| Toll-like receptors (TLRs), which involved in natural immunity and pathogeny recognization, and take important part in initiating the innate and adaptive immunity, are very critical in the defense of host against pathogenic microbe. Vitamin A is a kind of immune regulator, and plays important role in animal immunity. However, there is little research about the effect of vitamin A on TLRs gene expression in different species of pigs. In this research, the mRNA expression of TLRs in different breeds piglets was determined and the effect of vitamin A on the mRNA expression of TLRs was investigated. Two experiments are included in this research.A 2 X 4 factor design trial was carried out to determine the TLRs expression profile. Four litters of Rongchang and DLY piglets were selected randomly. One male piglet in each litter was slaughtered at the 0,7,14, and 21 day respectively after the animals were born. The liver, spleen, lung, jejunum and mesentery lymph follicle were collected for total RNA isolation. Real-time PCR was applied to determine the expression of TLR2,3,4,7, and 9. The results showed that the mRNA expression of TLR2,3,4,7, and 9 in the liver, spleen, lung, and mesentery lymph follicle of Rongchang pigs were significantly higher than those in DLY (P<0.05). And the gene expression of TLRs in older pigs was significantly higher than younger ones (P<0.05).24 health weaned Rongchang piglets (21 days old, body weight 3.5-4 kg) and 24 health weaned DLY piglets (21 days old, body weight 6.5-～7 kg) were fed with vitamin A-deficient diet for 2 weeks, piglet was raised in separate cage. Then the two breeds piglets were allotted into 2 groups respectively, each group piglets were fed with vitamin A-deficient diet or normal diet (2200 IU/kg) respectively. After 2 weeks, each group was divided into 2 treatments and were injected PRRS modified live vaccine vaccination or PBS as a control. Each treatment had 6 replicates with 1 piglets per replicate. After 2 weeks, all piglets were slaughtered and samples were collected. Results showed that,1, Animal Model with differennt Vitamin A nutrition status was established. The serum retinol concentrations in DLY were significantly higher than those of Rongchang piglets at the end of 2w,4w, and 6w. The serum retinol concentrations of piglets fed vitamin A-deficient diet were lower, compared with the groups with normal diet. And at the end of 4w and 6w,9% and 25.11% reduced respectively. At the same time, the vaccination lowered the serum retinol concentration.2, PRRSV vaccination model was established. On the 35d, serum PRRSV antibody was detected negative, while on day 42, serum PRRSV was detected positive in all the inoculated pigs. At the same time, PRRSVmRNA was detected in lung and respiratory tract of all the inoculated pigs, but not in the uninoculated.3, DLY piglets'ADG(P<0.0001) and ADFI (P<0.0001)were significantly higher than Rongchang piglets. After piglets vaccinated PRRS, the performance of both Rongchang and DLY piglets were declined. The effect of PRRS to DLY piglets performance was bigger than to Rongchang piglets.4, At the end of 4w, the serum concentration of IFN-y in DLY was significantly lower than Rongchang (P<0.05), while the concentration of IL-2 and IL-4 had no significant difference. The serum concentration of IFN-γ, IL-2 and IL-4 were not influenced by vitamin A level and the interaction between breed and VA.. At the end of 6w, the serum concentration of IFN-γ, IL-2 and IL-4 had no significant difference in two breeds. The triple interaction of breed, vitamin A level and vaccination influenced (P=0.0251) the serum concentration of IL-2.5, The mRNA expression of TLR2,3,7, and 9 in the liver, spleen, lung, and mesentery lymph follicle of Rongchang pigs were higher than those in DLY. Vitamin A-deficient diet increased the mRNA expression of TLR2,3,7, and 9 in tissues significantely (P<0.05), exception in spleen. PRRS vaccination resulted in the improvement of mRNA expression of TLR2,3,7, and 9. The interactions of breed X VA, breed X vaccination, VA X vaccination, and breed×VA×vaccination influenced the mRNA expression of TLR2,3,7, and 9.The result indicated that the expression of TLR-2,3,4,7, and 9 in liver, spleen, lung, jejunum, and mesentery lymph follicle of Rongchang pigs were higher than those of DLY piglets, and the expression was higher in the older pigs. After vaccination of PRRS live vaccine, the TLR-2,3,4,7, and 9 expressions were still higher in Rongchang pigs than DLY pigs. The immunity of different breeds might relate to the TLRs expression.Vaccination of PRRS vaccine increased TLR-2,3,7, and 9 expressions in the pigs and DLY pigs were more sensetive than Rongchang pigs. The deficiency of vitamin A increased gene expression of TLR-2,3,7, and 9 in piglets significantly, while the supplement of vitamin A decreased the expressions. |
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