**Julia C. LeCher 1,2,\*, Nga Diep 2, Peter W. Krug <sup>2</sup> and Julia K. Hilliard <sup>2</sup>**


Received: 9 May 2019; Accepted: 30 May 2019; Published: 31 May 2019

**Abstract:** Herpes B virus is a deadly zoonotic agent that can be transmitted to humans from the macaque monkey, an animal widely used in biomedical research. Currently, there is no cure for human B virus infection and treatments require a life-long daily regimen of antivirals, namely acyclovir and ganciclovir. Long-term antiviral treatments have been associated with significant debilitating side effects, thus, there is an ongoing search for alternative efficacious antiviral treatment. In this study, the antiviral activity of genistein was quantified against B virus in a primary cell culture model system. Genistein prevented plaque formation of B virus and reduced virus production with an IC50 value of 33 and 46 μM for human and macaque fibroblasts, respectively. Genistein did not interfere directly with viral entry, but instead targeted an event post-viral replication. Finally, we showed that genistein could be used at its IC50 concentration in conjunction with both acyclovir and ganciclovir to reduce their effective dose against B virus with a 93% and 99% reduction in IC50 values, respectively. The results presented here illuminate the therapeutic potential of genistein as an effective antiviral agent against B virus when used alone or in combination with current antiviral therapies.

**Keywords:** herpes B virus; macacine herpesvirus-1; genistein; flavonoids; acyclovir; ganciclovir; antiviral agents
