腺病毒/甲病毒复制子嵌合载体猪瘟疫苗rAdV-SFV-E2最早提供完全攻毒保护时间的研究

First onset of full protection against lethal classical swine fever virus challenge with a single immunization of rAdV-SFV-E2

本实验室前期构建了腺病毒/甲病毒复制子嵌合载体猪瘟疫苗rAdV-SFV-E2,其免疫效力与商品化猪瘟C株疫苗相同,并具有鉴别检测特性。为进一步确定该嵌合载体猪瘟疫苗最早提供完全攻毒保护的时间,本研究将rAdV-SFV-E2免疫健康仔猪(n=5),免疫后于不同时间点采用猪瘟病毒(CSFV)强毒石门株进行攻毒,并检测其抗体应答、临床症状、病毒血症、病理学及组织病理学变化等。结果显示,rAdV-SFV-E2免疫后1周和2周,分别能对致死性CSFV强毒的攻击提供部分保护(3/5存活)和不完全保护(全部存活,但出现了短暂的发热和低水平的病毒血症);免疫后3周和4周,能够完全抵抗致死性CSFV强毒的攻击,表现为无病毒血症,无临床症状,无病理变化和组织病理学变化。该研究进一步证实rAdV-SFV-E2能够作为一种新型猪瘟标记疫苗,在猪瘟的紧急防控中能够起到一定的作用。

The adenovirus/alphavirus replicon chimeric vector-based vaccine rAdV-SFV-E2 against classical swine fever （CSF） was constructed in our previous study,which showed an equal efficacy to the commercial CSF vaccine of C-strain and possessed a unique characteristic of differentiating infected from vaccinated animals （DIVA）.To determinate the first onset of full protection provided by rAdV-SFV-E2,groups of pigs （n=5） were immunized once intramuscularly with 107 TCID50 rAdV-SFV-E2 and challenged with the highly virulent CSFV Shimen strain at different weeks post-immunization （WPI）.The results showed that the rAdV-SFV-E2 immunized pigs were completely protected from the lethal challenge at 3 or 4 WPI,without fever,viremia or pathological and histopathological lesions.However,rAdV-SFV-E2 provided only partial （3/5 survived） or incomplete （all survived,but showed short-term fever and viremia） protection for the immunized pigs when challenged at 1 or 2 WPI,respectively.These results demonstrate that rAdV-SFV-E2 is a promising DIVA vaccine and has a potential to be used as a safe and efficient candidate vaccine against CSF.