Full genome characterization of human Rotavirus A strains isolated in Cameroon, 2010-2011: diverse combinations of the G and P genes and lack of reassortment of the backbone genes.

Over the past few years whole genome sequencing of rotaviruses has become a routine laboratory method in many strain surveillance studies. To study the molecular evolutionary pattern of representative Cameroonian Rotavirus A (RVA) strains, the semiconductor sequencing approach was used following random amplification of genomic RNA. In total, 31 RVA strains collected during 2010-2011 in three Cameroonian study sites located 120 to 1240 km from each other were sequenced and analyzed. Sequence analysis of the randomly selected representative strains showed that 18 RVAs were Wa-like, expressing G1P[6], G12P[6], or G12P[8] neutralization antigens on the genotype 1 genomic constellation (I1-R1-C1-M1-A1-N1-T1-E1-H1), whereas 13 other strains were DS-1-like, expressing G2P[4], G2P[6], G3P[6], and G6P[6] on the genotype 2 genomic constellation (I2-R2-C2-M2-A2-N2-T2-E2-H2). No inter-genogroup reassortment in the backbone genes was observed. Phylogenetic analysis of the Cameroonian G6P[6] strains indicated the separation of the strains identified in the Far North region (Maroua) and the Northwest region (Bamenda and Esu) into two branches that is consistent with multiple introductions of G6P[6] strains into this country. The present whole genome based molecular characterization study indicates that the emerging G6P[6] strain is fully heterotypic to Rotarix, the vaccine introduced during 2014 in childhood immunization program in Cameroon. Continuous strain monitoring is therefore needed in this area and elsewhere to see if G6s, besides genotype G1 to G4, G8, G9 and G12, may become a new, regionally important genotype in the post vaccine licensure era in Africa.

Shared G12 VP7 gene among human and bovine rotaviruses detected in Cameroonian villages.

Group A rotaviruses (RVA) are an important enteric pathogen in humans and livestock animals. Transmission of animal RVA strains to humans has been documented on several occasions. A reverse route of transmission of RVA under natural circumstances is anticipated, although evidence is scarce. However, experimental studies indicated that animals can be infected with human RVAs. By screening the stool samples collected from 157 cattle during 2011 in two Cameroonian villages, four samples (2.5%) were found positive for RVA. Upon sequence analysis of a 410 bp fragment of the VP7 gene, the RVA strains shared up to 100% nt identity to each other and to G12 RVAs identified in human patients living in the same geographic regions. This finding provides evidence for a human-to-animal transmission of an epidemic human rotavirus strain.