Abstract: Provided herein are compositions comprising novel MHC class II T cell epitopes and method using thereof. In some embodiments, a composition described herein comprises an immunogenic polypeptide comprising an MHC class II T cell epitope and a target antigen. In some embodiments, the target antigen is a viral, bacterial, parasite or tumor specific antigen. In some embodiments, the target antigen comprises a virus, bacteria, parasite or tumor specific polypeptide. In some embodiments, the composition comprises a fusion polypeptide comprising the immunogenic polypeptide and the target polypeptide. Also provided are polynucleotides encoding the fusion polypeptide, and methods of administering a composition comprising the polynucleotide to a subject to elicit an immune response. In some embodiments, the polynucleotide is an RNA comprising modified ribonucleotides.