QIAGEN Makes Proposal to Acquire Australian Diagnostics Company Cellestis Limited

VENLO, Netherlands and MELBOURNE, Australia, April 3, 2011 - — QIAGEN to acquire Cellestis Limited (CST:AU) via a Scheme of
Arrangement (the Scheme) for approximately A$341 million(1) (US$355 million),
or A$3.55 per share

— Unanimous support from Cellestis board of directors(2); QIAGEN granted
options to acquire up to 19.9% of Cellestis ordinary shares under certain
circumstances, subject to regulatory approvals

— Acquisition provides QIAGEN with exclusive access to QuantiFERON(R)
technology for high sensitivity, early disease detection not possible with
other diagnostic approaches

— QuantiFERON(R) technology successfully commercialized with two
marketed Cellestis tests for detection of latent tuberculosis (TB) and
life-threatening CMV virus

— QIAGEN to expand QuantiFERON(R) portfolio, migrate technology to
QIAsymphony and QIAensemble platforms and leverage synergies with current
QIAGEN assay portfolio and pipeline

— Acquisition would accelerate QIAGEN's sales and adjusted EPS growth
rates in 2012

QIAGEN N.V. (NASDAQ: QGEN; Frankfurt, Prime Standard: QIA) has reached an
agreement to acquire Cellestis Limited (CST: AU) for approximately A$341
million (US$355 million) in cash, providing QIAGEN with access to a novel
"pre-molecular" technology that offers a new dimension in disease detection
not currently possible with other diagnostic methods.

The acquisition of Cellestis, a publicly listed, profitable company
headquartered in Australia, will provide QIAGEN with exclusive rights to
QuantiFERON(R) technology, a proprietary approach for disease detection and
monitoring.

Cellestis has successfully commercialized this technology with
QuantiFERON(R)-TB Gold In-Tube (QFT), a leading test for latent tuberculosis
(TB), and is in the early stages of commercializing QuantiFERON(R)-CMV for
monitoring of disease risk from the life-threatening cytomegalovirus (CMV).
These tests are approved and commercialized in various countries and are
believed to have significant untapped market potential.

QuantiFERON(R) is a patent-protected platform technology that can provide
information on diseases far earlier than possible with other diagnostic
methods. QuantiFERON(R) tests whole blood samples for the presence of
systemically amplified molecular analytes which provide information from the
immune system's memory.

Based on its ability to provide diagnostic information far earlier than
DNA-based molecular tests, QuantiFERON(R) is considered a "pre-molecular"
testing technology. As a result, tests based on QuantiFERON(R) can even
provide critical information on latent infections, where pathogens (bacteria,
viruses, fungi) are present in such low amounts that they are not detectable
with traditional DNA-based molecular diagnostics.

QuantiFERON(R) is complementary to QIAGEN's portfolio of molecular
diagnostics. Its high sensitivity and ability to provide clinically relevant
information means that this technology can be used ahead of DNA- or RNA-based
molecular testing. Greater use of QuantiFERON(R) technology can help guide
and drive the use of traditional DNA- and RNA-based molecular diagnostics.
For example, patients identified through QuantiFERON(R)-based tests to be at
risk for certain diseases could then proceed for subsequent testing or
increased monitoring with corresponding DNA- or RNA-based molecular
diagnostics to assess disease activity levels and guide treatment decisions.

"We believe next-generation DNA- and RNA-based molecular testing can
benefit from greater use of QuantiFERON(R) technology, which has a unique
ability to identify patients at risk from potentially life-threatening
diseases. The power of QuantiFERON(R) can help save lives by enabling medical
treatment through earlier, deeper and much more sensitive disease detection
than previously possible," said Peer Schatz, Chief Executive Officer of
QIAGEN N.V. "Cellestis has developed a technology that is highly
complementary to our portfolio and which we expect to migrate onto our
QIAsymphony, QIAensemble and our point of need platforms, thereby adding a
new, unique assay menu to these QIAGEN platforms. We believe the addition of
Cellestis will further strengthen our capabilities to offer innovative sample
and assay technologies that are making improvements in life possible."

