Introduction BASHH guidelines state suppressive therapy for HSV in HIV+ individuals as aciclovir 400mg BD. Anecdotally some HIV+ patients report better control of genital HSV on different antiretroviral (ART) regimens. Previous studies have shown HIV protease inhibitors (PI) may induce antiviral effects against HSV. We audited our suppressive aciclovir (sACV) use in undetectable HIV patients on stable ART against BASHH standards. We noted frequency of genital HSV outbreaks in those on PI vs non-boosted ART regimens to see any signal that PIs may confer protection against HSV reactivation.

Methods Patients were eligible if they were receiving prophylactic aciclovir, male, 18–50 years of age, with HIV viral load below 50 copies/ml on current ART. The dose of aciclovir was recorded. We also collected information on: HSV outbreaks 1/10/16-31/1/17, ART regime, CD4 count, age/ethnicity, and duration of HIV infection.

Results 60 patients were identified. 47/60 patients were taking aciclovir 400mg BD. 13/60 were prescribed ACV 400mg OD only. For those on BD:

This gave a relative risk of HSV outbreak on a PI of 0.49 over the time studied.

Discussion Of eligible patients 78.3% of prescriptions met BASHH standards. Patients on sACV dosed at 400mg BD had a lower risk (RR 0.49) of symptomatic HSV recurrence if they were on PI based ART. This is important in the therapeutic management of co-infected patients and warrants further studies to better define the relationship.