一种减毒活嵌合猪圆环病毒2型（PCV2）疫苗可传播给接触猪，但不会因与猪细小病毒（PPV）和猪繁殖与呼吸综合征病毒（PRRSV）同时感染而上调，并且在PCV2b-PRRSV-PPV攻毒模型中有效。
A live-attenuated chimeric porcine circovirus type 2 (PCV2) vaccine is transmitted to contact pigs but is not upregulated by concurrent infection with porcine parvovirus (PPV) and porcine reproductive and respiratory syndrome virus (PRRSV) and is efficacious in a PCV2b-PRRSV-PPV challenge model.
作者信息
Opriessnig T, Shen H G, Pal N, Ramamoorthy S, Huang Y W, Lager K M, Beach N M, Halbur P G, Meng X J
机构信息
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
出版信息
Clin Vaccine Immunol. 2011 Aug;18(8):1261-8. doi: 10.1128/CVI.05057-11. Epub 2011 Jun 8.
The live chimeric porcine circovirus type 2 (PCV2) vaccine with the capsid gene of the emerging subtype 2b cloned in the genomic backbone of the nonpathogenic PCV1 is attenuated in vivo and induces protective immunity against PCV2. To further determine the safety and efficacy of this experimental vaccine, we tested for evidence of pig-to-pig transmission by commingling nonvaccinated and vaccinated pigs, determined potential upregulation by simultaneous vaccination and infection with porcine parvovirus (PPV) and porcine reproductive and respiratory syndrome virus (PRRSV), and determined vaccine efficacy by challenging pigs 4 weeks after vaccination with PCV2b, PRRSV, and PPV. Forty-six 21-day-old, PCV2-naïve pigs were randomly assigned to one of six groups. Twenty-nine of 46 pigs were challenged with PCV2b, PRRSV, and PPV at day 28, 8/46 remained nonvaccinated and nonchallenged and served as negative controls, and 9/46 remained nonchallenged and served as vaccination controls. All animals were necropsied at day 49. PCV1-PCV2 viremia was detected in nonvaccinated contact pigs commingled with vaccinated pigs, indicating pig-to-pig transmission; however, PCV1-PCV2 DNA levels remained low in all vaccinated and contact pigs regardless of concurrent infection. Finally, vaccination 28 days before challenge resulted in significantly (P < 0.05) decreased amounts of PCV2 in tissues and sera and significantly (P < 0.05) reduced macroscopic and microscopic lesions. The results of this study indicate that the experimental live-attenuated chimeric PCV2 vaccine, although transmissible to contact pigs, remains attenuated in pigs concurrently infected with PRRSV and PPV and induces protective immunity against PCV2b when it is administered 28 days before PCV2 exposure.
将新兴的2b亚型衣壳基因克隆于非致病性猪圆环病毒1型（PCV1）基因组骨架中的活嵌合猪圆环病毒2型（PCV2）疫苗在体内具有减毒作用，并能诱导针对PCV2的保护性免疫。为进一步确定这种实验性疫苗的安全性和有效性，我们通过将未接种疫苗的猪与接种疫苗的猪混群饲养来检测猪间传播的证据，确定同时接种疫苗以及感染猪细小病毒（PPV）和猪繁殖与呼吸综合征病毒（PRRSV）时的潜在上调情况，并通过在接种疫苗4周后用PCV2b、PRRSV和PPV对猪进行攻毒来确定疫苗效力。46头21日龄、未接触过PCV2的仔猪被随机分为6组。46头猪中有29头在第28天用PCV2b、PRRSV和PPV进行攻毒，46头中有8头未接种疫苗且未攻毒，作为阴性对照，46头中有9头未攻毒，作为疫苗接种对照。所有动物在第49天进行剖检。在与接种疫苗的猪混群饲养的未接种疫苗的接触猪中检测到PCV1-PCV2病毒血症，表明存在猪间传播；然而，无论是否并发感染，所有接种疫苗的猪和接触猪体内的PCV1-PCV2 DNA水平均保持较低。最后，在攻毒前28天接种疫苗导致组织和血清中的PCV2量显著（P<0.05）减少，宏观和微观病变也显著（P<0.05）减轻。本研究结果表明，这种实验性的减毒活嵌合PCV2疫苗虽然可传播给接触猪，但在同时感染PRRSV和PPV的猪中仍具有减毒作用，并且在PCV2暴露前28天接种时可诱导针对PCV2b的保护性免疫。
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