Vaginal formulations of carrageenan protect mice from herpes simplex virus infection

The observations from the present study indicate that vaginal formulations of the sulfated polysaccharide carrageenan are highly effective in protecting mice from herpes simplex virus type 2 (HSV-2) infection. Test formulations were placed in the vaginas of progestin-treated mice prior to inoculation with HSV-2. Infection was determined by the presence of inflammation in the genital region and death. At a dose of virus that infected half of the control animals, 1% solutions of either lambda, kappa, or iota carrageenan prevented infection of almost all of the animals. Concentrations as low as 0.05% protected a large majority of the mice. At a dose of virus that infected all of the control mice, 1% solutions of carrageenans protected 85% of the inoculated mice. Other sulfated polysaccharides were less effective or showed no efficacy in preventing HSV-2 infection. These findings suggest that a vaginal formulation of carrageenan may be effective in blocking sexual transmission of HSV-2 in women.