Fil: Levis, Silvana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: Morzunov, Sergey P. University of Nevada at Reno. Department of Microbiology; Estados Unidos.Fil: Rowe, Joan E. University of Nevada at Reno. Department of Microbiology; Estados Unidos.Fil: Enria, Delia. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: Pini, Noemí. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: Calderon, Gladys. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: Sabattini, Marta. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Virales Humanas; Argentina.Fil: St Jeor, Stephen C. University of Nevada at Reno. Department of Microbiology; Estados Unidos.Phylogenetic analysis of a 292-nucleotide (nt) fragment of the hantavirus M genome segment from 36 rodent and 13 human samples from three known foci of hantavirus infection in Argentina was conducted. A 1654-nt fragment of the M genome segment was analyzed for 1 representative of 7 genetically distinct hantavirus lineages identified. Additionally, the nt sequence of the complete M genome segments of Lechiguanas, Oran, and Hu39694 hantavirus genotypes was determined. nt sequence comparisons reveal that 7 hantavirus lineages from Argentina differ from each other by 11.5%-21.8% and from Sin Nombre, Bayou, and Black Creek Canal viruses by 23.8%-26.5%. Phylogenetic analyses demonstrate that they form a unique, separate branch within the clade containing other New World sigmodontine-borne hantaviruses. Most Oligoryzomys-borne hantavirus genotypes clearly map together. The Oligoryzomys-borne genotypes Lechiguanas, Oran, and Andes appear to be associated with human disease. Oligoryzomys longicaudatus was identified as the likely rodent reservoir for Andes virus.