Update on genetic engineering work with prion proteins

In the updated version of a statement by the Central Commission for Biological Safety (ZKBS) regarding the risk assessment of genetic engineering work for the expression of Prion proteins A differentiated assessment of corresponding experiments with laboratory animals is formulated. Furthermore, additional safety measures are recommended for handling recombinant prion protein mutants that may cause disease in humans. These two aspects are discussed below.

Misfolded forms of cellular Prion proteins (PrP, coded by PRNP gene ) represent a pathogenic factor in mammals (including humans) that can cause, among other things, the development of spongiform encephalopathy in the brain of infected animals. PrP in its non-pathological, cellular form is called PrPC, and the misfolded, pathological form is called scrapie-PrP (PrPSc). In contrast to PrPC, PrPSc is highly protease-resistant and particularly resistant to most physical and chemical inactivation methods. Certain mutations in the PRNP gene can Misfolding probability of translated PrP.

In the context of genetic engineering work, Transgenic animals expressing wild-type PRNP genes are assigned to risk group 1. Although symptoms of neuropathology have been demonstrated in individual cases in these animals, depending on the level of expression of the PRNP genes, the formation of protease-resistant forms of PrP has not been observed. There is also currently no evidence of the formation and release of infectious PrPsc from transgenic mice expressing wild-type PRNP genes from different donors. However, based on current knowledge, spontaneous misfolding of PrPsc into PrPsc and the release of infectious PrPsc cannot be completely ruled out in experiments with transgenic animals expressing specific, mutated PRNP genes. In these cases, the experimental animals are classified according to the risk group of the infectious PrPSc of the donor organism (rodents and sheep: risk group 2; cattle, cervids and humans: risk group 3**), even if they are clinically normal.

For genetic engineering work at safety level 1, additional security measures This is required in the laboratory when vector systems are used that can lead to high levels of expression in human cells of PrP that may cause disease in humans (mutated PrP from humans, cattle, or cervids). For genetic engineering work at containment levels 2 and 3 involving the expression of mutated PRNP genes from humans, cattle, or cervids, where the probability of conversion cannot be ruled out, the ZKBS also recommends taking additional safety measures. This includes wearing safety goggles, disposable gloves, and a mouth and nose mask (class P3 if necessary). The corresponding genetic engineering work should not be carried out by employees with impaired skin barrier function. Pointed or sharp objects should only be used when absolutely necessary. For the handling of purified PrP with mutations that can increase the probability of misfolding, as well as for genetic engineering work in which infectious PrPSc of risk groups 2 and 3** are handled or such can arise (including work with transgenic animals that can release infectious PrPSc), the ZKBS also generally recommends observing the "Resolution 603 of the Committee for Biological Agents (ABAS): Protective measures for activities involving agents associated with transmissible spongiform encephalopathy (TSE) in laboratories".

The complete, updated ZKBS statement can be found at File number 6790-10-75 can be retrieved.