The Virus in Your Mucus

Dec. 6, 2013

By Medical Discovery News

Though it has a reputation as slimy and gross, mucus is one of the most valuable lines of defense against the bacteria people are exposed to every day of their lives. It exists not only in a person’s nose, but their respiratory, digestive, urogenital, visual, and auditory systems. Now science shows it contains viruses called bacteriophage (phage for short) that attack and kill bacteria.

A virus is a tiny, infectious agent that is made of a protein coating and a core of genetic information. Although viruses can carry genetic information, undergo mutations, and reproduce, they cannot metabolize on their own and thus are not considered alive. Viruses are classified by the type of genetic information they contain and the shape of their protein capsule. There are viruses that infect every living thing on earth. There are even viruses that infect other viruses. Certain viruses that can infect bacteria have been found in mucus.

A healthy adult produces about one to one and one half liters of mucus per day. Mucus consists of water, salts, antibodies, enzymes, and a family of proteins called mucins. Different mucins are responsible for signaling between cells, forming a chemical barrier for protection, and working with the immune system.

Scientists know that wherever bacteria live, there are also phage viruses that infect them. Areas with mucus have 40 phage for every bacterium, while that ratio is only five to one in areas without mucus. To discover what these phage are doing in the mucus, scientists grew two types of lung tissue in the lab: one that produces mucus and one that cannot. When both lung cultures were exposed to the bacteria E. coli, about half the lung cells died. However, when phage that kill the bacteria were added, the lung cells in the presence of mucus survived. This suggests that the combination of phage and mucus can efficiently kill potentially harmful bacteria. 

The researchers also discovered that the outside of phage is studded with antibody-like proteins that attach the phage to the carbohydrates in the mucus. This would help keep the phage where the bacteria are likely to be. The host may use this system to select which phage are localized to the mucus layers and which can be washed away, explaining why beneficial bacteria are not harmed by phage. An important implication of this system is that it controls the microbial populations in the digestive tract, which play a role in obesity, diabetes, and inflammatory bowel disease.

It all started with investigating how phage actually work in the body, and uncovered the revelation that there are in fact beneficial viruses. In the future, this research could be the foundation for designing phage that reside in mucus and combat specific bacteria, or even change the body’s microbiome. 

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By Medical Discovery News

Oct. 13, 2012

Compression of the proteins of this bacterial virus can generate small amounts of an electric current

Increasingly, the mind-blowing technology portrayed in science fiction movies comes to life in labs around the world. As engineering interfaces with the physical sciences, remarkable new advances in biomedicine happen. Two recently published studies in particular have the feel of “Star Wars.”

One involves engineering viruses to generate electricity, with the hope they’ll one day power nano-size devices implanted in the human body. These viruses, called bacteriophage, attack bacteria. Bacteriophages are simple organisms with a small number of proteins and a genome consisting of DNA or RNA, both gene-encoding molecules. The proteins coat the genome, protecting it as it enters a bacterium’s cell. It’s the unique structure of these proteins that scientists are now exploiting.

In a bacteriophage called M13, the proteins have two distinct parts. One end is positively charged and the other end of the protein, facing out, is more negatively charged. This arrangement of opposing charges at opposite ends of the same molecule can be exploited in a piezo-electric effect.

Piezo-electric means when the shape of these molecules is compressed, they generate an electric current. A mechanical button on outdoor gas grills works the same way when pressed. Researchers used the same concept to build tiny generators made out of biomolecules that could be activated by a person’s movements, such as stair climbing.

These microgenerators could potentially power implanted devices that diagnose disease or monitor therapeutic treatments. In the future, such devices might sense and report the levels of medically important compounds like glucose or neurotransmitters. A step beyond that would use microgenerators as a power source for implanted devices, such as the cochlear implant or “bionic ear” for the hearing impaired, which currently uses an external battery.

Another technology with significant implications for human health is the biological ion transistor computer chip – the first ever produced. In these biological transistors, charged molecules called ions take the place of electrons found in a traditional transistor. In essence, this means a computer chip can now network with human cells.

In recent experiments in Sweden, researchers have been using a powerful neurotransmitter called acetylcholine as the charged molecule. Acetylcholine is a muscle activator that, when released by a neuron, initiates movement. This happens when a message from the brain travels along the nerves to a muscle, like the bicep. Then a neuron transmits acetylcholine ions to nearby muscle cells, triggering the arm to move. In theory, the ion transistor could be wired and integrated into the nervous system to accomplish the same job.

In the future, this could allow fine control of muscle movement or more importantly, restore movement in people with paralysis. The experiments in Sweden have only worked with acetylcholine, but researchers believe the same technology could be used with other charged molecules. A chip could be made to balance serotonin levels, thereby acting as an antidepressant. One could even be made to monitor and boost the immune response when an invading virus or bacteria is present.

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