Medivir Signs Research & Development Collaboration on Dengue Virus

HUDDINGE, Sweden, February 14, 2011 - Highlights of the Collaboration:

    - Collaboration with Janssen Pharmaceutica N.V. Focused on Dengue Virus
    - Both Parties to Contribute 50:50 Resources to the Research Program
    - Strengthens Medivir's Presence in Infectious Diseases And Utilises
      Strong Know-How in the Discovery of Protease Inhibitor Drugs

Medivir AB (OMX: MVIR), the emerging research-based specialty
pharmaceutical company focused on infectious diseases, announces today that
it has signed a collaboration agreement with Janssen Pharmaceutica N.V.
(Janssen) for the discovery and development of drugs for the prophylaxis and
treatment of dengue virus infection. Utilising both companies' core
competences in the discovery and development of protease inhibitors, Medivir
and Janssen will initiate an R&D program to co-develop drugs based on the
inhibition of the dengue NS3 protease activity. Both parties will contribute
equal resources to the research program and Medivir has an option to continue
to contribute equal funding for the non-clinical and clinical development
stages.

Terms

The terms of the agreement govern the discovery, clinical development and
commercialisation of any drugs developed under the agreement. Depending on
the level of funding through pre-specified decision points, each party has
the option to take products discovered through the research program forward
through development and on to commercialisation. If both parties remain in
the collaboration until product approval, Janssen will be responsible for
commercialization. Medivir will receive pre-agreed royalties on net sales of
future products that reflect its contribution to the development of products.

Dengue Virus and Disease

Dengue fever is a mosquito-borne viral infection, causing a severe
debilitating fever, rash, and muscle and joint pain. In an unpredictable
subset of cases, Dengue haemorrhagic fever occurs, which may lead to vascular
leakage and Dengue shock syndrome, a potentially lethal condition. Dengue
virus infection is a major problem in subtropical regions where the incidence
has increased 30-fold over the last 50 years. Up to 50 million infections are
now estimated to occur annually in more than 100 endemic countries and as the
disease continues to spread, approximately one third of the world's
population is at risk. Dengue hemorrhagic fever and Dengue shock syndrome
contribute significantly to hospitalization costs in endemic regions. This
growing prevalence has not been met by any significant advances in
treatment[1] and the annual death rate from dengue infection is approximately
30,000.

Development approach

Inhibition of the dengue NS3 protease is considered to be an attractive
target in developing novel efficacious drugs against dengue infection, due to
the critical role that the NS3 protease plays in viral replication. Drug
candidates that inhibit the dengue NS3 protease thus offer the prospect of
disease prevention and the control of outbreaks in endemic areas. In
addition, an NS3 protease inhibitor with therapeutic benefit could be used to
treat ongoing viral infections.

Medivir has extensive expertise and knowledge in the discovery of
protease inhibitors and the Company's lead drug TMC435, for the treatment of
hepatitis C, which is partnered with Tibotec (an affiliate of Janssen) has
recently reported positive interim data in three Phase 2b studies. Medivir
has further partnerships with Tibotec that utilise Medivir's unparalleled
knowledge in the discovery and development of treatments for infectious
diseases, including partnerships on hepatitis C polymerase and HIV protease
inhibitor drugs.

Ron Long, CEO and President of Medivir commenting on the announcement
said, "Medivir has strong experience in the discovery of protease inhibitors
for the treatment of infectious diseases and we are delighted to be
collaborating with Janssen in this important disease area. This strategic
collaboration represents a significant step forward in our ambition to retain
more value in products by taking them further into development and securing a
much more active role in our collaborations with partners. We believe that
dengue NS3 protease inhibitors offer the best prospect for effective
treatment of dengue fever and we look forward to working closely with our
partner to take this project forward."

Notes

[1] World Health Organisation, Fact sheet Number 117, March 2009.

About Medivir

Medivir is an emerging research-based specialty pharmaceutical company
focused on the development of high-value treatments for infectious diseases.
Medivir has world class expertise in polymerase and protease drug targets and
drug development. Medivir has a strong R&D portfolio and has recently
launched its first product Xerese(TM)/Xerclear(R). Medivir's key pipeline
asset, TMC435, a protease inhibitor, is in phase 2b clinical development for
Hepatitis C and is partnered with Tibotec Pharmaceuticals.

Xerese(TM)/Xerclear(R) is an innovative treatment for cold sores, which
has been approved in both the US and Europe. It is partnered with
GlaxoSmithKline to be sold OTC in Europe and Russia and with Meda AB in North
America. Medivir has retained the Rx rights for Xerclear(R) in Sweden and
Finland.

For more information about Medivir, please visit the Company's website:
www.medivir.se.

    For more information about Medivir, please contact:

    Medivir (www.medivir.se)
    Rein Piir, CFO & VP Investor Relations: Mobile: +46-708-537-292

    M:Communications

    Europe: Mary-Jane Elliott / Amber Bielecka / Nick Francis :
    Medivir@mcomgroup.com, +44(0)20-7920-2330
    USA: Jason Marshall: +1-212-897-5497

For more information about Medivir, please contact: Medivir (www.medivir.se): Rein Piir, CFO & VP Investor Relations: Mobile: +46-708-537-292; M:Communications: Europe: Mary-Jane Elliott / Amber Bielecka / Nick Francis : Medivir at mcomgroup.com, +44(0)20-7920-2330; USA: Jason Marshall: +1-212-897-5497