Is the Ebola virus real or fake

Dangerous intruders - is there a threat of bat flu in the future after swine and bird flu?

When viruses are transmitted from animals to humans, it can become dangerous: Whether swine flu, bird flu or SARS - the causers were all viruses that previously only infected animals. But how do these pathogens, which actually specialize in animals, suddenly also infect humans?

It was in 2003 when a serious infectious disease suddenly triggered an epidemic worldwide: SARS. Severe Acute Respiratory Syndrome, SARS for short, was caused by a completely new virus from the coronavirus family. Coronaviruses are actually harmless pathogens that cause colds in humans and also a number of animal diseases. Coronaviruses are particularly common in bats, but do not trigger any symptoms there. "As the pathogen causing a severe respiratory infection that kills up to ten percent of all infected people, these viruses had not yet appeared", explains Prof. Dr. Christian Drosten from the Institute of Virology at the University Hospital Bonn.

The infectious disease SARS is a prototype for the so-called zoonoses, which also include bird flu, swine flu and Ebola. What they have in common is that a pathogen that specializes in animals suddenly also infects people. So the virus changes host. Often the human immune system is more or less powerless to face the new challenge; Zoonoses can be correspondingly devastating. But how do the viruses even make this leap across the species boundary? The research association "Ecology and Pathogenesis of SARS", funded by the Federal Ministry of Education and Research (BMBF), deals with this question. "If we manage to understand the process of host change, our basic understanding of the development of new types of epidemics improves," says Professor Drosten.

Coronaviruses: the danger so far underestimated!

Several years after the SARS epidemic, it became clear that the importance of coronaviruses in both animals and humans was historically underestimated. "More recent studies indicate that coronaviruses - in contrast to many other zoonotic pathogens such as rabies, Ebola or Lassaviruses - have a particularly high potential to spread epidemically after a host change," explains Professor Drosten. In contrast to other human coronaviruses, which only cause simple symptoms of a cold, the dangerous SARS virus from 2003 had a few peculiarities. Here are just two examples: On the one hand, the SARS virus caused a certain protein, ACE2, which actually protects our lungs from damage, to be broken down. In addition, the SARS virus was caught by certain surface proteins, so-called spikes, antibodies of the human immune system that could be dangerous to it.

Bats - Are the Flying Mammals Carrying the Next Epidemic?

The world could well be threatened by a new SARS epidemic in the future: "Especially in bats, there is an enormous reservoir of new coronaviruses worldwide and also in Europe, from which new SARS epidemics could emerge." In order to assess how dangerous these coronaviruses actually are, the scientists are trying to assess the risk of the viruses. To do this, they are isolating different coronaviruses from wild bats from all over the world, for example from Ghana and Brazil, and investigating whether the pathogens can infect other mammalian cells or even human cells in addition to bat cells. "Here we examine, for example, how strongly a virus would have to change genetically in order to actually infect human cells," explains Professor Drosten. With this risk assessment, the scientists will be able to predict in the future which viruses have a high probability of triggering a new epidemic. "In return, however, this also means that we can prevent unnecessary and misleading reports about impending epidemics and give the all-clear at an early stage if a virus is rather harmless according to our risk assessment," said the expert.

Hurdles from animal to human

In order to change the host, a virus must overcome at least two hurdles. On the one hand, the animal virus has to penetrate human cells. "We are looking into the question of what has to happen for a virus to dock with its surface proteins on the cell receptors in humans - although this should actually only work in its host animal," explains Professor Drosten. Another important barrier in a viral host switch is usually the immune system, which protects our body from unwanted intruders. Here the scientists have already identified two virus proteins that the viruses use to protect themselves from the human immune system. Other studies by the BMBF research association have shown that two immunosuppressants that have been approved for a long time, cyclosporine A and tracrolimus, could represent a new general therapy option against coronaviruses. "We are currently testing which coronaviruses these drugs are effective against," says Professor Drosten.


Research against zoonoses
Swine flu, SARS and now the EHEC pathogen: The risk of the appearance of varying and also new pathogens requires research across all diseases and broad scientific approaches in terms of both content and method. The Federal Ministry of Education and Research (BMBF), the Federal Ministry of Food, Agriculture and Consumer Protection (BMELV) and the Federal Ministry of Health (BMG) therefore concluded a research agreement on diseases that can be transmitted from animals to humans (zoonoses) in March 2006. Funding of 60 million euros was made available for this. The aim is to improve the prevention, diagnosis and treatment of infectious diseases that can be transmitted from animals to humans in the long term. The National Research Platform for Zoonoses (www.zoonosen.net) was established in 2009 to improve coordination and networking of all actors involved and all research projects. As part of the zoonoses research agreement, the BMBF also funds specific research projects. From 2007 to 2010, research associations on zoonotic diseases were funded with 24.6 million euros; by 2013, around 28 million euros will be made available.


Contact Person:
Prof. Dr. Christian Drosten
Institute for Virology
University Hospital Bonn
Sigmund Freud Str. 25
53105 Bonn
Tel .: 0228 287-11055
Fax: 0228 287-19144
Email: [email protected]