Molecular characterization of G2P[4] and G9P[8] rotaviruses strains isolated from Moroccan children fully vaccinated with Rotarix™ between 2013 and 2014

Abstract

Background: Here, we describe the characterization of the VP7 and VP4 genes of rotavirus group A (RVA) strains isolated from Moroccan infants with acute gastroenteritis (AGE) after receiving the Rotarix. Methods: Stool samples were collected from seven infants suffering with AGE. Vesikari 20point was used while collecting the AGE information. RT-PCR followed by sequencing was employed to determine partial sequences from VP7 and VP4 encoding genes. RVA genotypes were determined using the RotaC online classification tool.The Neighbor-Joining phylogenetic tree was performed in the MEGA 6.06 software as well as the amino acid (aa) alignments of VP7 and VP8* antigenic epitopes. Results: Five children had gastroenteritis episodes defined as severe on the Vesikari scale. Analysis of VP7 gene sequences revealed five G2 and two G9 genotypes. These genotypes were associated with P[4] and P[8], respectively. Phylogenetic analysis demonstrated that G2 and G9 sequences grouped together with Italian strain belonging to lineage II and III respectively. Their P[4] sequences showed only 65-73% identity and grouped into two separate sub-clusters. The Moroccan P[8] isolates did not display this correlation and segregate to lineage III. The VP8* aa of P[8] when compared with that of the Rotarix vaccine, has a six aa differences. Conclusion: Although, this study does not reveal prevalence rates of RVA in infants after the vaccine introduction, it reports the detection and genetic characteristics of the G2P[4] and G9P[8] RVA types in vaccinated children in Morocco. The findings are suggestive of continuous surveillance program on rotavirus evolution in the vaccinated population.