Molecular detection and characterization of Mycoplasma gallisepticum and Mycoplasma synoviae strains in backyard poultry in Italy

Abstract

Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) represent the most important avian Mycoplasma species in the poultry industry, causing considerable economic losses. In Italy, the presence of MG or MS has been investigated especially in commercial poultry farms. To our knowledge, no systematic investigations on MG or MS presence using highly specific diagnostic assays have been performed in backyard poultry. The aim of this study was to detect and molecularly characterize MG and MS strains in 11 backyard poultry flocks located in different regions of Italy. Tracheal swabs were collected and DNA was extracted. For MS, a PCR targeting a vlhA gene fragment was performed, and typing and subtyping was attempted. The presence of MG was investigated by a screening PCR, then MG typing by gene-targeted sequencing (GTS). All the amplicons were sequenced, then MG and MS dendrograms were constructed. All the flocks examined resulted Mycoplasma positive: 5 out of 11 (45.45%) were MG and MS positive, 3 (27.27%) were MG positive, and the remaining 3 (27.27%) were MS positive. The MS detections were assigned to types C, D, and F. All strains of type D belonged to subtype D1 and 2 unknown subtypes were identified. A MS sequence showed peculiar characteristics, which did not allow assignment to a known MS type or subtype. MG GTS analysis identified 6 MG strains belonging to 5 subclusters circulating in Italian backyards chicken flocks. The results of this study provide evidence of a risk for commercial poultry farms, especially in areas where backyard and commercial farms are close, suggesting the implementation of biosecurity measures.

Keywords: Italy; Mycoplasma gallisepticum; Mycoplasma synoviae; backyard poultry.

Figure 1

Nucleotide sequences of the PRR region of vlhA gene of MS strains detected in the study and reference strain WVU1853. Only residues that differ from the sequence of WVU1853 are shown.

Figure 2

Nucleotide sequences of the PRR region of vlhA gene of IT/MS879/ck/17 strain detected in the study and reference strain WVU1853. Only residues that differ from the sequence of WVU1853 are shown.

Figure 3

Phylogenetic tree based on the alignment of nucleotide sequences of vlhA genes of MS strains detected in the study (circle) and reference strains. Only bootstrap values >70 are reported.

Figure 4

Phylogenetic tree based on the alignment of nucleotide sequences of gap A, MGA_0319, mgc 2, and pvp A genes of MG strains detected in the study (triangle) and reference strains. Only bootstrap values >70 are reported.