Short electropherotype rotaviruses isolated longitudinally from a cohort of Mexican infants.

Stool specimens obtained longitudinally during the first year of life of a cohort of 75 rural infants were tested for the presence of rotavirus with an enzyme-linked immunosorbent assay. Thirty four infants showed the presence of rotaviruses during the first year of life. Only 41% of these episodes were associated with diarrhea. Extraction of rotavirus RNA was still possible in 12 of 34 stool samples, ten of them obtained during episodes of associated-diarrhea. Electropherotyping of these rotavirus showed that nine had a short electropherotype. One diarrheal and two asymptomatic samples had a long electropherotype. Subgrouping the viruses with monoclonal antibodies showed that five of the nine rotaviruses with short electropherotype belonged to subgroup I, and two of the three with long electropherotype belonged to subgroup II. The rest of rotaviruses could not be subgrouped. This study confirms the prevalence of only few rotavirus strains in any defined geographic region over a specific period of time, in this case, a rotavirus with a short electropherotype.