Priming with rAAV encoding RBD of SARS-CoV S protein and boosting with RBD-specific peptides for T cell epitopes elevated humoral and cellular immune responses against SARS-CoV infection

Abstract

Development of vaccines against severe acute respiratory syndrome (SARS) coronavirus (SARSCoV) is crucial in the prevention of SARS reemergence. The receptor-binding domain (RBD) of SARS-CoV spike (S) protein is an important target in developing safe and effective SARS vaccines. Our previous study has demonstrated that vaccination with adeno-associated virus encoding RBD (RBD-rAAV) induces high titer of neutralizing antibodies. In this study, we further assessed the immune responses and protective effect of the immunization with RBD-rAAV prime/RBD-specific T cell peptide boost, as compared to those of vaccinations with RBD-rAAV and RBD-peptides alone. Our results indicated that RBD-rAAV prime/RBD-peptide boost induced similar Th1 and neutralizing antibody responses, but stronger Th2 and CTL responses than RBD-rAAV prime/boost. The resulting immune responses protected the vaccinated mice from subsequent SARS-CoV challenge, which was evidenced by lower level of viral replication in mouse lung tissues. However, no significant immune responses and protective effect were detected in mice vaccinated with RBDpeptides or blank AAV alone. Since T cell epitopes are highly conserved and boosting with peptides may induce the production of effector memory T cells, our results suggest that the vaccination protocol used may be ideal for providing effective, universal and long-term protection against SARSCoV infection.

Annexin A2 on lung epithelial cell surface is recognized by severe acute respiratory syndrome-associated coronavirus spike domain 2 antibodies

“…Recent reports have shown that the S protein may provide protective effects against SARS-CoV infection (Bai et al, 2008;Chou et al, 2005;Du et al, 2008;He et al, 2004;Lokugamage et al, 2008;Zeng et al, 2004). However, S2 shows sequence homology with selfantigens and the potential pathogenic role of the cross-reactivity of anti-S2 remains a concern.…”

Oligomerization of the carboxyl terminal domain of the human coronavirus 229E nucleocapsid protein

“…All of the size distributions were solved at a confidence level of P = 0.95, a best-fit average anhydrous frictional ratio (f/f 0 ), and a resolution N of 250 sedimentation coefficients between 0.1 and 20.0 S. To precisely determine the dimer-tetramer dissociation constants (K d , 24 ) of the C-terminal domains of the HCoV-229E N proteins in dimer-tetramer-oligomer equilibrium, sedimentation velocity experiments were performed for three different protein concentrations. The dimer-tetramer dissociation constant (K d, 24 ) of the C-terminal domains of the HCoV-229E N proteins was analyzed using the SEDPHAT program with a monomer-m-mer-n-mer self-association model [46]. The sedimentation velocity data collected for three different protein concentrations were globally fit with SEDPHAT.…”

Adeno-Associated Virus Vectors: Immunobiology and Potential Use for Immune Modulation

“…These studies have confirmed that AAV can stimulate humoral and cell-mediated immunity to the encoded transgene and that the vector is efficacious in disease prevention [22,120,122,123,128,131,135].…”

“…As a result of the numerous studies demonstrating immune responses after AAV gene transfer, AAV vectors have been investigated for genetic vaccine delivery in a range of disease models including infectious [120][121][122][123][124][125][126][127][128][129][130] and noninfectious diseases such as cancer [131,132], autoimmunity [133], Alzheimer's disease [134] and even stroke and epilepsy [135]. These studies have confirmed that AAV can stimulate humoral and cell-mediated immunity to the encoded transgene and that the vector is efficacious in disease prevention [22,120,122,123,128,131,135].…”