Molecular characterization of isolates of Haemophilus paragallinarum from China by ribotyping.

Ribotyping profiles were determined for 12 Page serovar A isolates of Haemophilus paragallinarum from five outbreaks of infectious coryza in Hebei province in the People's Republic of China. Four enzymes were used to generate restriction digests of chromosomal DNA: HaeIII, HindIII, HpaII and SspI. The digests were probed with a digoxigenin-11-dUTP-labelled DNA probe produced by PCR amplification of the 16S rDNA of the type strain of H. paragallinarum. Only one profile was seen among the 12 isolates when using either HindIII or SspI. Three different ribotype profiles were seen with HpaII, while four different profiles were detected with HaeIII. Cluster analysis of the profiles generated by HpaII and HaeIII corresponded with the known epidemiological history of the isolates. These results are the first molecular characterization of isolates of H. paragallinarum from China and confirm the existence of genetic diversity in the H. paragallinarum population in that country.