雞白痢沙門氏菌致病性及MyD88-依賴途徑信號分子表達的研究.pdf

1、Salmonella Pullorum infection is an acute and systemic disease， which results in a high mortality in young chickens but rare clinic symptoms in adult birds。As a fowl-specific pathogen， S． Pullorum continues to cause econ

2、omic losses worldwide． The ever-increasing problems of antibiotic abuse and chronic carrier of this bacteria in affected chickens also do a potentially huge harm to public health。 The innate immune system plays a cri

3、tical role in host defense against infectious disease． Despite the extensive knowledge of MyD88-dependent pathway in humans and mice， little information is available for the molecules of this pathway in chickens。 Tri

4、al 1 Two hundred and forty chickens were randomly divided into 6 groups of 40 each and were infected artificially with S． Pullorum on a basis of infectious rate at 0， 20％， 40％， 60％ and 100％ respectively． The serological，

5、 bacteriological and histopathological parameters of host were determined at day 1， 3， 7， 14， 21， and 28post infection。 The results showed that the propagation speed of S． pullorum in affected chickens was increased

6、in proportion to the infectious rate and so do the mortality （5．4％-35％）。The bacteria could spread through the entire flock from 20％ to 100％ within 72 h and had a suppressive impact on the growth and development of young

7、chickens． The characteristic lesion in tissue is mainly hepatitis， pericarditis and pneumonia， which mostly occurred between 3 and 7 day post infection． The bacterial burden of cecum was higher than the spleen． The serum

8、 concentrations of IgG and TNF-α were significantly increased at 3 day post infection （P<0．05）。 Trial 2 Chickens were randomly divided into 2 groups of 40 each on d 3． One group was orally inoculated with 0．5mL of th

9、e bacterial suspension containing 108CFU S． Pullorum and the control group was given 0．5ml saline． Eight chickens from each group were randomly chosen and sacrificed at 1， 3， 7 and 14 days post-infection。The spleen and c

10、aecum were removed and a portion of these two organs was immediately placed in RNAlaterTM for the determination of relative expression level of TLR4 signal pathway molecule genes （TLR4， MyD88， TRAF6 and NF-κB）。 The

11、results showed that the infected chickens had significant up-regulation ofTLR4， MyD88， TRAF6 and NF-κB mRNA expression in the spleen on clay 3 and NF-κB on day 1 post infection compared with control ones （P<0．05）． In the

12、 caecum，the mRNA expression levels of the pathway molecules gene were numerically up-regulated in infected group but not significant compared to uninfected controls on day 1 and 3 post infection（P>0．05）． In conclusion， t