Researchers at Duke University in North Carolina
have found a way to use the poliovirus as a weapon
against cancer: They genetically modifi ed the virus
so that it can only reproduce in tumor cells, but not in healthy
cells. The resulting virus, known as PVS-RIPO, is injected
directly into the tumor (red area in the brain scan, above).
Once there, it fi ghts cancer in two ways: First it destroys
tumor cells, and second, it calls immune cells to the scene,
which also begin destroying the cancer cells. The therapy
was approved for human testing in 2011, and so far these
tests have yielded promising results.Scientists have now fi gured out that it’s viruses, of all things,
that serve as something like the immune system of the oceans.
Each day they kill so much biomass that the balance there is
not disturbed. “If there were no viruses, the world’s oceans would get
clogged. Bacteria and algae would grow and grow, and in the end you’d
have an ocean full of sludge,” explains marine virologist Willie Wilson.
Higher organisms would likely never have developed. Viruses also
regulate biodiversity. (Below: bioluminescent plankton.) Because when
a population grows too large, it becomes susceptible to infections.Can viruses cure cancer?
Do viruses keep the oceans healthy?
Many viruses can only remain active for a few hours
outside of a host. The norovirus (above) is a special case: Even after
12 days had passed, it was still detected on a contaminated carpet.
The virus can also withstand extreme climates. Temperatures between – 4°F
and 140°F cannot destroy the hardy pathogen. Furthermore, the norovirus is
also extremely mutable, or more specifi cally, adaptable. Every two to three
years a new strain of norovirus emerges. For this reason, so far it hasn’t been
possible for researchers to develop a vaccine against this infectious agent.Which is themost aggressive virus in the world?
Vi s
SMARTER IN 60 SECONDS
151515PHOTOS: Fotogloria; PR; Science Photo Library–SCIEPRO; Stocktrek Images.
In 1967 grivet monkeys
were imported from
Uganda to Germany—
and the Marburg virus came
with them. It is considered to
be the most aggressive virus
in the world: The case fatality
rate can range as high as 88%.
So far, neither any vaccine nor
an effective antidote has been
found. Among the fi rst victims
in Germany were the Marburg
researchers who were using
the imported monkeys as test
animals in their laboratories.
(Hence the name.) To this day,
viruses such as Ebola and Lassa
(among others) are still being
studied in a high-security lab
at the University of Marburg’s
Institute for Virology (image).15How long can viruses survive without a host?