Lamontagne Lucie, Pagé Christian, Larochelle Renée, Magar Ronald
Dépt Sciences Biologiques, Université du Québec à Montréal, Montréal, Canada.
Viral Immunol. 2003;16(3):395-406. doi: 10.1089/088282403322396181.
Porcine reproductive and respiratory syndrome virus (PRRSV) induces a persistent viral infection suggesting an inefficient cellular immune response. The aim of the study was to evaluate the relationship between viral persistence and cytotoxic cells in blood, spleen, mediastinal lymph nodes (MLN) and tonsils of PRRSV experimentally infected pigs. Groups of four to six specific pathogen-free (SPF) pigs were infected with the LHVA-93-3 isolate, and blood and lymphoid organs were collected from 3 to 60 days post-infection (p.i.). Infectious particles and viral RNA were more or less rapidly eliminated in serum, spleen, lungs and MLN but persisted the longest in tonsils. Lymphocytes CD2+ CD4+, CD2+ CD8high, CD2+ CD8low and NK cells populations were phenotyped and their reactivity to PHA and ConA were tested. Analysis of T cell subsets in blood and lymphoid organs indicated that the percentages of CD2+ CD8+ T cells slightly increased in spleen at 17 days p.i, whereas no changes were observed in CD2+ CD4+ cells in blood or lymphoid organs. However, discrimination of CD8+ cells in CD8high and CD8low subsets revealed that the percentages of CD2+ CD8high cells increased in spleen and blood from 10 to 45 or 60 days p.i. while they transiently increased in MLN and decreased in tonsils. The CD8low/CD8high ratio increased in the blood of PRRSV-infected animals at three days p.i. due to a transient decrease of CD2+ CD8high cells. This same ratio decreased in the spleen of infected pigs from 10 to 45 days p.i. due to an increase of CD2+ CD8high cells. The CD2+ MIL-4+ cell subset (NK cells) was not significantly modified in blood or lymphoid organs. In addition, the ability of lymphoid T cells from blood and lymphoid organs to respond to ConA or PHA stimulation was transiently impaired in blood and spleen during the PRRSV persistent infection. Taken together, these results suggest that, in persistently infected pigs, an impaired CD2+ CD8high cell response in MLN and tonsils favors viral persistence in these organs, in contrast with the response seen in blood and spleen where viral elimination appears to occur sooner.
猪繁殖与呼吸综合征病毒（PRRSV）可引发持续性病毒感染，这表明细胞免疫反应效率低下。本研究旨在评估PRRSV实验性感染猪的血液、脾脏、纵隔淋巴结（MLN）和扁桃体中病毒持续性与细胞毒性细胞之间的关系。将4至6只无特定病原体（SPF）猪分为一组，用LHVA - 93 - 3毒株进行感染，并在感染后3至60天收集血液和淋巴器官。血清、脾脏、肺和MLN中的感染性颗粒和病毒RNA或多或少能迅速清除，但在扁桃体中持续时间最长。对淋巴细胞CD2 + CD4 +、CD2 + CD8high、CD2 + CD8low和NK细胞群体进行表型分析，并检测它们对PHA和ConA的反应性。对血液和淋巴器官中T细胞亚群的分析表明，感染后17天脾脏中CD2 + CD8 + T细胞百分比略有增加，而血液或淋巴器官中CD2 + CD4 +细胞未观察到变化。然而，区分CD8high和CD8low亚群中的CD8 +细胞发现，感染后10至45或60天，脾脏和血液中CD2 + CD8high细胞百分比增加，而在MLN中短暂增加，在扁桃体中减少。感染PRRSV的动物在感染后三天血液中CD8low/CD8high比值增加，原因是CD2 + CD8high细胞短暂减少。感染猪在感染后10至45天脾脏中该比值降低，原因是CD2 + CD8high细胞增加。血液和淋巴器官中的CD2 + MIL - 4 +细胞亚群（NK细胞）在血液或淋巴器官中未发生显著改变。此外，在PRRSV持续感染期间，血液和脾脏中来自血液和淋巴器官的淋巴T细胞对ConA或PHA刺激的反应能力暂时受损。综上所述，这些结果表明，在持续感染的猪中，MLN和扁桃体中受损的CD2 + CD8high细胞反应有利于病毒在这些器官中持续存在，这与血液和脾脏中出现的病毒清除更快的反应形成对比。
