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Antiviral resistance occurs when a virus can no longer be destroyed by the drug used against it. This resistance is a natural survival mechanism of the virus, a forced evolution caused by spontaneous mutation that is then passed down to later generations. Antiviral resistance is an ongoing problem in medicine, and doctors have to be both prudent and creative when keeping up with the evolving strains.
The resistance to antiviral drugs initially occurs through spontaneous mutation that allows a number of viruses to survive the drugs' effects. This mutation is then passed down to subsequent generations. There are a number of ways in which the mutation makes the virus immune. The mutation may result in the virus creating a form of inhibitor that either modifies or inactivates the drug itself. A virus may change the configuration of the site at which the drug would normally bind to it for destruction, making the drug unable to bind to and attack it.
The metabolic pathway of the virus may be altered, allowing it to find alternative ways of infecting the host so that the specifically designed drug becomes ineffective. Finally, the virus may decrease in permeability, reducing the ability of the drug to accumulate in great enough amounts to overcome it. As these characteristics are passed down through generations of the virus, the result is a drug-resistant strain. Virus strains can become resistant to single or multiple drugs, resulting in superbugs.
Antiviral resistance is a significant problem because it makes it much more difficult for doctors to effectively fight viruses. Viruses that were once treatable suddenly become untreatable, and the medical community has an uphill struggle to try and keep up. In conditions such as HIV, tuberculosis, and influenza, new single and combination drugs must continually be researched and created in order to keep the disease under control. Even viruses such as staphylococcus, which was easily treated, have developed resistant strains. There are significant implications both for immunosupressed patients and for potential pandemics with antiviral resistance.
Resistant virus strains are caused in large part by the overprescription of antibiotics and antimicrobials for illnesses that the patient could fight naturally. These medications are also often taken irresponsibly, with patients stopping the drugs before they have taken the full prescribed course. This subsequently results in some viruses surviving and becoming resistant. The excessive use of domestic cleaning products is also blamed as common viruses become continually exposed to the products but are not always killed, allowing the strains to build up a resistance.
Antiviral resistance is fought by the prudent and sparing prescription of drugs by doctors and the strong recommendation that patients take the full course of any medications they are prescribed. Multiple drugs are also used at the same time when treating infections such as HIV, with the hope that the virus will not become resistant to all, although this does happen. Finally, phage therapy is used where bacteriophages are released into the patient to consume and destroy the virus.