TDK conference 2017

Mycoplasma hyopneumoniae is a swine pathogen bacterium widespread all over the world. It plays an important role in the development of enzootic pneumonia, which is the most common chronic respiratory disease mainly among young pigs. M. hyopneumoniae causes considerable damage around the world. Decreased slaughter weight and elevated feed conversion ratio, costs of prophylaxis and treatment caused by enzootic pneumonia may lead to significant economic losses. Since M. hyopneumoniae is difficult to culture, PCR (polymerase chain reaction) technique is suggested for diagnostic purposes. The PCR based MLVA (multiple-locus variable-number tandem repeat analysis) is a reliable and well-reproducible technique. It is suitable for the recognition of the genetic diversity of bacterial strains and for epidemiological investigations. Since there is a lack of information about the Hungarian M. hyopneumoniae strains, the aim of this study was to establish a strain collection, and to describe the phylogenetic relationships between the isolates with MLVA.

A total of 44 M. hyopneumoniae isolates were collected between 2015 and 2016 by examining almost 1000 porcine lung samples originating from Hungarian slaughter houses. The targets of the MLVA examinations were four VNTR (variable-number of tandem-repeats) regions. The number of tandem repeats is characteristic and provides an individual MLVA profile for each isolate. We determined the number of tandem repeats by running the PCR products in agarose gel by means of a molecular weight marker. Our phylogenetic tree is based on the MLVA profile of the isolates.

According to the discriminatory power of the MLVA test, it was competent for comparative genetic analysis of the Hungarian M. hyopneumoniae strains. The strains clustered in three main groups and their subgroups. In accordance with previous studies we determined similar or completely identical MLVA profiles in isolates originating from the same farm. We described that isolates from farms at close quarters were highly similar to each other. However, we also detected strains with different genotypes from the same farms, similarly to previous observations in other publications. This is the first study examining the genetic relatedness of Hungarian M. hyopneumoniae strains in which we revealed high genetic diversity among the isolates.