Comparison of two automated immunoassays for the determination of Puumalavirus IgM and IgG

BACKGROUND: Puumala virus (PUUV), a member of the genus hantavirus, can cause nephropathia epidemica, a mild form of haemorrhagic fever with renal syndrome. The method of choice for the serodiagnosis of hantavirus infections are enzyme-linked immunosorbent assays (ELISAs).

OBJECTIVES: Two commercially available PUUV ELISA kits were compared: Hantavirus (Puumala) IgM/IgG ELISA (Progen, Heidelberg, Germany) and PUUMALA IgM and IgG EIA AutoM (Reagena, Toivala, Finland).

STUDY DESIGN: The sensitivity of the ELISA kits was evaluated with a panel of 55 serum samples from patients with an acute (n=27) or past (n=28) infection based on Progen or Reagena. A panel of 56 serum samples was composed to evaluate the specificity: samples with potentially false positive Progen Puumala IgM results (n=12), seronegative samples for Puumala IgG/IgM with Progen (n=20), and potentially cross reacting samples (n=24). Discrepancies between the two assays were resolved with strip immunoblot. As measure of agreement between Progen and Reagena results, Cohen kappa coefficient was calculated.

RESULTS: Reagena showed a higher specificity (IgM 100%, IgG 100%) than Progen Puumala (IgM 73.21%, IgG 100%). However, Reagena showed a slightly lower sensitivity (IgM 96.15%, IgG 97.78%) compared with Progen (IgM 100%, IgG 100%). Substantial agreement with a Cohen kappa of 0.67 and 0.76 was found between the two assays for Puumala IgM and IgG respectively.

CONCLUSIONS: This study showed a higher specificity of Reagena in comparison to Progen with a lower sensitivity, probably caused by selection bias. In spite of Reagena's lower sensitivity, no acute infection was missed with this assay.