Practical updates in clinical antiviral resistance testing

The laboratory diagnosis of antiviral resistance is a quickly changing field due to new drug availability, the sunsetting of older drugs, the development of novel technologies, rapid viral evolution, and the financial/logistic pressures of the clinical laboratory. This mini-review summarizes the current state of clinically available antiviral resistance testing in the United States in 2024, covering the most commonly used test methods, mechanisms, and clinical indications for herpes simplex virus, cytomegalovirus, human immunodeficiency virus, influenza, hepatitis B virus, and hepatitis C virus drug resistance testing. Common themes include the move away from phenotypic to genotypic methods for first-line clinical testing, as well as uncertainty surrounding the clinical meaningfulness of minority variant detection as next-generation sequencing methods have become more commonplace.