Update re Trace Group plc

Microgen PLC
22 May 2007



NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION, IN WHOLE OR IN PART, IN OR INTO
THE UNITED STATES OF AMERICA, CANADA, AUSTRALIA OR JAPAN OR ANY JURISDICTION
WHERE TO DO SO WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OF SUCH
JURISDICTION

For immediate release

22 May 2007

                           Microgen plc ('Microgen')

                   Update regarding Trace Group plc ('Trace')


On 11 May 2007 Microgen announced that it was in preliminary discussions with
the Independent Directors of Trace and was considering a possible competing
offer in cash for the share capital of Trace at a price of not less than 150
pence per ordinary Trace share. Following that announcement, on 11 May 2007 the
Independent Directors of Trace urged Trace shareholders to take no action in
relation to the proposed scheme of arrangement by Tulip Holdings Limited
('Tulip') at 135 pence in cash per ordinary Trace share (the 'Tulip Proposal')
for the time being, pending an announcement by Microgen of its firm intention to
make an offer or confirmation that Microgen will not make an offer.

Following its announcement on 11 May 2007, Microgen and the Independent
Directors have continued their discussions, and Trace has adjourned the Trace
Court Meeting and Trace Extraordinary General Meeting (by way of the Trace
announcement on 18 May 2007) until 31 May 2007. During the period from 14 May
2007 to 21 May 2007, Tulip has announced a number of updates regarding the level
of irrevocable undertakings it has received in respect of the Tulip Proposal.

The Board of Microgen announces that on 21 May 2007 it approached the
Independent Directors of Trace with a revised proposal of a competing offer at
155 pence in cash per ordinary Trace share.

Whilst the continued discussions with the Independent Directors of Trace have
enabled Microgen to make progress in the fulfilment of its preconditions to
announcing a firm intention to the making of an offer, the preconditions remain
as follows:

(a) a short period to complete due diligence;

(b) the finalisation of financing arrangements; and

(c) the recommendation of the Independent Directors of Trace that Trace 
    shareholders accept the offer.

Microgen reserves the right to waive any or all of the preconditions set out in
this announcement and emphasises that there can be no certainty that any offer
will ultimately be made even if the preconditions are satisfied or waived. This
announcement does not constitute an offer or invitation to purchase any
securities in Trace.

A further announcement may be made, if and when appropriate.

Enquiries:

Microgen plc                                                 Tel: [phone]
Martyn Ratcliffe
Philip Wood

Arbuthnot Securities Limited                                 Tel: [phone]
(Financial adviser and broker to Microgen in relation 
to the transaction)
Ian Williams
Richard Dunn


Notes:

The distribution of this announcement in jurisdictions other than the United
Kingdom may be restricted by law and therefore persons into whose possession
this announcement comes should inform themselves about, and observe such
restrictions. Any failure to comply with the restrictions may constitute a
violation of the securities laws of any such jurisdiction.

Arbuthnot Securities Limited, which is authorised and regulated in the United
Kingdom by the Financial Services Authority, is acting exclusively for Microgen
in connection with the possible offer and no one else and will not be
responsible to anyone other than Microgen for providing the protections afforded
to clients of Arbuthnot Securities Limited, nor for providing advice in relation
to the possible transaction.


Dealing Disclosure Requirements

Under the provisions of Rule 8.3 of the Takeover Code (the 'Code'), if any
person is, or becomes, 'interested' (directly or indirectly) in 1% or more of
any class of 'relevant securities' of Trace, all 'dealings' in any 'relevant
securities' of that company (including by means of an option in respect of, or 
a derivative referenced to, any such 'relevant securities') must be publicly
disclosed by no later than 3.30 p.m. (London time) on the London business day
following the date of the relevant transaction. This requirement will continue
until the date on which the offer becomes, or is declared, unconditional as to
acceptances, lapses or is otherwise withdrawn or on which the 'offer period'
otherwise ends. If two or more persons act together pursuant to an agreement or
understanding, whether formal or informal, to acquire an 'interest' in 'relevant
securities' of Trace, they will be deemed to be a single person for the purpose
of Rule 8.3.

Under the provisions of Rule 8.1 of the Code, all 'dealings' in 'relevant
securities' of Trace by Microgen or Trace, or by any of their respective
'associates', must be disclosed by no later than 12.00 noon (London time) on the
London business day following the date of the relevant transaction.

A disclosure table, giving details of the companies in whose 'relevant
securities' 'dealings' should be disclosed, and the number of such securities in
issue, can be found on the Takeover Panel's website at
www.thetakeoverpanel.org.uk.

'Interests in securities' arise, in summary, when a person has long economic
exposure, whether conditional or absolute, to changes in the price of
securities. In particular, a person will be treated as having an 'interest' by
virtue of the ownership or control of securities, or by virtue of any option in
respect of, or derivative referenced to, securities.

Terms in quotation marks are defined in the Code, which can also be found on the
Panel's website. If you are in any doubt as to whether or not you are required
to disclose a 'dealing' under Rule 8, you should consult the Panel.



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