PRRSV感染猪肺泡巨噬细胞后对Ⅲ型干扰素应答的调控

Regulation of Type Ⅲ Interferon Response after RRSV Infection of Alveolar Macrophages in Pigs

Ⅲ型干扰素(IFN-λ)是一种新发现的抗病毒因子,在天然免疫和获得性免疫应答方面具有多重功能;猪繁殖与呼吸综合征病毒(PRRSV)感染后造成猪的免疫抑制状态,Ⅰ型和Ⅱ型干扰素的应答受到抑制,IFN-λ的应答情况还不清楚。为揭示PRRSV感染猪后IFN-λ的应答情况与调控机制,以期进一步揭示PRRSV抑制宿主抗病毒免疫应答的分子机理。利用PRRSV强毒与弱毒株感染猪肺泡巨噬细胞(PAM),通过实时荧光定量PCR(real-time PCR)和Western blot检测IFN-λ在mRNA与蛋白水平的差异,并检测了不同非结构蛋白(NSP)对IFN-λ的调控作用。结果发现PRRSV感染PAM细胞后均在mRNA水平上诱导IFN-λ1和IFN-λ3表达上调,且IFN-λ3比IFN-λ1上调更明显;然而在蛋白水平上二者均为表达下调。人源IFN-λ3比IFN-λ1显示出更强的抑制PRRSV复制的作用,且对强毒株GSWW/15的抑制效果更明显。PRRSV NSP7b和NSP9转染PK-15细胞后能使IFN-λ3的mRNA上调表达,但蛋白水平无变化;而NSP7a对IFN-λ3的mRNA和蛋白水平均无影响,提示NSP7b和NSP9可能通过某种机制抑制IFN-λ3的应答。

Type Ⅲ interferon (IFN-λ) is a newly discovered antiviral agent that has multiple functions in innate immunity and acquired immune response;porcine reproductive and respiratory syndrome virus (PRRSV) infection causes immune suppression in pigs.The response to type Ⅰ and type Ⅱ interferons was inhibited,and the response to IFN-λ was unclear.The purpose of this study was to reveal the response and regulation mechanism of IFN-λ in pigs infected with PRRSV to further reveal the molecular mechanism of PRRSV in inhibiting the host antiviral immune response.Porcine alveolar macrophages (PAM) were infected with virulent and attenuated strains of PRRSV.Real-time PCR and Western blot were used to quantitatively detect differences in mRNA and protein levels of IFN-λ,and different non-structural proteins were detected in regulateing IFN-λ.The results showed that PRRSV induced IFN-λ1 and IFN-λ3 expression at the mRNA level after infection with PAM cells,and IFN-λ3 was more significantly up-regulated than IFN-λ1;however,both proteins were down-regulated at the protein level.Human IFN-λ3 showed stronger inhibition of PRRSV replication than IFN-λ1,and the inhibitory effect on virulent strain GSWW/15 was more pronounced.The expression of IFN-λ3 mRNA was up-regulated by PRRSV NSP7b and NSP9 transfected PK-15 cells,but the protein level was not changed.NSP7a had no effect on mRNA and protein levels of IFN-λ3,suggesting that NSP7b and NSP9 may inhibiting response to IFN-λ3 by some mechanism.