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Complex Decay Dynamics of HIV Virions, Intact and Defective Proviruses, and 2LTR Circles Following Initiation of Antiretroviral Therapy
White et al., PNAS. 2022.
https://doi.org/10.1073/pnas.2120326119
In people living with HIV-1 (PLWH) who start antiretroviral therapy (ART), virus in blood decreases rapidly to below detection, but remaining infected cells may become part of the latent reservoir. Researchers investigated viral decay dynamics and identified decay processes with pronounced differences between intact and defective proviruses. Infected cells that survive second-phase decay may down-regulate HIV-1 gene expression and enter the stable latent reservoir. This research provides insight into meaningful latent reservoir markers and mechanisms for elimination of cells with intact viral genomes. Supported by ORIP (R01OD011095) and NIAID.
Natural Disaster and Immunological Aging in a Nonhuman Primate
Watowich et al., PNAS. 2022.
https://www.pnas.org/content/119/8/e2121663119
Weather-related disasters can exacerbate existing morbidities and increase mortality risk. Researchers examined Hurricane Maria’s impact on immune cell gene expression in large, age-matched, cross-sectional samples from free-ranging rhesus macaques (Macaca mulatta) living on an isolated island. Hurricane Maria was significantly associated with differential expression of 4% of immune-cell-expressed genes and was correlated with age-associated alterations in gene expression, in addition to expression of key immune genes, dysregulated proteostasis networks, and greater expression of inflammatory immune cell-specific marker genes. These findings illuminate that natural disasters might become biologically embedded and contribute to earlier onset of disease and death. Supported by ORIP (P40OD012217), NIA, NIMH.
Progression and Resolution of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection in Golden Syrian Hamsters
Mulka et al., The American Journal of Pathology. 2022.
https://www.doi.org/10.1016/j.ajpath.2021.10.009
To catalyze SARS-CoV-2 research, disease progression was characterized in a robust model. Male and female golden Syrian hamsters were inoculated intranasally with SARS-CoV-2 to track clinical, pathology, virology, and immunology outcomes. Inoculated animals lost body weight during the first week of infection, had higher lung weights at terminal time points, and developed lung consolidation. At day 7, when the presence of infectious virus was rare, interstitial and alveolar macrophage infiltrates and marked reparative epithelial responses dominated in the lung. These lesions resolved over time. The use of quantitative approaches to measure cellular and morphologic alterations in the lung provides valuable outcome measures for developing therapeutic and preventive interventions for COVID-19. Supported by ORIP (T32OD011089).
The Early Life Microbiota Mediates Maternal Effects on Offspring Growth in a Nonhuman Primate
Petrullo et al., iScience. 2022.
https://www.doi.org/10.1016/j.isci.2022.103948
Mammalian mothers influence offspring development by providing nutrients and other bioactive compounds through the placenta or milk. A relatively unexplored mechanism for maternal effects is vertical transmission of bacteria through milk to the infant gut. Infants that receive more glycan-utilizing bacteria from milk might better exploit oligosaccharides, which could improve nutrition and accelerate growth. Researchers found that first-time vervet mothers harbored a milk bacterial community that was less diverse due to the dominance of Bacteroides fragilis, a glycan-utilizing bacteria. These low-parity females had infants that grew faster, suggesting that vertical transmission of bacteria via milk can mediate maternal effects on growth. These results indicate non-nutritive milk constituents play important roles in development. Commercial milk formula might need to be improved or supplemented to better support infant health. Supported by ORIP (P40OD010965) and NCATS.
Vaccine-Induced, High-Magnitude HIV Env-Specific Antibodies with Fc-Mediated Effector Functions Are Insufficient to Protect Infant Rhesus Macaques against Oral SHIV Infection
Curtis et al., mSphere. 2022.
https://www.doi.org/10.1128/msphere.00839-21
A tailored, effective HIV vaccine is needed to prevent mother-to-child viral transmission. In nonhuman primate models, infection with simian–human immunodeficiency virus (SHIV) can be prevented by administering broadly neutralizing HIV envelope (Env)–specific antibodies. Investigators tested the efficacy of an intramuscular vaccine regimen against SHIV infection in male and female infant rhesus macaques. The vaccine induced Env-specific antibodies in plasma, with antibody-dependent cellular cytotoxicity and phagocytic function. These antibodies, however, were insufficient for protection against infection. Future studies could focus on improving the breadth of antibody response and improving cell-mediated immunity. Supported by ORIP (P51OD011107), NCI, NIAID, and NIDCR.
