Um total de 8.961 amostras fecais coletadas de pacientes com diarréia aguda, no período de 1996 a 2006, no Estado de São Paulo foi testado para rotavírus por EIE. Destas, 20,0% foram positivas e posteriormente realizadas a caracterização dos rotavírus em genótipos G e P por nested RT-PCR. O genótipo G1 de rotavírus foi o mais freqüente, detectado em 35,2% das amostras, seguidos dos tipos G9, G2, G3, G4, infecção mista e G12. A associação mais freqüente foi a P[8]G1 e P[8]G9. Foi realizada a sequencia nucleotídica do gene 9 (VP7) de 38 rotavirus genótipo G1. Duas cepas foram analisadas dos anos de 1997, 1998, 2001 e 2002, três cepas dos anos 1996, 1999 e 2003, quatro cepas em 2000, sete cepas em 2004 e 2005, e cinco em 2006. Os 38 rotavírus G1 foram classificados em duas linhagens distintas, linhagem G1-I e linhagem G1-II. A linhagem G1-I foi detectada durante seis anos, 1996-1997, 2001-2002 e 2004-2006, e a linhagem G1-II foi detectada durante os anos de 1998-2001, e 2003-2005. Análises preliminares mostraram que Rotarix ® foi eficiente contra estas linhagens G1.

Rotavirus (RV) infections are recognized as a major cause of severe gastroenteritis in children worldwide. In March 2006, a monovalente P[8]G1, human RV vaccine (Rotarix® GlaxoSmithKline Biologicals) was introduced in Brazil into the routine childhood immunization schedule. Therefore, the study of genetic diversity among rotavirus strains before and after the introduction of this vaccine may be important for the development of vaccination strategies. A total of 8,961 fecal samples collected from patients with acute diarrhea, during the 11-year period surveillance in São Paulo State (1996 to 2006) were tested for rotavirus by ELISA. One thousand seven hundred eighty- four (1,784, 20.0%) were positive, and the characterization of the G and P genotypes was performed on 1,300 rotavirus samples by nested RT-PCR. The G1 type was the most prevalent rotavirus strain (35.2%). The second most prevalente was the G9 type (31.2%), followed by G2 (4.0%), G3 (3.5%), G4 (2.2%), mix infection (1.8%) and G12 (0.5%). The more frequent association was P[8]G1 and P[8]G9. We performed a sequence analysis of 38 P[8]G1 rotavirus strains, selected from a total of 341 P[8]G1.Two strains from 1997, 1998, 2001, and 2002 were analyzed; three strains from 1996, 1999, and 2003; four strains from 2000; seven strains from 2004, and 2005; and five strains from 2006. All 38 rotavirus G1 sequence in this study were found to be classified into two distinct lineages, lineage I with 44.7% (17/38) and lineage II with 55.3% (21/38). The G1I lineages were detected during six rotavirus seasons 1996-1997, 2001- 2002, and 2004-2006 whereas and lineage G1- II was detected during 1998-2001, and 2003-2005. Preliminary analyses 4 demonstrated that Rotarix® has been efficacious against these G1 lineages.