The Hemagglutination-Positive Phenotype of Mycoplasma synoviae Induces Experimental Infectious Synovitis in Chickens More Frequently than Does the Hemagglutination-Negative Phenotype

Abstract

ABSTRACT Inoculation with hemagglutination-positive (HA + ) cultures of Mycoplasma synoviae AAY-4 induced acute synovitis significantly more frequently ( P = 0.001) in chicken tibiotarsal-tarsometatarsal joints than did inoculation with HA-negative (HA − ) cultures derived from the same clone of AAY-4. Immunoblotting analyses showed that HA + cultures abundantly expressed two phase-variable hemadherence-associated surface membrane proteins of 53 kDa and 48 to 50 kDa defined by monoclonal antibodies. HA − cultures lacked the 53-kDa proteins and synthesized truncated 27- to 30-kDa forms of the 48- to 50-kDa proteins. Inoculation of cyclosporin A (CsA) into infected joints significantly decreased the frequency of acute synovitis ( P = 0.001). Moreover, repeated intra-articular inoculation of CsA (three doses of 1 mg at 2-day intervals) significantly reduced the local antibody response to M. synoviae in the joints treated with CsA.