Astroviruses

Astroviruses are positive-sense, single-stranded RNA viruses. Their genomes contain three open reading frames, but the exact number of encoded proteins remains unknown. Astroviruses were originally identified in association with childhood diarrhea; subsequently, they have been identified as a common enteric virus infecting children under the age of 2. Infection is not restricted to humans, however, and host-specific astroviruses have been found in association with a variety of mammalian and avian species. Generally, infection causes a mild, self-limiting gastroenteritis, although infection in chickens and ducklings can result in nephritis or severe hepatitis, respectively. The immune response to astrovirus infection is only poorly characterized and may differ between mammalian and avian species. In this article, the current knowledge of astroviruses is reviewed, including their molecular virology, viral evolution, pathogenesis, and immune response.