title: Anti-idiotypic antibodies reduce efficacy of the attenuated vaccine against highly pathogenic PRRSV challenge.
abstract: BACKGROUND
  The inability of current vaccines to provide effective protection against porcine reproductive and respiratory syndrome virus (PRRSV) infection is not fully understood. One of the reasons might be the presence of anti-idiotypic antibodies (Ab2s) to the envelope glycoprotein GP5 induced by PRRSV infection since our previous studies demonstrated the presence of auto-Ab2s (aAb2s) in pigs infected with PRRSV. To test this hypothesis, PRRSV negative piglets were injected with a monoclonal Ab2 (Mab2-5G2) and aAb2s that are specific for anti-GP5 antibody, vaccinated with the attenuated PRRSV vaccine CH-1R and then challenged with the highly pathogenic PRRSV HuN4 strain. The animals were evaluated for clinical signs, pathological changes of the thymus and lungs, viremia, levels of serum antibodies and cytokines.
  
  
  RESULTS
  The piglets injected with Mab2-5G2 or aAb2, and who received the attenuated PRRSV vaccine CH-1R before challenge, produced high levels of anti-N antibodies, IL-2 and IL-4, but low levels of neutralizing antibodies. After PRRSV HuN4 challenge, the animals showed obvious clinical signs, including lung lesions, severe thymus atrophy and decreased production of IL-4 and higher level of viremia.
  
  
  CONCLUSIONS
  When anti-GP5 Ab2s are present, the use of attenuated PRRSV vaccine CH-1R against HP-PRRSV infection is not recommended. It can result in poor health status with pneumonia and thymus atrophy.
authors: Ying
authors: Y
authors: Yu
authors: Xuehui
authors: X
authors: Cai
authors: Gang
authors: G
authors: Wang
authors: Ning
authors: N
authors: Kong
authors: Yonggang
authors: Y
authors: Liu
authors: Yihong
authors: Y
authors: Xiao
authors: Chong
authors: C
authors: Zhang
authors: Yang
authors: Y
authors: Mu
authors: Shuqi
authors: S
authors: Xiao
authors: Qin
authors: Q
authors: Zhao
authors: Chengbao
authors: C
authors: Wang
authors: Gaiping
authors: G
authors: Zhang
authors: Julian A
authors: JA
authors: Hiscox
authors: Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Northwest A&F University, Yangling, Shaanxi 712100, China. zhouem@nwsuaf.edu.cn.
authors: En-Min
authors: EM
authors: Zhou
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology*; D013552:Swine; D014613:Vaccines, Attenuated / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000888:Antibodies, Anti-Idiotypic; D014613:Vaccines, Attenuated; D014765:Viral Vaccines