Issn Print: 0269-9370
Publication Date: 2001/02/01
Biology of mucosal transmission of HIV in the genital tract
Excerpt
Some of the most important physical barriers to the mucosal transmission of HIV during heterosexual intercourse are having an intact and healthy vaginal and cervical epithelium, a robust microbial flora predominated by Lactobacillus species, and low levels of inflammation. Conversely, factors which are known to enhance HIV transmission include disruptions in the genital epithelium which can be induced by repeated exposure to agents found in contraceptives or microbicides, the presence of infectious agents which cause genital ulcer disease. Similarly, there is a growing body of data suggesting that HIV transmission efficiency is enhanced when the condition known as bacterial vaginosis is present. The presence of inflammatory cells which are present due to exposure to irritating chemicals or contraceptive agents, or inflammation induced by STDs, is also known to enhance HIV transmission efficiency. The introduction of an agent to prevent transmission of HIV via the genital tract may have multiple effects on these innate defenses. For example, the introduction of nonoxynol-9 may have direct microbicidal activity against infectious agents, but may also enhance epithelial disruption. Exposure to nonoxynol-9 may enhance sub-epithelial inflammation. The resulting release of myeloperoxidase from activated neutrophils may be beneficial to women whose vaginal microflora includes H2O2-producing lactobacilli due to the enhanced activity of the myeloperoxidase-H2O2 killing system, but may be detrimental among women without H2O2-producing lactobacilli. In vitro and preclinical studies will never provide adequate information to accurately predict the multiple biologic effects of any topically applied agent on resistance to HIV at the mucosal level. Clinical trials evaluating the effectiveness of strategies for prevention of sexual transmission of HIV should include, whenever possible, measures of inflammation, disruption of the epithelium and the components of the microflora in order to better understand the relative importance of these factors in altering the transmission efficiency of HIV.
Facebook
Twitter
LinkedIn
Email
