Viruses are a particularly fearsome “germ.” Though viral infections may resemble bacterial
infections, antibiotics are useless against viruses. There are very few dedicated antivirals
to kill them off. But who even knows if ‘kill’ is the right word to use for something that
stretches the definition of ‘alive’? Viruses: they’re like microscopically tiny zombie-robots,
hijacking cells and turning them into factories for themselves. But humanity can exploit viruses’
supremely odd workings and sneaky ways for their own purposes.
10. Blue Eggs
If you’ve ever wanted to find some green eggs for some Dr. Seuss-style green eggs and
ham, you’re in luck. Thanks to a virus, you don’t even need the eggs of some exotic
wild bird.
Most chicken eggs are white or brown, but a few chickens lay eggs that are green or
blue. These breeds include the Chilean Mapuche breed, its descendant breed, the Araucana,
and the Chinese Dongxiang and Lushi breeds.
Two things are responsible for the colorful eggs: viral infections and blood. Long ago,
a Mapuche fowl was infected by a retrovirus, a virus which can insert its genetic code
into the host’s. The retrovirus’s effect was to trigger the buildup of biliverdin in
the eggshell, a breakdown product from a part of hemoglobin that can cause a greenish tint
to bruises.
The Dongxiang and Lushi breeds developed their colorful eggs independently, but from the
same viral cause. According to historical evidence, the Dongxiang breed has had the
bluish-greenish egg mutation since at least 500 years ago, and the Mapuche fowl since
between 200 and 500 years ago. The trait is autosomal dominant, so chickens need only
one parent with the mutation to lay the colorful eggs. However, those who have both copies
of the gene variant lay darker-colored eggs.
9. Tulip-breaking virus
For the beauty of a virus-infected egg, one only has to pay a little more than usual.
But for a beautiful virus-infected tulip in the Netherlands of the 17th century, one had
to pay a lot more.
Back then, some tulips mysteriously had beautiful streaking and feathering patterns. These are
called “broken” tulips. They were so expensive, they could leave their owners “broke”
too, as well as the whole Dutch economy.
In 1623, some bulbs were sold for 1,000 florins, when the average annual income was 150 florins.
Due to their high price, it cost less for some citizens to get still-life paintings
of “broken” tulips than the tulips themselves.
Their beauty was short-lived, as the broken tulips’ bulbs shrank over successive generations.
Eventually, it could no longer flower, and soon died. No one knew what caused tulips
to break. People turned to all sorts of odd things, such as pigeon dung, to try to reproduce
the pattern.
It was later discovered a virus called a potyvirus made the tulips break. The infection spread
through aphids or by contact with an infected tulip.The virus worked by affecting the distribution
of the pigment anthocyanin.
Today, such tulips are still costly, but for the damage potyvirus poses to gardens rather
than their beauty. Potyvirus-infected tulips, once so valuable, are now carefully weeded
out of gardens. Now there are specially-bred tulips that mimic the patterns of a “broken”
tulip, without the virus.
8. Electricity-Making Virus
Computer viruses were named after their biological counterparts. Now, biological viruses lead
back to electronics.
Some solids build electric charges when compressed. This is called the piezoelectric effect, and
it’s most well-known in quartz watches. The piezoelectric effect has several applications,
but materials used to make piezoelectric devices are toxic and difficult to work with. This
limits the widespread use of the piezoelectric effect.
Berkeley Lab scientists could change that with a virus. They used the M13 phage virus,
which targets bacteria and is harmless to humans. It’s useful for several reasons:
it multiplies itself by the millions, naturally arranges itself into orderly films like chopsticks
in a box, and is easy to genetically engineer. The ease in genetically engineering it helps
scientists boost its voltage, and its self-arrangement helps with the goal of self-assembly in nanotechnology.
The Berkeley Lab scientists tested their approach by making a generator. The generator works
by tapping a finger on a stamp-sized electrode patch coated with viruses. The viruses then
turn the force of the tap into electricity, producing enough current to operate a liquid-crystal
display (LCD).
With this technology, future devices could be charged from the vibrations of everyday
tasks, such as climbing stairs or shutting doors.
7. Battery Virus
Some computer and smartphone owners worry about viruses that can overclock their devices’
batteries and leave them with a useless metal brick. But biological viruses could do the
opposite: make batteries better.
In 2006, scientists at the University of Massachusetts (MIT) used a virus called M13 to make part
of a battery. This part, the anode, is part of a pair of poles in the battery with opposite
electrical charges. In 2009, the scientists completed the tricker task of making the anode’s
counterpart, the cathode.
