The present invention provides compositions and methods for enhancing immunogenicity of polysaccharide antigens. Immunogenic compositions and vaccines comprising polysaccharide-protein conjugates comprising a chimeric carrier protein having a universal epitope are provided. Methods of preparing the compositions, and methods for treating or preventing bacterial infections are further provided. The compositions and methods are useful for enhancing immune response in young children, elderly and immunocompromised individuals.

The invention relates to a method for preparing double-layered virus-like particles of rotavirus in vitro. The method comprises the following steps: purifying rotavirus VP6 proteins from a lysis supernatant, and in vitro assembling double-layered virus-like particles consisting of VP2 proteins and VP6 proteins, wherein the proteins and the virus-like particles can be used for preventing or reducing the clinical symptoms caused by rotavirus infection.

The present invention provides compositions and methods for enhancing immunogenicity of polysaccharide antigens. Immunogenic compositions and vaccines comprising polysaccharide-protein conjugates comprising a chimeric carrier protein having a universal epitope are provided. Methods of preparing the compositions, and methods for treating or preventing bacterial infections are further provided. The compositions and methods are useful for enhancing immune response in young children, elderly and immunocompromised individuals.