Abstract
The spread of sexually transmitted infections caused by herpes simplex virus type 2 (HSV-2) has continued unabated despite educational efforts generated in response to the human immunodeficiency virus (HIV) epidemic. Given the absence of effective vaccines, this indicates the need to develop prophylactic measures such as topical antiviral agents. Chemical modification of bovine β-lactoglobulin (β-LG), the major protein of whey, by hydroxyphthalic anhydride (3HP) led to the generation of a potent HIV-1 inhibitor designated 3HP-β-LG. This agent was shown to also have antiviral activity against HSV-2 and HSV-1 in vitro. Recent studies indicate that 3HP-β-LG binds to HSV-1 virions, which, at least in part, involves the viral glycoprotein gE. Here we show that 3HP-β-LG inhibits HSV-2 infection in the mouse model of genital HSV-2 infection. Simultaneous exposure to HSV-2 and 3HP-β-LG caused a significant decrease in the proportion of infected animals (27% virus shedding, 5% lesion development and 0% fatality for 3HP-β-LG as compared to 80% shedding, 60% lesion development and 53% fatality in micetreated with PBS). The proportion of animals with HSV-2 infection after treatment with β-LG was similar to that in the PBS-treated group. Pretreatment with 3HP-β-LG formulated in a gel, which prolongs the presence of the agent in the vagina, also significantly reduced the proportion of HSV-2-infected mice (5% virus shedding, 5% lesion development and 0% fatality for 3HP-β-LG as compared to 70% shedding, 60% lesion development and 40% fatality in vehicle-treated mice). These differences were significant (P≤0.0005, 0.002 and 0.008 for shedding, lesion development and fatality, respectively). Virus titres in the minority of mice that developed infection were similar to those in untreated mice. HSV-2 infection was not inhibited by treatment of an ongoing infection, indicating that 3HP-β-LG interferes with the initial infection. These data suggest that 3HP-β-LG may be an efficacious agent for preventing vaginal transmission of genital herpesvirus infections.