Chaintoutis Serafeim C, Diakakis Nikolaos, Papanastassopoulou Maria, Banos Georgios, Dovas Chrysostomos I
Diagnostic Laboratory, Department of Clinical Sciences, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece.
Equine Unit, Companion Animal Clinic, Department of Clinical Sciences, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece.
Clin Vaccine Immunol. 2015 Sep;22(9):1040-9. doi: 10.1128/CVI.00302-15. Epub 2015 Jul 15.
Although experimental data regarding cross-protection of horse West Nile virus (WNV) vaccines against lineage 2 infections exist, the cross-protective efficacy of these vaccines under field conditions has not been demonstrated. This study was conducted to evaluate the capability of an inactivated lineage 1 vaccine (Equip WNV) to protect against natural infections from the Nea Santa-Greece-2010 lineage 2 strain. In total, 185 WNV-seronegative horses in Thessaloniki, Greece, were selected during 2 consecutive years (2011 and 2012); 140 were immunized, and 45 were used as controls. Horses were examined for signs compatible with WNV infection. Neutralizing antibody titers against the Greek strain and the PaAn001/France lineage 1 strain were determined in immunized horses. WNV circulation was detected during both years in the study area. It was estimated that 37% and 27% of the horses were infected during 2011 and 2012, respectively. Three control animals developed clinical signs, and the WNV diagnosis was confirmed. Signs related to WNV infection were not observed in the vaccinated animals. The nonvaccinated animals had a 7.58% ± 1.82% higher chance of exhibiting signs than immunized animals (P < 0.05). Neutralizing antibodies raised against both strains in all immunized horses were detectable 1 month after the initial vaccination course. The cross-protective capacity of the lowest titer (1:40) was evident in 19 animals which were subsequently infected and did not exhibit signs. Neutralizing antibodies were detectable until the annual booster, when strong anamnestic responses were observed (geometrical mean titer ratio [GMTR] for lineage 1 of 30.2; GMTR for lineage 2 of 27.5). The results indicate that Equip WNV is capable of inducing cross-protection against natural infections from a virulent lineage 2 WNV strain in horses.
尽管存在关于马西尼罗河病毒（WNV）疫苗对2型病毒感染的交叉保护作用的实验数据，但这些疫苗在野外条件下的交叉保护效力尚未得到证实。本研究旨在评估一种灭活的1型疫苗（Equip WNV）预防希腊内阿圣塔2010株2型病毒自然感染的能力。连续两年（2011年和2012年），在希腊塞萨洛尼基共挑选了185匹WNV血清阴性马匹；140匹进行免疫接种，45匹用作对照。对马匹进行检查，观察是否有与WNV感染相符的体征。测定免疫接种马匹针对希腊毒株和法国1型PaAn001毒株的中和抗体滴度。在研究区域的两年中均检测到WNV传播。据估计，2011年和2012年分别有37%和27%的马匹被感染。3只对照动物出现临床体征，WNV诊断得到证实。在接种疫苗的动物中未观察到与WNV感染相关的体征。未接种疫苗的动物出现体征的几率比免疫接种动物高7.58%±1.82%（P<0.05）。在初次接种疫苗疗程1个月后，所有免疫接种马匹针对两种毒株产生的中和抗体均可检测到。最低滴度（1:40）的交叉保护能力在随后被感染但未出现体征的19只动物中明显可见。在每年进行加强免疫时，中和抗体均可检测到，此时观察到强烈的回忆反应（1型的几何平均滴度比[GMTR]为30.2；2型的GMTR为27.5）。结果表明，Equip WNV能够诱导马匹对2型强毒WNV毒株的自然感染产生交叉保护。