"Cellestis has succeeded in developing QuantiFERON(R) as a breakthrough
technology, via the QFT-TB test that is becoming the standard for latent TB
diagnosis," said Cellestis CEO Anthony Radford. "We believe QIAGEN as an
industry-leading company provides the best strategic fit in terms of
capabilities and resources. As part of QIAGEN, we will be able to accelerate
our growth much faster than as a stand-alone company and offer even greater
benefits to patients and healthcare providers."

Following successful completion of the transaction, QIAGEN plans to
migrate QuantiFERON(R) onto QIAensemble, a next-generation high-throughput
automation system in development and nearing market entry; QIAsymphony, a
highly versatile automation system for low- to mid-throughput volumes
available around the world; and QIAGEN's point of need testing platforms
acquired from ESE GmbH.

Successful commercialization of QuantiFERON(R) technology

Cellestis has launched, depending on regional regulatory approvals and
clearances, two commercial diagnostic products and has several new products
based on QuantiFERON(R) technology under evaluation. It has also developed an
extensive R&D program targeting other diseases and conditions. In the fiscal
year ending June 30, 2010, net sales rose 17% to A$40.4 million (US$42.0
million). Profit from operations before tax and non-recurring items in FY2010
was A$10.2 million (US$10.6 million), up 26% from FY2009.

Its flagship product, QuantiFERON(R)-TB Gold In-Tube (QFT), accounts for
the majority of current sales and was launched in 2006 as a third-generation
test for detection of latent tuberculosis (TB). QFT is recommended in many
national guidelines since the test overcomes significant shortcomings of the
previous standard test used to detect latent TB: the 110-year-old Tuberculin
Skin test (TST). Benefits of QFT include its accuracy and significantly
improved workflow, making it the only next-generation assay which has been
widely commercialized in an instrument and kit format. Most latent infections
today cannot be detected using DNA-based molecular diagnostics. QFT is
available in many markets and has been approved in many countries, including
the U.S. (pre-market approval, or PMA), Canada and Japan and has been CE
marked for use in Europe.(3)

Cellestis' other commercialized diagnostic product is QuantiFERON(R)-CMV(
4) which was launched in 2009 and is the first commercially available test
designed to allow physicians to monitor a person's risk of cytomegalovirus
(CMV) disease. CMV is one of the most common and problematic viral infections
in immunosuppressed patients (in cancer, transplantation, HIV therapies).
QIAGEN has DNA-based molecular diagnostic tests for CMV viral load testing
which could be complemented by QuantiFERON(R)-CMV to monitor patients for
risk of CMV-induced disease.

Products based on QuantiFERON(R) technology can enhance QIAGEN's leading
portfolio in DNA- and RNA-based molecular diagnostics:

    - Prevention example: QFT is rapidly expanding as a new
      treatment standard for testing asymptomatic patients for latent TB
      infection (and identifying those at risk for active disease), and it is
      expected to be synergistic with QIAGEN's leading portfolio of real-time
      PCR and Pyrosequencing DNA-based molecular diagnostic detection
      technologies which, depending on the indication are use as adjunct
      tests or reflex/subsequent tests.
    - Profiling example: QuantiFERON(R)-CMV has the potential to
      accelerate the fast-growing leadership position of QIAGEN in providing
      a broad range of diagnostic testing solutions for use in monitoring
      immunosuppressed patients for life-threatening infectious diseases.
      These patients are being treated with medicines that suppress the
      body's immune system, which increases the risk for infections.
      QuantiFERON(R)-CMV is expected to be synergistic with QIAGEN's DNA- and
      RNA-based molecular tests used in transplantation medicine. QIAGEN
      plans to submit a PMA application with the U.S. Food and Drug
      Administration (FDA) in 2011 for approval of the artus RG PCR CMV test.
    - Personalized healthcare examples: Several new classes of
      medicines require patients to be free of latent TB in advance of
      treatment initiation, creating new opportunities for QFT. In addition,
      a number of medicines require patients to be free of viral infections
      and other pathogens or clinical profiles, which could be verified with
      tests based on QuantiFERON(R) technology.
    - Point of need example: QuantiFERON(R) technology will be adapted
      for use with QIAGEN's ESE detection technology, a battery-operated
      mobile device, and in particular QFT for latent TB testing in areas
      without immediate access to a laboratory.

