Can Viruses Be Our Allies?
Every day, an invisible struggle for survival takes place on our planet. Its participants are bacteria and even smaller viruses, bacteriophages. Although invisible to the naked eye, they have been shaping life on Earth for millions of years, controlling bacterial populations and influencing the functioning of all ecosystems
鈥� says Dr Magdalena Moryl from the Department of Biology of Bacteria, Faculty of Biology and Environmental Protection, 91桃色
Bacteriophages, commonly referred to as phages, are viruses that infect only bacteria. They are highly specialised. A given bacteriophage is usually capable of infecting only a specific bacterial species and often only selected strains within that species [1]. They are unable to infect plant, animal or human cells and therefore pose no threat to us.
It is now known that bacteriophages are the most abundant biological particles on Earth. They occur virtually everywhere: in soil, water, on plants, in food, as well as in the bodies of animals and humans [2]. They are particularly abundant in our intestines, as this is where the largest number of bacteria forming the gut microbiota reside. We come into contact with them from the very first moments of life and they are a natural component of our bodies. They form part of the so-called virome, the collection of all viruses present in the human body [3,4].
Although the word 鈥渧irus鈥� usually brings disease to mind, bacteriophages should be viewed quite differently. They are our invisible allies. They control bacterial populations in the environment and help maintain microbiological balance within our bodies.
Bacteriophages: The Snipers of the Microbial World
The feature of bacteriophages that attracts the greatest attention from scientists is their remarkable specificity. Every phage must find the 鈥渞ight鈥� bacterium. This is possible thanks to proteins located on its surface that recognise specific receptors on bacterial cells. This mechanism can be compared to a key that fits only one lock. Since different bacterial species, and even strains, have different receptors, bacteriophages are also highly selective. Once a suitable bacterium has been found, the phage attaches itself to its surface and injects its genetic material into the cell. The subsequent course of infection depends on the type of bacteriophage. Virulent phages take control of the bacterial cell and use its machinery to produce new virus particles. After a short time, the bacterium bursts (undergoes lysis), releasing more bacteriophages capable of infecting additional cells. This property is precisely what makes virulent phages so attractive as a natural weapon against pathogenic bacteria. They are used, among other things, in phage therapy and in improving food safety [3,5,6].
However, not all bacteriophages function like that. Temperate phages do not destroy the cell immediately after entering it. Their genetic material can become integrated into the bacterial genome and remain there for many generations in the form of a so-called prophage [5,6]. This property also makes bacteriophages valuable tools in biotechnology and genetic engineering.
Allies in the Fight Against Resistance
It is precisely the extraordinary specificity of bacteriophages that has brought them back into the spotlight of scientific research. Unlike many antibiotics, they can eliminate selected bacteria with great precision, while leaving the natural microbiota intact. This characteristic is gaining particular importance in an era of increasing antimicrobial resistance, when more and more bacteria are no longer responding to conventional treatment.
Phage therapy, the treatment of bacterial infections using viruses that attack bacteria, is one of the most promising applications of bacteriophages. This method is not new and dates back to the early twentieth century. Today, in the era of growing antimicrobial resistance, it is once again attracting enormous interest from scientists and physicians [5]. In Poland, phage therapy is conducted in specialised centres and is currently experimental in nature. It is primarily used for patients for whom standard antibiotic treatment has proved ineffective [7]. Therapy begins with the isolation of the bacteria responsible for the infection. Bacteriophages capable of effectively destroying them are then selected. Most often, a so-called phage cocktail, a mixture of several phages, is used. This increases the chances of successful treatment and reduces the risk of bacteria developing resistance to phages [8].
Challenges of Phage Therapy
Like antibiotics, bacteriophages are not a perfect solution. Bacteria can eventually develop resistance to phages as well, although this phenomenon is observed less frequently than resistance to antibiotics [6]. For this reason, scientists develop preparations containing several different phages that recognise different receptors on the bacterial surface. In addition, bacteriophages can be used together with antibiotics. Numerous studies have shown that such a combination produces better results than either method used independently [8,9,10].
