| Porcine circovirus type2(PCV2) is the causal agent of post weaning multisystemic wasting syndrome (PMWS). It has been widely disseminated around the world since first emerged in western Canada in1991and has caused huge effects on world pig industry. The innate and adaptive immune in piglet work inefficient and cause immunosuppression in pigs when PCV2infected. Toll-like receptors is the most important advances in the innate immune recently, and plays an important role in the innate immune response. It identifys one or more specific pathogen-associated molecular patterns, starts the early response against invading pathogens, causes the expression of inflammatory cytokines, and finaly induces the adaptive immune response. It is the bridge that connects to the innate immune and the adaptive immune. Lymphocytes are important immune cells in the body, and also main target cells of PCV2. Our previous study has confirmed that PCV2cause disorder of the expression and secretion of pro-inflammatory and anti-inflammatory cytokines in piglet lymphocytes. Is there any relations between immunosuppression caused by PCV2and TLR, which TLRs are participate in the process of immunosuppression caused by PCV2. Based on these hypothesis, the experiment researches on the effect of PCV2infection on TLR in piglet’s lymphocytes. It can provide a theoretical basis for the prevention of PCVD in the clinical.Six thirty-day conventional post-weaning piglets were chosen as the experiment animals, which were free of PCV2and PRRSV antibody and antigen detected by ELISA and RT-PCR. The cells isolated from spleens were randomly distributed into two groups, control group and PCV2group. The suspended lymphocytes were harvested after cells treated with or without PCV2for0,6,12,24and48h respectively. The amount of the PCV2infected cells was observed by Indirect Immunofluorescence Assay (IFA).The expression of TLR2, TLR3, TLR4, TLR7, TLR8and TLR9mRNA was detected by Real time-PCR after extracted lymphocytes’ total RNA. The result of IFA showed that there was no PCV2infected cells after lymphocytes incubated for0,6,12,24and48h in control group, and the amount of the PCV2infected cells was gradually increased with the lasting incubation time. And the result of RT-PCR showed that the transcription of TLR2mRNA in PCV2group was extremely significant increased at12,24and48h than control group (P<0.01). The transcription of TLR3mRNA in PCV2group was extremely significant elevated at24and48h than control group (P<0.01). The transcription of TLR4mRNA in PCV2group extremely significant rised at24h (P<0.01), and was significant higher at48h than control group (P<0.05). The transcription of TLR7mRNA in PCV2group only has little changes, but there was no significant change between PCV2group and control group (P>0.05). The changes of TLR8mRNA was similar with that of TLR7. The transcription of TLR9mRNA in PCV2group was extremely significant elevated at12,24and48h than control group (P<0.01). The results demonstrated that when PCV2infected, the signal pathway of TLR2, TLR3, TLR4and TLR9in piglet’s lymphocytes could be activated, and mediated the production of correlation inflammatory cytokines, but there was no evidence relation between PCV2infection and TLR7or TLR8.Six thirty-day conventional post-weaning piglets were chosen as the experimental animals, which were free of PCV2and PRRSV antibody and antigen detected by ELISA and RT-PCR. The cells isolated from spleens were randomly distributed into two groups, control group and PCV2group. The suspended lymphocytes were harvested after cells treated with or without PCV2for0,6,12,24and48h respectively. The levels of TLR3and TLR4protein were detected by Western blot. The results showed that the TLR3protein content in piglet’s lymphocytes were significantly higher at6and12hour post infection(HPI) than0HPI, and significantly increased (P<0.05) when compared with control group and PCV2group at the same HPI. The levels of TLR4protein in piglet’s lymphocytes of PCV2group were significantly increased (P<0.05) than control group at6,12,24and48HPI. The results demonstrated that the TLR3protein may play important role in the lymphocytes on early stage of piglets infected with PCV2; PCV2could constantly up-regulate the expression of TLR4, this may has relation with the disorder secretion of inflammatory cytokines caused by PCV2. |
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