Bacteriophage: Mr. Nice Guys of the Virus World
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It's widely accepted that HIV, Hepatitis C, Ebola, and the ongoing coronavirus have acquired a bad reputation for viruses due to their aggressive and infectious nature. But actually, there are nice guys in the virology world, microscopic bacteriophages. Different from dreadful bad viruses that will invade the host cell to take over the cellular machinery, release more infectious viral particles, and finally cause illness, phages are protective viruses that can attack and destroy bacteria.
About Phages
Bacteriophage, or known as phage, whose name is derived from the Greek word phagein, indicating the eater of bacteria. These spidery-looking viruses have a population of over 1031, larger than the total number of all other organisms, including bacteria, remaining the most abundant life-form on the planet. They could be found almost everywhere bacteria exist, including water, air, soil, the mucous membrane lining of digestive, respiratory, and reproductive tracts in bodies.
Phages are generally classified into virulent and temperate phages according to whether they cause host cell lysis. Virulent phages kill bacteria by infecting bacteria and lysing host cells, while the temperate bacteriophages integrate genes into bacterial DNA, which will synchronously replicate with hosts' DNA without causing cell lysis.
Bacteriophages As Therapy
With the powerful nature of killing bacteria and the undeniable fact that antibiotic-resistant infections are increasingly causing deaths, phages are chosen as the potential anti-bacterial therapies.
Compared to antibiotic treatments, bacteriophage therapy represents more excellence in different aspects. One obvious upside to phage therapy is that no obvious side effect is observed in the patients. Different from antibiotics that work on all bacteria, including the good ones, phages only attack a specific type or group of bacteria. Besides, phage-based therapies do not depend on dosage so much.
Although bacteria will also develop resistance to phages to survive, it takes less time to develop new phage therapies than novel antibiotic development. Moreover, the biological nature of phages enables them to evolve along with bacteria if they adjust to escape from the phages.
Phages have been allowed to treat dysentery, sepsis caused by Staphylococcus aureus, salmonella infections, and skin infections in some European and Asia countries and are approved by the FDA and USDA in the USA for treating processed poultry and meat products.
The Future of Phages
Public usage of phages as therapeutics still is an open case due to lack of research. However, it's undeniable that both unmodified and engineered phages keep attracting researchers in various fields. For instance, researchers use phage display to modify and isolate antibodies for in vitro and in vivo diagnostic and therapeutic purposes. Furthermore, phage or phage display vaccines could contribute to treating bacterial and viral pathogens, as well as cancer diseases. To sum up, bacteriophages are the Mr. nice guys in the virus world in the forms of reporter phages, labeled phages, therapeutic phages, etc.