CpG-free Cloning Vectors

Bacterial DNA is rich in unmethylated cytosine-phosphate-guanine (CpG) sites, unlike mammalian DNA, in which most CpG sites are methylated (specifically, at the 5’-position of the cytosine). Unmethylated CpGs in specific sequence contexts activate the vertebrate immune system. Genes with these sequences are recognized as foreign DNA by the vertebrate host, leading to a progressive decline in their expression. InvivoGen has developed 5 families of reporter plasmids completely devoid of CpG dinucleotides:

• pCpGfree:  for in vivo studies
• pCpGfree-vitro: for in vitro studies.
• pCpGfree-ova: for DNA immunization in animal models
• pCpGfree-basic:  to study the effect of CpG methylation in the promoter
• pCpGfree-promoter: to study the effect of CpG methylation in enhancer elements.

Given that many non-mammalian genes are widely used as resistance, reporter or cytotoxic genes in molecular and cellular studies, InvivoGen has synthesized new alleles of these genes, with reduced or no CpG dinucleotides. These synthetic genes exhibit higher activity and lower immunogenicity than their wild-type counterparts. CpGfree plasmids contain elements that either naturally lack CpG dinucleotides, were modified to remove all CpGs, or entirely synthesized such as genes encoding selectable markers or reporters.

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