Partial genetic characterization of seoul hantavirus in rats of Buenos Aires City and genetation of a seoul recombinant nucleoprotein antigen

PADULA P.J.,; VIAZZOTTI L.,; NAIPAUER J.,; CUETO G.R.,; CAVIA R.,; MARTINEZ V.; SUÁREZ O.V

Buenos Aires, Argentina

Conferencia; VII International conference on HFRS, HPS and Hantaviruses; 2007

Fundación Mundo Sano

Serological surveys in humans and /or rodents performed in the Americas showed that Seoul virus (SEOV) is present in the continent. In Argentina, non confirmed human infections have been described, and although Rattus norvegicus have been found to be antibody positive, viral genome have not been demonstrated in these animals. We present here the first genetic evidence of SEOV in R. norvegicus in Buenos Aires city. We also generated a SEOV recombinant nucleocapsid protein (rNP) antigen for serology use. To determine the prevalence of infection with hantavirus in wild R. norvegicus and R. rattus populations in different areas of Buenos Aires city, rat captures were performed from 2003 to 2005. For that purpose we constructed a plasmid encoding SEOV NP, 430 amino acid length. After expression, the rNP was tested as antigen in ELISA test. Blood samples from rats were tested for specific IgG antibodies to SEOV and Andes virus (ANDV). Hantavirus seroprevalence was of 11.8 % for R. norvegicus (n =151). Although there was cross reaction detected between hantavirus antigens, 2 rats reacted with a high value to ANDV and a very low value with SEO antigen. Serologically positive rats were tested for SEOV by RT-PCR using specific primers for 2 fragments of M segment-encoding G1and G2 proteins.Viral genome was detected in 12 out of 21 positive rats (57.1%) captured in 2 parklands. Amplimers from 6 representative rats were sequenced. Genetic comparison showed 4% nucleotidic diversity between Argentinean strains. Sequence analysis of a 364-nt region of the G2-encoding M segment showed identity of 97% and 96% with Baltimore and Brazil strains respectively (Xiao et al, 1994). Approximately 92-95 % sequence identity (416 bp) is shared between G1 fragment Argentinean and Chinese (BjHD01 and K24-v2) SEOV strains. Phylogenetic analysis with other known SEOV M segment sequences was performed. The presence of seropositive R. norvegicus individuals in different locations indicates that SEOV are geographically widespread in Buenos Aires city, implying potential danger for humans. Our genetic data confirm that SEOV show a very low diversity within the Hantavirus genus. The NP SEOV recombinant antigen is recommended as an efficient antigen for hantavirus infection diagnosis by ELISA.