Modification Of Acute Phase Proteins Profiles Induced By Porcine Circovirus Type2in Experimental Infected Piglets

In order to obtain the evidence on the developing mechanism and diagnosis clinicly about PCV2relevant disease, the thesis was studied the dynamic changes of acute phase proteins(APPs) concentration in serum and APPs expression in liver of PCV2infected piglets, and detected the changes of IL-IR-NF-κB and IL-6R-NF-κB,the two mainly APPs modulation pathways in the liver.Nineteen commercial piglets without antibodies against PCV2and PRRSV were obtained from a farrow-to-finish farm, certified as having a health status. Animal were divided into two group, the control group4piglets and the challenge group15piglets, at randomly. The blood and serum samples were collected from all animals on0(pre-inoculation)7,14,21,28and35DPI for the detection of APP concentration. The control group piglets were slaughtered on0, and5from the challenge group to slaughter on14,21and35DPI. The dynamic changes in concentration of C-reactive protein,(CRP) Haptoglobin(HP), Serum Amyloid A (SAA), alpha-1Acid Glycoprotein (AGP), Pig-Main Acute Phase protein (Pig-MAP), Apolipoprotein-A I (Apo-A I) were detected by ELISA respectively. APPs mRNA, IL-1R mRNA, IL-6R mRNA expression were detected using fluorescence quantitative RT-PCR, and while liver tissue NF-κB translocation was detected using confocal laser scanning microscope.The results shows the clinical signs of PCV2infection, i.e. lethargy, recumbency, and progressive weight loss, dyspnea and body temperature increase. There were a variable degree pathological lesions of parenchymal cell in liver of PCV2post inoculation piglets. There was a abviously outline of Hepatic lobule, hyperplasia of connective tissue in perilobuler area, disorganization of hepatic plates, hepatic vacuolar degeneration, and had a variable degree of eosinophilic granulocyte inflammatory infiltration in the perilobular and parenchymal area. The hepatic vacuolar degeneration was along with the time post inoculation PCV2, and then got recovery at35DPI. Time-course analysis of APP concentrations in sera from experimental animals revealed significant variations. The maximum values of pig-MAP were reached on day7day post inoculation (DPI), a significant increase with respect to the serum concentrations before the infection (0DPI)(P<0.05), and the values were gradually recovered after14days DPI to baseline. SAA concentration have a significant increase on7and21DPI compared to the pre-infected(P<0.05). ApoA-Ⅰ was have a significant difference at21DPI (P<0.05). They were only a slightly increased on14DPI. AGP concentration in serum were got a significantly decrease at10and35DPI (P<0.05). The HP concentration decreased sharply on14and28DPI(P<0.05) referred to control group, and it showed minimum values on28DPI. There were no significance changes about CRP concentration in serum.Time-course analysis of APPs mRNA expressions in liver from experimental animals revealed significant variations. There was a positive correlation between IL-1R mRNA expression and type Ⅰ APPs (CRP,SAA,AGP) mRNA expression, coefficient correlation was got at0.65,0.83,0.78respectively. This correlation was not happened between IL-6R mRNA expression and type Ⅱ APPs (HP, Pig-MAP) mRNA expression. The translocation of NF-κB in to nuclear was increased at14and21DPI, and there need further study to reveal the expression mechanism of type Ⅱ APPs.The above test results show that:(1) The liver lesion were characterized with hepatocytes degeneration, hyperplasia of connective tissue in perilobuler area, and eosinophilic granulocyte inflammatory infiltration in the perilobular and parenchymal area in PCV2inoculation piglets.(2) Time-course analysis of APP concentrations in sera from experimental animals revealed difference variations. Pig-MAP could be a valuable marker for monitoring the course of PCV2infection and prognosis.(3) The type Ⅰ APPs mRNA expression was regulated by PCV2through IL-1R-NF-ΚB signal system.