Calreticulin as a hydrophilic chimeric molecular adjuvant enhances IgG responses to the spike protein of severe acute respiratory syndrome coronavirus

• DOI: 10.1111/j.1348-0421.2012.00467.x
• Publication Date: 2012-04-24T22:23:28Z
• Authors: Xiang Qiu; Chao Hong; Yue Li; Wanrong Bao; Xiao‐Ming Gao
• Keywords: spike protein; Coronavirus; 2019-20 coronavirus outbreak

ABSTRACT Fragment 450–650 of the spike (S) protein (S450–650) severe acute respiratory syndrome‐associated coronavirus (SARS‐CoV) contains epitopes capable being recognized by convalescent sera SARS patients. Vaccination mice with recombinant S450–650 (rS450–650) can induce Abs against SARS‐CoV, although titer is relatively low. In present study, a fusion linking fragment (residues 39–272) murine calreticulin (CRT) to in prokaryotic expression system was created. Compared target antigen alone, product (rS450–650‐CRT) has much improved hydrophilicity and immunogenicity. The S450–650‐specific IgG BALB/c subcutaneously immunized rS450–650‐CRT were substantially higher (approximately fivefold more). Furthermore, protein, but not rS450–650 able elicit responses T cell deficient nude mice. Given that rCRT/39–272 drive maturation bone‐marrow‐derived dendritic cells, directly activate macrophages B also helper vivo , we propose 39–272 CRT an effective molecular adjuvant enhancing Ag‐specific humoral both cell‐dependent independent manner. Fusion potential candidate vaccine SARS‐CoV infection.