The in vitro mammalian cell gene mutation test is used to detect mutations of the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene in Chinese hamster ovary (CHO) or lung (V79) fibroblasts.
Screening and Regulatory Support
- Cultures are incubated with several concentrations of the test compound for three to four hours in the presence and absence of metabolic activation (S9).
- Cells are subcultured for seven to eight days after treatment to allow expression of the mutant phenotype, and then plated in media with and without 6-thioguanine (TG) to select for mutants and determine cloning efficiency.
- A positive outcome is characterized by a statistically significant, dose-dependent increase in mutant frequency that exceeds historical negative control limits.
When To Perform
- Reduced volume and/or abbreviated formats available
- REACH requirement
- As part of Annex VIII testing
- To confirm presumed mutagenic activity arising from limited/small genetic damage (e.g., positive Ames or large colony MLA)
- To assess mutagenicity when the Ames assay may not be appropriate (e.g., antibiotics, nanomaterials)