Development and evaluation of a solid-phase enzyme immunoassay based on Andes hantavirus recombinant nucleoprotein.

Hantavirus pulmonary syndrome (HPS) with high mortality rate has been reported in five countries in South America. Rapid accurate methods are important both for monitoring acute infections and for epidemiological studies. The Andes virus nucleoprotein amino acid sequence has a high identity percentage compared with other sequences of this region and has been chosen for the development of diagnostic reagents. Andes nucleoprotein expressed in Escherichia coli was applied as antigen in IgG, IgA and mu-capture IgM enzyme-linked inmunosorbent assays (ELISAs). An evaluation of this reagent was conducted to establish its usefulness for differential diagnosis of HPS and seroprevalence studies. Samples from 135 reverse transcription (RT)-PCR-confirmed HPS cases, 77 individuals with other respiratory infections and 957 healthy inhabitants from endemic and non-endemic areas were analysed. The hantavirus-infected patients had an early and strong IgM, IgG and IgA serum antibody response, in most of the cases as early as 1, 7 and 1 days following onset of symptoms, respectively. IgM and IgG detection showed a specificity and sensitivity of 100%. Andes-specific IgM antibodies were found in all patients in the first available sample, which remained detectable for at least 43 days. Specific IgA antibodies were also detected in saliva of patients with acute HPS. The short duration of the disease and the risk for contacts due to person-to-person transmission of Andes virus necessitate the use of highly sensitive tests which might lead to earlier detection of infected people and improve the treatment and management of patients with HPS.