To make it work, the scientists had to tweak two of the virus’s genes. The first gene
made proteins in the virus’s coat. The modifications allowed bits of iron phosphate to stick to
it and bulge “like tiny fists all along the length of the virus,” in the words of
study co-author Angela M. Belcher. The second gene let carbon nanotubes attach, forming
a network of millions of electricity-conducting viruses.
To make similar technologies, extremely high temperatures of about 660 degrees Fahrenheit
(350 degrees Celsius) were needed. However, the researchers could turn M13 into a battery-making
tool at or below room temperature.
According to Belcher, a third of an ounce (10 grams) of the virus battery could power
an iPod for 40 hours. However, she believes it is more suitable for large, high-power
things like electric cars.
In 2013, progress was made on that goal. With viruses, lithium-air batteries of electric
cars could be greatly improved. The M13 virus was used to make manganese-oxide nanowires
for lithium-air batteries. Unlike typically-made nanowires of the metal, the virus-made wires
had a rough, spiky surface, which greatly increased the wires’ surface area. The increase
in surface area could be a big advantage in the batteries’ charging rate. The process
has other benefits, too, such as increased electrode stability and less need for expensive
metals like palladium for the batteries.
6. Cancer-Fighting Viruses
Herpes and cancer: two diseases people really don’t want to talk about. But using herpes
to fight cancer is definitely worth discussing.
Imlygic is a new anti-cancer drug. On average, it extends melanoma patients’ lives by less
than four and a half months. This is barely statistically significant, but Imlygic is
special: it’s made using a virus. To be specific, it is a live, infectious, modified
version of HSV-1, the herpesvirus variety that’s the usual cause of cold sores.
Though Imlygic is not especially effective by itself, its flu-like side effects are mild
compared to chemotherapy. When cells turn cancerous, their virus-fighting machinery
breaks down. Herpesvirus prefers to attack cancer cells. When it attacks, the debris
of burst-open cells alerts the immune system, and the immune system then targets the cancer
cells.However, it is unclear whether the immune system targets all the cancer cells of the
body, or only those infected by the virus.
Though Imylgic is the first to get approval in the US as a cancer treatment, it is not
the only one in development. Tumor-killing viruses are a popular topic among scientists,
and the idea has been around for decades. More virus-based cancer treatments may join
Imlygic in the future.
5. Orange Virus Vaccine
It’s tradition to treat colds (which are caused by a virus) with orange juice. But,
using viruses, the orange trees themselves can fight off bugs spread by bugs.
Citrus greening (or huanglongbing, to use the Chinese name) is a deadly disease for
citrus trees. It is caused by the bacterium C. liberibacter, which is spread by sap-sucking
insects.
Before citrus greening came around, the most devastating orange virus was the citrus tristeza
virus. (or CTV) The virus was named after tristeza, a Portuguese word meaning “sadness”,
for the sadness that came from the virus’s arrival.
Now these two major citrus pests will be pitted against each other, with the fate of the USA’s
orange juice hanging in the balance.
Bill Dawson, a plant pathologist from the University of Florida, modified a local strain
of CTV. With this, anyone could insert new bits of DNA into the virus’s genome and
make it a protein factory. One of the world’s largest orange juice manufacturers, Southern
Gardens Citrus, licensed the viral vector from Dawson’s lab. With the virus as a needle,
all Southern Gardens needed was something to inject. The company chose genes from spinach,
which coded for antibacterial proteins called defensins.
Southern Gardens plans on infecting trees with a harmless strain of CTV. Branches from
CTV-infected trees would then be grafted onto other trees to spread the virus. As the virus
copies itself, it becomes a spinach defensin factory, and the defensins destroy C. liberibacter.
Since the biology of the tree is not modified, orange juice from these plants would not have
to carry a genetically-modified label. This makes getting regulatory approval much easier,
sidestepping the issue of distrust of genetically-modified plants.
4. Food Poisoning Protection
It’s terrible to hunch over a toilet, waiting to throw up, and idly wonder which of the
things you ate was germ-filled. Intralytix, founded in 1998, has a plan to give germs
a taste of their own medicine, so to speak: it uses viruses to infect (and kill) bacteria
that cause food poisoning.
Each of its products has a mix of viruses that target the same bacteria species.The
company’s first product, ListShield™, was approved in 2006. It is aimed at Listeria
bacteria, which cause listeriosis, a kind of food poisoning with a death rate of about
20%. ListShield™ is meant to be applied to ready-to-eat meats, such as deli meats
and hot dogs. To kill off Listeria, ListShield™ is sprayed on meat and the drains, floors
and other surfaces of a food processing plant.
Intralytix’s second product, EcoShield™, is for the O157:H7 strain of E.coli. EcoShield™
is sprayed on meat before it is ground into hamburger to kill E. coli. In studies with
government investigators, Sulakvelidze showed the product killed 95-100% of the E.coli strain
within 5 minutes.
