Determination of Serotypes A1, A2, and A6 in Mannheimia haemolytica Isolates by Real-Time PCR and Molecular Characterization by BOX and RAPD PCR Methods

Abstract

In this study, the detection of serotypes A1, A2, and A6 in Mannheimia haemolytica isolates obtained from sheep was investigated using the Real-Time PCR method, and genotyping of the isolates was performed using RAPD and BOX PCR methods. A total of 44 Mannheimia haemolytica isolates isolated from sheep and preserved in the culture collection of the Department of Microbiology, Faculty of Veterinary Medicine, Van Yüzüncü Yıl University, were included. Using Real-Time PCR, 27 (61.4%) of the 44 isolates were successfully serotyped, while 17 (38.6%) could not be serotyped. Of the serotyped isolates, 22.2% were identified as serotype A1, 44.4% as serotype A2, and 33.4% as serotype A6. Genotyping by RAPD PCR revealed 18 different genotypes using the OPA 4 primer and three different genotypes using the OPA 9 primer, whereas BOX PCR analysis identified 15 different genotypes. No statistically significant association was found between Mannheimia haemolytica serotypes (A1, A2, A6) and genotypes. The Real-Time PCR method used in this study was found to be suitable for the molecular identification of these serotypes. For RAPD PCR genotyping, the OPA 9 primer was determined to be unsuitable, while the OPA 4 primer and BOX PCR BOXA1R primer were appropriate for epidemiological studies, with the BOXA1R primer providing clearer band profiles. In conclusion, serotype A2 was identified as the dominant serotype in the Van Province sheep population, followed by serotype A6, both of which should be prioritized in future regional vaccine formulations targeting ovine respiratory disease in eastern Turkey. Among the genotyping methods evaluated, BOX-PCR is recommended for routine epidemiological investigations. Identifying the prevalent serotypes and genotypes at regional and national levels is therefore of critical epidemiological importance for the development of effective prevention, control, and vaccination programs against Mannheimia haemolytica-associated pneumonia in small ruminants. Content of this journal is licensed under a Creative Commons Attribution-Noncommercial 4.0 International License.