Herpesvirus infections are important after stem cell and organ transplant. During the last decades several
antiviral agents have been introduced with efficacy against herpesviruses. These agents are the
nucleoside analogues
aciclovir,
valaciclovir,
famciclovir, and
ganciclovir; the
nucleotide analogue
cidofovir; and the
pyrophosphate analogue
foscarnet. Several studies have been performed with
antiviral agents with the aim to reduce morbidity and mortality associated with
herpesvirus infections in transplant recipients.
Aciclovir and
valaciclovir have been examined in randomised, controlled trials in both solid organ and stem cell transplant patients, and were shown to be very effective for the prevention of herpes simplex virus (HSV) and varicella-zoster virus
infections. In addition, these drugs were shown to reduce cytomegalovirus (CMV)
infection and improve survival in allogenic stem cell transplant patients and to reduce CMV
infection, CMV disease (
aciclovir and
valaciclovir), and acute rejection (
valaciclovir) in renal transplant patients.
Ganciclovir is very effective for the prevention of CMV
infection and disease in both stem cell and solid organ transplant recipients. It can also be used in preemptive strategies in which the aim is to prevent CMV disease in patients who have ongoing CMV
infection documented by antigenaemia or detection of CMV
DNA. The latter strategy has the advantage of reducing the exposure to the
drug and thereby the risk for toxicity.
Foscarnet has also been shown to be effective as preemptive
therapy for CMV in allogenic stem cell transplant patients and as
therapy for
aciclovir-resistant HSV
infections. Finally
cidofovir is an interesting agent with broad spectrum antiherpesvirus efficacy. However, because of the
drug's toxicity profile, further studies are needed.