Graduate Institute of Veterinary Microbiology, College of Veterinary Medicine, National Chung Hsing University, 250 Kuo Kuang Road, Taichung 40227, Taiwan, ROC.
Vet Microbiol. 2009 Nov 18;139(3-4):369-74. doi: 10.1016/j.vetmic.2009.06.027. Epub 2009 Jun 21.
Classical swine fever (CSF) is an economically important swine disease worldwide. The glycoprotein E2 of classical swine fever virus (CSFV) is a viral antigen that can induce a protective immune response against CSF. A recombinant E2 protein was constructed using the yeast Pichia pastoris expression system and evaluated for its vaccine efficacy. The yeast-expressed E2 (yE2) was shown to have N-linked glycosylation and to form homodimer molecules. Four 6-week-old specified-pathogen-free (SPF) piglets were intramuscularly immunized with yE2 twice at 3-week intervals. All yE2-vaccinated pigs could mount an anamnestic response after booster vaccination with neutralizing antibody titers ranging from 1:96 to 1:768. Neutralizing antibody titers at 10 weeks post booster vaccination ranged from 1:16 to 1:64. At this time, the pigs were subjected to challenge infection with a dose of 1x10(5)TCID(50) (50% tissue culture infective dose) virulent CSFV strain. At 1 week post challenge infection, all of the yE2-immunized pigs were alive and without symptoms or signs of CSF. Neutralizing antibody titers at this time ranged from 1:4,800 to 1:12,800 and even to 1:51,200 one week later. In contrast, the control pigs continuously exhibited signs of CSF and had to be euthanized because of severe clinical symptoms at 6 days post challenge infection. All of the yE2-vaccinated pigs were E(rns) antibody negative and had seroconverted against E(rns) by post challenge day 11, suggesting that yE2 is a potential DIVA (differentiating infected from vaccinated animals) vaccine. The yeast-expressed E2 protein retains correct immunogenicity and is able to induce a protective immune response against CSFV infection.
古典猪瘟（CSF）是一种在全球范围内对养猪业具有重要经济意义的猪病。猪瘟病毒（CSFV）的糖蛋白 E2 是一种病毒抗原，可诱导针对 CSF 的保护性免疫反应。本研究使用毕赤酵母表达系统构建了重组 E2 蛋白，并评估了其疫苗效力。结果表明，酵母表达的 E2（yE2）具有 N 连接糖基化，并形成同源二聚体分子。4 头 6 周龄无特定病原体（SPF）仔猪间隔 3 周肌内免疫 yE2 两次。所有 yE2 疫苗接种的猪在加强免疫后都能产生回忆应答，中和抗体滴度范围为 1:96 至 1:768。加强免疫后 10 周的中和抗体滴度范围为 1:16 至 1:64。此时，这些猪用 1x10(5)TCID(50)（50%组织培养感染剂量）强毒猪瘟病毒株进行攻毒感染。攻毒感染后 1 周，所有 yE2 免疫的猪均存活且无 CSF 症状或体征。此时的中和抗体滴度范围为 1:4,800 至 1:12,800，甚至 1 周后为 1:51,200。相比之下，对照猪在攻毒感染后 6 天持续出现 CSF 症状和体征，不得不因严重的临床症状而被安乐死。所有 yE2 疫苗接种的猪均为 E(rns)抗体阴性，且在攻毒后第 11 天转为 E(rns)抗体阳性，表明 yE2 是一种潜在的区分感染动物和免疫动物的（DIVA）疫苗。酵母表达的 E2 蛋白保留了正确的免疫原性，并能诱导针对 CSFV 感染的保护性免疫反应。
