Serodiagnosis of Lumpy Skin Disease Using Sheep Pox Virus Compared to a Commercial ELISA Kit

Evaluation of the humoral immune response against Lumpy Skin Disease (LSD) in vaccinated and infected cattle is a very important issue for controlling it in Egypt. This study was conducted to evaluate and compare newly commercial ELISA kit and traditional virus neutralization test (VNT) using sheep pox virus (SPV) and Lumpy Skin Disease Virus (LSDV) for monitoring the humeral response against LSDV. Sensitivity and specificity of VNT were higher in case of using LSDV (96% and 100%,  respectively) than in case of using SPV (89.3% and 98.6%, respectively) while they were 98.6% and 97.3%, respectively in case using of commercial ELISA Kit, which detected the highest number of positive samples (n =76) and (70 %) followed by VNT using LSDV (n =72) and (67.5 %) and finally VNT using SPV (n =68) and (67.5 %) for tested 150 control and 200 field samples respectively. The agreement between VNT using SPV and ELISA was achieved in (67) and (123) positive, (73) and (58) negative control and field samples, respectively, with overall proportion agreement (Po) as 0.93 and 0.90 with Kappa index of 0.86, and 0.78 for control and field samples respectively, while in case of using LSDV the agreement between VNT and  ELISA was achieved in (72) and (134) positive, (74) and (59) negative control and field samples with overall proportion agreement of 0.97 and 0.96 with a Kappa index of 0.94 and 0.90 for control and field-tested samples respectively. Using hyperimmune sera prepared against LSD, the highest dilution gave positive results in the commercial ELISA kit and VNT using LSDV was 1/128 while it was 1/64 using SPV. This study illustrated that the VNT using LSDV is the most specific serological test for detecting LSD antibodies rather than ELISA commercial kit and VNT using SPV. Still, the test is not as sensitive enough as the commercial ELISA kit which was the most sensitive test for detection of LSD antibodies in vaccinated and infected cattle.