Genetic diversity of Mycoplasma hyopneumoniae isolates from conventional farrow-to-finish pig farms in Serbia.

Mycoplasma hyopneumoniae is a primary agent associated with mycoplasma pneumonia and the porcine respiratory disease complex (PRDC). Various reports have indicated that different strains of M. hyopneumoniae are circulating in the swine population. Lysates from lung swabs from naturally infected pigs of different ages were tested according to a new variable number of tandem repeats (VNTR) genetic typing method based on the polyserine repeat motif of the P146 lipoproteoadhesin, which can be applied directly on clinical material without isolation of M. hyopneumoniae. The aim was to determine the diversity of M. hyopneumoniae isolates from conventional farrow-to-finish pig farms located in different geographical areas of Serbia. PCR amplification was carried out using M. hyopneumoniae -specific designed, conserved primers (p146MH-L and p146MH-R) flanking the region encoding the repeat motif, followed by sequencing and cluster analysis. Five groups of M. hyopneumoniae with thirteen to twenty-four serine repeats were observed. Analysis of three samples from each farm indicated that the specific isolate is ubiquitous in pigs of different ages. Furthermore, seven clusters were observed within 27 tested samples. The results indicated a considerable diversity among M. hyopneumoniae field isolates in the swine population from conventional farrow-to-finish farms in Serbia and suggest close genetic relatedness of the corresponding isolates.