Mixed Infection Of Avian Leukosis Virus And Salmonella Pullorum

Avian leukosis (AL) is a neoplastic diseases reflecting as the hyperplasia ofhematopoietic cell. The sick chickens often showed immunosuppression, thus the secondaryinfection of other pathogens is possible to happen. The pullorum diseases (PD) was one ofmost important reason for the high mortality of chicks. Both of avian leukosis virus (ALV)and salmonella pullorum (SP) have been wildly spread in china. Both of them can betranslated vertically and the main measures of the prevention and control of them was theeradication of pathogen. Reports of the infection of ALV or SP have been very common.However, the co-infection of them was rarely reported.This study was designed to investigate the co-infection status and interaction mechanismof ALV and SP. ALV antigen and antibody was tested via ELISA, and SP antibody wasdetected by SPAT (serum plate agglutination test). Firstly, the co-infection status of ALV andSP was investigated in the CL “ShouGuang” chickens, and their preliminary eradication wasfinished subsequently. Secondly, the same work was done in another three flocks in Shandongprovince, in order to found whether the co-infection of them was universal. Thirdly, theanimal model of avian leukosis was induced using the virus from Chinese local “Bairi”chickens to explore the intestinal microbial community structure of the sick chickens withALV, in order to conjecture the risk of secondary infection of opportunistic bacteria. All theresults were listed as follow.1. The co-infection of ALV and SP was confirmed and the positive rate of both SP andALV-P27or ALV-A/B was10and1%, respectively in CL “ShouGuang” flocks. There wereobvious tumor nodules and lymphoid tumor cells in the comb, liver and spleen of theco-infected chickens. The degenerative and atrophic ovarian follicles, inflammatory cellinfiltration in muscle biopsies were also found. The elimination rate of ALV-p27, ALV-A/Band SP positive chickens was55.4,13and6.1%, respectively. The final amount of the breederconservation was309chickens. The flocks without ALV and SP was constructed, which wasof great significant to the population safety of “ShouGuang” chickens.2. The co-infection of ALV and SP was universal. In the JNS “Ma” flocks, the co-positive rate of ALV-P27and SP, ALV-A/B and SP, ALV-J and SP was10,3.3and20%,respectively. In the SS “Bairi” flocks, the co-infection was also found. In the YXQY flocks,the co-infection was not found, however, the ALV or SP was detected.3. The animal model of avian leukosis was successfully induced. The serological andpathological detection results showed that both of the antigen and antibody positive chickenswere found. Platelet-related-index, such as the Platelet count, Mean platelet volume,Thrombocytocrit, Platelet large cell ratio of the sick chickens was significantly decreased; thesick birds were extremely emaciated and hemorrhage also could be seen on the scale layer ofthe feet and leg. Typical tumor nodules occurred on different parts of the liver and spleen.Hyperplasia of tumor cells was observed in the portal area and hepatic lobule, and the normalliver lines were squeezed to destruction. The similar lesions also could been found in thespleen.The CFU/g (Colony-Forming Units per gram of the contents in intestines) of Escherichiacoli and enterococci in the cecum or rectum of the antibody or tumor positive group wassignificantly higher than the negative. The lactic bacteria and bifidobacterium in the ileum,rectum or duodenum of the antibody or tumor positive group was significantly decreased. Itreminds the risk of secondary infection of these opportunistic bacteria, and the mainlyinfected parts may be the duodenum, cecum and rectum.