Genetic characterisation of G3 rotaviruses detected in an Italian infantile population in 19932005
Abstract number: P1888
De Grazia S., Giammanco G.M., Ramirez S., Colomba C., Cascio A., Aiello P., Arista S.
Objectives: Group A rotavirus are the most common aetiologic agents of acute gastroenteritis in children worldwide. Sequence analysis of the genes coding for the two outer capsid proteins VP7 and VP4, for the inner capsid protein VP6 and for the non structural protein NSP4 is useful to gather epidemiological information on rotaviruses. To date, 15 VP7 G-types, 27 VP4 P-types, 4 VP6 subgroup specificities (SGs I, II, I+II and nonI/nonII) and 5 NSP4 genotypes (A to E) have been established. The most common genotypes are G1P, G3P and G4P, in association with SGII and NSP4 B, and G2P SGII NSP4 A. Recently, epidemiologic studies showed an increasing detection of G3 strains in Japan, China, Russia, Ireland and Spain. In Italy, in the past G3 rotaviruses have been detected sporadically or at very low prevalence. However, in 2003 and 2005 they acquired an important epidemiological role. To investigate the emergence of G3 rotaviruses in Italy a sequence analysis was performed on G3 strains detected in Palermo during 13 years.
Methods: A total of 1012 rotavirus positive faecal specimens were collected from children (<5 years) hospitalised with acute gastroenteritis at the "G. Di Cristina" Children's Hospital of Palermo, Italy from 1993 to 2005. Rotaviruses were genotyped by nested RT-PCR to define their G and P type. Sequencing and phylogenetic analysis of the VP7, VP4, VP6 and NSP4 genes was performed after amplification with type-specific primers on representative G3 strains.
Results: Fifty-seven (5.6%) rotavirus positive samples were genotyped as G3. Of the 19 strains submitted to sequence analysis 11 were typed as G3P SGII NSP4 B, three as G3P SGII NSP4 A and one as G3P SGI NSP4 C. In the phylogenetic tree of VP7, the Italian G3P and G3P rotaviruses were distributed into lineage I while the G3P in lineage III. Sequence analysis of VP4 revealed that all Italian G3P rotaviruses clustered in the P-3 lineage. Phylogenies of the NSP4 gene showed the clustering of Italian strains in two separate groups according to the year of sampling.
Conclusions: The genetic analysis performed ascertained that strains circulating in Palermo shared common features in the genome segments analysed but amino acids mutations in the NSP4 sequence appeared in 2003 and were conserved through 2005. The periodical increase of G3 strains circulation seems more linked to a loss of immunity in the population that to changes in their antigenic determinants.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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