Toro H, van Santen V L, Ghetas A M, Joiner K S
Department of Pathobiology, College of Veterinary Medicine, 264 Greene Hall, Auburn University, AL 36849.
Avian Dis. 2015 Dec;59(4):532-6. doi: 10.1637/11231-070615-Reg.1.
Infectious bronchitis virus (IBV) cross-protection trials were performed in healthy chickens maintained under controlled environmental conditions. Chickens primed or primed and boosted with a Massachusetts (Mass)-type attenuated vaccine were subsequently challenged with either IBV Arkansas (Ark) or GA13-type virulent strains. In addition, Ark-vaccinated chickens were challenged with IBV GA13. Spike protein 1 (S1) amino acid identities between IBV vaccine and challenge strains varied from 76.0% to 77.3%. Contrary to expectations, assessments of clinical signs, viral load, and histopathology indicated a significant level of cross-protection among these antigenically distant IBV strains. Moreover, prime and booster vaccination with Mass protected against GA13 and improved protection against Ark when compared with Mass single vaccination. These results emphasize the need to include both single vaccination control groups and control groups primed and boosted with a single serotype when testing the efficacy of IBV protectotypes and/or novel IBV vaccine combinations against heterologous serotypes under controlled experimental conditions. Such controls are of distinct importance in experiments supporting the introduction of attenuated IBV vaccine strains exotic to regions, since these exotic strains may provide new genetic material for recombination and emergence of novel IBV strains.
在可控环境条件下饲养的健康鸡群中进行了传染性支气管炎病毒（IBV）交叉保护试验。用马萨诸塞州（Mass）型减毒疫苗进行初次免疫或初次免疫并加强免疫的鸡，随后用IBV阿肯色州（Ark）株或GA13型强毒株进行攻毒。此外，用Ark疫苗免疫的鸡用IBV GA13进行攻毒。IBV疫苗株和攻毒株之间的刺突蛋白1（S1）氨基酸同源性在76.0%至77.3%之间。与预期相反，临床症状、病毒载量和组织病理学评估表明，这些抗原性不同的IBV毒株之间存在显著水平的交叉保护。此外，与单次接种Mass疫苗相比，用Mass疫苗进行初次免疫和加强免疫可抵御GA13，并提高对Ark的保护效果。这些结果强调，在可控实验条件下测试IBV保护型和/或新型IBV疫苗组合针对异源血清型的效力时，需要同时设置单次接种对照组以及用单一血清型进行初次免疫和加强免疫的对照组。在支持引入某地区外来减毒IBV疫苗株的实验中，此类对照具有至关重要的意义，因为这些外来毒株可能为新型IBV毒株的重组和出现提供新的遗传物质。
