The Astroviridae is a family of nonenveloped, positive-sense single-stranded RNA viruses. They are classified into mamastroviruses and avastroviruses and are known to infect mammalian and avian species, respectively. In humans, the classical human astroviruses are genetically closely related and can be classified into 8 serotypes (HAstV1-8). In addition, several genetically distinct human astroviruses (e.g. MLB1) have been recently identified in stool samples from patients suffering from gastroenteritis. Although astroviruses are one of the major causative agents of gastroenteritis, there is relatively little information on the ecology and evolution of these viruses. The recent discoveries of genetically diverse astroviruses in bats and other animals highlights the genetic diversity of astroviruses in nature and suggest that there might be many more novel astroviruses circulating in peri-domestic and wild animals. Bats represent the second largest group of mammals (comprises 20% of all mammals). The remarkably high detection rate of astroviruses in bats prompted researchers to perform a surveillance study on rodents, which are the largest group of mammals accounting for 40% of known mammalian species. They specifically targeted rodent species that have a long history of living in close proximity to human populations. This paper describes the discovery of rat astroviruses (RAstVs) from urban rats.
Detection of novel astroviruses in urban brown rats and previously known astroviruses in humans. J Gen Virol. Jun 16 2010
Several novel astroviruses have been recently discovered in humans and in other animals. Here, we report results from our surveillance of astroviruses in human and rodent fecal samples in Hong Kong. Classical human astroviruses (N=9) and a human MLB1 astrovirus were detected in human fecal samples (N=622). Novel astroviruses were detected from 1.6% of the fecal samples of urban brown rat (Rattus norvegicus) (N=441), indicating the prevalence of astrovirus infection in rats might be much lower to those recently observed in bats. These rat astroviruses were phylogenetically related to recently discovered human astroviruses MLB1 and MLB2, suggesting the MLB viruses and these novel rat astroviruses may share a common ancestor.