Virus World

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA generally becomes undetectable in upper airways after a few days or weeks postinfection. Here we used a model of viral infection in macaques to address whether SARS-CoV-2 persists in the body and which mechanisms regulate its persistence. Replication-competent virus was detected in bronchioalveolar lavage (BAL) macrophages beyond 6 months postinfection. Viral propagation in BAL macrophages occurred from cell to cell and was inhibited by interferon-γ (IFN-γ). IFN-γ production was strongest in BAL NKG2r+CD8+ T cells and NKG2Alo natural killer (NK) cells and was further increased in NKG2Alo NK cells after spike protein stimulation. However, IFN-γ production was impaired in NK cells from macaques with persisting virus. Moreover, IFN-γ also enhanced the expression of major histocompatibility complex (MHC)-E on BAL macrophages, possibly inhibiting NK cell-mediated killing. Macaques with less persisting virus mounted adaptive NK cells that escaped the MHC-E-dependent inhibition. Our findings reveal an interplay between NK cells and macrophages that regulated SARS-CoV-2 persistence in macrophages and was mediated by IFN-γ. Huot et al. show that interferon-γ (IFN-γ) regulates the persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in bronchoalveolar macrophages from cynomolgus macaques up to 18 months postinfection.

Published in Nat. Immunology (Nov. 2, 2023):

https://doi.org/10.1038/s41590-023-01661-4 

Monkeys infected with SARS-CoV-2 were protected from subsequent exposures, a finding that has vital implications for vaccine design. 

Concerns about SARS-CoV-2 infection have reached an all-time high in the United States and around the globe. With increasing numbers of COVID-19 cases, hospitalizations, and deaths—and “social distancing” now a household word—the possibility of being infected is on everyone’s mind. As if that weren’t enough to worry about, the surfacing of multiple personal accounts—primarily out of China and Japan—of patients who recovered after infection only to fall ill a second time, have some worried about the possibility of reinfection. Now, a collaboration of Chinese scientists has dug deeper into whether or not reinfection with SARS-CoV-2 is possible with a small monkey study. The team looked at whether or not non-human primates, rhesus macaques, can become reinfected with SARS-CoV-2. The work was posted on the preprint server bioRxiv on March 14 in a paper titled, “Reinfection could not occur in SARS-CoV-2 infected rhesus macaques.” Their conclusion: there may be no reason to worry about reinfection.

The study used four, adult Chinese rhesus macaques. After intratracheal infection, the monkeys were analyzed on schedule, including measurements such as body weight, body temperature, lung x-rays, sampling of sera, nasal/throat/anal swabs, and primary tissues. The rhesus monkeys were successfully infected, as measured by weight loss, viral replication mainly in the nose, pharynx, lung, and gut, as well as moderate interstitial pneumonia....

Original Study available at bioRxiv  (March 14, 2020):

https://doi.org/10.1101/2020.03.13.990226

Close contact through sexual activity has been associated with the spread of monkeypox virus (MPXV) in the ongoing, global 2022 epidemic. However, it remains unclear whether MPXV replicates in the testes or is transmitted via semen to produce an active infection. We carried out a retrospective analysis of MPXV-infected crab-eating macaque archival tissue samples from acute and convalescent phases of infection of clade I or clade II MPXV using immunostaining and RNA in situ hybridization. We detected MPXV in interstitial cells and seminiferous tubules of testes as well as epididymal lumina, which are the sites of sperm production and maturation. We also detected inflammation and necrosis during the acute phase of the disease by histological analysis. Finally, we found that MPXV was cleared from most organs during convalescence, including healed skin lesions, but could be detected for up to 37 d post-exposure in the testes of convalescent macaques. Our findings highlight the potential for sexual transmission of MPXV in humans. Detection of monkeypox viruses (MPXV) in archival testes samples from acute and convalescent MPXV-infected macaques provides evidence supporting the potential for sexual transmision of MPXV.

Published  (Oct. 17, 2022) in Nature Microbiology:

https://doi.org/10.1038/s41564-022-01259-w