The NIH Guidelines has certain host-vector systems which are exempt.
One of the organisms that is exempt under specific circumstances (Appendix C-II) are strains/derivatives of E. coli K-12. E.coli K-12 and its derivatives are considered nonpathogenic to humans for a number of reasons:
- The outer membrane has a defective LPS core which affects attachment to gut mucosa
- Lacks the type of glycocalyx required for attachment
- Is unable to express capsular (K) antigens necessary for colonization and virulence.
Thus K-12 is unable to colonize the human intestinal tract under normal conditions.
The ancestral strains of K-12 include 58, 679 and WG1.
K-12 derivatives include DH1, DH5 alpha, DH10B, XL1-Blue and TOP10.
E. coli strains that are NOT exempt and require registration with the IBC include many of the strains used for protein expression such as B, C, TOPP and BL-21. These strains typically contain the lambda temperate prophage, a genetically mobile element that could lead to specialized transduction and genetic exchange with other organisms. These strain still possess colonization factors that could lead to gut colonization.
If you are unsure of your E.coli strains, please contact the BSO.