Borst Luke B, Patterson Sheila K, Lanka Saraswathi, Barger Anne M, Fredrickson Richard L, Maddox Carol W
Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
Am J Vet Res. 2011 Aug;72(8):1130-8. doi: 10.2460/ajvr.72.8.1130.
To evaluate a commercially available modified-live Streptococcus equi subsp equi vaccine for safety and persistence in vaccinated ponies and to detect recombination or reversion events in the vaccine strain.
5 ponies that were 1.5 to 8 years old (group 1) and 4 ponies that were 6 months old (group 2).
Ponies were vaccinated, with a subsequent booster vaccination 2 to 3 weeks later, and monitored for 50 days. At booster vaccination, an equal amount of a tetracycline-resistant wild-type strain of S equiwas administered. Recovery of all strains was performed by use of bacteriologic culture and PCR assays.
Ponies in group 1 had background antibody titers against S equi antigen before vaccination despite the lack of known exposure to S equi. Ponies in group 2 were immunologically naïve. Increases in anti-S equi antibody titers were detected in both groups. Ponies in group 1 did not have clinical signs of disease caused by S equi. In group 2, all ponies developed abscesses in retropharyngeal lymph nodes; 1 pony developed severe clinical disease and was euthanized. The vaccine strain was recovered from ponies in group 2 for up to 24 days after vaccination.
Although the vaccine was successful in inducing IgG antibodies against S equi in all ponies, findings suggested that the vaccine may have caused substantial morbidity and some deaths in the young ponies. In young ponies, the vaccine strain persisted in tissues for weeks; however, no evidence of recombination was detected.
评估一种市售的马链球菌兽疫亚种活疫苗在接种小马中的安全性和持续性，并检测疫苗株中的重组或回复事件。
5匹1.5至8岁的小马（第1组）和4匹6个月大的小马（第2组）。
给小马接种疫苗，2至3周后进行加强免疫，并监测50天。在加强免疫时，接种等量的四环素抗性马链球菌野生型菌株。通过细菌培养和PCR检测回收所有菌株。
第1组的小马在接种疫苗前尽管没有已知的马链球菌接触史，但对马链球菌抗原有背景抗体滴度。第2组的小马免疫初免。两组均检测到抗马链球菌抗体滴度升高。第1组的小马没有由马链球菌引起的疾病临床症状。在第2组中，所有小马的咽后淋巴结都出现脓肿；1匹小马出现严重临床疾病并被安乐死。接种疫苗后长达24天，在第2组的小马中回收了疫苗株。
尽管该疫苗成功地在所有小马中诱导了针对马链球菌的IgG抗体，但研究结果表明该疫苗可能在幼龄小马中引起了严重发病和一些死亡。在幼龄小马中，疫苗株在组织中持续存在数周；然而，未检测到重组证据。
