Viral resistance toward Acyclovir, which has been used for more than 20 years, is on the rise. – Proceedings of the National Academy of Sciences (PNAS) (1)
Not long ago, we talked about how some members of the herpes virus family, such as the varicella zoster virus (VZV), are becoming resistant to antiviral drugs like acyclovir (ACV). But, it’s becoming apparent that VZV is not the only herpes strain that is developing immunity to antiviral drugs.
This is an important thing for the public to realize since Dr. Adalbert Krawczyk and colleagues wrote in a study that “In immunocompetent individuals HSV may cause clinical recurrences with sometimes painful yet usually self-limiting orolabial or genital lesions. However, infections may become chronic and result in physical disabilities, social exclusion, and psychological distress over time.” (1) Dr. Krawczyk is from the Institute of Virology at the University Hospital Essen in Essen, Germany.
Dr. Krawczyk emphasized that “for more than two decades viral DNA targeting chemotherapeutics such as acyclovir (ACV) have been used as drugs for the prophylaxis and treatment of HSV infections. Viral resistance toward these compounds is, however, increasingly observed. ACV-refractory HSV keratitis, for example, is a leading cause of corneal morbidity and blindness in humans of industrialized countries.” (1)
People with a healthy immune system are usually able to control the HSV virus and keep it from becoming more than an occasional, painful annoyance. People with a healthy immune system have herpes outbreaks that rarely last more than two weeks, and their herpes sores are small and short lived. However, another study said that, “In contrast, immunocompromised patients might not be able to control HSV infection.” (2)
This means that someone who has a weakened immune system is at risk for longer and more painful herpes outbreaks.
In these people, “frequent and severe reactivations are often seen.” (2) This happens for two reasons. The first is that the person’s immune system is weak. The second is because the virus has built resistance against the most commonly prescribed antiviral drugs. The over prescription of anti-herpes medications has given the herpes virus an opportunity to mutate and develop a resistance to those drugs.
The bottom line?
Acyclovir and related drugs are the current drugs of choice for the treatment of herpes infection and viral reactivation. However, as the studies above found, the herpes virus is becoming resistant to the most commonly prescribed antiviral drugs, including ACV.
References:
(1) Adalbert Krawczyk, Michaela A. E. Arndt, Ludger Grosse-Hovest, Wilko Weichert, Bernd Giebel, Ulf Dittmer,a Hartmut Hengel, Dirk Jäger,b Karl E. Schneweis, Anna M. Eis-Hübinger,g Michael Roggendorf, and Jürgen Kraussb “Overcoming drug-resistant herpes simplex virus (HSV) infection by a humanized antibody” Proc Natl Acad Sci U S A. 2013 Apr 23; 110(17): 6760–6765.
(2) Chilukuri S, Rosen T. “Management of acyclovir-resistant herpes simplex virus.” Dermatol Clin. 2003 Apr;21(2):311-20.