Currently, there is limited knowledge about the immunological profiles of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). We used computer-based immunoinformatic analysis and the newly resolved 3-dimensional (3D) structures of the SARS-CoV-2 S trimeric protein, together with analyses of the immunogenic profiles of SARS-CoV, to anticipate potential B-cell and T-cell epitopes of the SARS-CoV-2 S protein for vaccine design, particularly for peptide-driven vaccine design and serological diagnosis. Nine conserved linear B-cell epitopes and multiple discontinuous B-cell epitopes composed of 69 residues on the surface of the SARS-CoV-2 trimeric S protein were predicted to be highly antigenic. We found that the SARS-CoV-2 S protein has a different antigenic profile than that of the SARS-CoV S protein due to the variations in their primary and 3D structures. Importantly, SARS-CoV-2 may exploit an immune evasion mechanism through two point mutations in the critical and conserved linear neutralization epitope (overlap with fusion peptide) around a sparsely glycosylated area. These mutations lead to a significant decrease in the antigenicity of this epitope in the SARS-CoV-2 S protein. In addition, 62 T-cell epitopes in the SARS-CoV-2 S protein were predicted in our study. The structure-based immunoinformatic analysis for the SARS-CoV-2 S protein in this study may improve vaccine design, diagnosis, and immunotherapy against the pandemic of COVID-19.

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Supporting materials is available from http://zhangroup.aporc.org/bioinfo/ptg/bti572supplementary.pdf

Isothermal crystallization kinetics, subsequent melting behavior, and the crystal morphology of short carbon fiber and poly(ethylene 2,6-naphthalate) composites (SCF/PEN) were investigated by using differential scanning calorimetry and polarized optical microscopy. The crystal morphology of the composites isothermally crystallized at T c 5 2208C is predominantly banded spherulites observed under polarizing micrographs, while the pattern of banded spherulites changed from ring to serration as the SCF content added into the PEN. Moreover, nonbanded spherulites formed at T c 5 2108C. The commonly used Avrami equation was used to fit the primary stage of the isothermal crystallization. The Avrami exponents n are evaluated to be 2.6-3.0 for the neat PEN and 3.7-4.0 for SCF/ PEN composites, and the SCF acting as nucleation agents in composites accelerates the crystallization rate with decreasing the half-time of crystallization, and the sample with SCF component of 2% has the fastest crystallization rate. The crystallization activation energy calculated from the Arrhenius formula suggests that the adding SCF component improved the crystallization ability of the PEN matrix greatly, and the sample with of 2% SCF component has the most crystallization ability. Subsequent melting scans of the isothermally crystallized composites exhibited triple melting endotherms, in which the more the component of SCF, the lower temperature of the melting peak, indicating the less perfect crystallites formed in those composites. Furthermore, the melting peaks of the same sample are shifted to higher temperature with increasing T c , suggesting the more perfect crystallites formed at higher T c .

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