Abstract: To clone and do the sequence analysis of the heme acquisition system receptor of Pasteurella multocida from healthy calves and calves with pneumonia, all DNA fragment of HasR gene was amplified from the chromosomal DNA of Pasteurella multocida from healthy calves and calves with pneumonia by PCR and cloned into pMD19-T vector and the cloned fragment was sequenced after identified by PCR and two restriction enzyme digestion. DNA sequence comparison of the amplified fragment with the published sequence of HasR gene in GenBank (strain Pm70) showed high nucleotide homology among the Pm-BS-a,Pm142-x-4,Pm142-x-3,Pm149-x,Pm-BS-d,and there was a higher homology between Pm149-x and reference strain Pm70. The high homology of HasR gene between healthy calves and calves with pneumonia indicated that the Pasteurella multocida inducing pneumonia of calf might be come from upper respiratory of their own or their parents.

Key words: Pasteurella multocida; heme acquisition system receptor; cloning; sequence analysis