TSUJIMURA Koji, SHIOSE Tomoki, YAMANAKA Takashi, NEMOTO Manabu, KONDO Takashi, MATSUMURA Tomio
Epizootic Research Center, Equine Research Institute, Japan Racing Association, Shimotsuke, Tochigi, Japan.
J Vet Med Sci. 2009 Nov;71(11):1439-48. doi: 10.1292/jvms.001439.
An equine herpesvirus type 1 (EHV-1) mutant, DeltagE, defective in glycoprotein E (gE) was evaluated as a modified live virus (MLV) vaccine. Colostrum-deprived Thoroughbred foals inoculated intranasally (i.n.) or intramuscularly (i.m.) with DeltagE did not exhibit any clinical signs of respiratory disease except for a mild nasal discharge in 1 i.n. inoculated foal on Days 1 and 3 post-infection. In contrast, the intranasal inoculation of foals with the revertant of DeltagE resulted in biphasic pyrexia, mucopurulent nasal discharge and swelling of submandibular lymph nodes. These results indicated that gE plays an important role as regards EHV-1 virulence in horses. The ability of DeltagE to protect against wild type EHV-1 challenge infection was assessed using i.m. vaccinated foals. Foals inoculated twice i.m. with 10(5) or 10(6) plaque-forming units (pfu) of DeltagE at an interval of 3 weeks exhibited no clinical evidence of local inflammation, respiratory disease or deleterious systemic responses. Remarkable increases in SN antibody titer to EHV-1 were observed in all vaccinated foals after the 2nd inoculation with DeltagE. Following a wild type EHV-1 challenge infection, vaccinated foals showed milder clinical symptoms than foals vaccinated with a placebo. Specifically, 1 of 3 foals vaccinated with 10(6) pfu of DeltagE exhibited no clinical symptoms other than a mild nasal discharge for 1 day. Additionally, the virus load of nasal shedding and viremia were reduced by vaccination. These results suggest that DeltagE would be a good candidate as an MLV vaccine.
对一种在糖蛋白E（gE）方面存在缺陷的1型马疱疹病毒（EHV-1）突变体DeltagE作为一种改良活病毒（MLV）疫苗进行了评估。初乳剥夺的纯种马驹经鼻内（i.n.）或肌肉内（i.m.）接种DeltagE后，除了1匹经鼻内接种的马驹在感染后第1天和第3天出现轻度鼻分泌物外，未表现出任何呼吸道疾病的临床症状。相比之下，用DeltagE的回复株对马驹进行鼻内接种导致双相发热、黏液脓性鼻分泌物和下颌下淋巴结肿大。这些结果表明，gE在马的EHV-1毒力方面起着重要作用。使用肌肉内接种疫苗的马驹评估了DeltagE预防野生型EHV-1攻击感染的能力。每隔3周肌肉内接种2次10⁵或10⁶空斑形成单位（pfu）DeltagE的马驹未表现出局部炎症、呼吸道疾病或有害全身反应的临床证据。在第2次接种DeltagE后，所有接种疫苗的马驹中针对EHV-1的血清中和（SN）抗体滴度均显著升高。在野生型EHV-1攻击感染后，接种疫苗的马驹表现出比接种安慰剂的马驹更轻的临床症状。具体而言，接种10⁶ pfu DeltagE的3匹马驹中有1匹除了1天出现轻度鼻分泌物外未表现出任何临床症状。此外，接种疫苗后鼻排毒和病毒血症的病毒载量降低。这些结果表明，DeltagE将是一种良好的MLV疫苗候选物。
