Group A rotaviruses (RVAs) are a leading cause of viral gastroenteritis in children, with G2P RVA being one of the most common human strains worldwide. The complete genome sequences of nine G2P RVA strains, selected from a 26-year archival collection (1985-2011) established in Palermo, Italy, were determined. A strain associated with a peak of G2P RVA activity in 1996 resembled a reassortant strain identified in Kenya in 1982 and differed completely in genomic make up from more recent strains that circulated during 2004-2011. Conversely, the 2004- 2011 G2P RVAs were genetically more similar to contemporary RVA strains circulating globally. Recent G2P strains possessed either single or multiple genome segments (VP1, VP3 and/or NSP4) likely derived from ruminant viruses through intra-genotype reassortment. Amino acid substitutions were selected and maintained over time in the VP7 and VP8* antigenic proteins, allowing the circulation of two contemporary G2P variants to be distinguished. Altogether, these findings suggest that major changes in the genomic composition of recent G2P RVAs occurred in the early 2000s, leading to the appearance of a novel variant of the DS-1-like genotype constellation. Whether the modifications observed in the neutralizing antigens and in the genome composition of modern G2P RVAs may affect the long-term effectiveness of the vaccination programmes remains to be explored.
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