Version 2: Differences in pMGA1.2 and pMGA1.3 sequences among isolated field strains of Mycoplasma gallisepticum that produce deformed eggs in laying hens.

Mycoplasmosis in poultry is a chronic disease that causes economic losses in farming and is difficult to eradicate in flocks. Mycoplasma gallisepticum (MG) is one pathogen that causes this disease. This bacterium has many important surface proteins involved in adhesion, transporter activity, and evasion of the immune system, all of which promote infection. The lipoprotein pMGA presents antigenic variability. It includes regions from the pMGA1.2 and pMGA1.3 sequences, which are stable segments with 97% amino acid identity. The aim of this study was to determine the similar and different regions of pMGA1.2 and pMGA1.3 in MG field strains compared with the M83178.1 sequence. We identified 18 MG field strains (16 from eggs, one from an oviduct membrane, and one from an air sac) of laying hen flocks based on the mgc2 gene. We generated six internal primers to amplify six segments that cover the pMGA1.2 and pMGA1.3 sequences; the MGS6 and MSWUV1853 strains served as a positive and negative control, respectively. Segments close to the C-terminal region were amplified more frequently. Interestingly, no field strains presented the same amplification pattern as MGS6. We performed bioinformatics of segments 4 and 6, translating the nucleotide sequences to amino acids. They were compatible with conserved sequences in Myco_haema protein domains in the genus Mycoplasma that belong to Q7NAP3_MYCGA VlhA.3.04. There were differences in the field strains along with a homologous region that suggests genetic transfer has occurred bacterial evolution. The outcomes showed the dynamic variability in pMGA, and these differences could represent an important factor for the development for vaccines to provide protection against MG infection in chickens.