Detection of G3P[3] and G3P[9] rotavirus strains in American Indian children with evidence of gene reassortment between human and animal rotaviruses.

The distribution and evolution of human rotavirus strains is important for vaccine development and effectiveness. In settings where rotavirus vaccine coverage is high, vaccine pressure could select for replacement of common strains (similar to those included in rotavirus vaccines) with uncommon strains, some of which could be generated by reassortment between human and animal rotaviruses. Between 2002 and 2004, a phase-III rotavirus vaccine clinical trial was conducted among American Indian children of the Navajo and White Mountain Apache tribes, which are known to be at high risk for rotavirus diarrhea. We evaluated the rotavirus strains collected from study participants who received placebo during the trial to determine the distribution of rotavirus genotypes and to detect emerging strains that contribute to disease and could influence rotavirus vaccine effectiveness. Three uncommon strains of human rotavirus, two G3P[3] and one G3P[9] strains were detected in stools of children aged 3 to 6 months of age. Segments of all 11 rotavirus genes were sequenced and genotyped by comparison of cognate gene fragments with reference strains. The G3P[3] strains had similar genotypes to each other and to reference dog and cat strains. The G3P[9] strain had similar genotypes to cow, cat and dog reference strains. Genetic analyses of these three strains support the known diversity generating mechanisms of rotavirus.