Comparison of Antigenic Dominants of VP7 in G9 and G1 Rotavirus Strains Circulating in La Rioja, Argentina, with the Vaccine Strains.

ABSTRACT

A massive vaccination in Argentina was implemented recently. The antigenic dominants of VP7 in G9 and G1 rotavirus strains, circulating in La Rioja, Argentina with strain vaccines were compared. From 2000 to 2010 in several attention centers of La Rioja, at northwestern Argentina, 418 stool samples from children younger than 5 years old were collected. Ninety were positive by immunochromatography and 51 were genotyped by reverse transcriptase-polymerase chain reaction followed by nested-multiplex polymerase chain reaction (PCR) with type-specific primers. Six G9 strains and four G1 strains were sequenced by MACROGEN Korea. The phylogenetic analysis was conducted in MEGA 6.0. The 940 bp were aligned using CLUSTALW and the tree was inferred using the UPGMA method. The antigenic dominants of VP7, 7-1a, 7-1b, and 7-2 were studied using BioEdit, 7.2.5. In the comparison between G9-lineage III d rotavirus (RV) strains circulating in La Rioja with ROTAVAC vaccine strain, three differences were detected corresponding to 100, 211, and 145 positions. In the comparison between G1-Lineage 1 strains and G1 Rotarix and G1 RotaTeq, three differences were observed in 94, 123, and 217 positions. All these positions were important for the escape to neutralization for study with monoclonal antibody. In conclusion, the differences between the G1 strains in La Rioja, Argentina and the G1 components of the RotaTeq and Rotarix vaccine strains are few, but important for the escape immunologic, and need to be monitored for appropriate evaluation of long-term impact of vaccine used in Argentina. Nevertheless, the VP7 antigenic regions of G9 RV strains circulating in La Rioja and ROTAVAC vaccine strains are different to other zones of Argentina and could play an important role in the failure of vaccine response in these regions and Argentina.