Swine enteric alphacoronavirus (swine acute diarrhea syndrome coronavirus): An update three years after its discovery

•A summary of the research progress in SeACoV (SADS-CoV) from 2017 to 2020.•Bat-derived SeACoV was most recently recognized prior to SARS-CoV-2 associated with COVID-19.•Focusing on the etiology, epidemiology, evolutionary perspective, potential for interspecies transmission, pathogenesis and diagnosis. Discovered in 2017, swine enteric alphacoronavirus (SeACoV), also known as swine acute diarrhea syndrome coronavirus (SADS-CoV) or porcine enteric alphacoronavirus (PEAV), is the fifth porcine CoV identified in diarrheal piglets. The presumed name “SADS-CoV” may not be appropriate since current studies have not provided strong evidence for high pathogenicity of the virus. SeACoV was the most recently recognized CoV of potential bat origin prior to the novel human severe acute respiratory syndrome CoV 2 (SARS-CoV-2), associated with the pandemic CoV disease 2019 (COVID-19). Although SeACoV is recognized as a regional epizootic virus currently, it possesses the most extensive cell species tropism in vitro among known CoVs. This review summarizes the emergence of SeACoV and updates the research progress made from 2017 to early 2020, mainly focusing on the etiology, epidemiology, evolutionary perspective, potential for interspecies transmission, pathogenesis and diagnosis.