Corona virus: “Evolution takes place in real time”

  • ofPamela Dörhöfer


The Essen-based virologist Ulf Dittmer works closely with researchers in Wuhan, China. A conversation about the origin of the new corona virus, its properties and why other pathogens are to be expected.

The appearance of the Sars-CoV-2 coronavirus was not a surprise, says Ulf Dittmer, director of the Institute of Virology at the University Hospital Essen. He gets first-hand information: his institute has been running a laboratory for virus researchers at the University of Wuhan for three years, supported by the provincial government of Hubei. There has been a cooperation between the Essen University Hospital and the Wuhan University Hospital since 1983.

Mr. Dittmer, your institute at the University Hospital in Essen maintains a laboratory for virus research at the University of Wuhan together with Chinese scientists. Did you and your colleagues expect a new virus like Sars-CoV-2 to appear?

It was not a surprise. We have always expected this because we have seen that there have been quite a few virus outbreaks in Asia in recent years. This is where the risk is greatest. For years we have therefore worked together with scientists in China to build stable structures. The interaction with the colleagues there means that we can get information much more quickly, for example about the nature of a virus or therapies. We are currently having a video conference with our colleagues from Wuhan twice a week in order to prepare ourselves optimally for the treatment of Covid-19 patients.

Why are new viruses so common in Asia?

There are risk factors that determine this. There is, for example, the long tradition in Asia to trade living animals as food. Although this was banned in China before the Sars-CoV-2 outbreak, live animals are still sold at every weekly market. For many people there has been true for centuries: meat is fresh when it is alive, which also applies to fish.

One theory is that the virus came to humans as an intermediate host via the bat and the pangolin, and cats have recently been discussed as intermediate hosts. Are there new insights into which path the pathogen has taken?

Twice a week in a video conference with colleagues from Wuhan: virologist Ulf Dittmer.

It is difficult to find out afterwards. The fact is that there is a very similar virus in bats in China. That was already described in 2015. It is no longer clear whether this virus was transmitted directly from the bat to humans or via an intermediate host who has become infected and is also eaten. The fact is that bats are also on the menu in China.

How do you imagine the process when a virus from another species leaps onto humans?

Take a market as an example: there are many living wild animals in a cage, behind them are people who sell them, other people walk past this cage. This type of contact alone poses a risk. The risk is even greater if people take such an animal home, slaughter it and prepare it for eating. Ebola was also a virus that was transmitted from fruit bats to humans in this way, albeit in Africa.

Could a virus theoretically spread to humans from any species?

This is possible with mammals. With reptiles or insects, however, the leap to mammal is so large that it usually does not work. The exception is when an insect, such as the mosquito, only transfers a virus from humans to humans as a vector. This shows that this virus must have come from a mammal. At the beginning, Sars-CoV-2 was talking about the snake as a host. I think that is very unlikely.

Do you expect the virus to mutate and change its properties in the course of the pandemic?

Sars-CoV-2 is one of the viruses with RNA genome. Such viruses are constantly changing. The most variable viruses we know are HIV and hepatitis C. Both are also RNA viruses. We will surely see changes in this corona virus, since evolution takes place in real time.

In which direction do you think the virus will weaken or become more dangerous?

“For many people in China it has been true for centuries that meat is fresh when it is still alive, which also applies to fish,” says virologist Dittmer.

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The virus is actually not interested in sitting deep in the lungs. It would rather settle in the upper respiratory tract because it can spread much easier from there. I therefore suspect that evolution tends to cause the virus to move upwards and eventually cause only mild flu infections. In Germany, three to four other corona viruses circulate every winter that cause such flu infections. I assume that hundreds of years ago they started out in a similar way to the new corona virus that we are seeing now.

In China, according to official government data, the number of infected people is falling significantly and the situation seems to be recovering. How do you and your Chinese colleagues explain this? Was it the drastic measures?

This can be justified primarily. Due to the drastic measures that could never be implemented here in Europe, infection chains were completely interrupted. Whether the numbers from China with supposedly zero infections are correct remains to be seen. If it were really the case that there were no new infections at all, the quarantine measures could be stopped immediately. The Chinese don’t do that. They are afraid of a second wave because they know that viruses can persist in immunocompromised people for a long time and can be eliminated by them.

To person

Ulf Dittmer is a professor of virology.He heads the Institute of Virology at the Essen University Hospital. He focuses on researching chronic viral infections and the interaction of the immune system with viruses. He received his doctorate in Göttingen and worked at the National Institute of Health in the USA.

He has been director of the institute since 2011in Essen and since 2016 visiting professor at the Huazhong University of Science and Technology in Wuhan. pam

Can you explain why the virus has spread so much in Italy despite curfew?

The death toll is related to the social and medical system. In Italy, there are many older people with pre-existing conditions who live in family home relationships. If Covid-19 sufferers are seriously admitted to an overloaded hospital, some are unfortunately sorted out and no longer ventilated. Italy also has the major disadvantage that the virus has grown exponentially much faster than we have. Italy was the first country in Europe to be affected at a time when it was unprepared.

There are different assessments among scientists as to whether the virus will weaken in summer. What do you think?

At the University Hospital Essen we have the largest aftercare for lung transplant patients in Germany. That is why we observe and diagnose the usual coronaviruses that only cause a flu-like infection all year round. We see a significant decline in the summer, albeit with a delay of at least one month compared to flu viruses. Corona viruses last longer, but become less when it is warm for a longer period. A new study confirms this seasonality of coronaviruses – but also notes that the decrease in the number of infected people can be delayed if too many people are still infected at the time of the seasonal weakening of the pathogen.

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But could the virus appear again next fall?

Yes, it can be assumed. Then hopefully weakened, as discussed.

Hopes are now high for finding a vaccine. Sars and Mers already had research on a vaccine. Both pathogens are also corona viruses and closely related to Sars-CoV-2. What has become of this research, can it be used to develop a Sars-CoV-2 vaccine?

You can use it very well. Sars 1 had excellent approaches that were not continued until the virus was completely gone. At Mers you can vaccinate dromedaries, which are the reservoir for the virus. Virologist Gerd Sutter from the German Center for Infection Research in Munich developed this vaccine and has now replaced a protein structure of the Mers virus in the vaccine with one of the new corona virus. What you have learned from Mers can be used very well as the basis for a new vaccine. But that’s just one approach, there are many others.

Do you also expect that a vaccine will be available next year?

It will be very quick – and a year is very fast, otherwise it will take ten years to develop a vaccine.

Medicines are also being researched. Bacteria can generally be combated well with antibiotics if resistance is left aside. Viruses seem to find it more difficult to find comparable active ingredients.

It is difficult, but there have been huge developments in the past ten years. Up until the 1990s, we actually had no virus-specific medication at all, today we have around 30 different types of HIV. And hepatitis C can now be cured with an antiviral agent.

Why is it generally harder to treat infections with viruses than those with bacteria?

Bacteria are given an antibiotic that works against them directly in the blood. This is not possible with viruses because they only multiply in cells. That’s why you have to develop drugs that work in cells and only against the viruses there, because they shouldn’t harm the cells. Only in the past 30 years have specific points of attack been found to intervene in the multiplication of viruses.

Do you anticipate further, previously unknown viruses in the future?

It won’t be the last time we see a new virus. We have to prepare for this and maintain international cooperation, especially with Asian countries. Because the next pathogens will probably come from Asia again. But we also have to keep an eye on Africa. The Chinese have an incredible virus monitoring program, much better than in Europe. If we keep the cooperation with the scientists there, we can benefit from the fact that viruses are discovered quickly.

Interview: Pamela Dörhöfer

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