Retroscreen Virology Ltd - Publication of paper on DNA vaccination for influenza

01 Apr 2009

Retroscreen Virology Limited, the global leader in anti-viral research, clinical trials and experimental challenge studies, is pleased to announce the publication of a paper, in association with Pfizer, showing that Pfizer’s DNA vaccination protects against an influenza challenge in a double-blind randomised placebo-controlled phase 1b clinical trial. This is the first report of protection of human subjects from infectious disease by DNA vaccination.

Pfizer purchased the UK company, Powdermed, who had developed a Trivalent DNA vaccine for influenza consisting of three plasmids expressing haemagglutinin from different seasonal influenza virus strains delivered using PMED (particle mediated epidermal delivery). It set out to determine whether the vaccine (with and without a molecular adjuvant DNA Encoded Immunostimulator-Labile Toxin (DEI-LT)) could protect subjects from a controlled influenza virus challenge.

Healthy adult subjects were screened for susceptibility to infection with influenza A/H3 Panama/2007/99 then vaccinated with 4microg Trivalent influenza DNA vaccine, 2microg Trivalent influenza DNA vaccine plus DEI-LT or placebo. Safety and serological responses to vaccination were assessed and on Day 56 subjects were challenged with A/H3 Panama/2007/99 virus.

The study sowed that vaccination with 4microg Trivalent or 2microg Trivalent/DEI-LT was well tolerated and induced antibody responses to two of the three influenza virus vaccine strains. Post challenge, subjects in the 4microg Trivalent group (N=27) showed reductions in disease symptoms and viral shedding compared to placebo (N=27), with an overall vaccine efficacy of 41% (95% confidence interval (CI)=?1.5, 67.7) for 'Any illness with or without fever' and 53% for 'Upper respiratory tract infection' (95% CI=8.0, 77.7).

It was concluded that PMED vaccination with 4microg Trivalent influenza DNA vaccine was safe and elicited immunological responses that protected human subjects from influenza; this is the first report of protection of human subjects from infectious disease by DNA vaccination.

For further information:

Retroscreen Virology Limited  
Robert Lambkin-Williams, CEO Tel: +44 (0) 20 8709 4900

Notes to Editors

About Retroscreen Virology Ltd

RVL is unique in being the only contract research organisation (CRO) in the world that offers experimental infection studies with viruses in human volunteers under quarantine conditions (human challenge studies). Founded in 1989 by John Oxford, Professor of Virology, University of London, the Company, a global leader in anti-viral research, designs and coordinates clinical trials for global pharmaceutical and biotechnology companies that are developing novel antiviral drugs and vaccines. To date, RVL has conducted over 30 such quarantines, infecting over 600 volunteers. Experimental challenge studies can help reduce both the cost and the duration of drug development by accelerating the selection of dose and dosing regimes for later licensing studies. RVL is ISO9001 accredited and is partnered with a number of leading UK universities, including Queen Mary, University of London.

Clinical trials: RVL offers a comprehensive service from protocol and case report form design through to effecting and co-ordinating the study. The Company is especially renowned for its unique experimental challenge studies, conducted under strict quarantine conditions at its UK Flu Camps (see

Analytical Services and Clinical Trial Support: RVL has invested in the development and optimisation of in vitro antiviral assay techniques to support clinical studies. The Company specialises in assays for respiratory viruses such as influenza, RSV, and rhinovirus (the common cold), as well as gastrointestinal viruses among others.

RVL is also part of a consortium led by QinetiQ Nanomaterials Limited, a wholly owned QinetiQ subsidiary, which is developing a range of viral treatments from nanomaterials. The two year programme, which was completed recently, was funded by the South East England Development Agency (SEEDA) who allocated £2 million to the project.

Furthermore, RVL is the lead participant in the European Surveillance Network for Vigilance against Viral Resistance (VIRGIL), which was established with a grant of £9 million from the European Union. Virgil is a network of excellence that aims to integrate and coordinate the activities of doctors and scientists from institutions across Europe who are investigating viral resistance.

For more information on RVL please visit