Detection Of Food-and-Mouth Disease By RT-PCR And Immune Antibody Surveillance

Foot-and-mouth Disease that is aroused by foot-and-mouth disease virus is a kind of high contagious and infectious disease. Seven serotypes (O, A, C, Asia I, SAT1, SAT2 and SAT3) and more than sixty five subtypes of FMDV are confirmed by cross protection and serological tests. No cross or cross immunity exists between all serotypes. Serotype O, A and C, which can mutate easily, are spreading all over Asia, Africa, Latin America and Europe. Serotypes SAT1, SAT2 and SAT3 are distributing mainly in Africa while serotype Asia I mainly in Asia such as Yunnan and Xinjiang province of China. Due to the fact that Foot Mouth Disease (FMD) is widely distributed, spread fast, and there are several serotypes and varieties of strains, it needs a disease prevention system with fast and correct reaction ability. Disease surveillance system is the key factor, which determines whether the reaction is fast and correct or not. Disease surveillance system is based on diagnostic technology, and a correct prevention plan can be made on the base of accurate and reliable diagnosis.Since 1998, FMD has been breaking out in Kunming, Yunnan province. In view of the current FMD prevention situation and consulting currently released FMDV sequence, we designed group and serotype specific primers of RT-PCR for FMD diagnosis, which is developed based on the technology of Yunnan Tropical and Subtropical Animal Virus Disease Key Laboratory. Comparison with RT-PCR and Capture-ELISA for FMD which is approved by OIE and the traditional virus isolation methods are carried out. Results show that group special primers P2B1/P2B2 can be used to amplify specific objective gene for both standard and wild strains of serotypes O and Asia-I. Serotype specific primers P1D1/ P2B1 and P1D2/ P2B1 can be used for fast typing of these two serotypes, which is compatible with the result of AC-ELISA. So this RT-PCR method is sensitive and specific for FMDV detection. According to detection results,animals in disease area were inoculated by vaccines from different producers. Antibody detection was carried out by forward indirect hemagglutination test. Results showed that antibody level difference between different vaccines is not dominant but the antibody level of cattle is higher than goat even more than swine. Antibody level began to decrease after 60 days of inoculation, which suggests that immune protection period of current vaccine is short, the titer of boost vaccination is higher than that of the primary vaccination, the concentrated vaccine is more excelled than common one, and co-use of inactivated FMDV vaccine and double-vaccine of hog cholera and swine pasteurallosis does not affect the effect of FMD inoculation. Result of this paper provides a important foundation for FMD inoculation plan designation.