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- Immunology
- 2021
Persistence of Viral RNA in Lymph Nodes in ART-suppressed SIV/SHIV-Infected Rhesus Macaques
Cadena et al., Nature Communications. 2021.
https://doi.org/10.1038/s41467-021-21724-0
The long-lived viral reservoir is a key obstacle to curing HIV/AIDS, yet the features of that reservoir during antiretroviral therapy (ART) remain poorly understood. Researchers undertook a comprehensive analysis of the SIV/SHIV reservoir in multiple lymphoid and non-lymphoid tissues from SIV/SHIV-infected rhesus macaques suppressed with ART for one year. Their findings support a model in which the tissue viral reservoir is rapidly and broadly seeded early during acute infection. Viral RNA persists lymphoid tissues despite a long period of suppressive ART. Therefore, viral latency does not appear to be universally transcriptionally silent; the reservoir may include a spectrum of latency depths. Supported by ORIP (R01OD024917) and NIAID.
New SHIVs and Improved Design Strategy for Modeling HIV-1 Transmission, Immunopathogenesis, Prevention, and Cure
Li et al., Journal of Virology. 2021.
https://doi.org/10.1128/JVI.00071-21
Researchers knew that substitution of HIV-1 Env residue 375-serine by aromatic residues enhances binding to rhesus CD4 enabling primary HIV-1 Envs to support replication as simian-human immunodeficiency virus (SHIV) chimeras in rhesus monkeys. The investigators constructed SHIVs containing 10 primary Envs corresponding to HIV-1 subtypes A, B, C, AE, and AG. Only one with histidine at Env375 replicated efficiently in rhesus cells. Replacement of wild-type Env375 residues by tryptophan, tyrosine, phenylalanine, or histidine in the other 9 SHIVs led to efficient replication. These new SHIVs transmit via mucosal routes like HIV-1 and have use for vaccine testing in nonhuman primates. Supported by ORIP (U42OD021458, P40OD012217), NIAID, and NCI.
Autologous Transplant Therapy Alleviates Motor and Depressive Behaviors in Parkinsonian Monkeys
Tao et al., Nature Medicine. 2021.
https://www.nature.com/articles/s41591-021-01257-1
Generation of induced pluripotent stem cells (iPSCs) enables standardized of dopamine (DA) neurons for autologous transplantation therapy to improve motor functions in Parkinson disease (PD). Adult male rhesus PD monkeys receiving autologous, but not allogenic, transplantation exhibited recovery from motor and depressive signs of PD over a 2-year period without immunosuppressive therapy. Mathematical modeling showed correlations between surviving DA neurons with PET signal intensity and behavior recovery regardless of autologous or allogeneic transplant, suggesting a predictive power of PET and motor behaviors for surviving DA neuron number. The results demonstrate favorable efficacy of the autologous transplant approach to treat PD. Supported by ORIP (P51OD011106) NINDS, and NICHD.
Immune Variations Throughout the Course of Tuberculosis Treatment and its Relationship with Adrenal Hormone Changes in HIV-1 Patients Co-Infected with Mycobacterium tuberculosis
Vecchione et al., Tuberculosis. 2021.
https://doi.org/10.1016/j.tube.2020.102045
The probability of developing tuberculosis (TB) is 19 times higher in people infected with human immunodeficiency virus (HIV) compared to the general population. As host immune response defines the course of infection, researchers aimed to identify immuno-endocrine changes over six months of anti-TB chemotherapy in HIV+ people. Throughout the course of anti-TB/HIV treatment, plasma dehydroepiandrosterone (DHEA) and DHEA-sulfate levels increased while cortisol decreased. The balance between cortisol and DHEA, together with clinical assessment, served as a predictor of clinical outcome after anti-TB treatment. This research suggests that combined anti-HIV/TB therapies may partially restore both immune function and adrenal hormone levels. Supported by ORIP (P51OD011133).
Polyfunctional Tier 2–Neutralizing Antibodies Cloned Following HIV-1 Env Macaque Immunization Mirror Native Antibodies in a Human Donor
Spencer et al., Journal of Immunology. 2021.
https://doi.org/10.4049/jimmunol.2001082
HIV vaccine efforts are limited by viral strain diversity and the shielding of neutralization epitopes on the viral envelope, yet isolation of broadly neutralizing antibodies from infected individuals suggests the potential for eliciting protective antibodies through vaccination. Researchers cloned 58 monoclonal antibodies (mAbs) from a rhesus monkey immunized with envelope glycoprotein immunogens from an HIV-1 clade C–infected volunteer. Twenty mAbs exhibited some neutralizing activity. Cloned mAbs targeting the V3 region and CD4 binding site were capable of tier 2 (i.e., moderate) neutralization. This study demonstrates partial recapitulation of the human donor’s humoral immune response through nonhuman primate vaccination. Supported by ORIP (P51OD011092) and NIAID.
