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- Infectious Diseases
Infant Rhesus Macaques Immunized Against SARS-CoV-2 Are Protected Against Heterologous Virus Challenge 1 Year Later
Milligan et al., Science Translational Medicine. 2023.
https://doi.org/10.1126/scitranslmed.add6383
The Moderna and Pfizer–BioNTech mRNA vaccines received emergency use authorization for infants 6 months and older in June 2022, but questions remain regarding the durability of vaccine efficacy against emerging variants in this age group. Using a two-dose vaccine regimen consisting of stabilized prefusion Washington-strain spike protein encoded by mRNA and encapsulated in lipid nanoparticles, the investigators immunized 2-month-old rhesus macaques of both sexes. They found that the immune responses persisted and protected from severe disease after heterologous challenge with the Delta variant 1 year later. The decay kinetics of vaccine-induced neutralizing antibody responses in the infant monkeys are comparable to those observed in adult humans and nonhuman primates. Supported by ORIP (P51OD011107), NIAID, and NCI.
Fc-Mediated Pan-Sarbecovirus Protection After Alphavirus Vector Vaccination
Adams et al., Cell Reports. 2023.
https://pubmed.ncbi.nlm.nih.gov/37000623/
Group 2B β-coronaviruses (i.e., sarbecoviruses) have resulted in regional and global epidemics. Here, the authors evaluate the mechanisms of cross-sarbecovirus protective immunity using a panel of alphavirus-vectored vaccines covering bat to human strains. They reported that vaccination does not prevent virus replication, but it protects against lethal heterologous disease outcomes in SARS-CoV-2 and clade 2 bat sarbecovirus challenge models. Full-length spike vaccines elicited the broadest pan-sarbecovirus protection. Additionally, antibody-mediated cross-protection was lost in absence of FcR function, supporting a model for non-neutralizing, protective antibodies. Taken together, these findings highlight the value of universal sarbecovirus vaccine designs that couple FcR-mediated cross-protection with potent cross-neutralizing antibody responses. Supported by ORIP (K01OD026529), NIAID, and NCI.
Anti–Human Immunodeficiency Virus‑1 Activity of MoMo30 Protein Isolated from the Traditional African Medicinal Plant Momordica balsamina
Khan et al., Virology Journal. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10035133/
Momordica balsamina has been reported to produce a ribosome-inactivating protein with anti‑HIV-1 activity and is commonly used by traditional African healers for treatment of HIV. Investigators characterized the mechanism of action of the MoMo30 protein, as well as the sequence of the protein-coding gene. They reported that MoMo30 functions as a lectin or carbohydrate-binding agent (CBA) and inhibits HIV-1 at nanomolar levels, with minimal cellular toxicity at inhibitory levels. CBAs can block the binding of envelope glycoproteins with their target receptors on cells. Thus, this protein could represent a potential new treatment strategy for HIV. Supported by ORIP (R24OD010947), NCI, NIGMS, and NIMHD.
Late Gene Expression–Deficient Cytomegalovirus Vectors Elicit Conventional T Cells That Do Not Protect Against SIV
Hansen et al., Journal of Clinical Investigation Insight. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10070102/
Cytomegalovirus (CMV)–based vaccines aim to exploit unique immunological adaptations, including host manipulation and immune evasion strategies. Translating CMV-based vaccines from rhesus macaques to humans requires translating the immune factors responsible for efficacy, as well as vaccine vectors that are sufficiently safe for widespread use. Researchers examined the impact of a stringent attenuation strategy on vector-induced immune protection against simian immunodeficiency virus (SIV) in rhesus macaques of both sexes. They reported that elicited CD8+ T cells exclusively failed to protect against SIV challenge. These data suggest that late viral gene expression and/or residual in vivo spreading are required to induce protective CD8+ T cell responses. Supported by ORIP (P51OD011092, P51OD011107, S10OD016261), NCI, NIAID, and NCATS.
