Identification of Calomys fecundus as the truly rodent reservoir of Laguna Negra hantavirus in North Western Argentina.

PINI N, GARCÍA J, SEN C, CALDERÓN G, GONZÁLEZ ITTIG R, GARDENAL N, JAYAT P, RIPOLL C & LEVIS S.

Foz do Iguaçu

Congreso; XXIII Congresso Brasileiro de Virologia, VII Encontro de Virologia do Mercosul (XXIII CBV).; 2012

Laguna Negra virus (LNV) was first identified as etiologic agent of Hantavirus Pulmonary Syndrome (HPS) in Paraguay in 1997, and was isolated from Calomys laucha rodents. In 2000, LNV was found in Argentina and Bolivia from humans and rodents (Calomys callosus) samples and in 2012 in Brazil (humans and Calomys callidus samples). LNV sequences obtained from HPS cases and rodent samples from North Western Argentina (Jujuy province) were compared with LNV sequences from other regions; we also performed the molecular identification of  rodent reservoirs trapped in the same area in 2000 and 2011. Human samples with a positive IgM serology and rodent samples with positive IgG by ELISA using Maciel virus antigen were analysed to detect viral RNA. Mitochondrial DNA was used to confirm morphological field identification of  rodents captured in 2011 and 2000 (previously identified as C. callosus); all positive rodents corresponded to C. fecundus . Viral RNA was amplified by nested RT-PCR with specific primers for S (447 bp) and M (513 bp) segments. Phylogenetic analysis was carried out by Neighbor Joining method and bootstrap support calculated, as implemented in MEGA 5.0. For the S fragment, all argentine strains showed differences < 1% (nucleotides, nt) and were identical in aminoacids (aa). Jujuy strains showed less than 4% difference when compared with reference strain (Paraguay)  and Brazil strain (Bolivia strains were not available at GenBank). At present, LNV was identified in four different reservoir species of the Calomys complex: C. laucha (Paraguay), C. callosus (Bolivia), C. callidus (Brazil) and C. fecundus (Argentina); only molecular DNA mitochondrial analysis could determine the proper identification of this cryptic species. However, they are infected with variants of the same hantavirus. It is not common that a hantavirus infects different rodent species, and we agree with the hypothesis that LNV had infected a common ancestor to the genus.