The British-American biotech company Acambis reports the successful conclusion of Phase I trials of the universal flu vaccine in humans. The universal influenza vaccine has been pioneered by researchers from VIB and Ghent University. This vaccine is intended to provide protection against all ‘A’ strains of the virus that causes human influenza, including pandemic strains. Therefore, this vaccine will not need to be renewed annually.

Influenza

Influenza (flu) is an acute infection of the bronchial tubes and is caused by the influenza virus. Flu is highly contagious and causes people to feel severely ill. An average of 5% of the world's population is annually infected with this virus. In Belgium, an average of 1500 people die of flu each year. A "more severe flu year" − such as the winter of 1989-1990 − claimed in Belgium alone, 4500 victims. Moreover, occasionally pandemics occur.

These are caused by significantly different virus strains which overwhelm the immunity in the human population. Three pandemics occurred in the previous century, the first one, the “Spanish Flu” in 1918-1919, was responsible for at least 50 million human deaths worldwide. There is a fear that the avian H5N1-influenza strain could adapt to humans and cause the next pandemic.

Every year, another vaccination

Today's flu vaccines need to be adapted every year to new virus strain variants and, consequently, they must also be administered again every year. This is needed because the external structure of the flu virus mutates regularly, giving rise to new strains of flu. Due to these frequent changes, the virus is able to elude the antibodies that have been built up in the population during a previous infection or vaccination.

advertisement

This is why we run the risk of catching a flu infection each year. To prevent an infection, we need yearly a new influenza vaccination adapted to currently circulating flu strains. A universal flu vaccine that provides broad and lifelong protection − like the vaccines we have for polio, hepatitis B or measles − is not yet available.

One vaccination for life

In the 1990s, VIB researchers connected to Ghent University, under the direction of Prof. Walter Fiers, invented a universal flu vaccine. This vaccine targets M2e, a conserved region of influenza "A" strains.

About two thirds of seasonal epidemics are due to type "A" strains, and also all pandemic influenza strains are type "A". Therefore the universal, M2e-based vaccine is expected to provide protection against pandemics. Previously, the universal vaccine had been successfully tested in mice and other laboratory animals: the M2 vaccine provided total protection against "A" strains of flu, without side effects.

Successful clinical trials in humans

Acambis − a British-American biotech company that specializes in the development of vaccines − has been exclusively licensed rights to VIB's influenza vaccine patent portfolio for human applications, and has entered into a collaboration with VIB for further research and development. In the randomized, double-blind, placebo-controlled phase I trial of the universal vaccine, now named ACAM-FLU-ATM, the vaccine's safety and ability to generate an immune response was evaluated. The vaccine was tested at multiple centers in the US and involved 79 healthy volunteers. The trial results demonstrate that ACAM- FLU-ATM is well tolerated and immunogenic, and no significant side-effects were observed.

advertisement

Acambis also tested whether an M2-based vaccination could protect ferrets from a deadly infection by the highly lethal avian H5N1 influenza strain "Vietnam 2004". 70% of the vaccinated animals survived, while all the placebo-treated animals succumbed to the viral infection.

Michael Watson, Acambis Executive Vice President, Research & Development, said: “M2e is one of the most discussed new approaches for universal influenza vaccination. These are exciting data as they show that our ACAM-FLU-ATM vaccine can generate a robust M2e antibody response and that M2e-based vaccines can protect against H5N1 avian influenza. We believe that these results confirm we have an approach worthy of further development.”

Promising future

Dr Xavier Saelens, and Prof. Emeritus Walter Fiers are leading the basic research forward with respect to protection against influenza epidemics and pandemics. This involves, amongst other, supporting research required for the planned Phase II and III clinical trials, as well as optimizing the vaccine for response against a potential pandemic caused by a highly pathogenic strain such as the H5N1 avian flu virus. Through their collaboration with Acambis, they hope that annually renewed flu vaccines can be replaced by the universal influenza vaccine. The goal is that two immunizations would suffice to protect people for a long time against all "A" strains of flu.

Relevant scientific publications

De Filette et al., Vaccine 24, 544-551, 2006.

De Filette et al., Virology 337, 149-161, 2005.

Fiers et al., Virus Research 103, 173-176, 2004.

Fiers et al., Philos T Roy Soc B 356, 1961-1963, 2001.

Neirynck et al., Nature Medicine 5, 1157-1163, 1999.

This research is being funded by Acambis, the National Institutes of Health (US), IWT, FWO, UGent and VIB.