Viruses are interesting parasites that are unable to survive without a host. They are relatively simple and generally replicate within their hosts in one of two cycles: the lytic cycle, where the virus uses its host’s resources to make many copies of itself in order to cause the host to burst, or the lysogenic cycle, where the virus incorporates its genetic information into its host and remains hidden as the host replicates. There are certain viruses, called bacteriophages, that are known to specifically infect bacteria. In fact, phage therapy, or using bacteriophages to treat bacterial infections, has been attempted to varying degrees of success for some time. One recent study uncovered a novel viral mechanism of infection that may help improve the efficacy of future phage therapy.
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Researchers have discovered that certain bacteriophages, such as VP882, can tell when the bacteria they invaded have reached a certain density. Bacteria are able to communicate amongst themselves through quorum sensing, which allows the bacteria to inform each other when an optimal number of bacteria have replicated in order to collectively thrive within their surrounding environment. Interestingly, this study found that bacteriophages like VP882 “listen in” on the “conversations” between bacteria, which serves a very useful purpose by helping the viruses determine when to transition from a lysogenic to a lytic cycle. This prevents the viruses from killing their host when there are no other viable hosts around. The researchers also uncovered the specific pathway by which VP882 triggers its lytic cycle. They then sought to elucidate potential therapeutic applications by introducing genetically modified VP882 to Vibrio cholerae, Salmonella, and E. coli. The VP882 successfully invaded and killed each bacteria.
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The results of this study suggest that despite their deceivingly simple nature, viruses and how they function are still not completely understood. However, it is clear that they may serve to help us immensely. The researchers believe that these bacteriophages have great potential to treat numerous bacterial infections due to their ability to invade a wide range of bacteria. Many bacterial infections are currently treated using antibiotics, and although effective, this form of therapy has led to the issue of antibiotic resistance. If phage therapy is perfected, this issue resulting from conventional usage of drug treatments against bacteria could largely be avoided.
Feature Image Source: Arek Socha
