Studay On Pathogenicity Of The Streptococcus Suis Serotype2 And Dual Real-time PCR For Detedtion Of Streptoccous Suis Serotype2

Through eliminating toxic material in swine,we did the System Research onpathematology change caused by streptoccous suis serotype2. And set up the accurate andspeedly method of the duel real-time PCR on streptoccous suis serotype2 detection.This experiment used streptoccous suis serotype2 preserved in National Diagnostic Centerfor Exotic Animal Disease to eliminate toxic material in piglets.we choosed nine 30 day-ageSPF piglets, fractionated them in three groups. We eliminated toxic material in the piglets byintramuscular injection,intravenous injection and PO.We researched pathology caused bystreptoccous suis serotype2,through clinical observation, clinical observation and tissuesection dyed by HE. The results showed that the streptoccous suis serotype2 had a strongpathopoiesis on healthy piglet.The group of IM was invasied after 12h,and dead after 16h, it'sfaster than the group of IV, the group of PO and group CK had no morbidity. The results ofprosection showed this bacterium could cause affection in most organs.After research ofpathology,we found the alveolar wall was widen by dropsy, inflammatory cell gathered, bulkof Fibrin thrombus in blood vessel; the degeneration of parenchymal hepatic cells, Fibrinthrombus in the sinus hepaticus; glomcrulus was broaden,bleed, necrosis, nephric tubule wasnecrosis,the other organs had not serious pathological change.The other purpose of this experiment is to set up a more accurate and more quickly methodto detect the streptoccous suis serotype2,by dual real-time PCR which can detect the twomarker genes of CPS2J and MRP,We designed specificial amplification primer and theirprobes to aim directly at capsular bolysaccharides,muramidase protein (CPS2J marker withHEX, MRP marker with ROX) by BEACON Desigener 2.0. through the optimization of eachparameters, to set up dual real-time PCR method to detect the two genes simultaneously.Compared this method with common PCR,we found this method has good specificity(there isno consensual reaction with other serological type chain coccus and pathogenic bacteria),high sensitivity(the lowest bacterial number detection was 24CFU/ml), better stability andreproducibility (we detect the eight samples in three different times, the results showed that theP＞0.05).We detected the tissue from animal experiment with this method,the results showed itcould detect streptoccous suis serotype2.The pathogenic microorganism exsisted in the liverwas the most,the brain and the heart had little than the liver by the CT value. The CT valuesof CPS2J and MRP were similar at the same sample.