Molecular characterization of human G8P[4] rotavirus strains in Italy: Proposal of a more complete subclassification of the G8 genotype in three major lineages

•We sequenced the VP4, VP6, VP7, and NSP1-5 genes of 2 G8P[4] rotaviruses in Italy.•Both G8P[4] strains shared genotype constellation 1 with very similar sequences.•Phylogenetic analyses show 3 lineages in the G8 VP7 genotype, based on aa sequence.•Phylogenetic analyses suggest a dual reassortment involving the VP7 and NSP2 genes. In 2011, two children with acute rotavirus gastroenteritis were hospitalized in Sardinia, Italy. Two RVA strains with G8P[4] genotype were detected in their stools, and were named SS56/2011 and SS65/2011. The aim of the study was to characterize these two rare strains, collected within a national RVA gastroenteritis surveillance program. Eight of the 11 RVA genes were sequenced and phylogenetic analysis performed. VP7 amino acid sequence was also analyzed. Sequencing of genes encoding the VP4, VP6, VP7, and NSP1-5 proteins classified both strains as G8-P[4]-I2-A2-N2-T2-E2-H2, not detected previously in Italy. Phylogenetic analysis revealed that most genes of Italian RVA strains were closely similar to typical DS-1 like strains circulating worldwide, whereas the VP7 gene was strictly related to G8 strains firstly reported in Africa. This finding of G8P[4] RVA strains with a DS-1 like genomic constellation also in a southern European country further confirms the wide circulation of this uncommon genotype in the world. Comparison of the deduced amino acid sequence of the VP7 capsid protein of the Italian G8P[4] RVA strains with sequences reported previously suggests that the G8 genotype should be divided into three major lineages.