Detecting SARS-CoV-2 in bats of New Mexico using immunohistochemistry on formalin- fixed, paraffn-embedded tissues

Abstract

Objectives: The emergence of severe acute respiratory syndrome coronavirus (SARS-CoV-2) and its zoonotic origin have raised critical questions regarding the potential role of local bat populations as reservoirs or intermediates for the transmission of this or related coronaviruses to humans. The goal of this project is to investigate the presence and diversity of coronaviruses in bat species native to the Southwest USA. Broadly, this study has two primary aims: (1) to detect antigens of coronaviruses in tissues of local bat populations via histological methods and (2) to perform a molecular screen of coronaviruses in these bats. Methods: Individuals from five bat species were evaluated: Artibeus jamaicensis, Myotis velifer, Antrozous pallidus, Tadarida brasiliensis, and Eptesicus fuscus. All species were local, wild-caught bats, with the exception of Artibeus jamaicensis, which is from a colony established at New Mexico State University (NMSU). Tissue was sourced from bats collected by TJO at NMSU. Bat tissue was fixed with formalin and samples subsequently taken of lung, kidney, nasal epithelium, and uterus. Tissue was further processed and embedded in paraffn wax. The embedded tissue was sectioned via a rotary microtome at 4 μm thickness and mounted onto slides. Slides were stained with general coronavirus anti-nucleocapsid primary antibody and a hematoxylin counterstain to visualize cellular structures. Slides were cover-slipped with DPX mounting medium and observed via light microscopy. Results: The immunohistochemistry protocol was performed on tissue from each of the five bat species investigated and on human placenta samples known to be positive for SARS-CoV-2. The latter was used as positive controls. Putative positive staining was seen in both human placenta and bat tissues. Interestingly, coronavirus was detected in Artibeus jamaicensis samples, an unexpected finding given its status as a laboratory colony. Verification of this putative finding is ongoing. Further work on our samples will determine the genetic identity of the coronaviruses detected and contribute to developing a molecular screen for more effcient detection of coronavirus antigens in local bat tissue. This work will serve as a springboard for further understanding coronavirus ecology and evolution in bats of the US southwest, and it can be used to further inform both local surveillance efforts and public policy surrounding the interaction between humans and animals in the natural environment and in controlled settings. Conclusions: Putative detection of coronavirus antigens was found in tissues from bat samples from the Southwestern USA. Implications for this work include broadening our understanding of the diversity and abundance of coronaviruses in the US. Burrell College; US National Science Foundation. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.