Анотация: Random DNA fragments (500-3000 bp) were obtained from the genome of avian Pasteurella multocida CVCC474 using the restriction enzyme Sau3AI and cloned into the BamHI site of the eukaryotic expression vector pcDNA3.1(+) to construct a genomic expression library. The library was subdivided into five clone pools and recombinant plasmids were extracted from each pool. Balb/c mice were allocated to groups 1-5 and vaccinated with these recombinant plasmids, whereas mice injected with pcDNA3.1(+) and PBS were used as negative controls