Activities with genetically-modified polioviruses
COGEM has been asked to advise on activities with two genetically-modified (GM) polioviruses. These GM polioviruses are derivatives of the attenuated Sabin poliovirus type 3 vaccine strain, and express the capsid proteins from poliovirus type 2.
Poliomyelitis is caused by infection with poliovirus, and mainly affects children below the age of 5. Infection with poliovirus can cause paralysis and may even be lethal. Poliovirus type 1 is still present in Afghanistan, Pakistan and Nigeria. Infection with type 3 has not been observed since 2012 and poliovirus type 2 has officially been declared to be eradicated. Recently, poliovirus type 2 has been re-classified from a class 2 to a class 3 pathogen. As a result, activities with chimeric viruses containing poliovirus type 2 genomic sequences, need to be performed at ML-III. Due to the attenuated nature of the GM polioviruses, the applicant wants to conduct activities with these chimeric viruses at ML-II.
The GM polioviruses have a strongly diminished replication potential at 37°C. Mainly because of this, COGEM is of the opinion that the introduced mutations have attenuated these viruses even further compared to the attenuated Sabin poliovirus type 3 vaccine strain. COGEM deems the chance negligibly small that reversal of the introduced mutations occurs, resulting in the formation of a more virulent virus. Moreover, COGEM is of the opinion that the risks to the environment associated with these GM polioviruses are negligibly small if these viruses are inadvertently introduced into the environment.
With these considerations, COGEM is of the opinion that activities with these two GM polioviruses can be safely conducted at ML-II with a number of prerequisites. With these biosafety measures, COGEM deems the risk to the environment to be negligibly small.