嵌合猪圆环病毒对仔猪的免疫保护研究

为分析嵌合猪圆环病毒(PCV1-2)对仔猪的免疫效力，检测了PCV1-2免疫诱导仔猪产生抗猪圆环病毒II型(PCV2)感染的保护性免疫。将10头28日龄健康普通仔猪随机平均分成两组，一组肌注免疫106.05TCID50 PCV1-2作为免疫组；另一组不予免疫作为对照。到免疫后28天，免疫组仔猪血清中PCV2 ORF2蛋白抗体全部转为阳性。在免疫后28天，所有仔猪经口鼻予以106.95TCID50 PCV2攻击。攻毒后，免疫组仔猪全部保持临床健康，而对照组仔猪全部出现了PCV2疾病的临床症状；免疫组血清和淋巴组织中PCV2 DNA载量均显著(P<0.05)减少；对照组仔猪淋巴组织普遍出现中度到重度的淋巴细胞减少与组织细胞浸润，而免疫组没有。研究数据表明：PCV1-2免疫诱发了仔猪对PCV2感染的保护性免疫，有望成为候选PCV2弱毒疫苗。

Protective Immunity Induced by a Chimeric Porcine Circovirus in Piglets

To explore the immunity efficacy of a chimeric porcine circovirus（PCV1-2） to piglets,the protective immunity induced by the PCV1-2 against porcine circovirus type 2（PCV2） infections in piglets were investigated.A total of 10 healthy conventional piglets were randomly and equally assigned to two groups of 5 piglets each.Piglets in group 1 were vaccinated by intramuscular injection with 10 6.05 50% tissue culture infective doses（TCID 50） of the chimeric PCV1-2 live virus.Piglets in group 2 were not vaccinated and served as controls.By 28 days post-vaccination（DPV）,all piglets in group 1 had seroconverted to PCV2 ORF2 antibody.At 28 DPV,all piglets were challenged orally and intranasally with 50 6.25 TCID 50 wild pathogenic PCV2 viruses.All vaccinated piglets remained clinically healthy after challenge,while unvaccinated animals developed clinical signs relative to PCV2 diseases.The PCV2 DNA loads in sera and lymphoid tissues were significantly（P0.05） reduced in vaccinated piglets.Moderate to severe lymphoid depletion and histiocytic replacement were detected in most lymphoid tissues of unvaccinated piglets but none in vaccinated piglets.These data indicated that the Chimeric PCV1-2 induced protective immunity against PCV2 infection and could potentially serve as an attenuated PCV2 vaccine candidate.