Detection of antibodies against Lumpy skin disease virus by Virus neutralization test and ELISA methods

Abstract

Infection of cattle with lumpy skin disease virus (LSDV) is very important from the aspect of livestock production. Although it can cause significant economic losses, available serological assays are still not sufficiently efficient and reliable. A 3-day VNT was performed using Madin-Darby bovine kidney (MDBK) cell line and LSDV isolated from clinically infected cow to improve serological diagnostics of lumpy skin disease (LSD). In total, 325 cattle sera samples were tested in order to compare the performances of VNT and ELISA. Tested samples originated from 125 cows before the occurrence of LSD in the Republic of Serbia and 200 tested samples originated from vaccinated cows. Sera samples from vaccinated cows were collected starting from the vaccination day to 4 months after vaccination. In 7 different time intervals after vaccination sampling was carried out in 20 cows originating from one herd and in 3 different time intervals in 20 cows originating from a different herd each time of sampling. Out of 200 samples from vaccinated cows, antibodies against LSDV were detected in 68 (34%) samples by VNT, and in 60 (30%) samples by ELISA. No positive finding was detected by VNT in samples collected before the occurrence of LSD in Serbia, while one positive finding was detected in the same samples by ELISA. The first presence of antibodies in vaccinated cattle was detected by both tests 20 days after vaccination, and the largest number of animals with antibodies against LSDV was detected 30 days after vaccination. Comparing the results obtained by VNT and ELISA, it was calculated that kappa index was 0.913. The specificity of VNT and ELISA was 100% and 99.2%, respectively. VNT is simpler to perform compared to the recommended virus neutralization test by the OIE and can improve LSD serological diagnostics with additional sensitivity testing.

Evaluation of Serological Tests for Detection of Antibodies against Lumpy Skin Disease Virus

“…The specific CPE became evident 96 h p.i. In VNT/MDBK, the first signs of CPE were evident 48 h p.i., and after 72 h, the specific changes were clearly evident as described also by Samojlović et al ( 20 ). Furthermore, the test results 72 h p.i.…”

“…The CPE caused by LSDV in MDBK cells was clearly different from the LSDV CPE in LTe cells. The effects of LSDV on MDBK manifested as cell proliferation and accumulation in the forms of lumps on the cell monolayer, as already demonstrated ( 20 ).…”

“…The methods were technically similar to those for the VNT/MDBK used here, but the VNT/MDBK is the only one that compared the results to the gold standard VNT/OIE. Differences related to VNT described by Samojlović et al ( 20 ) are reflected in several factors, such as the virus used, dilution fold, and slight difference in cell number. Samojlović et al ( 20 ) used wild-type virus isolated during an LSD outbreak in Serbia, while we used a vaccine strain isolated from a skin nodule on a vaccinated animal ( 19 ), which was passaged eleven times in MDBK cells with clear cytopathic effect.…”

“…Two previous studies ( 16 , 20 ) also described VNT for LSDV antibody titer estimations. The methods were technically similar to those for the VNT/MDBK used here, but the VNT/MDBK is the only one that compared the results to the gold standard VNT/OIE.…”

Non-vector-borne transmission of lumpy skin disease virus

“…Virus neutralization. Virus neutralization in flat-bottomed microplates (96 wells) was conducted using the protocol described previously 24 , with a few modifications. The test was performed on ovine testis cells using 2 replicates.…”