Sestak K, Lanza I, Park S K, Weilnau P A, Saif L J
Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Wooster 44691, USA.
Am J Vet Res. 1996 May;57(5):664-71.
To determine the ability of porcine respiratory coronavirus (PRCV) infections to induce passive immunity in suckling pigs to transmissible gastroenteritis virus (TGEV) challenge exposure. DESIGN AND ANIMALS: 4 TGEV seronegative sows and their litters (group A) served as controls, whereas 2 other groups (B and C) of sows (also TGEV seronegative) were oronasally inoculated with live PRCV during 1 or 2 subsequent pregnancies, respectively.
Effectiveness of passive immunity provided to pigs via colostrum and milk was assessed after TGEV challenge exposure, and TGEV antibody responses in colostrum and milk were analyzed.
Mortality in the 3 groups of young pigs correlated with severity of clinical signs of TGEV infection and was highest in control litters (86% in group-A pigs) and lowest in litters of sows inoculated with PRCV in 2 subsequent pregnancies (14% in group-C pigs). Virus-neutralization and IgA and IgG TGEV antibody titers of milk collected from sows at challenge exposure had significant positive correlation with litter survival. Significantly higher numbers of TGEV-specific IgA and IgG antibody-secreting cells were found in group-A pigs than in group-C pigs, suggesting that high titer of maternal antibodies (induced in group-C sows multiply exposed to PRCV) may interfere with active antibody responses.
Results suggest that, in PRCV-infected pig herds, multiple exposures of pregnant sows are associated with higher IgA and IgG antibody titers to TGEV in milk, and these titers contribute to protection against TGEV infection.
确定猪呼吸道冠状病毒（PRCV）感染诱导哺乳仔猪对传染性胃肠炎病毒（TGEV）攻击暴露产生被动免疫的能力。设计与动物：4头TGEV血清阴性母猪及其仔猪（A组）作为对照，而另外两组（B组和C组）同样为TGEV血清阴性的母猪，分别在随后的1次或2次妊娠期间经口接种活的PRCV。
在TGEV攻击暴露后评估通过初乳和乳汁提供给仔猪的被动免疫的有效性，并分析初乳和乳汁中的TGEV抗体反应。
3组仔猪的死亡率与TGEV感染临床症状的严重程度相关，对照组仔猪死亡率最高（A组仔猪为86%），在随后2次妊娠中接种PRCV的母猪所产仔猪死亡率最低（C组仔猪为14%）。在攻击暴露时从母猪采集的乳汁的病毒中和以及IgA和IgG TGEV抗体滴度与仔猪存活呈显著正相关。在A组仔猪中发现的TGEV特异性IgA和IgG抗体分泌细胞数量显著高于C组仔猪，这表明高滴度的母源抗体（在多次暴露于PRCV的C组母猪中诱导产生）可能会干扰主动抗体反应。
结果表明，在感染PRCV的猪群中，怀孕母猪多次暴露与乳汁中针对TGEV的IgA和IgG抗体滴度升高有关，并且这些滴度有助于预防TGEV感染。
