Bovine viral diarrhea virus continues to threaten animal health with serious economic losses worldwide. Various killed, live-modified, or recombinant vaccine strategies are being developed for protection and control against this virus. The most important thing discovered is the choice of local and widespread strains in the vaccine content. In this study, the effectiveness of a Montanide^® ISA 206 adjuvanted killed trivalent vaccine containing endemic local strains (TR-21 [BVDV-1l], TR-26 [BVDV-1f], and TR-15 [BVDV-2b]) isolated from Türkiye, was evaluated with a cattle challenge study. Experimental groups were designed as single dose vaccination (Group-I, n:11), two dose vaccination (Group-II, n:11), and unvaccinated (Group-III, n:6) with male calves aged about 6 months. Following the immunization, challenge virus (TR-72 [BVDV-1l], TCID₅₀ 10^6.5) was given intranasally to each group (5 animals in Group-I and II and 4 animals in Group-III), and clinical findings, hematological changes, virus shedding, side effects, and viremia were monitored for 14 days after inoculation. Serological monitoring of the remaining animals against homologous and heterologous strains was carried out at one-month intervals between the 21st and 201st days after the first vaccination. The obtained results showed that the viremia, hematological changes, and clinical findings shown in unvaccinated animals (Group-III) were significantly suppressed (p < 0.05) in the vaccinated groups (Group-I and II). In addition, it was found that serologically monitored animals maintained protective neutralizing antibody (nAb) titers ≥ 8 log₂ for vaccinal and also for all reference BVDV-1 strains, which is more than three-fold protective antibody response, lasting more than 7 months after the first vaccination, whether in single or two dose application. The rise of nAbs was also detected for heterogous BVDV strains. The detected nAb titers were significantly higher (p < 0.05) in the two dose vaccination group. Based on the results, it was concluded that this trivalent- inactivated vaccine candidate can protect cattle against acute BVDV infections.

Keywords: Bovine viral diarrhea virus; Challenge study; Killed vaccine; Local strains; Neutralising antibody.

© 2025. The Author(s).

牛病毒性腹泻病毒继续对动物健康构成威胁，并在全球范围内造成严重的经济损失。为了保护和控制这种病毒，各种灭活、减毒或重组疫苗策略正在被开发。最重要的是发现了疫苗中包含地方性和广泛流行株的选择问题。在这项研究中，通过一项牛挑战实验评估了含有从土耳其分离的地方性三价株（TR-21 [BVDV-1l]、TR-26 [BVDV-1f] 和 TR-15 [BVDV-2b]）的蒙特尼德® ISA 206佐剂灭活疫苗的有效性。实验组设计为单剂量接种（I组，n=11）、双剂量接种（II组，n=11）和未接种对照组（III组，n=6），受试者为约6个月龄的雄性牛犊。免疫后，各组均通过鼻内途径给予挑战病毒（TR-72 [BVDV-1l]，TCID50 10^6.5）。随后，在接种后的14天内监测临床表现、血液学变化、病毒排出、副作用和病毒血症情况。在首次免疫后第21至201天之间，以一个月为间隔对剩余动物进行针对同源和异源株的血清学监测。结果显示，未接种对照组（III组）出现的病毒血症、血液学变化和临床表现，在接种组（I组和II组）中显著受到抑制（p < 0.05）。此外，血清学监测显示，在首次免疫后超过7个月的时间里，无论是单剂还是双剂接种，受试动物均维持了针对疫苗株以及所有参考BVDV-1株的保护性中和抗体(nAb)滴度≥8 log2，这表明存在三倍以上的保护性抗体反应。此外还检测到了针对异源BVDV毒株的nAbs水平上升现象，在双剂量接种组中测得的nAb滴度显著更高（p < 0.05）。根据研究结果得出结论：这种三价灭活疫苗候选物可以为牛提供对急性牛病毒性腹泻病毒感染的保护。

关键词：牛病毒性腹泻病毒；挑战实验；灭活疫苗；地方株；中和抗体。