Determination of serotypes of astroviruses by reverse transcription-polymerase chain reaction and homologies of the types by the sequencing of Japanese isolates.

Human standard astroviruses, serotypes 1 to 7, and 35 Japanese isolates were typed by reverse transcription and polymerase chain reaction (RT-PCR) with serotype-specific primers for the first time. The results were identical with those obtained by enzyme immunoassay with serotype-specific polyclonal antibodies, a method which has already been reported. RT-PCR with serotype-specific primers is useful for epidemiological studies of astroviruses where serotype-specific polyclonal antibodies are not available. Two parts of the capsid region, N terminus and C terminus, were sequenced. Serotypes differed in those regions. The N terminus differed less than the C terminus between serotypes. Both the N terminus and C terminus were similar intraserotypically with the exception of serotype-4 isolates which could be divided into A and B subgroups on the basis of their C terminus sequences, which were not known previously.