The power of a potential universal ‘flu vaccine has been boosted according to a study by researchers at McMaster University and the Icahn School of Medicine. They found that a universal vaccine produced from a live, but damaged, version of the influenza virus may grant immunity better if it were given in the lungs, nose, and throat.
[caption id="attachment_187" align="alignright" width="228"] Under the microscope: Last winter's seasonal menace - Influenza H3N2 (green). Image credit: Dr Fred Murphy, CDC.[/caption]
The make-up of the influenza virus changes every year. Currently, seasonal ‘flu vaccines are made from dead influenza particles and designed to predict the next influenza type. Like predicting the weather, it’s not always accurate, and last season’s ‘flu vaccine was off the mark, meaning the vaccine was less effective than usual. The need for a universal ‘flu vaccine, which would protect against every ‘flu type, is more prominent than ever now that bird and swine ‘flu scares of recent years have not gone away.
In this study, a seasonal ‘flu vaccine, which targets a specific form of the virus, was compared to a broad “universal” vaccine, which should protect against many influenza types. In the lab, researchers were able to show that polyclonal antibodies, immune proteins of the body, raised against influenza by a specific and universal vaccine were equally effective – and the universal vaccine produced universal antibodies.
Further investigation by the team discovered that antibodies in the lungs and throat, a type known as IgA antibodies, were more effective at neutralising the ‘flu virus. According to lead author, assistant professor Matthew Miller, this would help design an appropriate vaccine. He says “This is also very encouraging and provides guidance as to what vaccine would be best for delivering a universal flu vaccine - that is, inactivated versus live-attenuated.” Live-attenuated virus is a living but damaged/non-disease causing version of the virus.
Live-attenuated vaccines can be delivered to the sites where immunity would be strongest – the lungs and throat – where the virus can replicate but not cause disease. Their use has several small risks according to the World Health Organization, chief among them is reversion into a disease-causing virus. However, properly applied, live attenuation of viruses for vaccines can be more effective than using inactivated viruses or virus particles, and pose little threat to healthy individuals.
Dr Miller hopes that their findings will help lead to a viable universal vaccine to all influenza A strains within five to seven years.