G2 rotavirus infections in an infantile population of the South of Italy: Variability of viral strains over time

Abstract

Rotavirus positive samples collected in Palermo, Italy, during 2002-2004 did not react with the G2 type-specific RV5:3 monoclonal antibodies (MAbs) and could be identified as G2 only by RT-PCR genotyping. The genetic variation of VP7 and VP4 antigenic proteins was studied in 14 G2 samples including a selection of both those successfully characterized by serotyping and those failing to be serotyped. The phylogenetic analysis performed on partial VP7 sequences showed a temporal clustering of these strains, with those isolated in Palermo in 2003 belonging to the same lineage of G2 MAbs-unreactive strains identified in UK in 1996-1997 and in Bari, Italy, in 2003-2004. A single amino acid substitution in VP7 antigenic region A, at position 96 (Asp-->Asn), was consistently associated with the loss of antigenic reactivity. Five of the G2 strains were further characterized by sequencing of VP4-encoding genes as belonging to the P[4] type, and separate lineages clustering the strains according to a temporal distribution could be described. VP7 and VP4 antigenic proteins analysis provided evidence that over the last 11 years, at least two different populations of G2P[4] rotavirus strains have been infecting the infant population in Palermo. Considering the role of anti-VP7 and anti-VP4 neutralizing antibodies in rotavirus immunity, the emergence of new VP7-VP4 gene combinations might influence rotavirus circulation in the infant population and should be taken into consideration when devising vaccination strategies.

Heterogeneity and Temporal Dynamics of Evolution of G1 Human Rotaviruses in a Settled Population

“…A high overall variability was demonstrated in the VP7 sequences of the G1 rotaviruses analyzed in this study, with at least 23 amino acid substitutions being detected. By contrast, only 5 amino acid changes were observed in G2 strains and 12 were observed in G4 strains (1,2). The high intraserotypic genetic and antigenic heterogeneity is a possible reason for the consistent predominance of G1 serotype rotaviruses throughout the world over the years.…”

“…In 15 of the 20 years examined, G1P [8] HRVs have represented the first most common rotavirus serotype circulating. Fluctuations of the other rotavirus serotypes were observed over time, characterized by peaks of G4P [8] strains in 1990 to 1993, 1999 to 2001 and 2003; of G2P [4] strains in 1996 and 1997; and of G9P [8] strains in 1999 and 2000 (1,2). Cross-sectional analyses showed that the epidemics of G2P [4] and G4P [8] were due to the introduction into the infant population of Palermo of new rotavirus strains rather than to the reemergence of old epidemic strains (1,2).…”

Evolution of DS-1-like human G2P[4] rotaviruses assessed by complete genome analyses

“…In the 26-year period 1985-2011, the prevalence of G2P [4] RVAs in the paediatric population of Palermo showed yearly fluctuations (Arista et al, 2005;De Grazia et al, 2007), with peaks in 1985, 1996 to 1998, 2003 and 2004, 2006 to 2008, 2010 and 2011 (Fig. 1).…”

Development of a Microtiter Plate Hybridization-Based PCR-Enzyme-Linked Immunosorbent Assay for Identification of Clinically Relevant Human Group A Rotavirus G and P Genotypes

“…The PCR products were analyzed by agarose gel electrophoresis and visualized by staining with ethidium bromide. Rotavirus strains Wa (G1P [8]), K8 (G1P [9]), DS-1 (G2P [4]), P (G3P [8]), RRV (G3P [3]), ST-3 (G4P [6]), OSU (G5P [7]), UK (G6P [5]), 69 M (G8P [10]), WI61 (G9P [8]), B223 (G10P [11]), and YM (G11P [7]) were used as control viruses.…”

“…Although ELISA using type-specific monoclonal antibodies is a simple assay and accessible to laboratories in less developed countries, it presents limitations: it relies on the presence of substantial numbers of triple-layered particles in stool samples, which is not always the case due to digestion or degradation of the particles; type-specific monoclonal antibodies are not widely available; and virus strains bearing point mutations at the antibody binding site cannot be detected in the assay (5,20,39,40). Molecular methods are, in general, more sensitive and accurate than serological assays.…”