| Chicken Toll-like receptor (TLR) plays an important role in pattern recognition receptors which regulates the down-stream genes for anti-virus. However, less evidence has been found in the differential expression of TLRs and inflammatory related genes which resist the Newcastle disease virus (NDV) infection. In this study, we investigated the response of TLRs and inflammatory related genes to NDV infection and explored the body responsese after challenged with different virulent strains.110 fourteen-day-old chicks were randomly divided into three groupsin which 35 chicks infected with NDV-F48E9 strain,35 chicks infected with NDV-Mukteswar strain and 35 chicks with mock-infected. Five chicks were euthanized respectively from infected and age-matched non-infected groups at 1,2, and 4 days post-infection (dpi). Bursas, spleens, and thymuses were collected to study the differential expression of genes (including TLR3, TLR7, TLR15, TLR21, and inflammatory related genes like IL-2, IL-6, IL-18, TNF-a). In lymphoid tissues of NDV-infected and non-infected chickens were determined by real-time PCR at the three time points. Fifteen genes were study this research and the results are as follows:The tendency of expression for TLR3 and the down-stream TRIF were basically the same, which suggesting that TLR3 could against NDV-F48E9 and NDV-Mukteswar infection in spleen, thymus, bursa of Fabricius. TLR3 paly a key role in the early process of anti Mukteswar infection, while after F48E9 infection the TLR3 was inhibited in the early process, and participated in the advanced anti infection process. The results of TLR3 in thymus and bursa of fabricius against NDV infection was better than that in spleen.TLR7 could resist Newcastle disease infection in the spleen, and TLR7 played a more important role in the thymus and bursa against NDV infection than in spleen tissue. In thymus and bursal tissue, the expression trends of inflammation factors were consistent with TLR7, the expression trends of TLR7 and inflammation factors were the same in spleen and thymus after F48E9 infection which showed that TLR7 significant associated in the anti-F48E9 infection in spleen, thymus, induced strong inflammatory, but have no reaction of the bursa.The expression of TLR15 was all up-regulated in thymus and so as TLR15. It was showed that TLR15 resist Newcastle disease reaction in thymus and bursa, but there was no significant difference in the expression of TLR15 in spleen tissues, indicating that TLR15 might against NDV in spleen.The expression trend of TLR21 in bursa was similar to that in spleen, but we found no different expression of TLR21 in thymus. It might indicate the association of TLR21 and the infection of NDV in spleen and bursa. But the expression pattern and reason still needed further research.Inflammation factors(IL-1β, IL-2, IL-6, IL-8, IL-18) in various stages resist in NDV infection in spleen, thymus and bursa. After Mukteswar infection, the early immune response and acute inflammatory response occurred in organisms, it was not the same as F48E9 infection. After F48E9 infection, organisms mainly occurred the late immune response and a strong inflammatory response, eventually leaded to serious pathologic damage and spread until the death of chickens.TLR3, TLR7, TLR15, TLR21 and inflammatory related genes such as IL-1β, IL-2, IL-6, IL-8, IL-18 might be as the candidate gene for chicken ND resistance. This study could provide some referencese for breeding for chicken NDV resistance. |
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