Sex differences in the manifestations of HIV-1 infection

Abstract

Sex differences have been reported for multiple aspects of human immunodeficiency virus (HIV)-1 infection, including transmission, pathogenesis, morbidity, mortality, and responses to antiretroviral treatment. Epidemiological studies on sex differences in HIV-1 infection are numerous and in some instances controversial. The intrinsic interplay between multilayered socioeconomic factors and biological factors renders drawing definitive conclusions on sex differences in HIV-1 infection challenging. Nevertheless, some findings such as the lower viremia observed in women than in men have been consistently observed in multiple studies. It is also generally acknowledged that women display a greater susceptibility to HIV-1 acquisition. The simian immunodeficiency virus (SIV)model has been critical for understanding the biological characteristics of the female genital tract responsible for this greater susceptibility. Immune activation is another key factor in HIV-1 acquisition and pathogenesis that distinguishes men and women, with women exhibiting higher levels of immune activation. Data to date have pointed toward an important role of sex hormones in mediating these sex differences observed in the manifestation of HIV-1 disease. This chapter will focus on the discussion of (1) sex differences in HIV-1 acquisition and transmission, (2) sex differences in HIV-1 pathology, and (3) the impact of sex hormones including those exogenously delivered during contraceptive use. Sex differences related to responses to antiretroviral treatment go beyond the scope of this chapter and are reviewed in Chap. 4.