Control plasmids and uses thereof

A set of vectors comprising:

• (i) a first vector comprising a vector backbone and a first reference nucleic acid sequence, wherein said first reference nucleic acid sequence comprises at least one CpG dinucleotide site, and wherein said first reference nucleic acid sequence comprises a sequence identical to or at least 95% identical to the corresponding length of a nucleic acid sequence selected from the group consisting a mammalian promoter, the 3′ downstream sequence of said promoter and 5′-upstream sequence of said promoter, and
• (ii) a second vector comprising a vector backbone and a second reference nucleic acid sequence, wherein said a second reference nucleic acid sequence is a variant of the first reference nucleic acid sequence, wherein the cytosine of said at least one CpG dinucleotide site of the first reference nucleic acid sequence has been substituted with a thymidine or a uracil nucleobase.