Genomic and antigenic variation among rotavirus strains circulating in a large city of Argentina

Abstract

Knowledge of the antigenic diversity of rotaviruses circulating in a region should be acquired before introducing a rotavirus vaccine. In a collection of 151 rotavirus-positive samples from Mendoza, Argentina, strain diversity was evaluated utilizing G-typing monoclonal antibodies (MAbs), reverse-transcriptase-polymerase chain reaction (RT-PCR) G and P typing, and electropherotyping (PAGE). The G type of 137 (91%) specimens was determined. Typing MAb reactivity with the homologous type ranged from 25-94%. For the seven G1 MAbs utilized, 28 patterns of reactivity among 68 G1 strains occurred. For the 48 G2 strains, six patterns of reactivity occurred utilizing three G2-specific MAbs. Of the 92 samples G- and P-typed by reverse-transcriptase-polymerase chain reaction, 89% had single G/P combinations: eight G1[P4], one G1[P6], twelve G1[P8], 58 G2 [P4], and two G2 [P6]. Nine samples had more than one G type with a single P type, one sample had two P types associated with one G type, and one sample contained multiple G and P types. Twenty-nine PAGE patterns occurred for all G types, but differences of antigenic reaction did not predict differences in migration of gene segments 7, 8, and 9. For three specimens showing discordant results between G type by enzyme-linked immunosorbent assay (EIA) and RT-PCR, we observed unexpected electropherotypes. Complementary evaluation by RT-PCR and MAb-based EIA with multiple typing MAbs revealed genetic and antigenic diversity of circulating rotaviruses, including extensive intratypic variation of the G1 and G2 neutralization antigens, in Mendoza during a single season of rotavirus activity.