The two treatments are odorless, tasteless, invisible and non-corrosive. The concentration
of phages in the liquid spray is 0.001%, making the product as harmless as water to anything
but target bacteria.
Later, another company, Micreos BV, made its own phage treatments, Listex™ (P100) and
Salmonelex™. Listex™ (P100) targets a Listeria species, while Salmonelex™ targets
Salmonella.
3. Antibiotic Viruses
Bacteriophages (or “phages”) are the natural enemy of bacteria. They copy themselves inside
bacteria, and the bacteria eventually burst open with viruses.
In the 1920s and 1930s, doctors treated a variety of infections with phages. However,
phage therapy had some problems. Scientists at the time did not know phages had to be
matched precisely with bacteria targets to work, which made phage treatments unreliable.
In addition, people sometimes became sick from the treatments because they were not
purified properly.
After World War II, antibiotics were mass-produced. They were more reliable than phages, so interest
in phages declined. Though phages were mostly forgotten in the United States, they weren’t
forgotten in the Soviet Union. Due to the Iron Curtain blocking access to some of the
best antibiotics of the West, the Soviets made do with phages and made phage therapy
more effective. In the modern day, phage therapy administered in several forms, such as tablets,
liquids, and injections, and remains a standard treatment in Poland, Georgia and Russia.
Unlike antibiotics, phages are very precise and leave the “good” bacteria of the body
alone. With the rise of antibiotic resistance, phages might make a comeback in the English-speaking
world.
2. Viruses killing other viruses
Ever heard the expression “fighting fire with fire”? Well, in this case it works,
if by “fire” one means HIV.
In 2011, scientists at the University of California-San Diego and UCLA made a harmless version of
HIV that relies on HIV to reproduce. This virus was called a therapeutic interfering
particle, or TIP. By slowing the replication of the HIV virus, TIPs might give someone
five to ten extra years before AIDS sets in.
The TIP’s genetic code was stripped to one-third of its original size, and it lacks important
pieces needed to copy itself. The TIP can only copy itself by sneaking into HIV’s
genetic code and copying when it does. TIPs also contain HIV-inhibiting sequences and
compete for the same proteins as HIV. Leor Weinberger, the leader of the team that made
TIPs, likens it to a “virus of a virus.”
According to Weinberger, TIPs could help with HIV “superspreaders.” These people, such
as drug users, are responsible for a disproportionately large amount of HIV infection.
In 2016, scientists orchestrated another virus-on-virus match, this time between reovirus and hepatitis
C. During childhood, reovirus can cause colds, but by adulthood most have been exposed to
it and are immune. It’s like an early-game enemy: inconvenient at first, but a piece
of cake once one’s gotten stronger.
In comparison, hepatitis C is like a final boss, one some find unbeatable. Hepatitis
C is a common cause of liver cancer, and cancers originating from the liver is the third-highest
cause of cancer deaths worldwide.
When this early-game enemy is pitted against the final boss…well, it’s the player (or
rather the patient) who wins. When introduced to the body, reovirus stimulates a signal
protein called an interferon, which activates a kind of white blood cell called a Natural
Killer cell. In experiments on human cancer samples and mice, the Natural Killer cells
then kill the tumor and cells infected with hepatitis C. The reovirus therapy could also
be used for other cancers associated with virus infections, like Epstein-Barr virus-associated
lymphoma.
1. Humans Made by Viruses
In The Matrix, bad guy Agent Smith likens humanity to a virus, a disease of the planet.
In real life, he’s right… to a degree.
More than 45 million years ago, a mammal was infected by a retrovirus. By turning their
RNA-based code to DNA, retroviruses such as HIV can sneak their instructions into the
host’s genome. Whenever the host’s cell copies itself, it also copies the virus. This
ancient retrovirus happened to infect a germ line cell and so could be spread to the primate
ancestor’s offspring.
17 years ago, in 2000, a team of Boston scientists discovered a strange gene in humans. This
gene, called syncytin, coded for a protein made only by cells in the placenta.
The two events are related: syncytin comes from the virus.
While the virus used that gene to fuse with a host cell, a developing fetus uses the gene
to fuse some placental cells into one single-celled layer. This layer is essential for the fetus
to draw nutrients from its mother.
The syncytin protein comes in two varieties, the previously mentioned being syncytin 1.
Reflecting its viral heritage, syncytin 2 tamps down the mother’s immune system and
prevents the immune system from attacking the developing fetus.
HERV-K inserted itself as recently as 200,00 years ago, making it the newest of all retrovirus
genes in humans. It activates important genes that help with embryo development, and its
viral particles and proteins help protect very young embryos from infection by other
viruses.
It is estimated that over 8% of human DNA came from viruses.