HANTAVIRUS ANTIGEN-DETECTION USING HUMAN SERUM IMMUNOGLOBULIN-M AS THE CAPTURING ANTIBODY IN AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY

An enzyme-linked immunosorbent assay (ELISA) was developed to detect d ifferent hantavirus antigens in cell culture; i.e. Puumala (PUU), Hant aan (HTN): and Dobrava (DOE) viruses. The assay was based on binding h uman serum immunoglobulin M (IgM) antibodies to the solid phase by use of goat anti-IgM antibodies. The captured IgM antibodies were present in the acute phase serum from two patients: one infected in Sweden an d the other in Bosnia. Antigens being bound to the solid phase by the human anti-PUU and anti-DOB/HTN IgM antibodies were detected by a broa dly reacting polyclonal rabbit anti PUU-recombinant nucleocapsid prote in antiserum. The IgM isotype was proven to be at least five times mor e efficient than IgG when used as the capturing antibody. The sensitiv ity of the PUU antigen ELISA was approximately 0.5 ng/ml, as measured by titration with a PUU recombinant nucleoprotein antigen. Cell-associ ated PUU antigen in tissue culture was seen after 48 hr by the PUU-ELI SA and after 96 hr by immunofluorescent assay. When tested for capacit y to discriminate between PUU, DOE, and HTN viruses, significant diffe rences were found: the Swedish serum detected PUU antigen at high tite rs, whereas no reactivity was found against DOE and HTN; the Bosnian s erum detected both DOE and HTN at high titers but had a low reactivity to PUU. The method was also tested for its usefulness in detecting PU U antigen in bank vole (Clethrionomys glareolus) lungs. Of 59 animals captured from the surroundings of patients with nephropathia epidemica , three became positive with a high activity in the PUU-ELISA, but wit h low reactivity in the DOB/HTN-ELISA. It is concluded that a sensitiv e ELISA has been developed to detect different hantaviruses in cell cu lture and lungs of bank voles.