Viruses have spent billions of years perfecting the art of invading cells, hijacking their machinery and spreading with ruthless efficiency. Now researchers are turning that evolutionary expertise against some of medicine’s hardest problems, from drug resistant infections to aggressive cancers. By stripping out harmful genes and rewriting viral genomes, they are transforming microscopic threats into precision tools that can hunt and kill disease.
I see a clear pattern running through this work: instead of fighting biology head on, scientists are co‑opting it. Whether they are building bacteriophages from digital code, refitting herpes viruses to attack tumors or using artificial intelligence to sketch entirely new viral blueprints, the goal is the same, to program infection so it helps rather than harms.
Rewriting nature’s code: how engineered viruses are built
The basic recipe for a therapeutic virus starts with subtraction. Researchers first remove or disable the genes that make a virus dangerous, then insert sequences that turn it into a delivery vehicle for drugs, immune stimulants or genetic instructions. One group describes this as a process to Strip a virus of its pathogenic genes and replace them with therapeutic ones, effectively converting a former pathogen into a programmable courier that can slip into specific cells and drop off its cargo.
What makes this approach so powerful is that evolution has already solved the hardest engineering problems. Viral shells are built to protect fragile genetic material, navigate the immune system and fuse with target cells. By swapping in different payloads, scientists can tailor the same chassis to very different jobs, from turning on an immune response to silencing a rogue gene. As one analysis of Reprogramming Viruses into Medicines notes, the same platform can be tuned depending on the therapeutic goal, whether that is killing infected cells outright or training the immune system to recognise a pathogen.
From digital DNA to AI designed hunters
Until recently, even engineered viruses started from something found in nature. That is changing as teams learn to assemble entire viral genomes from scratch. Using a method known as Golden Gate Assembly, scientists at New England Biolabs have shown they can build complete bacteriophages outside living cells, a project described as Building Phages From with the NEB Golden Gate Assembly platform. Instead of isolating a virus from sewage or soil, they start from a digital sequence, order the DNA fragments and snap them together like molecular Lego, which opens the door to designs that have never existed in nature.
Artificial intelligence is pushing that idea further by helping to write viral genomes that are both functional and highly specialized. In one landmark project, Scientists used machine learning to generate coherent viral DNA that produced working bacteriophages capable of killing resistant strains of bacteria, creating what they describe as the first AI designed viruses of concern for superbugs rather than for people. A related effort focused on Escherichia coli zeroed in on Using AI to design coli killing viruses that could infect and destroy strains that the classic phage ΦX174 could not touch, underscoring how algorithms can explore sequence space far beyond what evolution has already tried.
Those designs are not just theoretical. In another study, a team computationally generated hundreds of candidate phages, then synthesized and tested them in the lab. They report that they narrowed the field to 302 potential candidates and evaluated their ability to infect and destroy bacteria, confirming that several AI designed viruses could replicate and kill their targets as intended. Another group describes how Scientists have successfully used artificial intelligence to create bacteriophages that target and eliminate specific harmful bacteria strains, with an eye toward reshaping the biotech supply chain by making virus design faster and more predictable.
Phage therapy and the fight against antibiotic resistance
The most immediate battlefield for these engineered hunters is antibiotic resistance. As standard drugs lose their punch, clinicians are revisiting bacteriophages, viruses that infect bacteria, as precision weapons. One overview notes that Bacteria in our bodies have been learning to evade medicine by evolving and mutating until antibiotics no longer work, while bacteriophages, which are viruses that infect bacteria, can be engineered to track those same microbes down. The appeal is obvious, phages can be tuned to a specific pathogen, sparing the rest of the microbiome, and they can evolve alongside their targets.
The human stakes are not abstract. In one harrowing account, a mother describes how an antimicrobial resistant infection stalked her daughter, Mallory, and ultimately stole her life, while phage therapy remained out of reach. Stories like that are driving efforts to make customized phage treatments more routine. One technology platform describes Engineered viruses and phages capable of targeting pathogenic bacterium using a Unique approach that combines multiple strains into therapeutic phage cocktails, with Computer guided design intended to reduce the risk of bacteria becoming resistant to antibiotics and to the phages themselves.
Engineers are also starting to build phages that never existed in nature but are optimized for clinical use. A recent report on a Virus Designed in the Lab Could Help Defeat Antibiotic Resistance describes how a synthetic bacteriophage was built to attack a specific drug resistant bacterium, with the work credited to By New England Biolabs February in a concise 4 Mins Read summary. By combining that kind of bespoke design with platforms like NEB’s Golden Gate Assembly, phage therapy is edging closer to a world where a patient’s infection can be sequenced, matched to a digital library and treated with a made to order virus.
Turning cancer’s favorite viruses into tumor killers
Cancer presents a different challenge, since the enemy is not a foreign microbe but the body’s own cells gone rogue. Here, the strategy is to exploit viruses that naturally infect human tissues and redirect them toward tumors. Oncolytic viruses are designed to specifically target and kill cancer cells while leaving healthy cells unharmed, as one explainer on Oncolytic Viruses Work? puts it, and they are being refined to boost the immune response as they replicate. A detailed review of Retargeting viral tropism lays out Four layers of specificity for retargeting viral tropism, illustrated in Figure 2, from modifying the Virus particle itself to shielding it from the host immune response so it can reach tumors more reliably.
Some of the most advanced platforms build on viruses that once terrified public health officials. The Vaccinia Virus, best known for its role in smallpox vaccination, has become the backbone of several cancer therapies. Treatment platforms based on the vaccinia virus, such as Pexa Vec (JX 594), take advantage of the virus’s large genome to pack in genes that both lyse tumor cells and stimulate immune attack. Another effort focuses on the herpes simplex virus, or HSV, with Scientists turning HSV into a cure for multiple cancers by exploiting its ability to selectively replicate within and destroy tumor cells while being combined with standard care like chemotherapy and radiation.
Researchers are also layering in gene therapy techniques to sharpen that selectivity. One group working on cancers linked to herpesvirus describes a specialized technique that uses highly targeted gene therapy to kill cancer cells infected with the virus while leaving healthy cells unharmed, effectively turning the virus’s own presence into a homing signal. A separate program from Theolytics invites clinicians to Learn how Theolytics is pioneering a new approach to cancer treatment using oncolytic viruses that selectively infect and destroy tumour cells, underscoring how this field is moving from theory into commercial development.
Trojan horses and future frontiers
Not all cancer killing viruses work alone. Some are being paired with bacteria or other agents to mount multi pronged attacks on tumors. According to one report, According to UZH News, researchers engineered a common respiratory virus, called an adenovirus, to act like a Trojan horse that teams up with bacteria to penetrate solid tumors and destroy cancer cells from within. By combining the strengths of each microbe, the therapy aims to overcome the physical barriers and immune defenses that often blunt single agent treatments.
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*This article was researched with the help of AI, with human editors creating the final content.
