Detection and genotyping of astroviruses by RT-PCR and sequencing.

Three primer pairs, AV244Mon and 82b, AV-15Gr and AV-12Gr, and Beg and End, were used for the detection of standard astroviruses (serotype 1 to serotype 7) in cell culture and astroviruses isolated from 89 diarrheal stool specimens negative for pathogenic bacteria, rotavirus and adenovirus by the reverse transcription-polymerase chain reaction (RT-PCR). All the standard strains and two isolates were detected by primer pairs AV244Mon and 82b, and AV-15Gr and AV-12Gr. All serotypes except serotype 4 were detected by the primer pair Beg and End. The molecular sizes of the RT-PCR products obtained by Beg and End were almost the same among the different serotypes except serotype 6. Sequence analyses of the nucleic acid in the regions between the primer pairs AV244Mon and 82b, and between Beg and End from PCR products of the standard strains and from the isolates of the two stool specimens revealed that each serotype had a unique sequence. These results indicate that the RT-PCR is useful for detecting and genotyping astroviruses.