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

Abstract

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.

FIG. 1

Immunoperoxidase staining of NY-1 proteins in Vero E6 cells. Vero E6 cells in 24-well plates were infected, the inocula were removed from cells, and at various times p.i. monolayers of infected cells were fixed with 100% methanol (−20°C) for 10 min. Following three washes in PBS, rabbit anti-nucleocapsid hyperimmune sera (made to the baculovirus-expressed SN nucleocapsid protein, 1/5,000) were added to cells in PBS–1% BSA for 1 h. Cell monolayers were washed five times with PBS and reacted with a horseradish peroxidase anti-rabbit conjugate (1/2,000) for 1 h. Monolayers were washed three times and were developed with the horseradish peroxidase substrate amino-ethyl-carbazole, producing a brown precipitate in cells (15, 46). Mock-infected (A) or NY-1-infected (B to D) monolayers were stained at 24 (panels A and B), 48 (panel C), or 72 (panel D) h p.i. Magnification, ×200.

FIG. 2

Titration of human serum neutralizing antibodies. Twofold serial dilutions of SN- or NY-1-specific sera were mixed with approximately 200 FFU of NY-1 (A) or SN (B) in 100 μl of PBS–2% FCS for 1 h at 37°C. Virus was adsorbed to confluent monolayers of Vero E6 cells in duplicate wells of a 96-well plate. Viral inocula were removed, and following washing, cells were incubated in DMEM–2% FCS for 24 to 36 h. Viral antigen present in infected cells was detected by immunoperoxidase staining and quantitated as described previously (15, 46). Experiments were repeated at least three times, and error bars reflect the range of values obtained from these experiments.