Sequence polymorphisms within the pMGA genes and pMGA antigenic variants in Mycoplasma gallisepticum

Abstract

Antigenic variants of Mycoplasma gallisepticum major surface lipoprotein, pMGA, are encoded by a large gene family. In this study sequence analyses of the PCR‐amplified pMGA genes showed two types of sequences similar to the pMGA1.2 gene in M. gallisepticum strains. They differed in the sequence encoding a proline‐rich region (PRR) at the N‐terminus of the pMGA protein. The type A genes had sequences similar to the published pMGA1.2 gene sequence of strain S6, whereas the type B genes lacked the second repetitive segment encoding PTPN sequence within PRR and were similar to the published sequence of PG31 strain. Low in vitro passages of M. gallisepticum strains isolated recently in Slovenia from four avian species showed very different expression patterns of pMGA1.2 and pMGA1.9 genes. Among isogenic populations of S6B and IHB1 strains a high frequency of pMGA antigenic variants lacking an epitope for monoclonal antibody (mAb) 71 was found. Strain IHB1 clones, which synthesized pMGA recognized by mAb 71, transcribed pMGA genes whose partial sequence encoded the amino acid sequence 262TNGDEPRSVS of the mAb 71 epitope. Other IHB1 clones synthesized pMGA variants with different isoelectric points, lacking the epitope for mAb 71, but expressing downstream epitopes for other mAbs. Our study suggests that a molecular basis for pMGA antigenic variation lies in the corresponding changes at the DNA level.

Molecular basis of the length variation in the N-terminal part of Mycoplasma synoviae hemagglutinin

“…Indeed, chickens infected with M. synoviae raised high levels of antibodies against MSPB, including antibodies which blocked binding of mAb 125 ( [5]; see also Section 3.2). Besides M. synoviae strain diversity in length of the predicted PRR, we observed diversity in the number of PNPT repeats in the N-terminal part of deduced pMGA sequences in M. gallisepticum strains [14]. Strain K1968 was the only M. synoviae strain capable of causing lesions in joints of chickens following eyedrop inoculation [3].…”

“…In addition, rMSPB was used as a subunit MSPB antigen with a known number of residues and known amino acid sequence. Immunoblots were conducted with appropriate MSPB-speci¢c antibodies (mAbs or pAb RB), secondary antibodies labeled with horseradish peroxidase and diaminobenzidine tetrahydrochloride [10,14].…”

“…M. gallisepticum pMGA genes, which are related to vlhA, also encode a proline-rich region in the N-terminal part of mature pMGA proteins [7]. We have recently reported that M. gallisepticum strains with type B pMGA genes lack the second repetitive segment encoding sequence PTPN within the PRR [14]. It is not known whether such deletions exist in vlhA in M. synoviae strains, because only a single M. synoviae strain (WVU1853) has so far been sequenced for the vlhA gene [11].…”

Transfer of maternal immunoglobulins and antibodies toMycoplasma gallisepticumandMycoplasma synoviaeto the allantoic and amniotic fluid of chicken embryos

“…gallisepticum strains were grown in mycoplasma media with 10% horse serum. In most assays, type strain PG31 and strains S6, R and G11 were used as antigens (Benčina et al ., 1994;Miloševič-Berlič et al ., 2000). In the indirect immunoperoxidase assay (IIPA), M. gallinarum strain JA5 isolated from the chicken oviduct was also used .…”

Prevalence, diagnosis and treatment of mycoplasmosis in game birds

“…Pourbakhsh et al (2010) suggested that these false negative results from culturing might be due to the deficiency of several substances (NAD, serum, CO 2 and certain other materials) in the medium and during transportation, over-chilling of the specimen and destruction of viable MS at room temperature. In addition, this strain contained a small amount of cytadhesins (MGC1 and MGC3) and no PvpA protein (Milosevic-Berlic et al, 2000). They isolated one MG strain (ULB 992) from the infra-orbital sinuses of peafowl and two MG strains (ULB 971 (trachea) and ULB 972) in vitro from pheasants.…”