Why do people make viruses

Viruses That Help

A virus kills cancer cells

Because some viruses attack the bacteria that colonize lobsters. The breeding animals then no longer have to be treated with antibiotics, but the viruses kill the unwanted germs. Other marine viruses protect against an algae plague.

And: "More than a hundred years ago people observed that viral infections can defeat cancer," says Antonio Marchini.

The virologist is currently investigating precisely such a virus at the German Cancer Research Center (DKFZ), the parvovirus H1. This virus, which actually occurs in rats, multiplies in tumor cells and kills them, leaving healthy tissue intact.

"We don't know why it has this ability," explains Marchini. It is clear that the virus can only multiply with the help of the special properties of cancer cells. The cancer cells also lack a natural defense mechanism against the parvovirus that healthy cells bring with them.

Especially in brain tumors, which are otherwise difficult to treat, the H1 virus has already proven to be an effective weapon during research at the German Cancer Research Center.

"Apart from an initial application in China, there is still no virus cancer therapy on the market," says Antonio Marchini. "If all goes well, the first patients could be treated with H1 in five to ten years."

The side effects are so far unknown

A clinical study has been running since 2011 to test the safety of the parvovirus in humans. And the researchers are already testing nine other viruses on patients with various cancers.

"The viruses not only show better cure rates than the common cancer drugs, there are no signs of side effects either," says Marchini. And that could only be one of the advantages. But it's still too early to jump into the air. In medicine, the following applies: no effect without side effects.

The virus therapy apparently goes well with other therapies, as the researchers at the DKFZ examined in a study: They treated rats with cervical and pancreatic cancer with a combination of parvoviruses and valproic acid, a drug that is already used for cancer therapy. It supports the viruses by activating the virus protein NS1. This allows the H1 virus to multiply faster and kill the cancer cells better.

After the combination treatment, the tumors partially regressed completely, as the Heidelberg researchers report. Even within a year, the cancer did not come back. However, it is unclear whether the results can be transferred to humans.

In addition to being combined with other drugs, viruses offer another way of increasing their effectiveness against cancer cells: "We want to genetically modify viruses so that they are able to colonize the entire tumor and spread massively there," says Stefan Kochanek.

At the University Clinic in Ulm, the doctor is targeting pancreatic cancer with adenoviruses whose genome has been altered. The genetic information of the viruses is relatively simple. This makes it easier for researchers to work on them until the viruses have the desired properties.

Viruses do a lot of good in the oceans

The image people have of viruses is changing, and not just in medicine. Viruses that do good can also be found in the depths of the sea. "Without it, the ecological balance in the oceans would be upset," says Joaquin Martinez Martinez, who researches marine pathogens at the Bigelow Laboratory for Ocean Sciences in Boothbay, Maine.

The number of viruses that the researcher finds in salt water already gives an idea of ​​their influence on the ecosystem: up to a hundred million pathogens can swim in one teaspoon of sea water.

"Viruses can attack any form of life," says Martinez. And life abounds in the sea. In addition to fish, crabs and jellyfish, microorganisms such as phytoplankton, small unicellular organisms that are on the one hand part of the plant kingdom and on the other of the bacterial kingdom, cavort here. Every second there are 10²³ viral infections in the sea - this is calculated by marine biologists from the University of British Columbia in Canada.

Viruses ensure biodiversity

"Viruses literally control who lives in the sea and who doesn't," says Joaquin Martinez Martinez. They ensure a balance between the organisms and thus a wealth of species.

For years, researchers at the Bigelow Laboratory for Ocean Sciences have been observing a virus that is curbing the unrestrained growth of the alga Emiliana huxleyi. "The advantage of viruses is that they always choose their hosts very specifically," says Martinez Martinez.

If a species of algae like Emiliana dominates, the virus only attacks this and ensures that other phytoplankton species find space to live again.

"You can think of it as a forest that is so dense and dark that only one type of tree can survive there," says the marine virologist. If a pathogen attacked these trees, they would begin to die - and new plants would have a chance again.

Viruses are tiny, powerful. They even manage to influence the weather on earth from the sea. "Many plankton species produce the gas dimethyl sulfide, which rises into the atmosphere," says Joaquin Martinez Martinez.

The algae produce significantly more of this gas when they are infected with certain viruses. The good thing about it: Dimethyl sulfide promotes cloud formation. The clouds block out the sun's rays, which leads to a milder climate.

Bacteria killer in lobster farming

Marine viruses could help fight pathogenic bacteria, says Joaquin Martinez Martinez. The breeders in particular would benefit from this. Researcher Willie Wilson - a colleague at Bigelow Laboratory - discovered viruses that kill harmful bacteria in lobster farming. The advantage: Even if the bacteria try to get rid of their enemies through mutations, they hardly stand a chance.

The genetic information of the viruses reacts quickly to changes. So far, breeders have been using expensive antibiotics to protect their crustaceans from bacteria. The effort is high because the bacteria develop resistance. The medicines must therefore be continuously developed.

The viruses are still only being used on a test basis in the food industry. Martinez is already thinking a step further: "In a similar way, we could also fight bacterial infections in humans with viruses."

The marine viruses specialize in marine life and usually do not cause anything in the human body. "In the ocean, for example, there are viruses that attack bacteria that are related to the cholera pathogen," says the virologist.