The risk posed by replication-competent microorganisms (e.g., viruses or bacteria) can be significantly altered by the introduction of subgenomic nucleic acid fragments capable of modulating the immune system. According to the ZKBS statement on the classification of genetic engineering work in which nucleic acid segments with immunomodulatory potential are inserted into the genome of replication-competent microorganisms [PDF, 195 KB] , genetic engineering work involving such organisms is generally subject to a case-by-case assessment.
Exempt from this case-by-case assessment are, among others, combinations of recipient organisms and immunomodulatory nucleic acid segments that have already been evaluated by the ZKBS. An overview of which combinations have already been evaluated can be found in this Excel list.