Rotavirus G serotypes and p[],G genotypes identified in cases of reinfection among children participating in a trial with rhesus-human reassortant tetravalent vaccine (RRV-TV) in Belém, Brazil.

Group A rotaviruses are the most important agents of severe diarrhea in children and infants worldwide. The aim of present study was to identify rotavirus G serotypes and P[],G genotypes in cases of reinfection among children who participated in a vaccine trial with the tetravalent rhesus-human reassortant rotavirus vaccine (RRV-TV 4 x 10(4) pfu/dose) in Belém, Brazil. From July 1990 to June 1992, 540 children received, at their first, third and fifth months of life, oral doses of either vaccine or placebo. A total of 90 rotavirus diarrheal episodes among children who completed the three-dose vaccination schedule were recorded. We studied 11 reinfection rotavirus cases among five children (three female and two male). Fecal specimens were tested by using a enzyme immunoassay (IDEIA Rotavirus), followed by EIA with monoclonal antibodies to determine infecting serotypes Gl, G2, G3 and G4 and subgroups I and II. The viral dsRNA was extracted and electrophoresed through polyacrylamide gel and then subjected to reverse-transcription-polymerase chain reaction and nested-PCR for the determination of Gl, G2, G3, G4, G5 and G9 and P[4], P[6], P[8] and P[9] rotavirus genotypes. A total of 11 cases of reinfection (12 per cent) occurred among five children, three from the placebo group and two from the vaccine group. In four of the cases of reinfection G serotypes and P[],G genotypes were as follows: for the first and second infections, respectively: (1) G2/P[4],G2 and Gl/P[4],G1; (2) G2/P[4],G2 and G2/P[6],G5; (3) G2/P[4],G2 and G1/P[8],G1; and (4) G2/P[8],G1 and G1/P[8],G1. A fifth child had three successive infections caused by serotypes/genotypes G1/P[8],G1, in the first and second infections, and G2/P[4],G2 in the third infection. The common genotypes and unusual genotypes were detected in 8 (73 per cent) and 3 (27 per cent) of the isolates, respectively. With regards to the clinical severity, in two children a score indicated moderate/severe disease in both first and second infections. One child had three successive infections; the first episode was moderate/severe, the second very severe and the third was not available. In contrast, in two other children, the first episode was very severe, and the second episode was moderate/severe in one child and data was not available for the other child. The results obtained in the present investigation underscore the need to broaden our knowledge of the immunity in rotavirus reinfection. This should be useful regarding future rotavirus vaccination strategies in Brazil.