Development of a multiplex PCR and PCR-RFLP method for serotyping of Avibacterium paragallinarum

Avibacterium (Haemophilus) paragallinarum (A. paragallinarum) is a causative agent of infectious coryza in chickens and is classified into three serovars by agglutination tests. In an effort to identify the serovars easily, PCR and PCR-RFLP were employed. As the target gene for PCR, the hypervariable region of HMTp210, which encodes the HA antigen, was used. PCR using primer sets around the hypervariable region amplified 0.8, 1.1 and 1.6 kbp fragments for serovars A, B and C, respectively. Alternatively, the 1.6 kbp fragments were amplified with another primer pair encompassing the hypervariable region and was subjected to digestion with Bgl II, which resulted in the detection of serovar-specific digestion patterns. These results indicate that PCR and PCR-RFLP using the hypervariable region of HMTp210 are alternative methods to identify the serovar of A. paragallinarum.