Crisci Elisa, Kick Andrew R, Cortes Lizette M, Byrne John J, Amaral Amanda F, Love Kim, Tong Hao, Zhang Jianqiang, Gauger Phillip C, Pittman Jeremy S, Käser Tobias
Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27607, USA.
Department of Chemistry & Life Science, United States Military Academy, West Point, NY 10996, USA.
Vaccines (Basel). 2025 Jul 9;13(7):740. doi: 10.3390/vaccines13070740.
BACKGROUND/OBJECTIVES: The porcine respiratory disease complex (PRDC) is a multifaceted, polymicrobial syndrome resulting from a combination of environmental stressors, primary infections (e.g., PRRSV) and secondary infectious agents (viruses and bacteria). PRDC causes severe lung pathology, leading to reduced performance, increased mortality rates, and higher production costs in the global pig industry. Our goal was to conduct a comprehensive study correlating both the anti-PRRSV immune response and 21 secondary infectious agents with PRDC severity.
To this end, PRRSV-negative weaners were vaccinated with a PRRSV-2 MLV and put into a farm with a history of PRDC. Subsequently, anti-PRRSV cellular and antibody responses were monitored pre-vaccination, at 28 days post vaccination (dpv) and during PRDC outbreak (49 dpv). NanoString was used to quantify 21 pathogens within the bronchoalveolar lavage (BAL) at the time of necropsy (51 dpv). PRRSV-2 was present in 53 out of 55 pigs, and the other five pathogens (PCMV, PPIV, , , and ) were detected in BAL samples.
Although the uncontrolled settings of field trials complicated data interpretation, multivariate correlation analyses highlighted valuable lessons: (i) high weaning weight predicted animal resilience to disease and high weight gains correlated with the control of the PRRSV-2 field strain; (ii) most pigs cleared MLV strain within 7 weeks, and the field PRRSV-2 strain was the most prevalent lung pathogen during PRDC; (iii) all pigs developed a systemic PRRSV IgG antibody response which correlated with IgG and IgA levels in BAL; (iv) the induction of anti-field strain-neutralizing antibodies by MLV PRRSV-2 vaccination was both late and limited; (v) cellular immune responses were variable but included strong systemic IFN-γ production against the PRRSV-2 field strain; (vi) the most detected lung pathogens correlated with PRRSV-2 viremia or lung loads; (vii) within the six detected pathogens, two viruses, PRRSV-2 and PCMV, significantly correlated with the severity of the clinical outcome.
While a simple and conclusive answer to the multifaceted nature of PRDC remains elusive, the key lessons derived from this unique study provide a valuable framework for future research on porcine respiratory diseases.
背景/目的：猪呼吸道疾病综合征（PRDC）是一种多因素、多微生物引起的综合征，由环境应激源、原发性感染（如猪繁殖与呼吸综合征病毒，PRRSV）和继发性感染因子（病毒和细菌）共同作用导致。PRDC会引发严重的肺部病变，致使全球养猪业生产性能下降、死亡率上升以及生产成本增加。我们的目标是开展一项全面研究，将抗PRRSV免疫反应和21种继发性感染因子与PRDC的严重程度关联起来。
为此，对PRRSV阴性的断奶仔猪接种PRRSV - 2减毒活疫苗，并将其放入有PRDC病史的猪场。随后，在接种前、接种后28天（dpv）以及PRDC爆发期间（49 dpv）监测抗PRRSV细胞和抗体反应。在尸检时（51 dpv），使用NanoString技术对支气管肺泡灌洗（BAL）中的21种病原体进行定量分析。55头猪中有53头检测到PRRSV - 2，并且在BAL样本中检测到了其他5种病原体（猪巨细胞病毒，PCMV；猪副流感病毒，PPIV； ， ，和 ）。
尽管田间试验不受控制的环境使数据解读变得复杂，但多变量相关性分析得出了有价值的结论：（i）断奶体重高预示着动物对疾病的抵抗力强，体重增加多与PRRSV - 2田间毒株的控制相关；（ii）大多数猪在7周内清除了减毒活疫苗毒株，田间PRRSV - 2毒株是PRDC期间最常见的肺部病原体；（iii）所有猪都产生了全身性PRRSV IgG抗体反应，该反应与BAL中的IgG和IgA水平相关；（iv）PRRSV - 2减毒活疫苗接种诱导的抗田间毒株中和抗体出现较晚且有限；（v）细胞免疫反应存在差异，但包括针对PRRSV - 2田间毒株产生强烈的全身性干扰素 - γ；（vi）检测到的大多数肺部病原体与PRRSV - 2病毒血症或肺部载量相关；（vii）在检测到的6种病原体中，两种病毒，PRRSV - 2和PCMV，与临床结果的严重程度显著相关。
虽然对于PRDC多方面性质的简单确凿答案仍难以捉摸，但这项独特研究得出的关键结论为未来猪呼吸道疾病研究提供了有价值的框架。
