Detection of human astrovirus serotype 1 by the polymerase chain reaction.

Astroviruses are small, plus-strand RNA viruses associated with diarrhoea, mostly in children. The diagnostic method commonly used is electron microscopy. We have designed a nested polymerase chain reaction (PCR) based on the recently reported nucleotide sequence of the 3' end of the genome of a human astrovirus serotype 1, the most common form. The PCR was positive for the ten serotype 1 samples tested, while being negative for all other viruses tested, including astrovirus type 2, 3, 4 and 5, calicivirus, rotavirus and picornaviruses. Fecal extracts from patients with diarrhoea were analysed directly or after isolation of RNA, the former method being at least as sensitive. Titration of fecal extracts by PCR indicated the presence of up to 10(11) viral particles per ml in feces.