What is one limitation of using antiviral agents like Acyclovir for treating herpes viruses?

One significant limitation of using antiviral agents like Acyclovir for treating herpes viruses is the development of viral resistance. Over time, certain strains of the herpes virus can undergo mutations that make them less susceptible or entirely resistant to the effects of Acyclovir. This resistance can arise through various mechanisms, such as alterations in the viral thymidine kinase enzyme, which is crucial for the activation of Acyclovir into its active form that interferes with viral DNA synthesis. As a result, patients may experience treatment failures or a reduced effectiveness of the medication, making it challenging to manage infections effectively, especially in cases of prolonged or recurrent outbreaks.

Other potential limitations like high cost, short duration of action, or systemic allergic reactions may exist, but the issue of viral resistance is particularly noteworthy in the context of ongoing antiviral therapy and the need for effective treatment regimens over time.