Antiviral effect of the nucleoside analogue cidofovir in the context of sexual transmission of a gammaherpesvirus in mice.

Objectives: To investigate the efficacy of cidofovir to block gammaherpesvirus replication in the context of sexual transmission. Methods: A luciferase-expressing strain of murid herpesvirus 4 (MuHV-4) was used to monitor genital virus excretion from infected female BALB/c mice and sexual transmission to naive males. The efficiency of cidofovir to block genital excretion from infected females or replication and host colonization of naive males after sexual contact was tested by treating infected females (either once daily or at a single timepoint), naive males before exposure (either once daily or at a single timepoint) or males 24 h post-exposure. Results: We showed that daily treatment of infected females can reduce MuHV-4 genital shedding by 75%. Similarly, daily preventive treatment of naive males was sufficient to block viral replication and latency establishment in males. In contrast, a single administration of cidofovir to infected females at day 14 post-infection or to naive males 2 to 6 days before contact with MuHV-4-excreting females was not sufficient to significantly reduce viral shedding from females or infection of males, respectively. Interestingly, a single administration of cidofovir to males 24 h after contact with MuHV-4-infected females excreting the virus in the genital tract significantly reduced virus replication in males and seroconversion. Conclusions: Altogether, our results show that cidofovir can significantly reduce gammaherpesvirus replication, excretion and colonization of the naive partner in the context of sexual transmission. Such treatments could therefore be recommended in some specific conditions where gammaherpesvirus infections could be deleterious.