Two-Year Follow up from Birth of Thai Children for Rotavirus Infection: Serotypes and RNA Electropherotypes.

Twenty-two group A rotavirus positive stool specimens that had been collected from 19 children in Chiang Mai, Thailand, followed up for two years from birth in 1988 to 1990 (Supawadee et al., 1995), were examined for subgrouping (I and II), and VP7 serotyping (1, 2, 3 and 4) by enzyme-linked immunosorbent assay (ELISA) with specific monoclonal antibodies and RNA electropherotyping by polyacrylamide gel electrophoresis (PAGE). Of these, 18 (82%) could be subgrouped (10 subgroup I and eight subgroup II) and serotyped (five serotype 1, 10 serotype 2, one serotype 3 and two serotype 4). Serotype 1 virus was more predominant than type 2 during the period from January to June 1989 and type 2 was more predominant than type 1 from August 1989 to June 1990. Reinfection with rotavirus was observed in four children during the two years of the follow-up period after birth : one volunteer (No. 11) had an asymptomatic infection with serotype 2-RNA electropherotype S and a symptomatic infection with serotype 3-RNA electropherotype L. Each of the other three had asymptomatic infections twice, i.e. : one (No. 21) with serotype 1-RNA electropherotype L and undetermined serotype-RNA electropherotype L; one (No. 38) with serotype 2-RNA electropherotype S and undetermined serotype-RNA electroherotype L; and the other one (No. 23) with undetermined serotype-RNA electropherotype L and serotype 2-RNA electropherotype S. The results of 18 specimens from asymptomatic infections were compared with those of 202 specimens from symptomatic infections in the same geographical area in the same period of time and no definite relation was found between the VP7 serotype and severity of the illness.