猪繁殖与呼吸综合征病毒感染对猪肺泡巨噬细胞外源性抗原加工递呈相关分子和共刺激分子的影响

Effects of Porcine Reproductive and Respiratory Syndrome Virus Infection on the Molecules Associated with Processing and Presentation Function of Porcine Pulmonary Alveolar Macrophages for Exogenous Antigen and Costimulatory Molecules

采用定量竞争PCR技术对猪繁殖与呼吸综合征病毒(PRRSV)感染后不同时相猪肺泡巨噬细胞(PAM)中外源性抗原加工递呈相关分子SLA-DRI、i链和SLA-DM分子及共刺激分子CD40、CD80、CD86的mRNA转录动态进行了定量检测。结果表明,PRRSV感染后PAM的SLA-DR mRNA转录水平在3、7和14 d下调,低于对照组;感染后3 d,Ii链、SLA-DM和CD40的mRNA转录水平极显著下调(P<0.01);CD80和CD86mRNA转录水平也在感染后3 d明显下调(P<0.05)。用流式细胞术检测PAM表面的SLA-DR抗原的结果表明,在感染后3 d短暂上升,7 d之后一直低于对照组。由此说明,PRRSV感染早期对猪肺泡巨噬细胞的外源性抗原加工和递呈功能产生显著影响,导致其外源性抗原递呈功能下降,进而影响机体的体液免疫应答。

A quantitative competitive PCR （qcPCR） assay was used to detect mRNA transcription levels of SLA-DR, invariant chain （Ii）, SLA-DM and costimulatory molecules CD40, CD80 and CD86 of porcine pulmonary alveolar macrophages （PAMs） on different phases after porcine reproductive and respiratory syndrome virus （PRRSV） infection in vivo. The mRNA transcription level of SLA-DR was found to be downregulated and lower than that of the control at day 3, 7, 14 post-infection （PI）. The mRNA expression of Ii chain, SLA-DM and CD40 declined significantly at day 3 PI （P〈0.01）. CD80 and CD86 mRNA expression decreased markedly at day 3 PI （P〈0.05）. By using flow cytometry （FCM）, it was showed that the percentage of SLA-DR^ ＋ PAMs increased transiently at day 3 PI, declined quickly at day 7 PI and remained low level thereafter. Our results showed that PRRSV infection affected markedly processing and presentation of PAMs for exogenous antigen in early stage of infection, resulting in a decrease of antigen presentation function of PAMs for exogenous antigen and onset of impairment for humoral immune responses of swine.