High Wycombe, UK - 6th September 2007 Data showing how a new flu vaccine from PepTcell has the potential to protect against all strains of influenza, including pandemic and annual, has been published in this month’s European Journal of Immunology.

The pre-clinical results show how mice vaccinated with PepTcell’s novel flu vaccine, Flu-v,
had a significantly increased survival rate when challenged with a lethal dose of influenza
virus, compared with those that received a control vaccine.

Dr Wilson Caparros-Wanderley, PepTcell’s Chief Scientific Officer said: “These are extremely
encouraging results for PepTcell’s Flu-v vaccine. They show that a vaccine, targeted at parts
of the virus which do not change from year-to-year, can be effective against lethal influenza
strains.”

The data showed how PepTcell has used a novel proprietary prediction algorithm to locate
conserved immunogenic regions in animal and human strains of flu virus. The analysis
identified six highly conserved regions within several proteins that are capable of triggering an
immune response.

These six regions were then chemically synthesised as small protein fragments called
peptides. The resulting preparation, Flu-v, was used to immunise eight transgenic mice. At
the same time a group of eight control mice were immunised with a set of non-related
peptides.

Following immunisation with Flu-v the mice launched a specific T-cell immune response of
the CD8+ subtype against the peptides. T-cells are part of the immune system, helping to fight
off infection and disease by killing abnormal cells. The CD8+ T-cells isolated from the mice
showed activity against human cells infected with three unrelated influenza strains in in vitro
tests. This experiment confirmed that the peptide sequences in Flu-v are highly conserved
across strains, and that these peptides are naturally presented on the surface of flu-infected
cells, and therefore can be recognised by the immune system.

When the immunised mice were subsequently challenged with a lethal dose of influenza, the
researchers found that fifty seven percent of the mice who had been immunised with the Flu-v
vaccine survived, compared with none of the mice in the control group.

Greg Stoloff, Managing Director of PepTcell, commented: “These results suggest that
PepTcell’s Flu-v vaccine could eliminate the need for annual flu vaccination as the immunity
generated targets regions of the virus that remain constant. The results also suggest that Fluv
has the potential to provide effective protection against a pandemic flu strain by enabling
stockpiling and the initiation of a worldwide vaccination program ahead of an outbreak.”

PepTcell is in the process of finalising all the manufacturing processes for its vaccines, and
expects Flu-v to enter Phase I clinical trials during 2008.

-ENDS-