Transaction summary

QIAGEN and Cellestis have entered into a Scheme Implementation Deed (SID)
pursuant to which QIAGEN, or a wholly owned subsidiary, will acquire all of
the ordinary shares in Cellestis for approximately A$341 million in cash, or
A$3.55 per share. Based on an exchange rate of A$1.00 = US$1.04(5), the
transaction value is approximately US$355 million.

Under the SID, the consideration offered may be structured to include a
fully franked, special dividend (payable only if the Scheme becomes effective
and upon receipt of a favourable ATO ruling, and subject to Cellestis Board
approval). The cash consideration payable under the Scheme would be reduced
by the cash amount of any dividend paid.

The acquisition will be implemented by way of a Scheme of Arrangement
pursuant to which Cellestis shareholders will receive a cash payment for
their shares. Full details of the transaction will be set out in the Scheme
booklet.

The offer for Cellestis' shares represents a premium of:

    - 24.3% to the one-month volume weighted average share price prior to
      this announcement;
    - 31.5% to the three-month volume weighted average share price; and
    - 39.2% to the six-month volume weighted average share price.

The Cellestis board of directors unanimously recommends shareholders vote
in favour of the Scheme in the absence of a superior proposal and subject to
an Independent Expert concluding that the Scheme is fair and reasonable and
in the best interests of Cellestis shareholders. All members of the Cellestis
board of directors intend to vote or cause to be voted all of their direct
and indirect interests in Cellestis in favour of the Scheme (subject to the
same qualifications as their recommendations), which in aggregate amount to
approximately 27% of Cellestis' outstanding shares.

QIAGEN and Cellestis have agreed to customary exclusivity arrangements in
relation to the SID, including that unless the SID is terminated, Cellestis
will not solicit any competing transaction or (subject to the fiduciary
duties of the Cellestis directors) participate in any discussions or
negotiations in relation to any competing transaction. QIAGEN also has a
right in the SID to match a competing offer prior to Cellestis entering into
any other agreement regarding a superior proposal. Under certain
circumstances set out in the SID, Cellestis has agreed to pay QIAGEN a break
fee of A$3.5 million.

In addition, QIAGEN has entered into an option deed with each of the two
founders of Cellestis - Anthony Radford and James Rothel - and their
respective controlled entities and joint shareholders. Pursuant to this deed,
QIAGEN has been granted an option to acquire a total of 14.9% of the ordinary
shares in Cellestis for A$3.55 per share, and to acquire a further 5% at the
same price subject to approval by the Australian Foreign Investment Review
Board (FIRB) where a competing transaction is matched by QIAGEN under the
matching rights included in the SID or in certain circumstances where a
competing transaction is not matched by QIAGEN.

The Scheme is subject to a number of conditions, including FIRB approval,
court approval and the approval of Cellestis shareholders. A full copy of the
Scheme Implementation Deed has been released to the Australian Securities
Exchange (ASX).

A Scheme booklet with full details of the transaction, including an
Independent Expert's Report, is expected to be distributed to Cellestis
shareholders in May 2011. The shareholder meeting to approve the Scheme is
expected to be held in June 2011.

A more detailed timetable for the approval and implementation of the
transaction will be announced in due course.

QIAGEN will fund this acquisition from existing cash. On an adjusted
basis, which excludes one-time charges, integration and restructuring costs,
and amortization of acquisition-related intangible assets, the transaction is
expected to be moderately dilutive to full-year 2011 adjusted EPS due to
planned large investments in sales capabilities and R&D initiatives for
migration of existing Cellestis products onto QIAGEN platforms as well as for
new product developments.

For 2012, QIAGEN expects double-digit sales growth from QuantiFERON(R)
products and accretion of approximately US$0.02-0.03 to adjusted EPS.

Barclays Capital is acting as exclusive financial adviser and Freehills
is acting as legal adviser to QIAGEN in relation to the transaction.

Further information on this transaction can be found in the Investor
Relations section of the QIAGEN website at www.qiagen.com.

