Group M, but the genetic adaptations required for SIV progenitor viruses to become pathogenic and established as HIVs in the human population have remained unclear. Using humanized mice of both sexes, researchers mimicked the evolution of SIVcpz into HIV-1 Group M through serial passaging. After four generations, the researchers observed increased initial viral load, increased CD4+ T cell decline, and nonsynonymous substitutions.
Effect of Single Housing on Innate Immune Activation in Immunodeficiency Virus–Infected Pigtail Macaques (Macaca nemestrina) as a Model of Psychosocial Stress in Acute HIV Infection
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Psychosocial stress is associated with immune system dysregulation and worsened clinical outcomes in people with HIV. Investigators performed a retrospective analysis of acute simian immunodeficiency virus (SIV) infection of male pigtail macaques to compare the innate immune responses of social and single housing. The singly housed macaques showed reduced expansion of classical and intermediate monocytes, prolonged thrombocytopenia, and suppression of platelet activation during the first 2 weeks after inoculation.
System-Wide Identification of Myeloid Markers of TB Disease and HIV-Induced Reactivation in the Macaque Model of Mtb Infection and Mtb/SIV Co-Infection
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HIV is known to catalyze the reactivation of latent tuberculosis (TB) infection. The investigators characterized Mycobacterium tuberculosis (Mtb) and simian immunodeficiency virus (SIV) coinfection using a rhesus macaque model of both sexes, with a focus on pathways relevant to myeloid origin cells (e.g., macrophages). They identified gene signatures of host disease state and progression, as well as clustering algorithms for differentiation between host disease states and relationships among genes.
Control of Simian Immunodeficiency Virus Infection in Prophylactically Vaccinated, Antiretroviral Treatment–Naive Macaques Is Required for the Most Efficacious CD8 T Cell Response during Treatment with the Interleukin-15 Superagonist N-803
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Recent evidence suggests that immunotherapeutic agents, such as N-803, could improve the ability of CD8+ T cells to target and destroy cells infected with HIV. In this study, investigators defined the features that are associated with N-803-mediated suppression of simian immunodeficiency virus (SIV) replication in rhesus macaques of both sexes. They hypothesized that preexisting vaccine-elicited CD8+ T cells were required for suppressing replication.
Molecular Insights Into Antibody-Mediated Protection Against the Prototypic Simian Immunodeficiency Virus
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Most simian immunodeficiency virus (SIV) vaccines have focused on inducing T cell responses alone or in combination with non-neutralizing antibody responses. To date, studies investigating neutralizing antibody (nAb) responses to protect against SIV have been limited. In this study, researchers isolated 12 potent monoclonal nAbs from chronically infected rhesus macaques of both sexes and mapped their binding specificities on the envelope trimer structure. They further characterized the structures using cryogenic electron microscopy, mass spectrometry, and computational modeling.
Isoniazid and Rifapentine Treatment Effectively Reduces Persistent M. tuberculosis Infection in Macaque Lungs
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People with HIV and asymptomatic latent tuberculosis (TB) coinfection are at risk of developing active TB symptoms. The Centers for Disease Control and Prevention recommends a weekly dose of isoniazid and rifapentine for 3 months (3HP) for treatment of latent TB infection, but the sterilizing efficacy of the regimen has not been demonstrated previously. Using rhesus macaques of both sexes, researchers evaluated the efficacy of the 3HP regimen in eradicating persistent Mycobacterium tuberculosis infection.
Early Treatment Regimens Achieve Sustained Virologic Remission in Infant Macaques Infected with SIV at Birth
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About 150,000 children are infected postnatally with HIV each year. Early antiretroviral therapy (ART) in infants with HIV can reduce viral reservoir size, but ART-free virologic remission has not been achieved. The researchers hypothesized that proviral reservoir seeding in infants exposed to HIV might differ from that in adults. They characterized viral reservoirs in neonatal rhesus macaques of both sexes inoculated with simian immunodeficiency virus (SIV) at birth and given combination ART.