Comparison of Mycoplasma gallisepticum Strains by Hemagglutination-Inhibition and Restriction Endonuclease Analysis

Abstract
Mycoplasma gallisepticum strains, including a series of field strains from North Caroline [USA], were examined by homologous and heterologous hemagglutination-inhibition (HI) tests and by restriction endonuclease DNA analysis to determine whether they were closely related. HI results indicated wide antigenic diversity. Generally, homologous HI titers were higher than heterologous titers; exceptions were probably due to relative insensitivity of individual antigen batches. Strain A5969, commonly used as an HI antigen strain in many laboratories, was insensitive for detecting antibodies against all of the strains studied. None of the antigens was efficient in detecting HI antibodies against all other strains studied. Restriction endonuclease analysis indicated that North Carolina strains K501, K1453, and K1503 were closely related or identical, as were strains K1545, K1659, and K1486. Strain K1528, isolated from a peacock originally felt to be the source of many of the outbreaks, was not closely related to any of the other strains. Most strains identical or closely related by restriction endonuclease analysis were also closely related by HI. Strains 383T and 236C were identical by restriction enzyme analysis but unrelated by HI tests.