Variable expression of epitopes on the surface of Mycoplastna gattisepticum demonstrated with monoclonal antibodies

Abstract

SUMMARYTwelve monoclonal antibodies (Mabs) against Mycoplasma gallisepticum (Mg) strains F, R, S6(208) and PET2 were used for analysis of epitopes of 22 Mg strains. Six Mabs recognized surface epitopes in the majority of strains, but did not react with variant strains like K 503 and K 703. Two Mabs reacted with epitopes on about 56 kilodalton (kDa) proteins and showing consistent expression on Mg colonies. Three Mabs recognized three different variable surface epitopes associated with about 67 kDa proteins and one Mab variable epitope on about 33 and 80 kDa proteins. Two-dimensional immunoblotting showed considerable differences in the charge of proteins bearing variable surface epitopes in different Mg strains. Subcloning of four low passage Mg strains using Mabs for screening populations that derived from a single colony with defined surface epitopes showed that some colonies may switch surface epitopes associated with 67 and 80 kDa proteins. This switching was reversible and generated subpopulations of Mg expressing different combinations of surface epitopes. Phenotypic switching of epitopes probably occurs also in vivo and may be the mechanism enabling Mg to evade the host immune response.

Molecular Variability of the Adhesin-Encoding Gene pvpA among Mycoplasma gallisepticum Strains and Its Application in Diagnosis

“…Mycoplasmas exhibit a high degree of phenotypic variation, which is considered a major factor in pathogenicity and chronic infection of the host (22,23,24,29). Changes in the surface topology of M. gallisepticum during host infection and the molecular characteristics of several M. gallisepticum surface proteins have been described (1,6,14,21), including the recently described putative cytadhesin protein PvpA (2). PvpA is a phase-variable protein recognized by the chicken immune system (14,30).…”

“…Furthermore, technical factors such as the target DNA/primer ratio may significantly impact the reproducibility of RAPD patterns (27). Progress in the molecular biology of mycoplasmas has been achieved in the last decade, and several surface proteins in virulent mycoplasmas have been described (1,22). Mycoplasmas exhibit a high degree of phenotypic variation, which is considered a major factor in pathogenicity and chronic infection of the host (22,23,24,29).…”

Bi-Antigenic Immunoassay Models Based on the Recombinant PvpA Proteins for Mycoplasma Gallisepticum Diagnosis in Chickens

“…However, the accuracy of the serological tests was found to be closely related to the antigenic differences between the mycoplasma diagnostic strains or antigens and the infecting strains. 5,9,10 In addition, the cross-reactions also complicate differential diagnosis of mycoplasma infections due to common antigenic determinants. 2,4,15 Although a heterolog antigen adsorption method has overcome cross-reactions of the polyclonal sera, 2 this method is time consuming and difficult to apply in large-scale seromonitoring.…”

“…21 However, lack of specificity and/or sensitivity of serological tests often occurs because of antigenic differences between the mycoplasma diagnostic strains and the natural or experimental infecting strains. 5,10 In addition, the crossreactions also complicate differential diagnosis of mycoplasma infections due to M. gallisepticum and Mycoplasma synoviae, 2 major etiologic agents that share common antigenic determinants. 2,4,15 To overcome these disadvantages, production and use of recombinant proteins of the immunogenic molecules of several mycoplasma strains (or their functional fragments) for the standardization of diagnostic antigen and development of diagnostic tools have been undertaken by several research teams.…”

Poultry infected with Mycoplasma gallisepticum or Mycoplasma synoviae produce antibo dies to their cysteine proteas e CysP

“…CySP, reCOMBInAnt MSPB, PurIfIed PrOteInS And SynthetIC PePtIdeS M. synoviae wVu 1853 and M. gallisepticum S6 LP strains were used to prepare their whole-cell antigens (Benčina et al, 1994;2005). Their cells were grown in a modified frey's broth containing 10 % porcine serum and harvested as described (Berčič et al, 2008a;dušanić et al, 2009).…”