Characterization of human rotavirus genotype P[8]G5 from Brazil by probe-hybridization and sequence.

We report the molecular characterization of rotavirus genotype P[8]G5 strains found in fecal specimens collected in four different regions of Brazil, using digoxigenin(dig)-labeled oligonucleotide probes, sequence analysis, and RNA-RNA hybridization. The closest sequence relationships of the neutralization antigens of these strains were to the VP4 protein of P1A[8]G1 strain KU (93.3% identity in amino acids 11 to 282) and to the VP7 protein of G serotype 5 strain OSU (87.6% identity in amino acids 8 to 232). Based on VP7 sequence differences, we designed dig-probes that allowed us to discriminate porcine OSU-like strains from G5 strains isolated from Brazilian infants. The genetic relationships of two P[8]G5 isolates to other rotavirus genogroups were analyzed by RNA-RNA hybridization with [32P]-GTP probes representative of serotypes P1A[8]G1 (Wa), P[8]G3 (AU17), and P9[7]G5 (OSU). The Brazilian P[8]G5 strains showed sequence homology with genes of Wa-like and OSU-like strains, suggesting that these two strains were naturally occurring reassortants between members of the Wa and porcine rotavirus genogroups. The identification of these strains in diverse geographic areas of Brazil underscores their stability and demonstrates the emergence of clinically important rotavirus diarrhea strains by reassortment.

Rotavirus G and P types circulating in Brazil: characterization by RT-PCR, probe hybridization, and sequence analysis.

We used reverse transcription-polymerase chain reaction (RT-PCR) to determine the P and G genotypes of 130 culture-adapted rotavirus strains isolated from 181 fecal specimens of children under 5 years of age from 9 states and the Federal District of Brazil. The 4 genotypes found most commonly worldwide were also common in Brazil and P[8]G1 was the most prevalent (43%), followed by P[4]G2 (12%), P[8]G3 (6%), and P[8]G4 (6%). However, unusual types P[8]G5, P[6]G2, P[9]G1, P[9]G3, and mixed infections were responsible for 12% and 21% of the cases, respectively. Genotype G5 strains were detected in specimens collected in all 9 areas surveyed from all 4 regions of Brazil. The unusual strain diversity in Brazil suggests that when tetravalent rotavirus vaccines currently being developed are introduced into Brazil, laboratory surveillance will be essential to monitor protection against unusual strains, particularly those of genotype 5, as well as emergence of novel reassortants that may evolve from the large pool of children with mixed infections.

PIP: Rotavirus is an important cause of acute gastroenteritis in many species of animals and humans, and is responsible for about 870,000 deaths annually among children under 5 years old, mostly in developing countries. Rotavirus disease will most likely be controlled through the development and widespread use of an effective vaccine. In anticipation of the possible use of such a vaccine in Brazil, the authors characterized the most common strains of rotavirus in circulation in the country. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the P and G genotypes of 130 culture-adapted rotavirus strains isolated from 181 fecal specimens of children under age 5 years from 9 states and the Federal District of Brazil. The 4 genotypes found most commonly worldwide were also common in Brazil, with P[8]G1 being the most prevalent in 43% of cases, followed by P[4]G2 (12%), P[8]G3 (6%), and P[8]G4 (6%). The unusual types P[8]G5, P[6]G2, P[9]G1, and P[9]G3 were responsible for 12% of the cases, and mixed infections were responsible for 21% of cases. Genotype G5 strains were detected in specimens collected in all 9 areas surveyed from all 4 regions of Brazil. This unusual strain diversity in Brazil suggests that when tetravalent rotavirus vaccines currently being developed are introduced into Brazil, laboratory surveillance will be key to monitoring protection against unusual strains, especially those of genotype 5, as well as new reassortants which may evolve from the pool of children with mixed infections.