Rittipornlertrak Amarin, Modethed Wittawat, Sangkakam Kanokwan, Muenthaisong Anucha, Vinitchaikul Paramintra, Boonsri Kittikorn, Pringproa Kidsadagon, Punyapornwithaya Veerasak, Kreausukon Khwanchai, Sthitmatee Nattawooti, Singhla Tawatchai
Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.
Laboratory of Veterinary Vaccine and Biological Products, Faculty of Veterinary Medicine, Chiang Mai University, Chiang Mai, Thailand.
Front Vet Sci. 2024 May 21;11:1303424. doi: 10.3389/fvets.2024.1303424. eCollection 2024.
This study aimed to determine the persistent duration of maternal immunity against lumpy skin disease virus (LSDV) in dairy calves born from vaccinated cows using a virus neutralization test (VNT). The performance of the VNT and an in-house-ELISA test was also determined. Thirty-seven pregnant cows from 12 LSD-free dairy farms in Lamphun province, Thailand were immunized with a homologous Neethling strain-based attenuated vaccine and calved from December 2021 to April 2022. Blood samples from dam-calve pairs were collected within the first week after calving. Subsequently, blood samples were taken from the calves at monthly intervals over a period of 4 months and tested for the humoral immune response using a VNT. The calf sera were also tested with an in-house ELISA test to estimate the accuracy of both tests using a Bayesian approach. For the results, antibodies against LSDV can persist in cows for 4-9 months post-vaccination. Moreover, neutralizing antibodies and LSDV-specific antibodies against LSDV were detected in the majority of calves (75.68%) during the first week after colostrum intake. However, the percentage of seropositive calves declined to zero by day 120, with seropositivity dropping below 50% after day 60. Only a small number of seropositive calves (approximately 13.51%) were observed on day 90. These findings indicated that passive immunity against LSDV can last up to 3 months. The median of posterior estimates for sensitivity (Se) and specificity (Sp) of the VNT were 87.3% [95% posterior probability interval (PPI) = 81.1-92.2%] and 94.5% (95% PPI = 87.7-98.3%), respectively. The estimated Se and Sp for the ELISA test were 83.1% (95% PPI = 73.6-92.6%) and 94.7% (95% PPI = 88.4-98.5%), respectively. In conclusion, this study illustrates the transfer and persistence of maternal passive immunity against LSDV to calves under field conditions. This highlights a potential three-month vaccination gap in calves born from vaccinated cows, while an in-house ELISA test can be used as an ancillary test for LSDV immune response detection. However, further research is required to assess the vaccination protocols for calves as young as 2 months old to precisely determine the duration of maternal immunity.
本研究旨在通过病毒中和试验（VNT）确定接种疫苗的奶牛所产犊牛中母源抗结节性皮肤病病毒（LSDV）免疫力的持续时间。同时还测定了VNT和一种内部酶联免疫吸附测定（ELISA）试验的性能。泰国南奔府12个无LSD的奶牛场的37头怀孕母牛用基于同源Neethling毒株的减毒疫苗进行免疫，并于2021年12月至2022年4月产犊。在产犊后的第一周内采集母犊对的血样。随后，在4个月的时间里每月从犊牛采集血样，并使用VNT检测体液免疫反应。还用内部ELISA试验检测犊牛血清，以贝叶斯方法评估两种试验的准确性。结果显示，接种疫苗后抗LSDV抗体可在母牛体内持续4至9个月。此外，在大多数犊牛（75.68%）初乳摄入后的第一周检测到了抗LSDV的中和抗体和LSDV特异性抗体。然而，血清阳性犊牛的比例在第120天时降至零，在第60天后血清阳性率降至50%以下。在第90天时仅观察到少数血清阳性犊牛（约13.51%）。这些发现表明，抗LSDV的被动免疫可持续长达3个月。VNT敏感性（Se）和特异性（Sp）的后验估计中位数分别为87.3%[95%后验概率区间（PPI）=81.1 - 92.2%]和94.5%（95%PPI = 87.7 - 98.3%）。ELISA试验的估计Se和Sp分别为83.1%（95%PPI =
