Hi Warstekholic, What’s going on ? I hope you are doing well and this article will benefit your mind. Did you realize that we have been through the COVID-19 period for more than 2 years since it was announced on December 31st, 2019? [1] Despite the word “virus” is always associated with harmful things for humans, there is a virus which gives virtue to us. We call the virus bacteriophages which derived from the Greek words meaning “bacteria eater”, which is a virus that infects harmful bacteria and can not affect humans [2]. Like other types of viruses, bacteriophages vary a lot in their shape and genetic material. Using bacteriophages for the treatment of pathogenic bacterial infections is called Phage therapy.
History of Phage Therapy
In 1917, Twort and Felix d’Herelle, a microbiologist at the Institut Pasteur in Paris, published a paper describing the lysing of bacteria by an invisible microbe he named “bacteriophage.” The first known therapeutic use of phages occurred in 1919, when d’Herelle and several hospital interns ingested a phage cocktail to check its safety, then gave it to a 12-year-old boy with severe dysentery. The boy’s symptoms cleared up after a single dose and he fully recovered within a few days. Yet d’Herelle didn’t publish his findings until 1931 [3].
Western scientists “re-discovered” phage therapy in the 1980s. Since then, the growing threat of antibiotic-resistant bacterial strains has continued to further interest in phage therapy as a potential alternative. In the 2000s, human experiments began again and data from the first phase I clinical trial in the U.S. was published in 2009. That trial tested the safety of a cocktail of phages specific for E. coli, Staphylococcus aureus and Pseudomonas aeruginosa in 42 patients with chronic leg ulcers. Since it was a phase 1 trial, the study only analyzed safety, not clinical outcomes. No adverse events related to the phages were reported [4].
Bacteriophage infections
Bacteriophages, just like other viruses, must infect a host cell in order to reproduce. The steps that make up the infection process are collectively called the lifecycle of the phage. Some phages can only reproduce via a lytic lifecycle, in which they burst and kill their host cells. Other phages can alternate between a lytic lifecycle and a lysogenic lifecycle, in which they don’t kill the host cell (and are instead copied along with the host DNA each time the cell divides) [5]
We can simplify that bacteriophages kill bacteria by binding to them and then destroying them or breaking them apart. Viruses infect bacteria by injecting DNA or RNA genes. Then, the virus will reproduce or replicate itself in the bacteria. In one bacterium, there can be more than a thousand new viruses. From there, the virus will break down the bacteria and produce new bacteriophages. Given their nature as parasites, bacteriophages require a bacterial host to grow and reproduce. Once all the bacteria are dead, they will stop multiplying. Just like other viruses, bacteriophages can hibernate until there is another bacterium that can become the next host.
The beneficial bacteriophage for humans’ disease
Phage therapy is the 90-year-old practice of using bacteriophages as bactericidal agents to treat bacterial illnesses in humans and other species. Bacteriophages may help overcome the main drawbacks to today’s antibiotics. Every year, antibiotic-resistant infections kill more than 50,000 people in Europe and the United States alone [6]. A study commissioned in Britain suggests such infections could cause 10 million deaths a year by 2050 and some experts call that a conservative estimate. Still, the predictions have forced scientists to look beyond the antibiotic age to alternative methods of killing bacteria.
There are several advantages of bacteriophages in fighting bacteria compared to antibiotics, such as:
- killing bacteria that are resistant to antibiotics
- It can be used alone or in combination with antibiotics
- can multiply itself, so it only takes one dose.
- It does not interfere with the good bacteria in the body
- Easy to discover and natural
- Not harmful to the human body
- There is no potential to poison animals, plants and the environment.
The beneficial bacteriophage for Plants’ disease
Figure 1. Effect of Ralstonia solacacearum specific phage following inoculation with R. solacacearum on bacterial wilt. Plant on left was inoculated with bacterium only while plant on right was inoculated with bacterium and then bacteriophage.
The first pioneers were Mallman and Hemstreet, who in 1924 observed that filtrate of the liquid collected from the decomposing cabbage inhibited the growth of the bacterium that caused the rot, Xanthomonas campestris pv campestris [7]. In 1925, Kotila and Coons demonstrated that bacteriophages isolated from the soil suppressed growth of Pectobacterium carotovorum subsp atrosepticum, the causal agent of blackleg disease of potato [8]. They performed bioassays and successfully prevented rotting of potato tubers by co-inoculating the phage with the phytobacterium. Additionally, they isolated phages active against Pectobacterium carotovorum subsp carotovorum and Agrobacterium tumefaciens from a number of environmental sources, such as river water and soil. Several experiments also were conducted using phage specific to Ralstonia solanacearum, in which the phage suspensions were applied to soil surrounding tomato plants pre – and post-inoculation with the bacterial wilt pathogen.
There are several advantages of bacteriophages in fighting Plants’ diseases
- killing Xanthomonas campestris pv campestris
- killing Ralstonia solanacearum,
- killing Pectobacterium carotovorum subsp carotovorum
- killing Agrobacterium tumefaciens
- killing another plants’ diseases
References
[1] World Helth Organization. 2019. COVID-19 – China.
[3] Wittebole, X., De Roock, S., & Opal, S. M. (2014). A historical overview of bacteriophage therapy as an alternative to antibiotics for the treatment of bacterial pathogens. Virulence, 5(1), 226–235. https://doi.org/10.4161/viru.25991
[7] Mallmann WL, Hemstreet CJ. Isolation of an inhibitory substance from plants. Agricultural Research. 1924;28:599–02