Method for reducing immunogenicity of RNA
The present invention relates to RNA therapy and, in particular, decreasing immunogenicity of RNA. Specifically, the present invention provides methods for decreasing immunogenicity of RNA, said methods comprising modifying the nucleotide sequence of the RNA by reducing the uridine (U) content, wherein said reduction of the U content comprises an elimination of U nucleosides from the nucleotide sequence of the RNA and/or a substitution of U nucleosides by nucleosides other than U in the nucleotide sequence of the RNA. Using RNA having decreased immunogenicity allows administration of RNA as a drug to a subject, e.g. in order to obtain expression of a pharmaceutically active peptide or protein, without eliciting an immune response which would interfere with therapeutic effectiveness of the RNA or induce adverse effects in the subject.
1. A method of decreasing immunogenicity of RNA encoding at least one peptide or protein and comprising a first nucleotide sequence, said method comprising substituting uridine (U) nucleotide residues of the first nucleotide sequence with nucleotide residues selected from the group consisting of adenosine (A), guanosine (G), and cytidine (C) nucleotide residues, thereby forming an A-rich second nucleotide sequence encoding the same peptide or protein as the first nucleotide sequence; wherein the second nucleotide sequence has a higher A content and a lower U content compared to the first nucleotide sequence, thereby rendering RNA comprising the second nucleotide sequence less immunogenic than RNA comprising the first nucleotide sequence.
2. The method of claim 1 , wherein the peptide or protein encoded by the first and second nucleotide sequences is pharmaceutically active or antigenic.
3. The method of claim 1 , wherein the U content in the RNA comprising the second nucleotide sequence is at least 10% lower, at least 20% lower, or at least 30% lower than the U content of to the RNA comprising the first nucleotide sequence.
4. The method of claim 1 , wherein the U content of the second nucleotide sequence is lower in one or more of the 5′ untranslated region, the coding region and the 3′ untranslated region thereof compared to the U content of corresponding regions of the first nucleotide sequence.
5. The method of claim 1 , wherein the U content of the second nucleotide sequence is lower in the coding region thereof, compared to U content of the coding region of the first nucleotide sequence.
6. The method of claim 1 , wherein the substituting comprises substituting U nucleotide residues with A nucleotide residues.
7. The method of claim 1 , wherein the step of substituting U nucleotide residues comprises altering codons in the coding region of the first nucleotide sequence that comprise at least one U nucleotide residue resulting in codons that encode the same amino acids but comprise fewer U nucleotide residues or no U nucleotide residues.