About Cellestis

Cellestis Limited is a listed Australian biotechnology company
commercialising QuantiFERON(R) technology for diagnosing TB and other
diseases worldwide. QuantiFERON(R) - TB Gold tests for the presence or
absence of a protein (gamma-interferon) produced by a patient's white blood
cells after stimulation with specific TB proteins. The test has received
regulatory and policy approvals in the USA, Japan, Europe and elsewhere. The
Company operates through subsidiaries in the USA, Europe, Australia,
Singapore and Japan.

Further information about Cellestis can be found at
www.cellestis.com.

About QIAGEN

QIAGEN N.V., a Netherlands holding company, is the leading global
provider of sample and assay technologies. Sample technologies are used to
isolate and process DNA, RNA and proteins from biological samples such as
blood or tissue. Assay technologies are used to make such isolated
bio-molecules visible. QIAGEN has developed and markets more than 500 sample
and assay products as well as automated solutions for such consumables. The
company provides its products to molecular diagnostics laboratories, academic
researchers, pharmaceutical and biotechnology companies, and applied testing
customers for purposes such as forensics, animal or food testing and
pharmaceutical process control. QIAGEN's assay technologies include one of
the broadest panels of molecular diagnostic tests available worldwide. This
panel includes the digene HPV Test, which is regarded as a "gold standard" in
testing for high-risk types of human papillomavirus (HPV), the primary cause
of cervical cancer, as well as a broad suite of solutions for infectious
disease testing and companion diagnostics. QIAGEN employs nearly 3,600 people
in over 30 locations worldwide. Further information about QIAGEN can be found
at www.qiagen.com/.

Certain of the statements contained in this news release may be
considered forward-looking statements within the meaning of Section 27A of
the U.S. Securities Act of 1933, as amended, and Section 21E of the U.S.
Securities Exchange Act of 1934, as amended. These forward-looking
statements, which may include, but are not limited to, statements concerning
the financial condition, results of operations and businesses of QIAGEN and
Cellestis and the benefits expected to result from the contemplated
transaction, are based on management's current expectations and estimates and
involve risks and uncertainties that could cause actual results or outcomes
to differ materially from those contemplated by the forward-looking
statements. Factors that could cause or contribute to such differences may
include, but are not limited to, the risk that the conditions relating to the
required approvals and clearances might not be satisfied in a timely manner
or at all, risks relating to the integration of the technologies and
businesses of QIAGEN and Cellestis, unanticipated expenditures, changing
relationships with customers, suppliers and strategic partners, failure to
achieve anticipated growth in sales, conditions of the economy and other
factors described in QIAGEN's most recent reports on Form 20-F, Form 6-K and
other periodic reports For further information, refer to the discussions in
these reports that QIAGEN has filed with, or furnished to, the U.S.
Securities and Exchange Commission (SEC).

QIAGEN has included adjusted financial measures in this release to give
additional insight into QIAGEN's anticipated financial performance for
periods in which the corresponding measures prepared in accordance with
generally accepted accounting principles cannot yet be determined.

(1) Based upon 96.15 million ordinary shares and excludes any cash
payments to option holders.

(2) The Cellestis board of directors unanimously recommends shareholders
vote in favour of the Scheme in the absence of a superior proposal and
subject to an Independent Expert concluding that the Scheme is fair and
reasonable and in the best interest of Cellestis shareholders.

(3) QFT is indicated for use in the United States as an in vitro
diagnostic (IVD) test using a peptide cocktail simulating ESAT-6, CFP-10 and
TB7 7(p4) proteins to stimulate cells in heparinized whole blood drawn
directly into specialized blood collection tubes. Detection of interferon-y
by enzyme-linked immunosorbent assay (ELISA) is used to identify in vitro
responses to these peptide antigens that are associated with mycobacterium
tuberculosis infection.

(4) QuantiFERON(R)-CMV is IVD CE marked for clinical use in the European
Union and is a Research Use Only Product in the United States.

(5) Foreign exchange rates as of April 1, 2011.

Investor Relations: Dr. Solveigh Mahler, +49-2103-29-11710; Albert F. Fleury, +1-301-944-7028, ir at qiagen.com; Public Relations: Dr. Thomas Theuringer, +49-2103-29-11826, pr at qiagen.com; In Australia: Amanda Lee or Andrew Stokes, +61-2-8298-6100, Amanda.Lee at fd.com or Andrew.Stokes at fd.com