Interleukin-15 Response Signature Predicts RhCMV/SIV Vaccine Efficacy
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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.
Recrudescence of Natural Coccidioidomycosis During Combination Antiretroviral Therapy in a Pigtail Macaque Experimentally Infected with Simian Immunodeficiency Virus
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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.
Protection of Newborn Macaques by Plant-Derived HIV Broadly Neutralizing Antibodies: A Model for Passive Immunotherapy During Breastfeeding
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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.
Tissue-Specific Transcriptional Profiling of Plasmacytoid Dendritic Cells Reveals a Hyperactivated State in Chronic SIV Infection
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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.
Immune Inactivation of Anti-Simian Immunodeficiency Virus Chimeric Antigen Receptor T Cells in Rhesus Macaques
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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.
Gut Germinal Center Regeneration and Enhanced Antiviral Immunity by Mesenchymal Stem/Stromal Cells
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Researchers investigated the effects of mesenchymal stem/stromal cell (MSC) infusions on gut mucosal recovery, antiviral immunity, and viral suppression in SIV-infected rhesus macaques. MSC treatment heightened virus-specific responses and reduced viral load. Clearance of SIV-positive cells from gut mucosal effector sites was correlated with regeneration of germinal centers, restoration of follicular B cells and T follicular helper cells, and enhanced antigen presentation by viral trapping within the follicular dendritic cell network.
Western-Style Diet Consumption Impairs Maternal Insulin Sensitivity and Glucose Metabolism During Pregnancy in a Japanese Macaque Model
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Using a Japanese macaque model, investigators assessed the metabolic effects of obesity and a calorically dense, Western-style diet (WSD; 36.3% fat), either alone or together, on maternal glucose tolerance and insulin levels in dams during pregnancy (n = 95 females followed over multiple pregnancies [n = 273]). With prolonged WSD feeding, multiple diet switches, and/or increasing age and parity, WSD was associated with increasingly higher insulin levels during glucose tolerance testing, indicative of insulin resistance.
SARS-CoV-2 Vaccines Elicit Durable Immune Responses in Infant Rhesus Macaques
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The immunogenicity of two SARS-CoV-2 vaccines was evaluated in both sexes of infant rhesus macaques (n=8/group). Neither vaccine, stabilized prefusion SARS-CoV-2 S-2P spike (S) protein encoded by mRNA encapsulated in lipid nanoparticles or the purified S protein mixed with 3M-052, a synthetic TLR7/8 agonist in a squalene emulsion, induced adverse effects. Both elicited high magnitude neutralizing antibody titers peaking at week 6. S-specific T cell responses were dominated by IL-17, IFN-γ, or TNF-α. Antibody and cellular responses were stable through week 22.
Antibody-Based CCR5 Blockade Protects Macaques From Mucosal SHIV Transmission
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The efficacy of antiretroviral therapy (ART) as pre-exposure prophylaxis against HIV is hindered by incomplete patient adherence and ART-resistant variants. Researchers found that competitive inhibition of HIV Env-CCR5 binding via the CCR5-specific antibody Leronlimab protects rhesus macaques against infection following repeated intrarectal challenges with a CCR5-tropic simian-human immunodeficiency virus (SHIVSF162P3). Biweekly injection of Leronlimab at 50 mg/kg provided complete protection from SHIV infection.
Cryopreservation and Preparation of Thawed Spermatozoa from Rhesus Macaques (Macaca mulatta) for In Vitro Fertilization
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Optimizing procedures for cryopreservation and subsequent thawing for rhesus macaques is required to prevent cryodamage that negatively impacts artificial insemination and in vitro fertilization rates. Investigators systematically assessed two cryopreservation methods and four recovery methods in three interdependent experiments. Results demonstrated that slow-freezing, coupled with density gradient centrifugation provided the highest efficacy in functional sperm for in vitro use.