Durable Protection Against the SARS-CoV-2 Omicron Variant Is Induced by an Adjuvanted Subunit Vaccine
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Additional SARS-CoV-2 vaccines are needed, owing to waning immunity to the original vaccines and the emergence of variants of concern. A recent study in male rhesus macaques demonstrated durable protection against the Omicron BA.1 variant induced by a subunit SARS-CoV-2 vaccine comprising the receptor binding domain of the ancestral strain (RBD-Wu) on the I53-50 nanoparticle adjuvanted with AS03, an oil-in-water emulsion containing α‑tocopherol. Two immunizations with the vaccine resulted in durable immunity, without cross-reactivity.
Neuroprotective Effects of Electrical Stimulation Following Ischemic Stroke in Non-Human Primates
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Using rhesus macaques of both sexes, researchers identified a novel treatment for ischemic stroke, which occurs when brain cells die due to lack of oxygen. The treatment consisted of applying 60 minutes of electrical brain stimulation shortly after the stroke. The animals that received electrical stimulation had less brain damage, fewer cell deaths, and more protective neural activity patterns than the monkeys that did not receive electrical stimulation.
A Clade C HIV-1 Vaccine Protects Against Heterologous SHIV Infection by Modulating IgG Glycosylation and T Helper Response in Macaques
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Vaccines for HIV-1 capable of generating a broadly cross-reactive neutralizing antibody response are needed urgently. The researchers tested the protective efficacy of a clade C HIV-1 vaccination regimen in male rhesus macaques. The vaccine was administered either orally using a needle-free injector or via parenteral injection. Significant protection was observed for both vaccination routes following the simian–human immunodeficiency virus (SHIV) challenge, with an estimated efficacy of 68% per exposure.
Allogeneic MHC‑Matched T‑Cell Receptor Α/Β‑Depleted Bone Marrow Transplants in SHIV‑Infected, ART‑Suppressed Mauritian Cynomolgus Macaques
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Allogeneic hematopoietic stem cell transplants are effective in reducing HIV reservoirs following antiretroviral therapy (ART). A better understanding of this mechanism could enable the development of safer and more efficacious HIV treatment regimens. In this study, the researchers used a Mauritian cynomolgus macaque model to study the effects of allogeneic major histocompatibility complex–matched α/β T cell–depleted bone marrow cell transplantation following infection with simian–human immunodeficiency virus (SHIV). The macaques began ART 6 to 16 weeks post-infection.
Innate Immune Regulation in HIV Latency Models
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Researchers are interested in developing therapeutic approaches to target latent HIV reservoirs, which are unaffected by antiretroviral therapy. Previous studies suggest that HIV latency might be related to viral RNA sensing, interferon (IFN) signaling, and IFN-stimulated gene (ISG) activation. In this study, the researchers evaluated responses to stimulation by retinoic acid–inducible gene I agonists and IFN in multiple CD4+ T cell line models for HIV latency. The models represented various aspects of latent infection and viral control.
Substitutions in Nef That Uncouple Tetherin and SERINC5 Antagonism Impair Simian Immunodeficiency Virus Replication in Primary Rhesus Macaque Lymphocytes
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Tetherin inhibits the release of certain enveloped viruses from infected host cells. Most simian immunodeficiency viruses (SIVs) use Nef, a nonenzymatic accessory protein, to overcome this restriction. Nef also has been shown to enhance viral infectivity by preventing the incorporation of SERINC5 into virions. Researchers demonstrated previously that tetherin antagonism is necessary for efficient SIV replication in rhesus macaques. They explored this effect by defining substitutions within Nef that distinguish tetherin and SERINC5 antagonism.
Myeloid Cell Tropism Enables MHC-E–Restricted CD8+ T Cell Priming and Vaccine Efficacy by the RhCMV/SIV Vaccine
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Simian immunodeficiency virus (SIV) vaccines based on strain 68-1 rhesus cytomegalovirus vectors have been shown to arrest viral replication early in primary infection. The specific characteristics underlying this effect are not understood fully. In this study, the researchers used host microRNA–mediated vector tropism restriction to demonstrate that the targeted responses are dependent on vector infection of distinct cell types in a rhesus macaque model.
A Cellular Trafficking Signal in the SIV Envelope Protein Cytoplasmic Domain Is Strongly Selected for in Pathogenic Infection
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Envelope glycoproteins within the cytoplasmic domain of HIV and simian immunodeficiency virus (SIV) include a tyrosine-based motif that mediates endocytosis and polarized sorting in infected cells. Mutation of this tracking signal has been shown to lead to suppressed viral replication and failed systemic immune activation, but the mechanism has not been explored fully. Using rhesus and pigtail macaque models, the researchers demonstrated that molecular clones containing the mutations reconstitute signals for both endocytosis and polarized sorting.
Large Comparative Analyses of Primate Body Site Microbiomes Indicate That the Oral Microbiome Is Unique Among All Body Sites and Conserved Among Nonhuman Primates
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Microbiomes are critical to host health and disease, but large gaps remain in the understanding of the determinants, coevolution, and variation of microbiomes across body sites and host species. Thus, researchers conducted the largest comparative study of primate microbiomes to date by investigating microbiome community composition at eight distinct body sites in 17 host species. They found that the oral microbiome is unique in exhibiting notable similarity across primate species while being distinct from the microbiomes of all other body sites and host species.
The Ex Vivo Pharmacology of HIV-1 Antiretrovirals Differs Between Macaques and Humans
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Nonhuman primates (NHPs) are used widely for studies of antiretroviral (ARV)–based pre‑exposure prophylaxis (PrEP), but more work is needed to address dose–efficacy discrepancies between NHP studies and human clinical trials of PrEP candidates. Investigators explored the use of colorectal and cervicovaginal ex vivo mucosal tissue explants as a bridging model between NHPs and humans. They reported differences in inhibitory potency of drug combinations between NHP and human mucosal tissue explants.