Regulation of NFkB pathway by infecting macrophages with SARS-CoV coronavirus-like particles

• Main Authors: Ching-wen Hsiao, 蕭晴文
• Other Authors: 張鑫
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/88470225278251131738

碩士 === 國立臺灣大學 === 微生物學研究所 === 94 === SARS is an emerging disease discovered in 2003. The clinical symptoms included fever higher than 38℃, cough, and lymphocyte infiltration observed in chest X film. Besides, high level of cytokines could be detected even after the peak of viral load. Upon specimen inoculation, the causative agent was successfully cultured in VeroE6 cells and could be isolated from the culture medium. The causative agent was named SARS-CoV. SARS-CoV is composed of four major structure proteins, spike (S), membrane (M), envelope (E) and nucleocapsid protein (N). Previous studies with mouse hepatitis virus and transmissible gastroenteritis virus demonstrated that virus-like particles could be collected from culture medium when E and M proteins were co-expressed. Besides, VLPs composed of E and M proteins of transmissible gastroenteritis virus stimulated leukocytes to produce interferon α esults from a recent study indicated that cytokine stimulation in macrophage is independent of the replication ability of SARS-CoV. To understand the effects of SARS-CoV infection on macrophages, culture systems capable of producing SARS VLPs were established. When RAW264.7 macrophages were incubated with SARS-VLPs composed of S, M and E proteins, a reduction of IkBα level was detected. The reduction of IkBα could be blocked by proteasome inhibitor, MG132. These suggest that SARS VLPs stimulate the degradation of IkBα and activate NFkB. Mouse anti-60Co inactivated SARS-CoV antibodies neutralized the VLPs and eliminated the effect of SARS-VLPs on NFkB signaling pathway, further confirmed that the reduction of IkBα is indeed resulted from the presence of the SARS-VLPs. Recently, an interaction between SARS-CoV spike protein and DC-SIGN has been demonstrated. Therefore, a possible role of DC-SIGN involved in the reduction of IkBα was investigated. Preincubation of antibodies against DC-SIGN with RAW264.7 macrophages partially restored the negative effect of SARS VLPs on IkBα expression. This suggests that DC-SIGN may be involved in the NFkB activation caused by SARS-CoV.