The present disclosure provides materials and methods related to engineered bacteria for use in vaccines. In particular, the present disclosure provides novel compositions and methods for generating vaccine compositions comprising bacteria (e.g., Lactobacillus) engineered to express immunogenic polypeptides and immunogenicity-enhancing adjuvant polypeptides to treat and/or prevent infection from a pathogenic organism (e.g., coronavirus).

Modified alphaviruses encoding a SARS-CoV-2 spike protein or antigenic segment of the SARS-CoV-2 spike protein are provided. The modified alphaviruses include replicative defective Sindbis viruses. The modified viruses express or are administered with an immunomodulatory agent that is an agonist antibody or antigenbinding fragment thereof, or a cytokine, or a combination thereof. Pharmaceutical compositions that include the modified alphaviruses and methods of using the modified alphaviruses and compositions that contain them are provided. The compositions are used to stimulate a therapeutic or protective effect against SARS-CoV-2 infection that includes humoral and cell mediated responses.

Modified alphaviruses encoding a SARS-CoV-2 spike protein or antigenic segment of the SARS-CoV-2 spike protein are provided. The modified alphaviruses include replicative defective Sindbis viruses. The modified viruses express or are administered with an immunomodulatory agent that is an agonist antibody or antigenbinding fragment thereof, or a cytokine, or a combination thereof. Pharmaceutical compositions that include the modified alphaviruses and methods of using the modified alphaviruses and compositions that contain them are provided. The compositions are used to stimulate a therapeutic or protective effect against SARS-CoV-2 infection that includes humoral and cell mediated responses.

Provided herein are RNA molecules encoding viral replication proteins and antigenic proteins or fragments thereof. Also provided herein are compositions that include RNA molecules encoding viral replication proteins and antigenic proteins or fragments thereof, and lipids. RNA molecules and compositions including them are useful for inducing immune responses.

Provided herein are RNA molecules encoding viral replication proteins and antigenic proteins or fragments thereof. Also provided herein are compositions that include RNA molecules encoding viral replication proteins and antigenic proteins or fragments thereof, and lipids. RNA molecules and compositions including them are useful for inducing immune responses.

The present invention provides a method for preparing a coronavirus-targeting universal DC cell vaccine, and belongs to the technical field of virus vaccine preparation. The preparation method includes the following steps: ligating a fusion gene including a HLA gene and a coronavirus antigen gene onto an expression vector to obtain a recombinant vector; then transferring the recombinant vector into antigen-presenting cells to be transfected to obtain the coronavirus-targeting universal DC cell vaccine. The universal DC cell vaccine of the present invention has a targeting property against a coronavirus, can effectively stimulate a CTL, and has a killing effect on a target cell.

The present invention provides a method for preparing a coronavirus-targeting universal DC cell vaccine, and belongs to the technical field of virus vaccine preparation. The preparation method includes the following steps: ligating a fusion gene including a HLA gene and a coronavirus antigen gene onto an expression vector to obtain a recombinant vector; then transferring the recombinant vector into antigen-presenting cells to be transfected to obtain the coronavirus-targeting universal DC cell vaccine. The universal DC cell vaccine of the present invention has a targeting property against a coronavirus, can effectively stimulate a CTL, and has a killing effect on a target cell.

The present disclosure provides polypeptides derived from SARS-CoV-2 which have therapeutic use. One such polypeptide is a polypeptide, referred to as “Npep2,” is derived from the SARS-CoV-2 protein N and has at least 50 consecutive amino acids of the amino acid sequence having at least 90% identity with the amino acid sequence that ranges from the residue at position 276 to the residue at position 411 of SEQ ID NO:2. Further described are conjugates wherein a heterologous polypeptide is conjugated or fused to Npep2. The present disclosure further provides vaccines employing the polypeptides, polynucleotides encoding the polypeptides, and methods of vaccinating subjects against SARS-CoV-2 by administering a therapeutically effective amount of one or more of the polypeptides.

A vaccine combination against SARS-CoV-2 includes a primer vaccine composition and a booster vaccine composition. The primer vaccine composition includes an effective amount of an Alphacoronavirus, and the primer vaccine is a live vaccine. The booster vaccine composition includes an effective amount of a Betacoronavirus, and the booster vaccine is a live vaccine.

A vaccine combination against SARS-CoV-2 includes a primer vaccine composition and a booster vaccine composition. The primer vaccine composition includes an effective amount of an Alphacoronavirus, and the primer vaccine is a live vaccine. The booster vaccine composition includes an effective amount of a Betacoronavirus, and the booster vaccine is a live vaccine.