Evidence of rotavirus intragenic recombination between two sublineages of the same genotype.

Rotavirus G4 prevalence increased during the past decade, with one of the highest prevalences reported during rotavirus surveillance in Argentina. Intragenotype diversity analysis has led to its subdivision into lineages (I and II) and sublineages (Ia-Id). On analysis of Argentine and G4 VP7 sequences from other locations, one Argentine strain (ArgRes1723) appeared to be an intermediate between G4 sublineages Ib and Ic. Similarity and bootscanning analyses and Sawyer's test were carried out to demonstrate the recombinant nature of this strain. It was concluded that intragenic recombination occurred between sequences of sublineages Ib and Ic, with a crossover point between nucleotide positions 336 and 387. This study constitutes the first report of a mechanism of evolution in rotaviruses that is currently considered unusual - a recombination event between two strains of the same rotavirus genotype. These results will help increase current knowledge about rotavirus evolution and divergence, improving our understanding of the adaptation mechanisms used by these viruses.