A classification of laboratory strains of avian mycoplasma serotypes by direct immunofluorescence.

Direct immunofluorescence (IF) was used to assess cross-reactivity among 41 laboratory strains representing 11 serotypes of avian mycoplasmas. All the strains could be separated into distinct serotypes except the C-O-D-P group, which showed cross-relatedness unlike that demonstrated by other serological methods. With two exceptions, serotype C strains consistently cross-reacted with only the serotype P conjugate; the serotype O strain cross-reacted with the P and C conjugates. The two serotype C exceptions were found to be misclassified, as was the serotype P strain. Direct IF was found to be a quick, reliable method for measuring serological relatedness.