16S ribosomal RNA sequencing and molecular serotyping of Avibacterium paragallinarum isolated from Indian field conditions

AIM: This study was aimed at identifying Indian field isolates of Avibacterium paragallinarum on both molecular as well as serological levels that cause infectious coryza in chickens. MATERIALS AND METHODS: Species-specific polymerase chain reaction (HPG-2 PCR), and 16S ribosomal RNA (rRNA) sequencing were employed for molecular identification. Whereas, multiplex PCR technique was used for serological identification of Indian field isolates of A. paragallinarum. RESULTS: All three field isolates were identified as A. paragallinarum using HPG-2 PCR. The species-specific PCR results were validated using 16S rRNA sequencing. The partial 16S rRNA sequences obtained from all three isolates showed 96-99% homology with the NCBI database reference strains of A. paragallinarum. The aligned partial sequences of 16S rRNA were submitted to GenBank, and accession numbers were obtained. Multiplex PCR-based molecular serotyping showed that there are three serotypes of field isolates of A. paragallinarum, namely, strain IND101 is serovar A, strain IND102 is serovar B, and strain IND103 is serovar C. CONCLUSION: HPG-2 PCR, 16S rRNA sequencing, and multiplex PCR are proved to be more accurate, sensitive, and reliable diagnostic tools for molecular and serological identification of A. paragallinarum field isolates. These diagnostic methods can substitute conventional cultural characterization and would be much valuable to formulate quick and correct prevention and control measures against this detrimental poultry pathogen.