Identification and genetic characterization of a porcine hepe-astrovirus (bastrovirus) in the United States

Abstract

Here we describe the identification and genetic characterization of a porcine hepe-astrovirus, or bastrovirus, obtained from feces from pigs in the United States. The genome of the new bastrovirus is 5,955 nt long and contains two open reading frames (ORFs). ORF1 encodes a protein containing three domains, viral methyltransferase, RNA helicase and RNA-dependent RNA polymerase (RdRp), and is closely related to the RdRp of hepatitis E virus. The ORF2 protein shares similarities with the astrovirus capsid precursor protein. Although structural features of bastroviruses may resemble those of astroviruses, distinct characteristics of the newly identified bastrovirus include the presence of an RNA helicase domain in ORF1 and the lack of ORF1b. In addition to genetic characterization, screening of 368 porcine samples (oral fluids, oral swabs or fecal swabs) collected in the United States (US) using a porcine-bastrovirus-specific real-time PCR assay revealed that 31% of those samples were positive. These results suggest a broad distribution of bastroviruses in the swine population in the US. This represents the first description of bastrovirus in swine in the US.