Phage therapy also presents certain challenges. Cells of the immune system, macrophages, can capture viruses, reducing the number of phages available to combat bacteria. During therapy, the body may also gradually produce antibodies that neutralise the administered phages, which may limit treatment effectiveness [5,6]. In the case of infections involving biofilm formation (a compact structure of bacteria attached to a solid surface and surrounded by a layer of extracellular polymers that protect bacteria from external factors, such as medicines), treatment strategies also require careful planning [8]. Nevertheless, studies conducted so far indicate that phage therapy is well tolerated and that adverse effects occur rarely [1].
Viruses That Protect Food
The potential of bacteriophages extends far beyond medical applications. They are already used, or are being studied for possible use, in veterinary medicine, plant protection, agriculture and the food industry. They can serve as natural agents limiting the growth of dangerous bacteria in food and may even become components of innovative, environmentally friendly packaging that actively protects products against spoilage [11].
Scientists from the 91桃色 have been also working on such a solution in cooperation with partners from the Wroc艂aw University of Science and Technology and the University of Gda艅sk, as well as research institutions from Estonia, Belgium, Spain and Portugal. Together, they have been implementing the Bio4Pak project. Its aim is to develop biodegradable packaging containing a bacteriophage-release system that will extend shelf life and increase food safety [12]. It is an example of using microorganisms for the benefit of humanity. The visionary nature of Bio4Pak lies in combining natural mechanisms of bacterial control with the design of biodegradable packaging. This approach has the potential to transform the way we protect food, simultaneously increasing safety and reducing environmental impact.
References
- Mi臋dzybrodzki R, Borysowski J, Fortuna W, Weber-D膮browska B, G贸rski A. Terapia fagowa jako alternatywa w leczeniu zaka偶e艅 wywo艂anych przez bakterie antybiotykooporne. Kardiochirurgia i Torakochirurgia Polska. 2006;3(2):201-205.
- Clokie MR, Millard AD, Letarov AV, Heaphy S. Phages in nature. Bacteriophage. 2011;1(1):31-45. doi: 10.4161/bact.1.1.14942.
- Shkoporov AN, Hill C. Bacteriophages of the human gut: The "Known Unknown" of the microbiome. Cell Host Microbe. 2019;25(2):195-209. doi: 10.1016/j.chom.2019.01.017.
- W臋grzyn G. Should bacteriophages be classified as parasites or predators? Pol J Microbiol. 2022; 23;71(1):3-9. doi: 10.33073/pjm-2022-005.
- Strathdee SA, Hatfull GF, Mutalik VK, Schooley RT. Phage therapy: From biological mechanisms to future directions. Cell. 2023;186(1):17-31. doi: 10.1016/j.cell.2022.11.017.
- Olawade DB, Fapohunda O, Egbon E, Ebiesuwa OA, Usman SO, Faronbi AO, Fidelis SC. Phage therapy: A targeted approach to overcoming antibiotic resistance. Microb Pathog. 2024;197:107088. doi: 10.1016/j.micpath.2024.107088.
- Gordon M, Ramirez P. Efficacy and experience of bacteriophages in biofilm-related infections. Antibiotics (Basel). 2024;13(2):125. doi: 10.3390/antibiotics13020125.
- 艁usiak-Szelachowska M, Mi臋dzybrodzki R, Drulis-Kawa Z, Cater K, Kne啪evi膰 P, Winogradow C, Amaro K, Jo艅czyk-Matysiak E, Weber-D膮browska B, R臋kas J, G贸rski A. Bacteriophages and antibiotic interactions in clinical practice: what we have learned so far. J Biomed Sci. 2022;29(1):23. doi: 10.1186/s12929-022-00806-1.
- Moryl, M.; Szychowska, P.; Dzi膮g, J.; R贸偶alski, A.; Torzewska, A. The combination of phage therapy and 尾-lactam antibiotics for the effective treatment of Enterococcus faecalis infections. Int. J. Mol. Sci. 2025;26:11. .
- L贸pez-Cuevas O, Medrano-F茅lix JA, Castro-Del Campo N, Chaidez C. Bacteriophage applications for fresh produce food safety. Int J Environ Health Res. 2021;31(6):687-702. doi: 10.1080/09603123.2019.1680819.
Photos: Dr Bartosz Ka艂u偶ny, Centre for External Relations and Social Responsibility of the University, 91桃色
Source: Dr Magdalena Moryl, Department of Biology of Bacteria, Faculty of Biology and Environmental Protection
Edit: Centre for External Relations and Social Responsibility of the University, 91桃色
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