Abstract

Background:
Considerable economic and productivity losses result from the impact of Mycoplasma gallisepticum on the poultry industry, causing increased mortality and expenses from control practitioner implementations. The pathogenic success of M. gallisepticum is largely attributed to its surface antigen proteins, which facilitate adhesion to host epithelial cells, promote immune evasion, and contribute to antigenic variation. Phenomenon associated with the cytoadherence and adaptive variation of the PVPA (Putative Variable Protein A) and pMGA (Mycoplasma gallisepticum hemagglutinin protein) multigene families are notable; however, there is limited information on the expression, molecular characteristics, and genetic variation of local poultry isolates.

Aim:
The aim of the study was to examine and analyze the genomic organization, molecular characteristics, expression patterns, and phylogenetic relationships for PVPA and pMGA from M. gallisepticum isolates from poultry to pathogenicity and their genetic variation.

Methods:
Clinical poultry specimens (tracheal swabs) were incubated with PPLO broth and agar media with selective supplements for Mycoplasma. Isolates were diagnosed using standard cultural characteristics, Diene's staining, and molecular methods. PCR and RT-PCR were applied to extracted genomic DNA (16S rRNA, PVPA, and pMGA genes) and total RNA (PVPA, and pMGA genes). Agarose gel products were subjected to sequencing analysis of the 16S rRNA gene. Their sequence was analyzed and compared to international databases. Local and global 16S rRNA sequences were used to perform a phylogenetic analysis.

Results:
All isolates showed similar growth characteristics of M. gallisepticum, including the fried egg colony morphology (as observed in Diene's staining). Analysis of total cultured genomic DNA verified the 16S rRNA gene, as well as the presence of the specified amplified fragments of the PVPA (430 bp) and pMGA (222 bp) genes. Analysis of the transcriptome showed that the PVPA and pMGA genes were actively expressed during the infection. Analysis of the local isolates revealed strong sequence homogeneity, though the local isolates showed unique distinct clustering from neighboring countries in the phylogenetic trees. A few local sequences were deposited in the NCBI database, which serves the data as the first record of local, regional genomic information.

Conclusion:
This study provides molecular characterization of M. gallisepticum isolates at genomic, transcriptional, and phylogenetic levels, focusing on the PVPA and pMGA adhesion–associated genes. The results demonstrate the genetic relationships among local poultry isolates and confirm the transcriptional presence of these genes. These findings contribute to a better understanding of the molecular epidemiology of M. gallisepticum and may support improved monitoring and control strategies in poultry production.

Key words: Antigenic variation; Avian respiratory disease; Cytoadherence; Phylogenetics; Surface proteins