Diagnostic potential of puumala virus nucleocapsid protein expressed in Drosophila melanogaster cells

Puumala virus (PUU) nucleocapsid protein (N) was expressed in insect cells by using the Drosophila Expression System (DES; Invitrogen BV, Groningen, T he Netherlands). Stable transfectants were established by hygromycin B sele ction and showed continuous expression of the recombinant protein (DES-PUU- N) for at least 5 months. The antigenic property of DES-PUU-N was shown to be identical to that of native PUU N when examined with a panel of hantavir us-specific monoclonal antibodies. Enzyme-linked immunosorbent assays (ELIS As) for detection of human immunoglobulin M (IgM) and IgG antibodies were e stablished by using DES-PUU-N as antigen and were compared to assays based on native N. The ELISAs were evaluated for patient diagnosis and seroepidem iological purposes with panels of sera collected from patients with hemorrh agic fever with renal syndrome (HFRS) and from healthy blood donors. Equall y high sensitivities and specificities for detection of PUU-specific IgM in acute-phase HERS patient sera were obtained by the ELISA based on DES-PUU- N and the assay based on the native antigen. For detection of PUU-specific Igc, the ELISA based on monoclonal antibody-captured DES-PUU-N antigen show ed optimal sensitivity and specificity.