EFFICIENT VACCINE

1 . An isolated polynucleotide, which encodes alphavirus non-structural proteins nsp1, nsp2, nsp3 and nsp4 and a polypeptide comprising an antigenic protein fused to a signal sequence, a transmembrane domain and at least one peptide selected from CD4+ T cell epitopes and CD8+ T cell epitopes.

2 . The polynucleotide of claim 1 , wherein the antigenic protein is fused to a CD4+ T cell epitope, and wherein the CD4+ T cell epitope is a Pan-DR epitope (PADRE).

3 . The polynucleotide of claim 1 , wherein the antigenic protein is a protein derived from a virus, a cancer or cytokine.

4 . The polynucleotide of claim 1 , wherein the antigenic protein is a protein derived from a virus or bacterium selected from the group consisting of Severe acute respiratory syndrome-related coronavirus (SARS), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Ebola virus, HIV, Hepatitis B virus (HBV), influenza virus, Hepatitis C virus (HCV), Human papillomavirus (HPV), Cytomegalovirus (CMV), Chikungunya virus, Respiratory syncytial virus (RSV), Dengue virus, a orthymyxoviridae family virus, and Mycobacterium tuberculosis.

5 . The polynucleotide of claim 4 , wherein the antigenic protein is further fused to a CD8+ T cell epitope, and wherein the CD8+ T cell epitope is a peptide derived from the virus from which the antigenic protein is derived.

6 . The polynucleotide of claim 4 , wherein the antigenic protein is derived from a coronavirus.

7 . The polynucleotide of claim 6 , wherein the antigenic protein is a receptor binding domain (RBD) of the coronavirus S1 subunit.

8 . The polynucleotide of claim 1 , wherein the transmembrane domain is derived from Influenza Hemagglutinin (HA), CD80, or a modified transmembrane domain derived from the antigenic protein.

9 . The polynucleotide of claim 8 , wherein the transmembrane domain is derived from Influenza Hemagglutinin (HA).

10 . The polynucleotide of claim 8 , wherein the modified transmembrane domain comprises juxtamembrane domain and transmembrane domain of COVID-19 Spike (S) protein.

11 . The polynucleotide of claim 6 , wherein the coronavirus is COVID-19.

12 . A vector comprising the polynucleotide of claim 1 .

13 . The vector of claim 12 , which comprises a promoter, 5′ UTR, a polynucleotide encoding alphavirus non-structural proteins nsp1, nsp2, nsp3 and nsp4, a SG promoter, a gene of interest encoding a polypeptide comprising an antigenic protein which is fused to a signal sequence, a transmembrane domain and at least one peptide selected from CD4+ T cell epitopes and CD8+ T cell epitopes, 3′UTR and poly A tail.

14 . A vaccine composition comprising the polynucleotide of claim 1 or a vector comprising the polynucleotide of claim 1 , and a pharmaceutically acceptable delivery vehicle.

15 . A method of treating, preventing and/or immunizing against an antigen in a subject, comprising administering an effective amount of the vaccine of claim 14 to the subject in need thereof.

16 . An isolated polynucleotide, which encodes alphavirus non-structural proteins nsp1, nsp2, nsp3 and nsp4 and a polypeptide comprising an antigenic protein fused to a signal sequence, a transmembrane domain and at least one peptide selected from CD4+ T cell epitopes and CD8+ T cell epitopes, wherein the polynucleotide comprises a modified nucleoside.

17 . The polynucleotide of claim 16 , wherein the modified nucleoside is modified cytidine and/or modified uridine.

18 . The polynucleotide of claim 17 , wherein the modified cytidine is 5-methyl-cytidine and the modified uridine is N1-methyl-pseudouridine.

19 . The polynucleotide of claim 17 , wherein substantially 100% of cytidine in the polynucleotide are modified cytidine.

20 . The polynucleotide of claim 17 , wherein the less than 100% of uridine in the polynucleotide are modified uridine.