Development and evaluation of serological assays for detection of human hantavirus infections caused by Sin Nombre virus

Background: The hantavirus cardiopulmonary syndrome (HCPS) was first recognized in 1993 after a cluster of acute respiratory distress syndrome deaths in the southwestern of the United States. The major causative agent of HCPS in North America is the Sin Nombre virus (SNV) carried by the deer mouse Peromyscus maniculatus. The first HCPS case imported to Europe was reported in 2002. Objectives: The objective of the study was to develop and evaluate ELISA and Western blot tests for the serological detection of human infections caused by SNV including those imported to Europe. Study design: A polyhistidine (His)-tagged recombinant nucleocapsid (rN) protein of SNV was expressed in Saccharomyces cerevisiae and purified by nickel chelation chromatography. On the basis of the purified SNV rN protein p.-capture and indirect IgM and IgG ELISAs and an IgG Western blot were developed. The evaluation of the tests was performed using a negative serum panel and a blinded serum panel from the US containing acute-phase sera from HCPS patients. Results: Based upon the results obtained using a panel of negative control sera the specificity for SNV R-capture and indirect IgM and IgG ELISAs were found to be 100%. All 33 sera from SNV-infected HCPS patients included in the blinded panel were detected by the SNV l,L-capture and indirect IgM ELISAs. Twenty-nine out of the 33 SNV-IgM positive sera reacted also in the SNV-IgG ELISA. An SNV-IgG Western blot confirmed the data of the SNV-IgG ELISA. Although the majority of anti-SNV positive sera cross-reacted with rN proteins of Puumala virus and Dobrava virus, the lacking reactivity of a few sera with those heterologous rN antigens in the corresponding IgM and IgG ELISAs demonstrates the value of virus-specific test formats for acute-phase sera. Conclusions: The novel SNV ELISA and Western blot tests represent a useful tool for the serological detection of SNV infections.