Establishment Of Pathological Model Of HP-PRRSV Infected Pregnancy Sow

Porcine reproductive and respiratory syndrome (PRRS) is caused by porcine reproductive and respiratory syndrome virus.PRRSV infection can cause pregnantsow late abortion, premature and stillborn, piglets and fattening pigs, respiratory disease.In the summer of2006, HP-PPRS first took place in southern China. So far, it has caused unprecedented damage to our country’s pig industry.HP-PRRSV will cause more serious stillbirth, abortion of pregnant sows.Sowswere inoculated nasally HP-PRRSV TA-12strainon thepregnancy of30d,60d and90d.Clinical symptoms, cytokines, antibodies levels in peripheral blood sera, and pathogenic in organ tissue distribution were studied.The sows were necropsy on different day post inoculation.Various tissues and organs especially the reproductive organs were collected for histopathological observation.To investigate the immanent connection between the clinical symptoms, antibodies, cytokines, pathogen distribution and stillbirth, abortion of pregnant sows, in order to develop an infection pathological modelof pregnant sows for HP-PRRSV,and study the mechanism of reproductive disturbance.Sows were inoculated nasally HP-PRRSV TA-12strain on different gestational periods, regulaly collected peripheral blood, detectde levelsof PRRSV antibodies, and cytokine (IL-1, IL-2, IL-4etc.) in sera by using ELISA method;at the same time, taken anticoagulated blood to detect blood routine (mainly MCH, LYM, WBC); the cows were necropsy on different day post inoculation;tissues were collected for preparing tissuessections. Pathologicalchanges of different tissues were observed through HE staining; immunohistochemistry (IHC) protocol were developed to detect distribution of HP-PRRSV antigens in tissue samples.Histopathological observation results show, HP-PRRSV TA-12strain infection in different duration of pregnancy sow, the major difference of pathological changes lie in the different degrees lesions to uterus and oviduct, the extent of the lesion were aggravating with the infection prolong. Antibodies can be detected3days post-infection, and reached the peak14days post-infection which can last lweak.The mainly blood routine index had no significant change. PRRSV antigen-positive signals can be seen in the same tissues and organson different gestational periods.HP-PRRSV’s tissue tropism on sow has no matter with gestation time.Besides the uterus, PRRSV antigen-positive signals showed the same distribution in pregnant sows and sows. HP-PRRSV TA-12strain can cause a broad tissue tropism on sow, especially pregnant sows.The levels of cytokines in sera decreased weather taking positive role or negative regulatory role after HPPRS infection in pregnant sow, which may be related to the complex reproductive physiological changes during gestation. However, the mechanism remains to be further studied.The study showed:HP-PRRSV infection resulting in uterine localized lesions and severe immune reaction; peripheral blood cytokines levels drop, generalized lymphoid tissue necrosis and hemorrhage as the main manifestation of the immune system damage, all causes the pregnant sows abortion. However, the inner contact and interaction needs further study.