Valas Stephen, Ngwa-Mbot David, Stourm Sophie, Mémeteau Sophie, Tabouret Marc
French Agency for Food, Environmental and Occupational Health and Safety (Anses), Ploufragan-Plouzané-Niort Laboratory, 60 rue de Pied de Fond, CS28440, 79024 Niort Cedex, France.
Animal Health Protection Farmers' Organization (GDS France), 37 rue de Lyon, 75012 Paris, France.
Prev Vet Med. 2023 May;214:105890. doi: 10.1016/j.prevetmed.2023.105890. Epub 2023 Mar 7.
Pooled serum testing using whole-virus indirect ELISA has been recently recognized as an official method for surveillance of bovine herpesvirus 1 (BoHV1) in cattle herds in Europe. In this study, a retrospective analysis of data from the French BoHV1 surveillance campaign 2018-2019, including 7434 BoHV1-free certified herds and 157 infected herds, was performed in order to evaluate the diagnostic specificity and sensitivity of two pooled serum indirect ELISAs (from IDEXX and IDVet), in comparison with individual testing by blocking ELISAs targeting the gB and gE proteins. Pooled serum testing showed a relative specificity higher than 97.5% and a detection rate of 100% since all gB+/gE+ samples were found in positive pools. At the herd level, no more than one false positive pool was observed in most of BoHV1-free certified herds, leading to a herd relative specificity of 85.1% and 86.0% for the IDEXX and IDVet pooled serum ELISAs, respectively. Among infected herds tested by pool sizes up to 10 sera (n = 122), 46% of herds were detected through pools of size 10 containing a single positive sample, 23% through pools of size 10 containing at least two positive samples, and 31% through pools of smaller sizes. A complementary study based on manually constituted pools revealed that at least one positive sample in 100% and 93.4% of herds could be detected individually by pools of size 10 with the IDEXX and IDVet ELISAs, respectively. However, pooled serum ELISAs were influenced by the level of individual reactivity, since pools composed of either one weak-positive sample or one gB+/gE- sample could yield negative results. Altogether, these results provided the first evidence that pooled serum testing (pool size up to 10) is a suitable strategy for surveillance of BoHV1-free cattle farms.
使用全病毒间接ELISA进行混合血清检测最近已被公认为欧洲牛群中牛疱疹病毒1型（BoHV1）监测的官方方法。在本研究中，对2018 - 2019年法国BoHV1监测活动的数据进行了回顾性分析，其中包括7434个无BoHV1认证牛群和157个感染牛群，目的是评估两种混合血清间接ELISA（来自IDEXX和IDVet）与通过针对gB和gE蛋白的阻断ELISA进行个体检测相比的诊断特异性和敏感性。混合血清检测显示相对特异性高于97.5%，检测率为100%，因为所有gB+/gE+样本都在阳性混合样本中被发现。在牛群水平上，在大多数无BoHV1认证牛群中观察到不超过一个假阳性混合样本，导致IDEXX和IDVet混合血清ELISA的牛群相对特异性分别为85.1%和86.0%。在通过最多10份血清的混合样本检测的感染牛群（n = 122）中，46%的牛群通过含有单个阳性样本的10份血清混合样本被检测到，23%通过含有至少两个阳性样本的10份血清混合样本被检测到，31%通过较小规模的混合样本被检测到。一项基于人工组成混合样本的补充研究表明，分别使用IDEXX和IDVet ELISA，10份血清混合样本可在100%和93.4%的牛群中单独检测到至少一个阳性样本。然而，混合血清ELISA受个体反应水平的影响，因为由一个弱阳性样本或一个gB+/gE-样本组成的混合样本可能产生阴性结果。总之，这些结果首次证明混合血清检测（混合样本规模达10）是无BoHV1奶牛场监测的合适策略。
