Poređenje seroloških metoda (ELSA i BHT) za ispitivanje prisustva i trajanja maternalnog imuniteta kod teladi od krava vakcinisanih sa atenuiranom LSDV vakcinom

Abstract

The objectives of this study were to determine duration of maternal immunity against lumpy skin disease virus (LSDV) in calves born to vaccinated cows and to compare different serological methods (commercial ELISA and modified VNT) in detection of presence and duration of maternal antibodies against LSDV in calves. The study was carried out on two farms where cows were vaccinated and revaccinated with attenuated vaccine against LSDV (Neethling strain) in August 2016 and 2017. The farms are located in Južnobački and Južnobanatski district where no LSD outbreaks were reported in Serbia in 2016. On Farm 1 the blood samples from 15 cows were collected during September and October 2017 on the day of calving. On Farm 2 the blood samples from another 15 cows were collected during January 2018, also on the day of calving. Blood samples from calves born to above mentioned 30 cows were collected 1, 2, 3 and 4 months after birth on both farms. In order to determine presence of antibodies against LSDV a total of 30 cow sera samples and 120 calf sera samples were examined by commercial ELISA kit and modified VNT developed at Scientific Veterinary Institute „Novi Sad“. From 150 tested samples specific antibodies against LSDV were determined in 37% and 34% by ELISA and VNT respectively. By ELISA 19 out of 30 cows were tested positive for the presence of anti-LSDV antibodies, while the transfer of antibodies by colostrum was also confirmed in 19 calves one month after birth. On the other hand, VNT detected 22 positive sera samples of cows, and only 18 positive sera samples of calves one month after birth. Two, three and four months after birth higher number of positive samples were detected by ELISA compared to VNT. Four months after birth on Farm 1 just 2 calves were positive for the presence of anti-LSDV antibodies by ELISA and only 1 by VNT, while on Farm 2 there were no positive samples by both methods. The results show that duration of maternal immunity against LDSV in cows from vaccinated cows is less than 4 months and that the recommended age for vaccination of new born calves should be reconsidered. Comparative testing of samples for detection of anti-LSDV antibodies showed similar performance of both methods used, ELISA and VNT.