Results

Progress Working Group 3: Gene Transfer

In the discussions of gene transfer, most of the attention is not anymore spent on the "classical" gene transfer mechanism, such as transformation, sexual compatible transmission and conjugation. Even poorly understood mechanisms such as transencapsidation seem to have lost some interests. Much more attention is going to DNA transfer to mammalian cells, or to complex matrices such as milk or eggs.

The following is therefore a (first) list of topics/questions that will be addressed by the participants of WG 3:

• What are the types of gene transfer mechanisms that we want to address. Do we exclude certain modes such as transencapsidation?
• Shall we review the literature as such or shall we address topical issued, e.g. transfer to mammalian cells of naked DNA, transfer into primary food products such as milk?
• What about gene stability and gene expression?
• What about test strategies?
• How can we develop/evaluate models that mimic the habitat in the rumen and in the gastro-intestinal tract?
• What should be the alternative for antibiotic marker genes?
• How will we follow symposia held on the subject?

At the First Plenary Meeting (WG meeting), 12-13 May, Wageningen, the participants presented several points of considerations on the use of antibiotic resistance genes as markers. This was followed by a discussion of the Doerfler study and the implications regarding the labelling of meat. Other important topics were gene silencing, unintended effects, the contents of the gene pool (newly introduced genes), monitoring and the importance of the genomic background in relation to the specific gene expression. The discussions also included the DNA uptake and stability and the necessity of differentiation between micro-organisms and mammalian cells in relation to gene transfer. The following remarks relating specifically to the position paper were made: The position paper should not only be a review on the topic but should include clear conclusions in order to avoid misinterpretation. There should be focus on human health risk, but environmental effects can not be completely ruled out, as there may a close relation. A time schedule was made:

• October 2000:

• Background information available (reports, reference list)

• Definition of structure of the position paper

• Definition of interconnections to other groups.

• April 2001:

• Draft of the position paper ready for the IDP meeting

In the Second Plenary Meeting (WG meeting), 13-14 October, Copenhagen, three chapters of the position paper were presented. During the discussion of the material it was concluded that a lot of scientific data has been collected. However is was also pointed out that the position paper was not intended to be a comprehensive review on the gene transfer but a paper with focus on central points of scientific interest.

In summation the position paper has the following chapters:

Chapter 1: Natural Gene Transfer Background

Chapter 2: Use of marker genes.

Chapter 3: Consequences of Gene Transfer.

The next meeting will focus on a discussion of recommendations, status of the paper (do we cover the relevant parts), and the possible overlap to other groups. The next meeting will also start the work on chapter 3: Consequences of Gene Transfer. Finally a discussion on DNA transfer to mammalian cells is of paramount interest and that expertise from gene therapy is relevant to the working group. As a result of the discussion it is recommended that an expert in this field join the group.