Biology subjects

Janowski, A. B.

Publications and source records attributed to Janowski, A. B..

3 recordsLinked to original sources

bioRxiv2024

Novel murine model of human astrovirus infection reveals a cardiovascular tropism

Astroviruses are a common cause of gastrointestinal disease in humans and have been recognized to cause fatal cases of encephalitis. A major barrier to the study of human-infecting astroviruses is the lack of an in vivo model, as previous attempts failed to identify a suitable host that supports viral replication. We describe a novel murine model of infection using astrovirus VA1/HMO-C (VA1), an astrovirus with high seroprevalence in humans that is a causative agent of encephalitis. VA1 RNA levels peak in heart tissue at day 7 post-inoculation. The cardiotropism was observed in multiple different murine genetic backgrounds evidenced by high VA1 RNA loads in heart tissue of A/J, C57BL/6, C3H/HeJ, Balb/c, and J:ARC mice. Infectious VA1 particles could be recovered from heart tissue 3 and 5 days post-inoculation. Intracellular viral capsid was present in tissue sections based on immunofluorescent staining and viral RNA was detected in cardiac myocytes, endocardium, and endothelial cells based on fluorescent in situ hybridization and confocal microscopy. Histologically, we identified inflammatory infiltrates consistent with myocarditis in some mice, with viral RNA co-localizing with the infiltrates. These foci contained CD3+ T cells and CD68+ macrophages. Viral RNA levels increased by > 10-fold in heart tissue or serum samples from Rag1 or Stat1 knockout mice, demonstrating the role of both adaptive and innate immunity in the response to VA1 infection. Based on the in vivo tropisms, we also tested cardiac-derived primary cells and determined that VA1 can replicate in human cardiac microvascular and coronary artery endothelial cells, suggesting a novel cardiovascular tropism in human cells. This novel in vivo model of a human-infecting astrovirus enables further characterization of viral pathogenesis and reveals a new cardiovascular tropism of astroviruses. Author SummaryAstroviruses typically cause viral diarrhea in humans but can also cause serious infections of the brain. Previously, the methods available to study how these viruses lead to invasive infections were limited. Here, we describe the first system to study human-infecting astroviruses using mice. We demonstrate that mice are susceptible to astrovirus VA1, a strain that commonly infects humans and has been linked to fatal brain infections. The virus infected heart tissue and was associated with inflammation. When mice with impaired immune systems were infected with VA1, they were found to have higher amounts of virus in their hearts and blood. Linking back to human health, we also found that VA1 can infect cells derived from human blood vessels of the heart. This model will enable us to better understand how astroviruses cause disease and how the immune system responds to infection. Our findings also suggest that astroviruses could be linked to cardiovascular diseases, including in humans. In the future, we can develop interventions that will prevent and treat astrovirus infections in humans.

microbiology↗

bioRxiv2023

The highly conserved stem-loop II motif is dispensable for SARS-CoV-2

The stem-loop II motif (s2m) is a RNA structural element that is found in the 3 untranslated region (UTR) of many RNA viruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Though the motif was discovered over twenty-five years ago, its functional significance is unknown. In order to understand the importance of s2m, we created viruses with deletions or mutations of the s2m by reverse genetics and also evaluated a clinical isolate harboring a unique s2m deletion. Deletion or mutation of the s2m had no effect on growth in vitro, or growth and viral fitness in Syrian hamsters in vivo. We also compared the secondary structure of the 3 UTR of wild type and s2m deletion viruses using SHAPE-MaP and DMS-MaPseq. These experiments demonstrate that the s2m forms an independent structure and that its deletion does not alter the overall remaining 3UTR RNA structure. Together, these findings suggest that s2m is dispensable for SARS-CoV-2. IMPORTANCERNA viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contain functional structures to support virus replication, translation and evasion of the host antiviral immune response. The 3 untranslated region of early isolates of SARS-CoV-2 contained a stem-loop II motif (s2m), which is a RNA structural element that is found in many RNA viruses. This motif was discovered over twenty-five years ago, but its functional significance is unknown. We created SARS-CoV-2 with deletions or mutations of the s2m and determined the effect of these changes on viral growth in tissue culture and in rodent models of infection. Deletion or mutation of the s2m element had no effect on growth in vitro, or growth and viral fitness in Syrian hamsters in vivo. We also observed no impact of the deletion on other known RNA structures in the same region of the genome. These experiments demonstrate that the s2m is dispensable for SARS-CoV-2.

microbiology↗

bioRxiv2022

The highly conserved stem-loop II motif is important for the lifecycle of astroviruses but dispensable for SARS-CoV-2

The stem-loop II motif (s2m) is an RNA element present in viruses from divergent viral families, including astroviruses and coronaviruses, but its functional significance is unknown. We created deletions or substitutions of the s2m in astrovirus VA1 (VA1), classic human astrovirus 1 (HAstV1) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For VA1, recombinant virus could not be rescued upon partial deletion of the s2m or substitutions of G-C base pairs. Compensatory substitutions that restored the G-C base-pair enabled recovery of VA1. For HAstV1, a partial deletion of the s2m resulted in decreased viral titers compared to wild-type virus, and reduced activity in a replicon system. In contrast, deletion or mutation of the SARS-CoV-2 s2m had no effect on the ability to rescue the virus, growth in vitro, or growth in Syrian hamsters. Our study demonstrates the importance of the s2m is virus-dependent.

microbiology↗