PRRSV与PCV2体外共感染对猪肺泡巨噬细胞免疫学功能的影响

Effect of coinfection of porcine circovirus type 2 and porcine reproductive and respiratory syndrome virus on immunological function of porcine alveolar macrophage in vitro

制备猪肺泡巨噬细胞,分别接种PCV2、PRRSV、PCV2+PRRSV(先接种PCV2,12h后接种PRRSV)、PRRSV+PCV2(先接种PRRSV,12h后接种PCV2)、PRRSV/PCV2(同时接种)和对照组。接种后不同时间观察细胞病变(CPE),并用real-time PCR和IFA方法检测PRRSV和PCV2滴度,INF-α、INF-γ、TNF-α、IL-8和IL-10的mRNA。结果为:①PRRSV能在PAM中增殖,有CPE;PCV2在PAM中感染率较低,无CPE。②PRRSV对PCV2增殖无明显影响。PCV2先于或同时与PRRSV感染对PRRSV的复制具有抑制作用,而PCV2后于PPRSV感染,可促进PRRSV增殖。③PCV2单独感染PAM后能促进INF-α、INF-γ、IL-8和IL-10的大量表达,对TNF-α的表达量影响不大。④PCV2与PRRSV混合感染,尤其是PCV2后于PRRSV感染后,TNF-α、IL-8和IL-10的表达量与单感染组相比明显增加,而INF-γ的表达量明显受到抑制。实验结果表明,PCV2感染时间对PRRSV的增殖影响不同,PRRSV感染后如果再感染PCV2,可以明显促进PRRSV病毒增殖;两种病毒共同刺激了TNF-α、IL-8和IL-10的大量表达,抑制了抗病毒因子INF-γ的表达,从而可能抑制体液免疫和细胞免疫,加重了病理学免疫应答。

In order to determine pathogenesis of co-infection of porcine circovirus type 2 （PCV2） and porcine reproductive and respiratory syndrome virus （PRRSV）, porcine alveolar macrophage cells （PAMs） were infected with PCV2 and PRRSV alone or together with the different orders. The Cytopathic effect （CPE） and livability of PAMs were monitored and calculated, and the mRNA levels of the viruses and cytokines （INF-α, INF- γ, TNF-α, IL-8 and IL-10） in PAMs were detected by real-time PCR or indirect immunofluorescence assay （IFA）. The results showed as following： （a） PRRSV could replicate in PAMs and induce CPE. PCV2, however showed no replication nor induced CPE following infections. （b） PRRSV did not enhance PCV2 replication in PAMs. PCV2 could inhibit the replication of PRRSV in PAMs when infected before or together with PRRSV, but it could promote PRRSV replication and cell death when infected after PRRSV. （c） Infection of PCV2 could promote the expression of INF-α, INF-γ, IL-8 and IL-10 in PAMs, except TNF-α. （d） Coinfection of PCV2 and PRRSV increased the expression of TNF-α, IL-8 and IL-10 increase levels in PAMs and decreased the expression of INF-γ, as comparing to infection alone, thus enhanced the pathological reaction.