Sexually transmitted infections (
STIs) caused by viruses, including HSV-2, HIV-1, HPV, are among the most prevalent
infectious diseases worldwide and a major cause of morbidity and mortality. Despite decades of effort, the attempts to develop efficacious
vaccines against viral
STIs have failed repeatedly, with the exception of the recent
HPV vaccine. Given the higher prevalence rates of
STIs in women, it is becoming clear that a better understanding of gender-specific differences in
STIs may be critical for the development of preventative strategies for these diseases. In order to gain this insight, it is important to examine the distinct microenvironment of the female reproductive tract, the site of primary
infection, since it can significantly influence the outcome of
infection. An important
biological factor in the female reproductive tract is the presence of female
sex hormones,
estrogen and
progesterone, which are produced endogenously primarily by the ovaries and commonly provided exogenously via the use of hormonal
contraceptives. Here we review our current knowledge of the role played by the female
sex hormones in regulating susceptibility and immune responses to viral
sexually transmitted infections and whether this could contribute to higher prevalence of
STIs in women. Manipulating the microenvironment of the female genital tract with
sex hormones may contribute to the development of improved immunization strategies against
sexually transmitted infections.