Molecular systematics of the species of Oligoryzomys (Rodentia, Cricetidae) present in Argentina.

PAULA C. RIVERA1, RAÚL E. GONZÁLEZ ITTIG1, HERNÁN ROSSI FRAIRE1, SILVANA LEVIS2, CRISTINA N. GARDENAL1

Buenos Aires

Simposio; VII International Conference on HFRS, HPS and Hantaviruses; 2007

Fundación Mundo Sano

Several species of the genus Oligoryzomys have been recognized as natural hosts of the etiological agents of the Hantavirus Pulmonary Syndrome (HPS) in Argentina. In spite of their epidemiological interest, the taxonomy, ecology and life history of those species are poorly known. The study of the phylogenetic relationships and geographic distribution of the rodent hosts may help to identify factors associated with the risk of exposure to hantavirus infection. We analyzed data of restriction sites and sequences of the mtDNA D-loop region in individuals of almost all Oligoryzomys species known to occur in Argentina, including samples from the three regions where seropositive Oligoryzomys specimens and cases of HPS were reported. The phylogenetic relationships were inferred using several approaches: Maximum Parsimony, Neighbor Joining and Maximum Likelihood. Our results support the idea that the specific name Oligoryzomys longicaudatus should be applied only to individuals from the south of Argentina. In the north-west, three well diferentiated taxonomic entities were detected; one of them was formed by specimens identificated as O. chacoensis. Oligoryzomys nigripes and Oligoryzomys delticola would represent different populations of a unique species with a broad distribution in the country. Specimens identified as Oligoryzomys flavescens conform three related clades, probably belonging to a species complex. The first includes individuals from Buenos Aires, north of Santa Fe and Chaco. The second clade is formed by all the individuals from Cordoba, in the central area of Argentina, and the third groups individuals from Oran (Salta province), in the north-west. On the basis of the molecular data obtained, the following modifications in the rodent-hantavirus genotypes relationships are suggested: the only viral genotype associated to O. longicaudatus would be Andes Sout, while O. chacoensis would be the natural host of the genotype Oran. One of the forms of the O. flavescens complex would be the natural host of the genotype Bermejo. Our data are consistent with the hypothesis that each hantavirus genotype is associated with a specific rodent host.