Kaiser V, Nebel L, Schüpbach-Regula G, Zanoni R G, Schweizer M
Institute of Virology and Immunology, Federal Food Safety and Veterinary Office (FSVO) and Vetsuisse Faculty, University of Bern, Laenggass-Strasse 122, POB, CH-3001, Bern, Switzerland.
Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Schwarzenburgstrasse 155, CH-3097, Liebefeld, Switzerland.
BMC Vet Res. 2017 Jan 13;13(1):21. doi: 10.1186/s12917-016-0932-0.
In 2008, a program to eradicate bovine virus diarrhea (BVD) in cattle in Switzerland was initiated. After targeted elimination of persistently infected animals that represent the main virus reservoir, the absence of BVD is surveilled serologically since 2012. In view of steadily decreasing pestivirus seroprevalence in the cattle population, the susceptibility for (re-) infection by border disease (BD) virus mainly from small ruminants increases. Due to serological cross-reactivity of pestiviruses, serological surveillance of BVD by ELISA does not distinguish between BVD and BD virus as source of infection.
In this work the cross-serum neutralisation test (SNT) procedure was adapted to the epidemiological situation in Switzerland by the use of three pestiviruses, i.e., strains representing the subgenotype BVDV-1a, BVDV-1h and BDSwiss-a, for adequate differentiation between BVDV and BDV. Thereby the BDV-seroprevalence in seropositive cattle in Switzerland was determined for the first time. Out of 1,555 seropositive blood samples taken from cattle in the frame of the surveillance program, a total of 104 samples (6.7%) reacted with significantly higher titers against BDV than BVDV. These samples originated from 65 farms and encompassed 15 different cantons with the highest BDV-seroprevalence found in Central Switzerland. On the base of epidemiological information collected by questionnaire in case- and control farms, common housing of cattle and sheep was identified as the most significant risk factor for BDV infection in cattle by logistic regression.
This indicates that pestiviruses from sheep should be considered as a source of infection of domestic cattle and might well impede serological BVD surveillance.
2008年，瑞士启动了一项根除牛病毒性腹泻（BVD）的计划。在有针对性地清除了作为主要病毒储存库的持续感染动物后，自2012年起通过血清学监测BVD的缺失情况。鉴于牛群中瘟病毒血清阳性率稳步下降，牛感染主要来自小反刍动物的边境病（BD）病毒的易感性增加。由于瘟病毒的血清学交叉反应性，通过酶联免疫吸附测定（ELISA）对BVD进行血清学监测无法区分BVD和BD病毒作为感染源。
在这项工作中，通过使用三种瘟病毒，即代表BVDV-1a、BVDV-1h和BDSwiss-a亚基因型的毒株，使交叉血清中和试验（SNT）程序适应瑞士的流行病学情况，以便对BVDV和BDV进行充分区分。从而首次确定了瑞士血清阳性牛中的BDV血清阳性率。在监测计划框架内从牛采集的1555份血清阳性血样中，共有104份样本（6.7%）对BDV的反应滴度明显高于对BVDV的反应滴度。这些样本来自65个农场，涵盖15个不同的州，其中瑞士中部的BDV血清阳性率最高。根据在病例农场和对照农场通过问卷调查收集的流行病学信息，通过逻辑回归确定牛和羊共同饲养是牛感染BDV的最显著风险因素。
这表明来自绵羊的瘟病毒应被视为家牛的感染源，并且很可能会妨碍BVD的血清学监测。
