Different clinical presentations of subgenotype 2.1 strain of classical swine fever infection in weaned piglets and adults, and long-term cross-protection conferred by a C-strain vaccine
Different clinical presentations of subgenotype 2.1 strain of classical swine fever infection in weaned piglets and adults, and long-term cross-protection conferred by a C-strain vaccine
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DOI：
10.1016/j.vetmic.2020.108915
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发表时间：
2021-01-18
影响因子：
3.3
通讯作者：
Chen, Guanghua
中科院分区：
文献类型：
--
作者：
Wang, Qin;Liu, Huanhuan;Chen, Guanghua
猪瘟是中国的一种重要猪病，尽管强制接种，但临床症状轻微的零星疫情引发了人们对流行的2.1亚型毒株的毒力和致病性以及C株疫苗对它们的交叉保护能力的质疑。为了研究这一点，对三个野外分离株在实验感染的仔猪身上进行了评估，并与高毒力的参考石门株进行了比较。野生型菌株的临床症状从轻到重不等，死亡率从0到80%不等。这些数据显示了2.1亚型野毒株毒力的差异，支持使用GD191野毒株作为2型挑战病毒来评估C株疫苗的效果。与历史上的1亚型毒株在未接种疫苗的动物中引起急性感染并显著脱毒不同，2.1亚型GD191毒株在断奶仔猪和成年猪中产生不同的临床表现。成年猪表现为亚临床感染，有病毒脱落，而断奶仔猪表现出明显的感染迹象。在接种后12个月和15个月，使用参考石门株和野毒株GD191评估C株疫苗的免疫效力和免疫持续时间。在所有接种疫苗的动物中都看到了强大的抗体反应和消毒保护，并在接种疫苗后持续了长达15个月。这项研究证实，C株疫苗对历史基因1型石门株具有临床和病毒学保护作用，对流行的基因2型野毒株具有交叉保护作用。
Classical swine fever is an important swine disease in China, and sporadic outbreaks with mild clinical signs despite compulsory vaccination have raised questions about the virulence and pathogenicity of prevalent subgenotype 2.1 strains, and the ability of C-strain vaccines to cross-protect against them. To investigate this, three field isolates were evaluated in experimentally infected piglets and compared with the highly virulent reference Shimen strain. Clinical signs for the field strains ranged from mild to severe, and mortality ranged from 0 to 80 %. These data show differences in virulence among the subgenotype 2.1 field isolates and support the use of field strain GD191 as a genotype 2 challenge virus to assess efficacy of C-strain vaccines.In contrast to the historical genotype 1 strain, which caused acute infection with significant virus shedding in non-vaccinated animals, the subgenotype 2.1 GD191 strain produced different clinical manifestations in weaned piglets and adults. Adult pigs showed subclinical infection with viral shedding, whereas weaned piglets showed overt signs of infection. Efficacy of, and duration of immunity conferred by a C-strain vaccine were assessed using the reference Shimen strain and field isolate GD191 at 12 and 15 months after vaccination. A robust antibody response and sterilising protection were seen in all vaccinated animals and lasted up to 15 months post-vaccination. This study confirms that C-strain vaccines confer both clinical and virological protection against the historical genotype 1 Shimen strain and cross-protection against the prevalent genotype 2 field strain.