Modified Adenovirus Prime–Protein Boost Clade C HIV Vaccine Strategy Results in Reduced Viral DNA in Blood and Tissues Following Tier 2 SHIV Challenge
Malherbe et al., Frontiers in Immunology. 2021.
https://doi.org/10.3389/fimmu.2020.626464
Researchers conducted a comparative vaccine challenge study in rhesus macaques. One group of monkeys was vaccinated using co-immunization with DNA Gag and Env expression plasmids and trimeric Env gp140 glycoprotein. The other group was primed with two replicating simian adenovirus-vectored vaccines expressing Gag and boosted with trimeric Env gp140. Both strategies elicited antigen-specific humoral and cellular immune responses, but neither approach provided significant protection from viral acquisition upon repeated mucosal challenges with a heterologous Tier 2 SHIV. Nevertheless, both regimens significantly lowered cell-associated viral DNA in multiple tissues, thus potentially dampening the infection and providing clues for further vaccine development. Supported by ORIP (U42OD023038, P51OD011092) and NIAID.
Evaluating a New Class of AKT/mTOR Activators for HIV Latency-Reversing Activity Ex Vivo and In Vivo
Gramatica et al., Journal of Virology. 2021.
https://doi.org/10.1128/JVI.02393-20
Activation of latent HIV-1 expression could benefit many HIV cure strategies. Researchers evaluated two AKT/mTOR activators, SB-216763 and tideglusib, as a potential new class of LRAs. The drugs reactivated latent HIV-1 present in blood samples from aviremic individuals on antiretroviral therapy without causing T cell activation or impaired effector function of cytotoxic T lymphocytes or NK cells. When tested in vivo in monkeys, tideglusib showed unfavorable pharmacodynamic properties and did not reverse SIV latency. The discordance between the ex vivo and in vivo results underscores the importance of developing novel LRAs that allow systemic drug delivery to relevant anatomical compartments. Supported by ORIP (P51OD011092), NIAID, NIGMS, NIMH, and NCI.
BNT162b Vaccines Protect Rhesus Macaques from SARS-CoV-2
Vogel et al., Nature. 2021.
https://www.nature.com/articles/s41586-021-03275-y
The preclinical development of two BNT162b vaccine candidates, which contain lipid-nanoparticle formulated nucleoside-modified mRNA encoding SARS-CoV-2 spike glycoprotein-derived immunogens, was performed in rhesus macaques at the Southwest National Primate Research Center (SNPRC). BNT162b1 encodes a soluble, secreted, trimerised receptor-binding domain. BNT162b2 encodes the full-length transmembrane spike glycoprotein, locked in its prefusion conformation. Prime/boost vaccination of rhesus macaques with BNT162b candidates elicits SARS-CoV-2 neutralizing antibody titers that are 8.2 to 18.2 times that of a SARS-CoV-2 convalescent human serum panel. The vaccine candidates protected macaques from SARS-CoV-2 challenge, with BNT162b2 protecting the lower respiratory tract from the presence of viral RNA and with no evidence of disease enhancement. The BNT162b2 vaccine recently received emergency use authorization from FDA and is being administered within the United States. The SNPRC is supported by ORIP (P51OD011103).
Natural Killer Cells Activated Through NKG2D Mediate Lung Ischemia-Reperfusion Injury
Calabrese et al., Journal of Clinical Investigation. 2021.
https://www.jci.org/articles/view/137047
Pulmonary ischemia-reperfusion injury (IRI) causes early mortality and has no effective therapies. While natural killer (NK) cells are innate lymphocytes capable of recognizing injured cells, their roles in acute lung injury are incompletely understood. Here, investigators demonstrated that NK cells were increased in frequency and cytotoxicity in 2 different IRI mouse models. They showed that NK cells trafficked to the lung tissue from peripheral reservoirs and were more mature within lung tissue. Acute lung ischemia-reperfusion injury was blunted in a NK cell–deficient mouse strain but restored with adoptive transfer of NK cells. In human lung tissue, NK cells were increased at sites of ischemia-reperfusion injury and activated NK cells were increased in prospectively-collected human bronchoalveolar lavage in subjects with severe IRI. These data support a causal role for recipient peripheral NK cells in pulmonary IRI via NK cell NKG2D receptor ligation. Therapies targeting NK cells may hold promise in acute lung injury. Supported by ORIP (S10OD026940), NHLBI, and NIDDK.
Modified Vaccinia Ankara Vector-Based Vaccine Protects Macaques from SARS-CoV-2 Infection, Immune Pathology and Dysfunction in the Lung
Routhu et al., Immunity. 2021.
https://doi.org/10.1016/j.immuni.2021.02.001
Any SARS-CoV-2 vaccine may have limitations such as need for ultracold storage, poor induction of CD8+ T cell response, or lack of cross-reactivity with emerging strains. Thus, multiple vaccines may be needed to bring COVID-19 under control. Using rhesus macaques, researchers showed that a modified vaccinia Ankara (MVA) vector-based SARS-CoV-2 vaccine expressing prefusion-stabilized spike protein induced strong neutralizing antibody and CD8+ T cell responses. The vaccine protected macaques from SARS-CoV-2 infection as well as infection-induced inflammation and B cell abnormalities in the lung. These results are promising considering the excellent safety and performance of MVA vector-based vaccines for other pathogens. Supported by ORIP (P51OD011132, S10OD026799) and NIAID.