Evaluation Of Therapeutic And Prevention Effect On Flea Allergic Dermatitis In Cats By Pets Dermatitis Vaccine

Flea allergic dermatitis(FAD)is a worldwide skin disease because of flea bite,which can cause canine/feline dermatitis,severe itching and secondary infection owing to scratching.The FAD not only endanger the health of animals,but also bring the livestock owners some economic burden.Ctenocephalides felis,the most widely distributed k ind of flea,has no obvious host specificity.It is also the main kind of flea leads to serious hazard to all mammals including humans and some birds.It is of great clinical significance in the study of the treat/prevent to allergic dermatitis caused by fleas.There are many allergens in the flea's saliva,the most important one which can cause animal allergies is the flea salivary antigen 1(FSA1).Current research showed that co-immunization antigen of flea salivary matched with corresponded nucleic acid vaccine can induce the generation of regulatory T cells and immunosuppression.Based on previous studies,we developed an efficient and rapid r FSA1 expression and purification process.Then we used co-immunization method to evaluate the effect of pet dermatitis vaccine on allergic dermatitis caused by flea bite in cats.To prepare pet dermatitis vaccine,the synthetic target gene FSA1 was cloned into p ET28 a and p VAX1 plasmid vector,respectively.Recombinant plasmid p ET28a-FSA1 was used to transformed E.coli BL21(DE3)competent cells to obtain recombinant strain BL-FSA1.Recombinant plasmid p VAX1-FSA1 was used to transformed E.coli DH5? competent cells to obtain recombinant strain DH-FSA1.We got r FSA1 by having the BL-FSA1 strain breaked and its inclusion bodies were extracted,then through purificated,renaturated,removed endotoxin and other steps;DH-FSA1 was extracted by alkaline lysis method,and p VAX1-FSA1 was obtained after removal of endotoxin.The purified r FSA1 and recombinant plasmid p VAX1-FSA1 were combined to used as a pet dermatitis vaccine.In order to evaluate the pet dermatitis vaccine objectively.We tried to build the cat FAD model.The method was as follow: have each cat challenged 100 fleas,remove the fleas with drugs after 48 h,interval of 12 d,repeat the above steps for 4 times.The severity of the disease was evaluated by a quantitative criteria.Besides,blood was collected to test peripheral blood T cell proliferation activity,Ig E antibody level and eosinophil tatio.The result showed that the scores of cat FAD increased rapidly sinced the third round ofchallenge,after 4 rounds of flea challenges,the score could reach the maximum walue of nearly 6 points.More times of challenge fleas did not contribute to the excess dermatology scores.After the fourth round of challenged flea,dermatology scores can be maintained at 4.5~6.0 scores for at least 45 days.Compared with the blank control group,the proliferation of T cells was significantly increased,the level of specific Ig E was gradually increased,and the eosinophil ratio reached 10.6%.Therefore,it can be concluded that the FAD model was successfully builded,and the model can be used to evaluate the effect of pet dermatitis vaccine.In order to evaluate the therapeutic effect of pet dermatitis vaccine on FAD,we established the cat FAD model firstly,then implemented two times of immunization.The results showed that the clinical symptoms of cat dermatitis in the co-immunization group were improved remarkably,and the dermatitis scores decreased from 5.7 to 1.6 points,and the proliferation of T cells was inhibited.So we think that the method of co-immunization of r FSA1+p VAX-FSA1 could inhibit allergic dermatitis,and have a significant therapeutic effect on FAD.In order to evaluate the preventive effect of pet dermatitis vaccine on FAD in cats.First,the cats were given two times of immunization,and then induced the cat FAD.The results showed that in the co-immunization group(1.9 points)of cat dermatitis sco res was significantly lower than the FAD control group(5.5 points)after 4 times challenged flea.It was to say that co-immunization of r FSA1+p VAX-FSA1 could inhibit the clinical symptoms of FAD,and have a significant protective effect?In our study,the FAD model was established successfully.It was also proved that the pet dermatitis vaccine has a significant effect on the treatment and prevention of allergic dermatitis caused by flea bite in cats.The co-immunization of r FSA1+p VAX-FSA1 contributed to the clinical prevention and treatment of FAD and provide valuable reference for the prevention and treatment of other allergic diseases.