title: Recognition of Highly Diverse Type-1 and -2 Porcine Reproductive and Respiratory Syndrome Viruses (PRRSVs) by T-Lymphocytes Induced in Pigs after Experimental Infection with a Type-2 PRRSV Strain.
abstract: OBJECTIVE
  Live attenuated vaccines confer partial protection in pigs before the appearance of neutralizing antibodies, suggesting the contribution of cell-mediated immunity (CMI). However, PRRSV-specific T-lymphocyte responses and protective mechanisms need to be further defined. To this end, the hypothesis was tested that PRRSV-specific T-lymphocytes induced by exposure to type-2 PRRSV can recognize diverse isolates.
  
  
  METHODS
  An IFN-gamma ELISpot assay was used to enumerate PRRSV-specific T-lymphocytes from PRRSVSD23983-infected gilts and piglets born after in utero infection against 12 serologically and genetically distinct type-1 and -2 PRRSV isolates. The IFN-gamma ELISpot assay using synthetic peptides spanning all open reading frames of PRRSVSD23983 was utilized to localize epitopes recognized by T-lymphocytes. Virus neutralization tests were carried out using the challenge strain (type-2 PRRSVSD23983) and another strain (type-2 PRRSVVR2332) with high genetic similarity to evaluate cross-reactivity of neutralizing antibodies in gilts after PRRSVSD23983 infection.
  
  
  RESULTS
  At 72 days post infection, T-lymphocytes from one of three PRRSVSD23983-infected gilts recognized all 12 diverse PRRSV isolates, while T-lymphocytes from the other two gilts recognized all but one isolate. Furthermore, five of nine 14-day-old piglets infected in utero with PRRSVSD23983 had broadly reactive T-lymphocytes, including one piglet that recognized all 12 isolates. Overlapping peptides encompassing all open reading frames of PRRSVSD23983 were used to identify ≥28 peptides with T-lymphocyte epitopes from 10 viral proteins. This included one peptide from the M protein that was recognized by T-lymphocytes from all three gilts representing two completely mismatched MHC haplotypes. In contrast to the broadly reactive T-lymphocytes, neutralizing antibody responses were specific to the infecting PRRSVSD23983 isolate.
  
  
  CONCLUSIONS
  These results demonstrated that T-lymphocytes recognizing antigenically and genetically diverse isolates were induced by infection with a type 2 PRRSV strain (SD23983). If these reponses have cytotoxic or other protective functions, they may help overcome the suboptimal heterologous protection conferred by conventional vaccines.
authors: VMRD Inc., Pullman, WA 99163, United States of America.|Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99163, United States of America.
authors: Chungwon J
authors: http://orcid.org/0000-0002-4525-5539
authors: CJ
authors: Chung
authors: Department of Virology, Animal and Plant Quarantine Agency, Anyang, Republic of Korea.
authors: Sang-Ho
authors: SH
authors: Cha
authors: VMRD Inc., Pullman, WA 99163, United States of America.
authors: Amanda L
authors: AL
authors: Grimm
authors: VMRD Inc., Pullman, WA 99163, United States of America.|Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99163, United States of America.
authors: Grace
authors: G
authors: Chung
authors: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, United States of America.
authors: Kathleen A
authors: KA
authors: Gibson
authors: Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, United States of America.
authors: Kyoung-Jin
authors: KJ
authors: Yoon
authors: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99163, United States of America.
authors: Steven M
authors: SM
authors: Parish
authors: Gift of Life Michigan, Ann Arbor, MI 48108, United States of America.
authors: Chak-Sum
authors: CS
authors: Ho
authors: Department of Statistics, University of Idaho, Moscow, ID 83844, United States of America.
authors: Stephen S
authors: SS
authors: Lee
mesh_terms: D000281:Administration, Intranasal; D000595:Amino Acid Sequence; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology; D016366:Open Reading Frames / Q000235:genetics; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D010802:Phylogeny; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology* / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000302:isolation & purification / Q000502:physiology*; D017422:Sequence Analysis, DNA; D034421:Sus scrofa; D013552:Swine; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D000939:Epitopes; D010455:Peptides