佐剂对IBRVΔgG/ΔTK双基因缺失活疫苗牛体攻毒保护效果的影响

Effects of an Adjuvant on Protection of IBRVΔgG/ΔTK Double Gene Deleted Vaccine Against Virulent Challenge in Calves

牛传染性鼻气管炎是危害养牛业的一种重要病毒性传染病,疫苗免疫是最主要的防控手段。为研究水性佐剂对牛传染性鼻气管炎TK和gG双基因缺失活疫苗(IBRVΔgG/ΔTK株)的免疫增强作用,将18头1.5~2月龄的奶公犊分成4组,组1~3各5头牛,组4为3头牛。组1滴鼻接种IBRVΔgG/ΔTK疫苗株,组2滴鼻接种IBRVΔgG/ΔTK疫苗株和Gel 01 ST水性佐剂混合物,组3为未免攻毒对照组,组4为不做处理的空白对照组。免疫35 d后,1~3组滴鼻攻击毒力株IBRV HB06株。免疫期间,组1牛体温在正常范围内,有1头牛眼睛和鼻腔出现水样分泌物;组2有1头牛出现一个温次达到40℃,有2头在眼或鼻出现水样分泌物。组1和组2血清特异性抗体和中和抗体水平无显著差异。攻毒后,组1和组2各有1头在第3天体温分别升高一个温次,达到40.25℃和40℃,部分牛眼睛出现水样分泌物;组1鼻腔排毒到第8天,组2中有1头牛在第9天仍检测到排毒;而组3出现流眼泪、鼻分泌物、鼻黏膜出血等临床症状,鼻腔排毒持续到第11天;组1肺部病变与空白对照组(组4)无显著差异,组2略严重于组1,组3表现出明显的肺部病变。按症状分值计算,组1和组2总保护率分别为91.7%和61.41%。参考世界动物卫生组织关于IBRV活疫苗的免疫保护评判标准,组1和组2分别达到100%(5/5)和80%(4/5)保护。综上,此研究所用佐剂未达到预期效果,后期仍需进行更多筛选。

Infectious bovine rhinotracheitis(IBR)is an important viral contagious disease damaging cattle industry,and vaccination is the main measure for its prevention and control.This study aimed to investigate the immune enhancement effect of gene-deleted attenuated vaccine(IBRVΔgG/ΔTK)with an aqueous adjuvant.A total of 18 dairy male calves aged 1.5-2 months were divided into four groups,five in each of groups 1 to 3,and 3 in group 4.Group 1 was vaccinated intranasally with only IBRVΔgG/ΔTK vaccine strain,group 2 with a mixture of an equal dose of IBRVΔgG/ΔTK and aqueous adjuvant Gel 01 ST,group 3 was the virulent control group without vaccination but challenged,while group 4 was a blank control group with mocked vaccination and challenge.During the vaccination period,in group 1,the temperatures of all calves fluctuated within the normal range,but one calf developed aqueous eye and nasal discharge;group 2 had one calf showing elevated body temperature up to 40°C for one measure time,and two calves showing aqueous eye and nasal discharge,respectively;there was no difference in levels of serum-specific and neutralization antibodies between the two immunized groups.After the virulent IBRV challenge,one calf in each of groups 1 and 2 had a transient increase of body temperature 40.25℃and 40℃for one measure time at 3 d post challenge and only aqueous eye discharge was observed in partial calves;the nasal shedding time of group 1 lasted for 8 days,the nasal shedding time lasted for 9 days for one calf in group 2.However,the non-immune challenge group 3 showed severe clinical signs such as eyes discharge,nasal discharge and hemorrhage of nasal mucosa;the nasal shedding time lasted for 11 days.Furthermore,compared to group 4,the lung in group 1 was similarly normal,that in group 2 was slightly more severe,but that in group 3 was significantly more severe.Based on the scores on clinical signs and lesions,the overall protection in groups 1 and 2 was 91.7%and 61.41%,respectively.Referring to the World Organization for Animal Health evaluation criteria for immune protection of live IBRV vaccine,the efficacy in groups 1 and 2 was respectively 5/5 and 4/5.In conclusion,this adjuvant did not show an improvement effect on the attenuated IBRV vaccine.More adjuvant candidates might be tested to find a suitable adjuvant for this vaccine.