Cloning and sequence analysis of gene encoding outer membrane lipoprotein of Actinobacillus pleuropneumoniae in swine

The DNA was abstracted fromActinobacillus pleuropneumoniae (APP) QH-1 strain and HN-7 strain that are predominantly prevalent strains in China. The fragment of the outer membrane lipoprotein (OML) gene of A.pleuropneumoniae was amplified by polymerase chain reaction (PCR) and cloned into the pMD18-T vector. Positive clones of OML gene were identified by restriction analysis and PCR, and then sequenced. The result of sequence analysis for theORF of OML gene indicated that the nucleotide sequence of QH-1 strain shared 99.1%-100% homologywith that of the reference serotype 1,9,11 and 12, but the nucleotide sequence of HN-7 strain shared 97.3%-99.9% homologywith that of the reference serotype 3,4,6 and 7. The nucleotide sequence of QH-1 strain and HN-7 strain exhibited low homologywith that of other reference strains.