Four million people die every year from respiratory diseases such as viral influenza. For elderly people in particular, an infection can be dangerous. What is more, the flu vaccine is not as effective with this risk group as it is with younger people. The reason for this is that with age the fire power of the immune system is reduced. Why this is the case is largely unknown. An international EU project led by the University of Bonn is now starting which aims at shedding light on this. Among other things, the researchers want to get a step closer to solving this riddle by examining tens of thousands of blood samples. The objective is also to develop new medicines which largely inactivate the viruses and enable the immune system to deal with the small amount of residual viruses.

Spanish flu took the lives of at least 25 million people between 1918 and 1920. But the disease was not only exceptional because of its extreme virulence. The patho-gen, the influenza virus subtype A/H1N1, homed in on women and men in the prime of their lives. 'Normally respiratory diseases are dangerous for children and the over-60s,' the project coordinator Dr. Oliver Schildgen explains. 'What's more, in the case of the elderly the flu vaccine unfortunately only prevents the disease in six out of ten cases.' By contrast, with young adults, the success rate is as high as 90 per cent.

The reason for this is that the effectiveness of the immune system decreases with age. An international research consortium now wants to find out why this is the case. Roughly 1.8 million euros will be provided by the EU for this in the next three years. With other diseases it has already been proven that the older body can no longer produce a sufficient amount of effective antibodies. 'We want to know in particular whether this is the case with infectious diseases where the viruses were discovered recently,' Oliver Schildgen says.

SARS's little brother

To do this the scientists want to analyse up to 40,000 anonymised blood samples which have been collected over the last few years at Bonn University Clinic. They come from patients who were taken to hospital with completely different ailments. For each sample, the age of the person it was taken from is known. The scientists aim to obtain an overview of the immune status of the population which is as representative as possible. 'Recently a number of new respiratory viruses have been discovered,' the Bonn lecturer explains. 'We presume that we will find antibodies in the blood samples of older patients which are less effective against these pathogens than in the case of younger patients.'

The Dutch project partner, the Academic Medical Center in Amsterdam, discovered the coronavirus NL63. This virus belongs to the same group as the SARS virus, which gained notoriety during an epidemic in 2002 and 2003. The group from the Academic Medical Center in Amsterdam would now like to find out how an infection with this virus group progresses, in the hope of finding alternative ways of tackling the disease with new drugs.

A German software developer is also among the partners. The Hamann Company is developing a database solution to acquire the medical data and analyse the results, which are extensive. In this manner, current respiratory diseases in the EU are to be recorded in coming years using a standardised format. New immune tests which are being developed by the Spanish company INGENASA are intended to accelerate a solution to this problem. 'We want to find out which viruses are currently spreading, how dangerous they are and what risk factors make an infection particularly likely,' Oliver Schildgen explains.

In the meantime, a task force from the University of Siena is investigating how the immune response changes on a cellular level in elderly people. Studies with older mice are expected to provide further insights. For these, the University Clinic in Dijon is designing a corresponding animal model. The Belgian project partner RNA-Tec wants to test new approaches on the animals in order to coax maximum performance from the immune system of older animals.

If the immune system begins to flag with age, this could also be due to a long-forgotten infection. A suspected culprit is the virus causing Pfeiffer's glandular fever, for example. Due to the age group that is mainly affected and a possible path of infection, this disease is also known as 'Students' Kissing Fever'. After the symptoms have disappeared, the pathogen, the Epstein-Barr virus, remains in the body for life and could permanently weaken the body's immune system with increasing age, a theory which is being investigated by RWTH Aachen.

Note: This article has been adapted from a news release issued by University of Bonn.