Monoclonal antibodies to Legionella pneumophila serogroup 6: evidence of antigenic diversity.

Reactivity of monoclonal antibodies (Mabs) prepared against the type strain of Legionella pneumophila subsp. pneumophila serogroup 6 (Lp sg 6) was tested in the indirect immunofluorescence test using 16 environmental isolates of this sg and 58 strains of sg 1 to 5 and 7 to 14. Five out of 11 Mabs 5 were serogroup-specific, i.e. there was a reaction with all sg 6 strains tested, but not with strains from other sg. Further 4 Mabs reacted with all sg 6 strains and a few strains of other sg. Two Mabs were only reactive with the type strain of Lp sg 6 and one sg 6 strain isolated in Bratislava, Czechoslovakia. This report shows further evidence that Lp sg 6 can be divided into antigenically distinct subtypes.