♦️Bacteriophages, or phages, are viruses that specifically infect and kill bacteria, offering a potential alternative to traditional antibiotics. These viruses are highly selective, targeting specific bacterial species. For example, in the case of Escherichia coli (E. coli), the bacteriophage first attaches to the bacterial cell surface using specific receptors. After attachment, the phage injects its genetic material (usually DNA or RNA) into the bacterium. This genetic material then hijacks the bacterium’s machinery to replicate the viral genome and produce new phage particles. Once enough new phages are produced, they assemble within the bacterial cell. Eventually, the host cell bursts (lysis), releasing the newly formed phages to infect nearby bacteria. This process makes bacteriophages a promising tool in combating bacterial infections, especially those resistant to antibiotics.
♦️Bacteriophages are composed of proteins and a DNA or RNA genome that can be very simple, containing four genes, or complex, with hundreds of genes. The phages infect by injecting their genome into the bacteria which disrupts the bacteria’s normal replication cycle.
Phage Therapy;
🔷On discovering bacteriophages, Felix d’Hérelle noted that phages always appeared in the stools of patients suffering with Shigella just prior to recovery. This discovery led to increased research into the use of phages against bacterial infections in what became known as phage therapy.
🔷In comparison to using antibiotics as medicines, using phages does have benefits.
🔷Antibiotics kill bacteria indiscriminately, wiping out beneficial bacteria as well as the pathogens, whereas phages are much more specific as they only kill the pathogenic bacteria and are typically harmless to the host and their gut flora.
🔷In addition, bacteriophages have a high therapeutic index, the therapeutic index of a medicine is the measure of how safe a drug is, with a high index meaning they would be expected to have little to no side effects.
🔷When first discovered there was considerable excitement around bacteriophages for their possible use as medicines in what has become known as phage therapy.
🔷However, although the high specificity of phages is a benefit, there are also huge obstacles as vast ‘banks’ of phages are needed and must be regularly updated to keep up with the constantly evolving phages.
🔷These constantly changing banks make it difficult and expensive to safely check each treatment. As antibiotics were more effective and less expensive to produce, phage therapy was quickly side-lined.
The Journal of General Virology has launched the Bacteriophage Collection. Guest-edited by Professor Tetsuya Hayashi (Kyushu University, Japan), this collection brings together original research articles, methods, mini and full-length reviews relating to the diversity of bacteriophages and genomics-based research with a focus on their roles in the evolution of bacteria and ecosystems.
