抗猪FcγRⅡb多抗阻断猪繁殖与呼吸综合征病毒抗体依赖增强作用研究

Inhibition of Antibody-dependent Enhancement of PRRSV Infection by Anti-poFcγRⅡb Polyclonal Antibodies

为验证猪FcγRⅡb在抗体依赖增强(ADE)作用中的功能,从猪繁殖与呼吸综合征病毒(PRRSV)阳性血清中提取IgG并制备F(ab′)2片段,将104 TCID50的PRRSV病毒与80μg/mL的F(ab′)2片段或抗PRRSV阳性血清(中和效价1/5.9,经128倍稀释)混合,共同感染猪肺泡巨噬细胞(PAM)和Marc-145细胞,发现亚中和滴度的阳性血清能显著增强病毒对PAM的感染,但不能增强病毒对Marc-145细胞的感染;而F(ab′)2片断不能增强病毒感染;用兔抗猪FcγRⅡb多抗孵育PAM细胞,再用上述病毒与阳性血清复合物感染PAM,结果阳性血清对病毒感染的增强作用受到明显抑制。表明猪FcγRⅡb能够介导PRRSV ADE作用。

In order to elucidate the role of porcine FcγRⅡb in antibody-dependent enhancement（ADE）,F（ab′）2 fragments were generated from the IgG of anti-PRRSV sera.104 TCID50 of PRRSV BJ-4 virions were pre-incubated with the F（ab′）2 fragment（80 μg/mL） or anti-PRRSV sera（neutralizing antibody titer 1/5.9,1/128 diluted）,and then the opsonised virions were added to either porcine alveolar macrophages（PAMs） or Marc-145 cells.Sub-neutralizing antibodies observably enhanced the PRRSV infection in PAMs.No enhancement was observed in the normal Marc-145 cells and the F（ab′）2 fragment had no effect on any cell lines.PAM cells were incubated with anti-poFcγRⅡb polyclonal antibodies and were then infected with PRRSV in the presence of anti-PRRSV antibody.Anti-poFcγRⅡb antibody inhibited the enhancement of infection when cells were infected in the presence of anti-PRRSV antibody,indicating that poFcγRⅡb can mediate ADE of PRRSV infection.This research should expand our understanding of the mechanisms of pathogenesis of PRRSV.