Dialog in the Museum

Sometime between 1900 and 1930, a hunter in northern Congo or Cameroon shot a chimpanzee. Then as now, stalking wild animals in Central Africa was nothing unusual; their meat is highly valued and is sold at local markets. But this solitary hunting event around 100 years ago is still shaking the world today: It triggered a pandemic that not only struck Africa, but has so far claimed around 35 million lives worldwide. The ape that was killed and eaten at the time carried a special form of HIV, a variant that was easily transferred to humans as new hosts – and which then radically destroyed their immune system within only a few months as the “acquired immune deficiency syndrome” (AIDS).

“While we are discussing the current state of virus research here at the museum this evening, 100 people throughout the world will die of AIDS and about 5,000 will become newly infected,” said Prof. Dr. Hans-Georg Kräusslich, Head of the Department of Virology at Heidelberg University Hospital. “Whenever there is a local outbreak of Ebola or bird flu, for example, the media blare out headlines such as ‘The Demon from the Bush,’ ‘Murderous Epidemic,’ or ‘Killer Virus Outbreak.’ This raises readers’ blood pressure and the magazines’ circulation figures, but from a scientific point of view, we have bigger challenges to overcome,” Kräusslich noted. Over-dramatizing this issue does a service to no one.

While Ebola has caused about 13,000 deaths since 1976, influenza accounts for 400,000 fatalities worldwide every year. Nevertheless, we should not lose sight of the immense progress that research has made in the fight against epidemics caused by viruses: Thanks to comprehensive vaccination campaigns, smallpox was finally eradicated in 1977, Kräusslich continued; poliovirus, the pathogen responsible for polio, is now found in only three countries in the world; and chronic hepatitis has been curable for the vast majority of patients since 2014. With appropriate medical treatment, AIDS is likewise no longer a death sentence.

In total, there are an estimated ten million times more viruses in the oceans than there are stars in the universe. And even the fundamental question of whether or not a virus is a living being can be answered in different ways, said Kräusslich. But one thing is for certain: A virus comprises some 7,500 building blocks packed into a protein shell. It has a very simple structure, which we can regard as a biochemical compound at the interface between animate and inanimate matter. Without a host, the virus is nothing, with no function – but as soon as it encounters a suitable organism, it comes into action as an incredibly efficient reproduction machine, a radically “selfish genome”.

According to Kräusslich there is hardly any habitat on Earth, no matter how extreme, that is not already colonized by viruses. They can be found not only on our skin, under the rose bush in the garden or beneath the next street lamp, but also in the deep sea, in acidic springs at a temperature of 80 degrees, in salt mines, and at depths of up to two kilometers below the Earth’s surface. It is thus important to realize that viruses are not only potential pathogens, but also a basic constituent of ourselves as human beings.

Virus research will become increasingly important for medicine in the coming years. Despite numerous initial failures and setbacks in research, Kräusslich continued, some very promising new therapeutic approaches have now been developed: Viruses have proven to be ideal vehicles for introducing genetic information, such as therapeutic genes, into diseased cells. This has already made it possible to cure highly specific blood diseases in some patients. In future, virus therapies are likely to open up new opportunities for healing in the field of tumor medicine as well. The viruses could be introduced into cancer cells, for example, which they then strategically induce to self-destruct. “We still don’t understand many of these principles in detail, but in scientific terms we have now definitely reached a point from which we can open up completely new horizons,” Kräusslich concluded.