Two recent papers and the Japanese Committee for the Validation of Alternative Methods (JaCVAM) initiative demonstrate the increasing importance of the in vivo Comet assay in genotoxicity testing
One of the aims of the Fourth International Workshop on Genotoxicty testing (IWGT) held 9-10 September 2005 was to review methodology for the in vivo rodent, alkaline comet assay to produce a standardised protocol that would have maximum acceptability to international regulatory agencies.
Several areas were covered including scoring of comets and the results of the workshop are reported in the following publication:.
Fourth International Workgroup on Genotoxicity testing: Results of the in vivo Comet assay workgroup (2006) B Burlinson et al, Mutation Research 627(1):31-35.
As far as scoring of comets, the consensus was that image analysis was preferred and that where image analysis is used, %tail DNA appeared to be the most linearly related to dose and that other parameters such as tail moment may be used provided it was accompanied by %tail DNA and tail length.
The second publication reports on the proposals of a working group of the GUM (German-speaking section of the European EMS) for a revised strategy for genotoxicity testing.
One proposal is that a combination of the in vivo comet assay with in vivo micronucleus test be used in Phase II follow on testing depending on the outcome of initial Phase I testing.
Recommendation of a GUM working group for a simple and straightforward approach to genotoxicity testing.
(2007) S Pfuhler et al, Toxicological Sciences (Epub ahead of print).
JaCVAM.
The Japanese Committee for the Validation of Alternative Methods (JaCVAM) has as its first priority the development of an OECD guideline for the in vivo comet assay.
Preliminary comparative studies between participating laboratories have been assessed and a full validation exercise is at the planning stage.
Laboratories interested in participating in the in the validation excise will be invited to register.
Details will be posted on the Comet Assay Interest Group website, which is sponsored by Perceptive Instruments.
