The human body, from its respiratory system to its gastrointestinal tract, houses a diverse assortment of microorganisms. Among these microorganisms, bacteria-killing viruses play a crucial role. However, the precise nature of the interaction between these viruses and human cells has long remained a mystery.
Previous research has suggested that human cells can engulf bacteria-killing viruses when they ingest the fluid surrounding them. In pursuit of a deeper understanding of how these ingested viruses might impact the immune response of cells, microbiologist Jeremy Barr embarked on a research venture.
To his surprise, Barr's investigation uncovered a startling revelation: mammalian cancer cells, when cultivated in a laboratory environment, were using these viruses as a source of sustenance. The implications of this discovery, detailed in a report published in PLOS Biology on October 26, challenge conventional biological knowledge and prompt questions about whether noncancerous cells may display similar behavior.
Jeremy Barr, affiliated with Monash University in Melbourne, Australia, characterizes this emerging field of research as a significant departure from established biological paradigms. He points out that the prevailing belief has been that "phages simply do not interact with mammalian cells." This new insight emphatically contradicts that notion.
Bacteriophages, the viruses that target and eliminate bacteria, are prevalent within the human body. Barr's estimates suggest that human cells ingest as many as 30 billion of these viruses daily. To investigate how these phages interact with mammalian cells, the research team conducted experiments using cancer cells derived from humans and dogs. These cells were chosen due to their ease of cultivation in a laboratory environment. The researchers cultivated the cancer cells in an environment rich in bacteriophage T4, a common virus that preys on E. coli.
In their quest to understand the cellular response to phages, Barr's team employed a range of antibodies, each designed to bind to specific types of proteins. While the researchers initially anticipated observing variations in proteins linked to inflammation, a key component of the cell's immune response, they were astonished to detect alterations in the levels of proteins associated with cell growth and division. According to Barr, cells exposed to phages exhibited accelerated rates of growth, implying that they were utilizing phages as a source of nourishment.
It is important to recognize that the cells used in this study were cultivated in a laboratory and were derived from established cell lines commonly used in scientific research. As a result, questions remain regarding whether cells within the bodies of humans and other mammals exhibit similar behavior. Paul Bollyky, an immunologist at Stanford University, warns that cell lines exhibit unique behaviors, often resembling tumor biology more than normal cell biology, making it challenging to extrapolate these findings to non-laboratory conditions.
Nonetheless, this study is seen as a groundbreaking revelation, challenging established beliefs and prompting intriguing inquiries about the interaction between mammalian cells and bacteriophages. In his future research, Jeremy Barr intends to explore whether noncancerous cells derived from living animals also engage in the consumption of phages. He also plans to delve deeper into the study of a broader range of phages, including those inhabiting the human gut and those employed in phage therapy, where viruses serve as an alternative to antibiotics in combating infectious bacteria."