Previous Exposure to Dengue Virus Is Associated with Increased Zika Virus Burden at the Maternal-Fetal Interface in Rhesus Macaques
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Pre-existing immunity to dengue virus (DENV) results in antibody-dependent enhancement (ADE) among DENV serotypes; Zika virus (ZIKV) has homology with DENV suggesting pre-existing DENV immunity may have an impact on ZIKV pathogenesis during pregnancy. In a rhesus macaque model, prior DENV-2 exposure resulted in a higher burden of ZIKV viral RNA in maternal-fetal interface tissues as compared to DENV-naive macaques.
Factor XII Plays a Pathogenic Role in Organ Failure and Death in Baboons Challenged with Staphylococcus aureus
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Activation of coagulation factor (F) XI promotes multiorgan failure in rodent models of sepsis and in a baboon model for lethal systemic inflammation induced by infusion of heat-inactivated Staphylococcus aureus. The authors used the anticoagulant FXII-neutralizing antibody 5C12 to verify the mechanistic role of FXII. Inhibition of FXII prevented fever, terminal hypotension, respiratory distress, and multiorgan failure. All animals receiving 5C12 had milder and transient clinical symptoms; untreated control animals suffered irreversible multiorgan failure.
A Yeast Expressed RBD-Based SARS-CoV-2 Vaccine Formulated with 3M-052-alum Adjuvant Promotes Protective Efficacy in Non-Human Primates
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Using a rhesus macaque model (n=5 males per group), investigators tested a receptor binding domain (RBD) recombinant protein formulation COVID-19 vaccine candidate combined with an aluminum-based formulation of 3M’s Toll-like receptor 7 and 8 agonist 3M-052 (3M-052/Alum) and found the RBD+3M-052/Alum formulation produced a superior overall immune response than RBD+alum alone as demonstrated by higher SARS-CoV-2 neutralizing antibodies, improved Th1 biased CD4+ T cell reactions, and increased CD8+ T cell responses.
Systems Vaccinology of the BNT162b2 mRNA Vaccine in Humans
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It was poorly understood how mRNA vaccines against SARS-CoV-2 stimulate protective immune responses. To address this, researchers comprehensively profiled innate and adaptive immune responses of healthy volunteers vaccinated with the Pfizer-BioNTech mRNA vaccine (BNT162b2). Vaccination resulted in robust production of neutralizing antibodies against wild-type SARS-CoV-2, to a lesser extent, the beta variant, as well as significant increases in antigen-specific polyfunctional CD4+ and CD8+ T cells after the second dose.
Early Treatment With a Combination of Two Potent Neutralizing Antibodies Improves Clinical Outcomes and Reduces Virus Replication and Lung Inflammation in SARS CoV-2 Infected Macaques
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The therapeutic efficacy of a combination of two SARS-CoV-2 monoclonal antibodies (mAbs), C135-LS and C144-LS, were investigated in young adult macaques (3 groups of 4 animals; equal sex distribution). Animals were treated intravenously with low or high doses of C135-LS and C144-LS mAbs or control mAb 24 hours post-infection with SARS-CoV-2.
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.