Study On The Identification And Immunization Of Salmonella Abortus Equi Isolated From Xinjiang And Its FliC Protein Enhance Effect On The Humoral Immune Response Of Recombinant Protein SeM And GD

Salmonella abortus equi cause miscarriage of the pregnant mare horses,blood poisoning and the diarrhea of infant horses,orchitis and abscess of male horses.This infection caused serious economic losses to the horse industry. In this study.serological survey about Salmonella abortus equi in some areas of Xinjiang were carried out and 2 768 serum samples were collected from horses in Zhaosu county,Fuyun county,Turks county,Hejing county and Jimunai county.The indirect ELISA results showed that the average positive rate of Salmonella abortus equi was 27.93%;female horse antibody positive rate (36.9%) is slightly higher than male horse (29.7%),but with no significant difference;the horse antibody positive rate is relatively low for Hejing county and Jimunai county,at 3.24%?9.78%,the horse antibody positive rate is relatively high for Zhaosu county and Fuyun county,at 27.17%?43.91%; From statistical results of horse age,antibody positive rate existed in different age horse.In this study, the Salmonella abortus equi was isolated from horse abortion tissue and identified by biochemical assay and PCR.Flagella gene FliC2 of the Salmonella abortus equi isolates was amplified by PCR,which has length of 1427 bp.Then recombinant plasmid pET28a-FliC2 was constructed and was transducted in Escherichia coli BL21 (DE3) cell.SDS-PAGE analysis showed the recombinant protein FliC2 was about 52 KDa,and Western-blotting analysis indicated that it has better reactionogenicity.After immunizing the mice have higher levels of antibody and mice antibody titer could reach 1:218 700,the antibody mainly was IgGl subtypes.After immunization,the horse antibody titer could reach 1:72 900.Truncated flagella genes FliCl was amplified by PCR,which has the length of 840 bp.Then recombinant plasmids pGEX-FliCl was constructed.The purified pGEX-FliCl protein was 56 KDa by SDS-PAGE analysis.After purification the FliCl and gD protein were used incombination to immune horses,Our results showed that the combined immunization horse has higher antibody levels than single immunization horse.the antibody titer of the combined immunization horse could reach 1:218 700.The results showed that FliCl protein can promote the immune levels of gD protein.The antibodies induced in horse mainly was IgG1 subtypes.The antibody could last for 170 d at higher level.To compare the immune effects of two different size of FliC fragments,we used FliC1 and FliC2 respectively with SeM protein to immunize C57BL/6 mice.This results showed that FliC2 and SeM combined immunization group have higher antibody levels and the induced antibody mainly was IgG1 antibody.The protection rate of FliC2+SeM immunization group was 80%.This results showed that FliC2 has better immune enhancing effect than FliC1 when immunizing incombination with SeM.The results provided experimental basis to study using FliC in future.