Cloning And Expression Of Poultry Pastuerella Multocida Streptomycin Resistant Gene StrA And Sulfonamides Resistant Gene Su1â…¡ In Pronucleus

Pasteurellosis is acute infectious disease, which is caused by especial serum types of Pasteurellosis multocida and infects domestic animals. The acute type is characteristic by sapraemia and hemorrhagic inflammation of organs and tissues, so it is named hemorrhagic septicaemia and HC for short. The disease is across the world and every domestic animal can be infected. Among them, swine, scalper, buffalo, cattle, rabbit, chicken, duck, goose, wildfowl and fowl are more susceptible. 25 strains of Pasteurellosis multocida have been isolated from 11 domestic animals infected naturally. They can be divided into two types, Fg and Fo. Fg is strong toxic type to swine, cattle et al; Fo is strong toxic type to chicken, duck, goose. The incidence and mortality of the disease is high, bringing serious damage to the stockbreeding. Epidemiology datas display that owing to the antibacterial abuse drug resistance of pasteurellosis is usual, resulting in most of antibacterial inefficacy. At present, the resistance trend is transforming from single to multi-resistance in bacteria, from the low ratio to the high one in drug and become rapider and rapider. Moreover, improper use of antibacterial in domestic animal treatment causes increasingly serious drug resistance in bacteria. Presently, the drug resistance research of pasteurellosis focuses on resistant gene of tetracycline, Aminobenzyl penicillin, chloromycetin et al. The resistance and its mechanism caused by gene mutation because of drug combination are seldom reported. The bacterium isolated clinically is identified as Pasteurellosis. The bacterium has resistant to 21 antibacterial, especially highly resistance to streptomycin and sulfanilamide. We do the research about resistance gene of streptomycin and sulfanilamide in the light of this characteristic. Using two pairs of primers designed and synthesized according to pastuerella's streptomycin resistant gene StrA and sulfonamides one SulII, template that is plasmid DNA of pastuerella's streptomycin and sulfonamides resistant strains amplify pastuerella's and gene segment by PCR techique. Then, 804 bp StrA aim gene and 816 bp SulII one are cloned into pGEM-T vecter. After sequencing nucleotide, the software of DNAsis shows the sequences of StrA gene have 99.8% homology with that of the standard strain(NC₀01774)with only one base mutation(204 C→G),and those of Su1II gene have 98.9% with nine base mutation(159 C→T,246 A→C,384 G→A,584 T→C,590 C→T,591 T→C,592 G→T,597 T→G,582 A→G). Amino acids coded by StrA and Su1II do not alter. Arter the StrA and Su1II gene are directionally cloned into expressional vector pET-28c(+)according to right reading frame, the recombinant plasmid is correctly restriction digested, pronuclues expressional plasmids constructed such as pET-28c(+)-StrA and pET-28c(+)-Su1II are transformed into competent cell of BL-21(DE3).Then, they are induced by IPTG and carried out SDS-PAGE electrophoresis. The result shows that the expressional products of StrA and Su1II occupy 12% and 11% of general protein in bacterium. The expressional format of pertein is inclusion. The resistance difference in streptomycin and sulfanilamide between standard strain and resistance one is relative to StrA and Su1II gene mutation. The mutation of resistant gene induce conjunct target of antibacterial to alter. Thus, antibacterial is difficult to become resistant.