Genetic characterization of G12P[6] and G12P[8] rotavirus strains in six African countries

Abstract Background: G12 rotaviruses were first observed in sub-Saharan Africa in 2004 and since then have continued to emerge and spread across the continent and are reported as a significant human rotavirus genotype in several African countries, both prior to and after rotavirus vaccine introduction. This study investigated the genetic variability of 15 G12 rotavirus strains with either P[6] or P[8] identified between 2010 and 2014 from Ethiopia, Kenya, Rwanda, Tanzania, Togo and Zambia.Methods: The investigation was carried out by comparing VP7 and partial VP4 sequences of the African G12P[6] and G12P[8] strains with the available GenBank sequences and mapping the recognized neutralization epitopes of these strains.Results: The findings suggested that the VP7 and VP4 genes of the G12 strains circulating in African countries are homologous at the nucleotide and amino acid level, irrespective of country of origin and year of detection, although there was a unique clustering of the Ethiopian strains. The study strains shared a common ancestry with G12 strains circulating globally. Neutralization epitope mapping revealed that rotavirus VP4 P[8] genes associated with G12 had amino acids similar to those reported globally including the vaccines RotaTeq® P[8] and Rotarix®.Conclusions: It is unlikely that widespread vaccine use has driven the molecular evolution and sustainability of G12 strains in Africa. Furthermore, it is too early post vaccine introduction to indicate any effect of vaccine-induced pressure on maintaining the stability of these strains in circulation. Continuous monitoring of rotavirus genotypes is recommended to assess the long-term impact of rotavirus vaccination on the dynamic nature of rotavirus evolution on the continent.