Dvorak Cheryl M T, Payne Brian J, Seate Jessica L, Murtaugh Michael P
1 Department of Veterinary and Biomedical Sciences, University of Minnesota , St. Paul, Minnesota.
2 Boehringer Ingelheim Vetmedica , Inc., St. Joseph, Missouri.
Viral Immunol. 2018 Jan/Feb;31(1):40-46. doi: 10.1089/vim.2017.0058. Epub 2017 Aug 17.
Sow immunity plays an important role in preventing viral infection and disease in newborn piglets. Vertical transmission of porcine circovirus type 2 (PCV2) may perpetuate porcine circovirus associated disease (PCVAD) in newborn and growing pigs. Hence, the immunological effects of maternal immunoglobulin transfer of PCV2-specific antibodies on PCV2 viremia and immune response in piglets in commercial swine herds were evaluated. Sow vaccination has been shown to reduce viral shedding and viremia, and increases the neutralizing antibody (NA) titers. Since NAs are important for control of PCVAD and mammary secretions may contain high anti-PCV2 NA levels, we examined the PCV2 NA levels in colostrum, milk, sow serum, and piglet serum over time to investigate an association between NA levels and protection against infection. NA titers were remarkably high (up to 10 50% neutralizing titer) in sow serum and colostrum on all farms regardless of viremia levels. In piglets vaccinated at 3 weeks of age, NA titers peaked at 10 weeks of age and continued to maintain high viral neutralizing titers to slaughter. The impact of maternally derived neutralizing activity was most evident during the suckling period. Although PCV2 was transmitted from sows to piglets in colostrum, piglets were largely nonviremic at weaning. Thus, NAs appear to control or suppress initial infection even though they are unable to clear or prevent infection later in life.
母猪免疫力在预防新生仔猪病毒感染和疾病方面发挥着重要作用。猪圆环病毒2型（PCV2）的垂直传播可能会使新生仔猪和生长猪的猪圆环病毒相关疾病（PCVAD）持续存在。因此，评估了商业猪群中母猪免疫球蛋白转移PCV2特异性抗体对仔猪PCV2病毒血症和免疫反应的免疫学影响。已证明母猪接种疫苗可减少病毒排出和病毒血症，并提高中和抗体（NA）滴度。由于中和抗体对于控制PCVAD很重要，且乳腺分泌物可能含有高抗PCV2中和抗体水平，我们随时间检测了初乳、乳汁、母猪血清和仔猪血清中的PCV2中和抗体水平，以研究中和抗体水平与预防感染之间的关联。无论病毒血症水平如何，所有农场的母猪血清和初乳中的中和抗体滴度都非常高（高达10 50%中和滴度）。在3周龄接种疫苗的仔猪中，中和抗体滴度在10周龄时达到峰值，并持续保持高病毒中和滴度直至屠宰。母源中和活性的影响在哺乳期最为明显。尽管PCV2在初乳中从母猪传播给仔猪，但仔猪在断奶时大多没有病毒血症。因此，中和抗体似乎可以控制或抑制初始感染，即使它们无法清除或预防后期感染。
