Serotypes and electropherotypes of human rotavirus detected in the city of São Luís (MA), Brazil.

A total of 22 (65%) of 34 representative rotavirus-positive specimens from infants with acute gastroenteritis were electropherotyped (RNA genome segments) and serotyped using an enzyme immunoassay with monoclonal antibodies (ELISA with MAbs). Serotype 3 was predominant during the 10-month study period (41%), followed by serotype 1 (27%) and serotype 4 (9%). Serotype 2 was not found. Rotavirus strains were grouped into 3 major electropherotypes designated V, W and Z, each corresponding to a single serotype, i.e., serotypes 1, 3 and 4, respectively. Three strains that could not be typed by the serologic technique showed the W electrophoretic profile. The relative migration of the gene segments 7-9 was the main feature distinguishing the predominant serotype 3 from the other serotypes. The migration of segments 2 and 5 was also important for differentiating serotype 4 strains. The present study strengthens the view that electropherotyping, when used in conjunction with serotyping, can help characterize atypical and unusual strains, as well as rotaviruses that cannot be typed by the serologic technique.