Chronic Immune Activation and Gut Barrier Dysfunction Is Associated with Neuroinflammation in ART-Suppressed SIV+ Rhesus Macaques
Byrnes et al., PLOS Pathogens. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10085024/
About 40% of people with HIV develop neurocognitive disorders, potentially resulting from persistent infection in the brain and neuroinflammation. Investigators characterized the central nervous system reservoir and immune environment of simian immunodeficiency virus (SIV)–infected rhesus macaques of both sexes during acute, chronic, or antiretroviral therapy (ART)–suppressed infection. They reported that neuroinflammation and blood–brain barrier dysfunction correlated with viremia and immune activation in the gut. Their findings suggest that gastrointestinal tract damage can contribute to neuroimmune activation and inflammation, even in the absence of SIV or HIV infection. This work also has implications for other neurological disorders where chronic inflammation is associated with pathogenesis. Supported by ORIP (P51OD011132, P51OD011092, U42OD011023, R24OD010445), NIAID, NCI, and NIMH.
CD8+ Lymphocytes Do Not Impact SIV Reservoir Establishment under ART
Statzu et al., Nature Microbiology. 2023.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9894752/
The HIV-1 latent reservoir has been shown to persist following antiretroviral therapy (ART), but the mechanisms underlying the establishment and maintenance of the reservoir are not fully understood. Using rhesus macaques of both sexes, investigators examined the effects of CD8+ T cells on formation of the latent reservoir with simian immunodeficiency virus (SIV) infection. They found that CD8+ T cell depletion resulted in slower decline of viremia but did not change the frequency of infected CD4+ T cells in the blood or lymph nodes. Additionally, the size of the persistent reservoir was unchanged. These findings suggest that the viral reservoir is established largely independent of SIV-specific cytotoxic T lymphocyte control. Supported by ORIP (P51OD011132), NIAID, NCI, NIDDK, NIDA, NHLBI, and NINDS.
Human Hematopoietic Stem Cell Engrafted IL-15 Transgenic NSG Mice Support Robust NK Cell Responses and Sustained HIV-1 Infection
Abeynaike et al., Viruses. 2023.
https://www.mdpi.com/1999-4915/15/2/365
A major obstacle to human natural killer (NK) cell reconstitution is the lack of human interleukin‑15 (IL-15) signaling, as murine IL-15 is a poor stimulator of the human IL-15 receptor. Researchers show that immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice expressing a transgene encoding human IL-15 (NSG-Tg(IL-15)) have physiological levels of human IL-15 and support long-term engraftment of human NK cells when transplanted with human umbilical cord blood–derived hematopoietic stem cells (HSCs). These mice demonstrate robust and long-term reconstitution with human immune cells but do not develop graft-versus-host disease, allowing long-term studies of human NK cells. The HSC-engrafted mice can sustain HIV-1 infection, resulting in human NK cell responses. This work provides a robust novel model to study NK cell responses to HIV-1. Supported by ORIP (R24OD026440), NIAID, NCI, and NIDDK.
Gut Microbiome Dysbiosis in Antibiotic-Treated COVID-19 Patients Is Associated with Microbial Translocation and Bacteremia
Bernard-Raichon et al., Nature Communications. 2022.
https://www.doi.org/10.1038/s41467-022-33395-6
The investigators demonstrated that SARS-CoV-2 infection induced gut microbiome dysbiosis in male mice. Samples collected from human COVID-19 patients of both sexes also revealed substantial gut microbiome dysbiosis. Analysis of blood culture results testing for secondary microbial bloodstream infections with paired microbiome data indicated that bacteria might translocate from the gut into the systemic circulation of COVID-19 patients. These results were consistent with a direct role for gut microbiome dysbiosis in enabling dangerous secondary infections during COVID-19. Supported by ORIP (S10OD021747), NCI, NHLBI, NIAID, and NIDDK.
Molecular Insights Into Antibody-Mediated Protection Against the Prototypic Simian Immunodeficiency Virus
Zhao et al., Nature Communications. 2022.
https://www.doi.org/10.1038/s41467-022-32783-2
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. Their findings indicate that, in the case of humoral immunity, nAb activity is necessary and sufficient for protection against SIV challenge. This work provides structural insights for future vaccine design. Supported by ORIP (P51OD011106), NIAID, and NCI.
Durable Protection Against the SARS-CoV-2 Omicron Variant Is Induced by an Adjuvanted Subunit Vaccine
Arunachalam et al., Science Translational Medicine. 2022.
https://www.doi.org/10.1126/scitranslmed.abq4130
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. Further boosting with a version of the vaccine containing the Beta variant or the ancestral RBD elicited cross-reactive immune responses that conferred protection against Omicron challenge. Supported by ORIP (P51OD011104), NCI, and NIAID.