Molecular characterization of the genotype G9 human rotavirus strains recovered in Palermo, Italy, during the winter of 1999-2000.

Among the known human rotavirus serotypes, types G1-G4 are ubiquitous and account for >80% of global human rotavirus strains. Since 1994 an increase in reports of G9 serotype isolates has been observed in both developed and developing countries. In the winter season of 1999-2000 we detected the appearance of G9 rotavirus in Palermo, Italy, accounting for 19% of all rotaviruses circulating in our geographical area. Some of these Italian G9 isolates have been submitted to partial sequencing of their VP7 gene. All of them showed complete nucleotide identity suggesting a clonal origin. The Italian VP7 sequences were found to be very closely related to that of other G9 strains recently isolated in Europe, America, Africa and Asia. Our results confirm that G9 strains circulating worldwide since 1994 are closely related genetically in their VP7 genes.