Abstract: Provided are a DNA vaccine against SARS-CoV-2 virus infection in a subject which comprises a codon optimized polynucleotide sequence encoding a polypeptide of the SARS-CoV-2 virus. Also provided are a vaccine combination against SARS-CoV-2 vims infection, which comprises said DNA vaccine and an antigen peptide vaccine. The vaccine combination is able to confer a full protection against the SARS-CoV-2 vims infection in NHP studies.

Abstract: The present invention discloses a method for purification of bacterial capsular polysaccharide at low temperature (<20° C.) by salt-induced two-phase aqueous micellar system with TritonX-114 and can significantly reduce the endotoxins. Impurity proteins and the endotoxins need to be removed as many as possible in the preparation process of bacterial capsular polysaccharide vaccine to reduce the side reaction of the vaccines. Currently, the phenol extraction method, column chromatography and ethanol precipitation method all have a number of drawbacks. As compared with the phenol, the nonionic detergent has the advantages such as non-corrosiveness and non-carcinogenicity, and does not cause harm to the environment. As compared with the column chromatography, the method of the present invention is large in throughput, time-saving, economical, and easily expanding the scale production, which is a safe, environment-friendly and efficient.