SUIT AGAINST OPEN BIOSYSTEMS

Oxford Biomedica PLC
14 June 2006



For Immediate Release                                               14 JUNE 2006


Oxford BioMedica enquiries to:
Oxford BioMedica plc:                                   Tel: [phone]
                                                                 
Professor Alan Kingsman, Chief Executive
City/Financial Enquiries:                               Tel: [phone]
                                                                       
Lisa Baderoon/ Mark Court/ Mary-Jane Johnson Buchanan
Communications
Scientific/Trade Press Enquiries:                       Tel: [phone]
                                                                       
Katja Stout/ Susan Yu
Northbank Communications



OXFORD BIOMEDICA AND PARTNER SIGMA-ALDRICH PURSUE PROTECTION OF RNAi-RELATED IP
                            AGAINST OPEN BIOSYSTEMS



Oxford, UK - 14 June 2006: Oxford BioMedica (LSE: OXB), a leading gene therapy
company, announces that its partner, Sigma-Aldrich issued the following
announcement yesterday at 16:00 EST (BST:21:00).


      SIGMA-ALDRICH AND OXFORD BIOMEDICA PURSUE PROTECTION OF RNAi-RELATED
            INTELLECTUAL PROPERTY; FILE SUIT AGAINST OPEN BIOSYSTEMS


ST. LOUIS, MO - Sigma-Aldrich (NASDAQ: SIAL), a $1.7 billion Life Science
company, and Oxford BioMedica (LSE: OXB), a leading gene therapy company, have
announced today that they have filed a lawsuit against Open Biosystems, Inc. for
infringement of key patents that cover key lentiviral-based systems for delivery
of foreign DNA to a broad array of mammalian cells. The complaint, which was
filed in U.S. District Court Eastern District of Missouri, alleges that Open
Biosystems is infringing U.S. Patent Nos. 6924123 and 7056699. Rights to the
patents, both entitled Lentiviral LTR Deleted Vector, were exclusively licensed
for research use to Sigma-Aldrich by Oxford BioMedica in October 2005.


The suit states that, among other products, Open Biosystems' Lentiviral shRNAmir
Library is marketed and sold to researchers and research institutions for
incorporation into viral particles that infringe one or more claims of the
patents.


Sigma-Aldrich has invested in its RNAi program through significant intellectual
property and licensing activities. The lawsuit filed against Open Biosystems is
a result of Sigma-Aldrich's desire to actively protect its intellectual property
in this field.


Oxford BioMedica's LentiVector(R) system has broad applications in gene delivery
and can be used to deliver shRNA-encoding DNA to cells to enable RNA
Interference (RNAi) experiments. RNAi is a natural cellular process that is
involved in the regulation of gene expression. In recent years scientists have
developed methods that allow RNAi to be exploited as a research tool to decipher
the function of particular genes. Over the course of the last 12 months
Sigma-Aldrich has made several investments in technology and intellectual
property in the rapidly evolving area of RNAi through its membership in The RNAi
Consortium (TRC), the acquisition of Proligo to solidify its capabilities in RNA
synthesis and by obtaining exclusive and non-exclusive licenses to a broad
portfolio of RNAi related patents for the research field.


'Sigma-Aldrich has made significant investments in creating the most
comprehensive portfolio of intellectual property to allow our customers freedom
to operate in the cutting-edge arena of RNA

Interference,' said Shaf Yousaf, President of Sigma-Aldrich's Research
Biotechnology Business Unit. 'Our actions will be to defend our investments and
the valuable intellectual property.'


About Sigma-Aldrich: Sigma-Aldrich is a leading Life Science and High Technology
company. Its biochemical and organic chemical products and kits are used in
scientific and genomic research, biotechnology, pharmaceutical development, the
diagnosis of disease and as key components in pharmaceutical and other high
technology manufacturing. The Company has customers in life science companies,
university and government institutions, hospitals, and in industry. Over one
million scientists and technologists use its products. Sigma-Aldrich operates in
35 countries and has 7,000 employees providing excellent service worldwide.
Sigma-Aldrich is committed to Accelerating Customer Success through Leadership
in Life Science, High Technology and Service. For more information about
Sigma-Aldrich, please visit its award-winning Web site at sigma-aldrich.com.


About Oxford BioMedica: Oxford BioMedica is a biopharmaceutical company
specializing in the development of novel gene-based therapeutics with a focus on
oncology and neurotherapy. The Company was established in 1995 as a spin out
from Oxford University, and is listed on the London Stock Exchange. Oxford
BioMedica has core expertise in gene delivery, as well as in-house clinical,
regulatory and manufacturing know-how. The Company is underpinned by over 80
patent families, which represent one of the broadest patent estates in the
field. The Company has a staff of approximately 70 split between its main
facilities in Oxford and its wholly owned subsidiary, BioMedica Inc, in San
Diego, California. Oxford BioMedica has corporate collaborations with Wyeth,
Intervet, Sigma-Aldrich, Viragen, MolMed, VIRxSYS and Kiadis; and has licensed
technology to a number of companies including Merck & Co, Biogen Idec and
Pfizer. Further information is available at www.oxfordbiomedica.co.uk.


Cautionary Statement: This press release contains forward-looking statements
that reflect the Companies' current expectations regarding future events.
Forward-looking statements involve risks and uncertainties. Actual events could
differ materially from those projected herein and depend on a number of factors
including the success of the Companies' research strategy, the applicability of
the discoveries made therein, the successful and timely completion of clinical
studies and the uncertainties related to the regulatory process.



SIGMA-ALDRICH INQUIRIES TO:
Christina Bailey
[phone]
Sean Battles
[phone]




                                      ENDS



                      This information is provided by RNS
            The company news service from the London Stock Exchange