RECURRENT CIRCULATION OF SINGLE NONSTRUCTURAL GENE SUBSTITUTION REASSORTANTS AMONG HUMAN ROTAVIRUSES WITH A SHORT RNA PATTERN

To determine the relative frequency of intergenogroup reassortants of rotavirus in nature, we analyzed the genetic composition of 22 electro phoretically distinct stool isolates which accounted for 95.2% of stoo l rotaviruses with a short RNA pattern collected during 10 rotavirus s easons. These strains all showed subgroup I and G2 specificities, but two distinct hybridization patterns were observed when the probes prep ared from Wa (a member of the Wa genogroup) and KUN (a member of the D S-1 genogroup) were used. Genomic RNAs from 10 strains (accounting for 64% of the field rotaviruses with short RNA pattern) hybridized exclu sively to the KUN probe, and thus belonged to the DS-1 genogroup. On t he other hand, genomic RNAs of the remaining 12 strains (accounting fo r 36% of the field rotaviruses with short RNA pattern) formed one hybr id band with the Wa probe and 10 hybrid bands with the KUN probe. Thus , they were single gene substitution intergenogroup reassortants betwe en members of the Wa and DS-1 genogroups. They had a similar genetic c onstellation in that a gene segment encoding either NS35 or NS34 from a Wa-like strain was introduced into a DS-1-like genome background.