Detection Of The Distribution Of CSISV In SPF Chicks By RT-PCR And Fluorescence Quantitative RT-PCR Methods

Chicken Stunt and Immunosuppression Syndrome Virus (tentative name, abbreviation: CSISV) is one of important infectious diseases that mainly causes the suppression of growth and immunity on poultry. Based on the preceeding research, we studied the distribution of CSISV-ZZ2004 strain in 7-day-old SPF chicks with RT-PCR and TaqMan Fluorescence Quantitative RT-PCR(FQ RT-PCR) methods to find the tropism organs and growth regurity.According to the whole gene sequence of CSISV,we designed a pair of primers F1/F2 whose amplifying fragment size is 540bp, and another pair of primers F3/F4 whose amplifying fragment size is 117bp and a specific probe.Using this specific RT-PCR method developed above to study the distribution and shed virus of CSISV-ZZ2004 strain in 7-day-old SPF chicks.The results show that virus can be detected from all 15 organs of chicks after infection with CSISV; The viral nucleic acid can be detected in lungs, tracheas, and rectums on 9h after artificial infection firstly, and the viral nucleic acid can be detected in cardiac muscle on 120h lastly,viral nucleic acid is negative for all organizations after 408h.The tissues of longest duration of viral nucleic acid positive are pancreas (384h), and the shortest are cardiac muscles (72h) .CSISV have a broad tissue tropism. The duration time of virus in pancreas,bursas,kidneys,lungs,rectums,thymus and appendix is more than 288h after artificial infection. It indicates that these organs are important target organs of this virus.SPF chicks can continue to shed virus from 12h to 720h after artificial infection.By using this TaqMan FQ RT-PCR method developed above, we detect the virus content in tissues of SPF chicks. The results show that the lowest content of virus nucleic acid in all tissues is more than 1.57E +06 copies/μL.Viral nucleic acid content in all organs shows an increasing at the beginning and then downwarding trend,and the peak copies appear between 72h and 168h;The viral nucleic acid conctent in kidneys, bursas, lungs, tracheas, stomach, appendix, rectums are significantly higher than other organs from 48h to 216h after artificial infection, above 1.00E+08, shows that these organs are important target where virus replicate.