الفهرس | Only 14 pages are availabe for public view |
Abstract The aim of the study is to improve the diagnosis of babesiosis infected cattle in Egypt and analyzing the pattern of gene expression for a group of cytokines in these cattle. Blood samples were randomly collected from 296 apparently healthy cattle. Microscopic examination, cELISA and nPCR were used for diagnosis of babesiosis infected cattle. Also, real-time PCR was performed to evaluate the immune response of infected cattle through evaluation of IFN-γ, IL-1β and TGF-β1 cytokine genes expression. The results of the microscopic examination for babesiosis revealed that only 33 animals were infected with overall prevalence rate of 12%. cELISA analysis showed that of 296 serum samples tested, 130 (44%) were positive for Babesia spp., 64 (21.6%) were positive for B. bigemina, 32 (10.8%) were positive for B. bovis and 34 (11.6%) were positive both spp. In the nPCR, 117 (39.5%) samples were positive for Babesia spp., 55 (18.6%) were positive for B. bigemina, 32 (10.8%) samples were positive for B. bovis and 30 (10.1%) were positive for mixed infection. The present study results showed the high sensitivity of nPCR technique in detection of babesial infection as compared to microscopic examination. Statistically, using Chi square test, it was found that the differences between the three methods were statistically significant. Real-time PCR was carried out on 20 samples, positive for B. bovis; 20 samples, positive for both species and 10 samples, positive for B.bigemina using cELISA and nPCR and 20 samples negative for both spp. Real-time PCR results revealed that the animals with sub-clinical babesiosis had a decrease in IFN-γ cytokine gene expression compared to the uninfected animals. IFN-γ mRNA levels were significantly down-regulated by 18.1 fold (P<0.05) in B.bovis infected animals, significantly down-regulated by 10.1 fold (P<0.01) in mixed (B.bovis and B.bigemina) infected animals and significantly down- regulated by 11.9 fold (P<0.01) in B.bigemina infected animals compared to the uninfected animals. On the other hand, it was found that animals with sub-clinical babesiosis had an increase in TGF- β1 cytokine gene expression compared to the uninfected animals. TGF- β1 mRNA levels were significantly up-regulated by 4.7 fold (P<0.01) in B.bovis infected animals, significantly up-regulated by 7.1 fold (P<0.01) in mixed (B.bovis and B.bigemina) infected animals and significantly up-regulated by 9.8 fold (P<0.05) in B.bigemina infected animals. These results suggest that the down-regulation of IFN-γ gene expression noted in sub- clinically infected animals may be a result of the shift from Th1 type response to Treg type response (TGF-β1 gene). IL-1β mRNA levels were found to be significantly up- regulated by 2.9 fold (P<0.05) in B.bovis infected animals, significantly up-regulated by 3.4 fold (P<0.01) in mixed (B.bovis and B.bigemina) infected animals and significantly up-regulated by 1.8 fold (P<0.05) in B.bigemina infected animals through the sub-clinical phase of babesiosis compared to the uninfected animals. In conclusion, the combination between cELISA and nPCR may offer the greatest sensitivity for babesial diagnosis especially through the sub-clinical phase of infection. Also, the immune response of Babesia infected cattle during the sub-clinical phase of the disease may be achieved through the up-regulation of TGF-β1, a Treg cytokine and IL-1β that accompanied by the down- regulation of IFN-γ, a Th1 cytokine. |