MERS-CoV virus-like particles produced in insect cells induce specific humoural and cellular imminity in rhesus macaques

Wang, Chong; Zheng, Xuexing; Gai, Weiwei; Zhao, Yongkun; Wang, Hualei; Wang, Haijun; Feng, Na; Chi, Hang; Qiu, Boning; Li, Nan; Wang, Tiecheng; Gao, Yuwei; Yang, Songtao; Xia, Xianzhu

Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe respiratory disease in humans with a case fatality rate of over 39%, and poses a considerable threat to public health. A lack of approved vaccine or drugs currently constitutes a roadblock in controlling disease outbreak and spread. In this study, we generated MERS-CoV VLPs using the baculovirus expression system. Electron microscopy and immunoelectron microscopy results demonstrate that MERS-CoV VLPs are structurally similar to the native virus. Rhesus macaques inoculated with MERS-CoV VLPs and Alum adjuvant induced virus-neutralizing antibodies titers up to 1:40 and induced specific IgG antibodies against the receptor binding domain (RBD), with endpoint titers reaching 1:1,280. MERS-CoV VLPs also elicited T-helper 1 cell (Th1)-mediated immunity, as measured by ELISpot. These data demonstrate that MERS-CoV VLPs have excellent immunogenicity in rhesus macaques, and represent a promising vaccine candidate.