Genome Diversity and Evolution of Rotaviruses

Abstract

Rotaviruses (RVs) are a major cause of acute gastroenteritis (AGE) in infants and young children worldwide, and in the young of a large variety of animals (mammals and birds). This chapter describes the basic facts of genome diversity of RVs and discusses several mechanisms driving their evolution. An attempt is made to judge how the diversity of cocirculating wild-type (wt) RVs may be influenced by the ongoing vaccination programs. RVs are subdivided into different groups based on differences in antigenic properties of VP6, of which groups A through E are well distinguished. For the evolution of human RVs, the following genetic mechanisms have been found to be operative: accumulation of point mutations, genome reassortment, genome rearrangements (recombination), zoonotic transmission, and combinations of the above factors. Genome rearrangements have been found in combination with point mutations, and reassortment is frequently combined with zoonotic transmission. The conditions of genome diversity of RVs are very reminiscent of those of influenza viruses. Whole-genome sequencing, resulting in the assignment of genotypes to all 11 individual RV RNA segments, has allowed further insights into RV evolution. Since 2006, two RV vaccines have been licensed in various countries, and millions of doses have been distributed in universal mass vaccination (UMV) programs.