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Impact of combination oral contraceptives, Depot Medroxyprogesterone Acetate and the Levonorgestrel Intrauterine System on diffusion of HIV Type 1 within cervicovaginal mucus

Cassing Hammond, Northwestern University, 2010

Project abstract

Background: At least 14 prospective clinical studies have evaluated the association between risk of HIV-1 infection and contraception. Multivariate-adjusted relative risks of incident HIV-1 infection vary among study populations both for combination oral and injectable contraceptive users. The possibility that some forms of contraception might offer relative benefit or risk to women exposed to HIV deserves continued examination.

Many common contraceptive agents alter the cervicovaginal mucus and even depend on such alterations for optimal contraceptive efficacy. Because heterosexual transmission of HIV-1 requires that virus penetrate the mucus that covers epithelial layers within the female genital tract, any factor that alters diffusion of the virus within mucus might also impact rates of infection.

The proposed study examines how diffusion of HIV-1 in cervicovaginal mucus varies before and three months after initiation of three types of hormonal contraception.

Aims: This observational study compares rates of diffusion of HIV-1 in cervicovaginal mucus before and three months following initiation of combination oral contraceptives(COCs), the LNG-IUS (Mirena®), and Depo Provera Contraceptive Injection®

Methods: At baseline and three months after initiating contraception, cervical mucus aspirated from endocervix will undergo imaging evaluation to determine local microenvironments within imaging areas. Fluorescently labeled HIV will be added to the mucus, and movement of viral particles within a single focal plane of solution will be monitored using an ultra-sensitive EM-CCD camera at a capture rate of 10 frames per second for 120 seconds. 5 random fields will be imaged and characterized for each condition. Average ensemble particle displacements within each field will be analyzed using IDL particle trafficking software. Mean square displacements (MSDs) of virus like particles (VLP) will be determined and standard error calculated. Significant differences in MSD observed between baseline and 3 months post initiation of contraception will be determined within groups and between methods using paired sample ANOVA.

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