Mycoplasma hyopneumoniae genetic variability within a swine operation

• Published in: Journal of veterinary diagnostic investigation 2016-03, Vol.28 (2), p.175-179
• Main Authors: Pantoja, Lucina Galina, Pettit, Kalie, Dos Santos, Lucas F., Tubbs, Rick, Pieters, Maria
• Format: Article
• Language: English
• Subjects: Animals; Brazil; Genetic Variation; Minisatellite Repeats; Mycoplasma hyopneumoniae; Mycoplasma hyopneumoniae - genetics; Mycoplasma hyopneumoniae - isolation & purification; Pneumonia of Swine, Mycoplasmal - microbiology; Real-Time Polymerase Chain Reaction - veterinary; Swine; Weaning
• ISSN: 1040-6387; 1943-4936
• DOI: 10.1177/1040638716630767

The objective of our study was to characterize the Mycoplasma hyopneumoniae genetic diversity within a swine operation comingling weaned pigs. Bronchial swabs and tracheal aspirates were collected from 3 nursery-to-finish farms. During the finishing production stages, samples were obtained from mortalities and from live coughing pigs in rooms where mortality was not observed. A total of 105 samples were examined by a M. hyopneumoniae real-time polymerase chain reaction and subjected to genetic typing using a multilocus variable number tandem repeat analysis (MLVA) assay. The MLVA was used to identify genetic variants based on the number of repeats in 2 variable number tandem repeats loci, namely P97 and P146, thought to mediate adherence of M. hyopneumoniae to swine cilia. Four distinguishable M. hyopneumoniae variants were identified: MVLA variants 9-15, 11-21, 9-21, and 7-15. Variant 9-15 was the most prevalent, observed in 79% of rooms, and detected on all 3 farms. Variant 11-21 was present in 37% of the rooms on 2 of the 3 farms. Only one 9-21 variant was identified in 1 farm, and all samples of variant 7-15 were recovered from another farm. Based on the low prevalence and limited geographic distribution of the last 2 variants, it is hypothesized that they might be the result of in-situ recombination. All variants detected in this investigation appeared to belong to 3 clusters. Overall, a limited number of variants and clusters were identified in a system that comingles pigs from different sources, suggesting limited M. hyopneumoniae genetic variation within commercial swine production environments.