Abstract
An enzyme-linked immunosorbent assay was applied for determining separately IgM and IgG antibodies against tick-borne encephalitis virus. A micro-modification in microtitre plates proved to be at least as sensitive as the HI test. However, more precise information could be achieved by a macrotest using antigen coated polystyrene balls. False positive results in IgM antibody determinations could be caused by a rheumatoid factor. A high content of IgM antibodies in a serum could impair the determination of its IgG antibodies but not vice versa. Titres were expressed in comparison to a positive control serum.