CAR/CXCR5–T Cell Immunotherapy Is Safe and Potentially Efficacious in Promoting Sustained Remission of SIV Infection
Pampusch et al., PLOS Pathogens. 2022.
https://www.doi.org/10.1371/journal.ppat.1009831
HIV and simian immunodeficiency virus (SIV) replication are concentrated within the B cell follicles of secondary lymphoid tissues. In this study, the researchers developed immunotherapeutic chimeric antigen receptor (CAR) T cells that home to follicles and clear SIV-infected cells in a rhesus macaque model. The CAR T cells localized to the follicle, replicated, and interacted directly with infected cells. Most of the treated animals maintained lower viral loads in the blood and follicles, compared to control animals. These findings demonstrate the safety and potential efficacy of this immunotherapy approach for long-term remission of HIV without requiring the lifelong use of antiretroviral therapy. Supported by ORIP (P51OD011106), NIAID, and NHLBI.
Characterization of Near Full-Length Transmitted/Founder HIV-1 Subtype D and A/D Recombinant Genomes in a Heterosexual Ugandan Population (2006–2011)
Balinda et al., Viruses. 2022.
https://www.doi.org/10.3390/v14020334
About 80 percent of heterosexual HIV-1 transmission events are thought to be attributable to a single transmitted/founder (T/F) virus. Studies of HIV T/F viruses could yield valuable insights on transmission and help inform the design of vaccines and therapeutics. To date, most T/F studies have focused on subtype B and C viruses; few studies have focused on subtype D. In this study, the researchers characterized near full-length T/F viral genomes to identify subtype D and A/D recombinants from heterosexual mucosal transmissions in humans. They reported high viral diversity and high pathogenicity, underscoring the importance of matching vaccine designs to the predominant subtypes within populations. Further studies of the full genome sequence could provide additional information for subtyping. Supported by ORIP (P51OD011132) and NIAID.
Simian Immunodeficiency Virus Infection Mediated Changes in Jejunum and Peripheral SARS-CoV-2 Receptor ACE2 and Associated Proteins or Genes in Rhesus Macaques
Boby et al., Frontiers in Immunology. 2022.
https://www.doi.org/10.3389/fimmu.2022.835686
Recent studies suggest that people with HIV—particularly those not receiving antiretroviral therapy or those with low CD4 cell counts—are at increased risk of severe illness from SARS‑CoV-2 coinfection. Angiotensin-converting enzyme 2 (ACE2), the cellular receptor for SARS-CoV-2, is likely to play an important role in modulating physiological and pathological events during HIV infection. In this study, the researchers used a rhesus macaque model to characterize the expression profiles of ACE2, other renin-angiotensin system (RAS)–associated genes (AGTR1/2, ADAM17, and TMPRSS2), and inflammatory cytokines (IL-1β, IL-6, and TNF‑α) in the jejunum and lung during simian immunodeficiency virus (SIV) infection. SIV infection was associated with multiple changes in gene expression, including downregulation of ACE2, which could lead to loss of gut homeostasis. Further studies could provide insight on the role of RAS-associated proteins during HIV and SARS-CoV-2 co-infection. Supported by ORIP (P51OD011104) and NIDDK.
Expression, Activity, and Regulation of Phosphorylating Enzymes in Tissues and Cells Relevant to HIV-1 Sexual Transmission
Hu et al., AIDS Research and Human Retroviruses. 2022.
https://www.doi.org/10.1089/AID.2020.0250
Phosphorylating enzymes (PEs) are critical for activating nucleoside/nucleotide reverse transcriptase inhibitors (e.g., tenofovir [TFV]), but limited information is available about the expression of PEs in the female genital tract and colon tissue. Investigators compared the mRNA expression of seven PEs involved in metabolism of TFV in cervicovaginal and colon tissues. This work involved human, pigtailed macaque, and rabbit tissues; human cervicovaginal epithelial cell lines; T cell lines; and primary CD4+ T cells. Taken together, this study suggests that TFV activation differs among immune cells and local tissues under varying conditions. Additionally, the variability of PE expression levels found across species provides critical information to assist with the interpretation of data obtained using these animal models. Supported by ORIP (P51OD010425) and NIAID.
Estimation of the In Vivo Neutralization Potency of eCD4Ig and Conditions for AAV-Mediated Production for SHIV Long-Term Remission
Goyal et al., Science Advances. 2022.
https://www.doi.org/10.1126/sciadv.abj5666
The engineered protein eCD4Ig, a synthetic antibody-like inhibitor designed to limit HIV entry into cells, shows promise as an approach to achieve HIV remission without antiretroviral therapy. Researchers used mathematical modeling to characterize in vivo antiviral neutralization of eCD4Ig, as well as possible antibody-dependent cell-mediated cytotoxicity effects, in rhesus macaques infected with simian–human immunodeficiency virus (SHIV) (sex not specified). The research team modeled SHIV and pharmacokinetics dynamics and projected the levels of eCD4Ig needed with a viral vector production approach to suppress SHIV viremia. The data suggest that endogenous, continuous expression of eCD4Ig could overcome the diminishing effects of antidrug antibodies and allow long-term remission of SHIV viremia in nonhuman primates. Supported by ORIP (P51OD011132) and NIAID.