Development Of An ELISA For Detection Of Antibodies Against 3AB Non-structural Protein Of Foot-and-Mouth Disease Virus In Cattle And Swine

Foot-and-mouth disease (FMD) is a world-epidemic disease of livestock, which can cause severe economic losses and bad political influence. For the control of the disease, a clear technical system has been established: in developed countries, slaughtering of suspected and diseased animal is often adopted, which can rapidly break down the disease and recovered to disease free status. Nevertheless, in developing countries, systematic control measure based on vaccination is usually used. Under situation of vaccination. we can not differentiate vaccinated animals from infected animals by detection of antibodies anainst FMD virus(FMDV)structural protein However methods for detection of non-structural protein(NSP)antibody have been accepted as a reliable methods for differentiation of FMDV infected animals from vaccinated animals These methods have been widely used in many developing countries. In addition, it has become a necessary item in import and export quarantines. Methods for detection of NSP antibodies are now playing more and more important role in FMDV epidemiological investigation, screening subclinically infected animals, evaluation of the effect of prevention and control measure and foundation of a FMDV free zone.The full length of 3AB gene of foot-and-mouth disease virus (FMDV) was amplified and subcloned into pET-30a vector by two unique restriction sites. The product was analyzed by SDS-PAGE and Westernblot Then,we developed an ELISA method for detection of antibodies against FMDV NSP 3AB using prokaryotic expressed fusion protein 3AB as antigen. Sera derived from swine and cattle with different immune and infectious status were detected for determination of the cut-off value of the method. The cut-off value was established as follows: positive, sample value≥0.25; suspicious, 0.2≤value<0.25; negative, value<0.2. The coincident rate of 3AB-I-ELISA and 3ABC-I-ELISA were compared by detection of the same sera. The results indicate that the coincidence rate between 3AB-I-ELISA and 3ABC-I-ELISA were 98.9% and 99.2% for detection of sera from swine and cattle, respectively. However, the specificity of 3AB-I-ELISA was higher than 3ABC-I-ELISA.