Study Of The Expression Of ENOS And Related Factors In PRRSV Infected Pig Lungs

Porcine reproductive and respiratory syndrome(PRRS) is a highly contagious disease among pigs, which is characterised by early farrowings, increases in stillbirths, weak pigs, and difficulty breathing, pneumonia. Dissection studies usually shows interstitial pneumonia and a lot of petechiae, so the lung injury may be one of the causes of death.In the lung injury caused by PRRSV infection, the morphological and functional changes of capillary endothelial cells decided the lung injury. Morphology and function of endothelial cells are controlled by the nitric oxide(NO), and the synthesis of NO is controlled by endothelial nitric oxide synthase(e NOS) in vascular endothelial cells. Thus, the expression changes of e NOS and related factors may cause lung damage in PRRSV infected pigs. The aim of this study was try to find the role of e NOS and related factors on lung injury and understanding the mechanism of PRRS in pigs.Samples were collected from the large white pig lungs, and were divided into three groups: normal contorl lung samples, clinical PRRS lung samples, and artificial infection lung samples. Our work is comparison of the relative expression of e NOS and i NOS m RNA in contorl and PRRS infected pigs by quantitative PCR; comparison of the e NOS and Caveolin-1(Cav-1) in contorl and PRRS infected pigs by western blot; measurement of the NO level and ROS level in contorl and PRRS infected pigs were conducted by nitrate reductase and chemical fluorometric determination.; the vascular endothelial cell morphological changes and e NOS level in contorl and PRRS infected pigs by hematoxylin-eosin(HE) staining and immunohistochemical were also conducted.The results show that, compared with the contorl group, e NOS m RNA expression of PRRS pigs were significantly increased(P <0.05) in clinical and artificial infection group; i NOS m RNA has no significantly change(P> 0.05); e NOS protein levels were also significantly increased; however, NO level were significantly reduced(P <0.05); no changes of ROS levels were detected(P> 0.05); histological results showed that compared to the contorl group, vascular structures of clinical and artificial infection group were broken, capillaries become smaller, and less in contrast; e NOS level in PRRS pigs by immunohistochemistry werw significantly increased(P <0.05).Conclusions:1. The recult of clinical PRRS pigs and artificial infection PRRS pigs showed some conformity;2. The NO level in PRRS pig lungs decreased, while the e NOS m RNA and protein level were increased, indicating that PRRSV infection may lead to e NOS activity reduced, while the reduce of NO may increase e NOS expression; The increase of Cav-1 protein levels in clinical pigs may be one of the factors for the reduce of e NOS activity.3. The change of i NOS and ROS were not significant, the reason maybe in the process of PRRS, the decreased of NO may not due to the i NOS, and haven’t produce more ROS.