Abstract: A polymerase chain reaction method was used to amplify the RaDtxR gene from the identified Riemerella anatipestifer serotype 2 RA-FJ strain, the target fragment was then cloned and sequenced, which included the encoding open reading frame (ORF) of RaDtxR gene. The nucleotide sequence and deduced amino acid sequence were analyzed by the bioinformatics software. The cloned sequence was 654 nucleotides in length, coding an ORF with 217 amino acids. The molecular weight, theoretical isoelectric point and instability index of the Riemerella anatipestifer RaDtxR gene were 24.82 ku, 5.69 and 38.45, respectively. The cloned RaDtxR gene shared the highest homology with Riemerella anatipestifer vaccine strain RA-CH-1 (GenBank accession number was CP003787), with 100.0%. Also, it shared 99.8% with other 4 Riemerella anatipestifer RaDtxR genes, which shared only a nonsense mutation at the position 186. No amplification was detected from other bacteria or virus, such as duck E.coli, avain Pasteurella multocida and Salmonella, the PCR results of Riemerella anatipestifer serotypes 1, 2, 3, 11, 13 were positive, which demonstrated that RaDtxR gene could be used as a diagnosis target gene for Riemerella anatipestifer.The results showed that we had successfully cloned the RaDtxR gene from Riemerella anatipestifer, which would lay a foundation for research of its function.

Key words: Riemerella anatipestifer; RaDtxR gene; clone; bioinformatics analysis