New York 1 and Sin Nombre viruses are serotypically distinct viruses associated with hantavirus pulmonary syndrome.

New York 1 virus (NY-1) and Sin Nombre virus (SN) are associated with hantavirus pulmonary syndrome (HPS). NY-1 and SN are derived from unique mammalian hosts and geographic locations but have similar G1 and G2 surface proteins (93 and 97% identical, respectively). Focus reduction neutralization assays were used to define the serotypic relationship between NY-1 and SN. Sera from NY-1-positive Peromyscus leucopus neutralized NY-1 and SN at titers of >/=1/3,200 and </=1/400, respectively (n = 12). Conversely, SN-specific rodent sera neutralized NY-1 and SN at titers of <1/400 and 1/6,400, respectively (n = 13). Acute-phase serum from a New York HPS patient neutralized NY-1 (1/640) but not SN (<1/20), while sera from HPS patients from the southwestern United States had 4- to >16-fold-lower neutralizing titers to NY-1 than to SN. Reference sera to Hantaan, Seoul, and Prospect Hill viruses also failed to neutralize NY-1. These results indicate that SN and NY-1 define unique hantavirus serotypes and implicate the presence of additional HPS-associated hantavirus serotypes in the Americas.