Effect of Seminal Fluid on the Colon Wall; Implications for HIV Transmission

Design of effective rectal microbicides to prevent HIV infection requires an understanding of rectal HIV transmission and the location within the lower gastrointestinal (GI) tract (luminal and mucosal) of HIV (cell-free and cell-associated) following exposure to infected seminal fluid. These basic details of HIV transmission have yet to be determined in human subjects, yet they are essential to select microbicide candidates if they are to be rationally designed to achieve effective concentrations at sites of HIV transmission. Rational development of a rectal microbicide also requires an understanding of those factors that may contribute to colonic mucosal injury - potential confounders of microbicidal effect. Such factors include exposure to seminal fluid which has been shown in animal and in vitro studies to cause histologic and permeability changes that might facilitate HIV transmission.

Inclusion criteria

• Able to provide signed informed consent
• Men of 21 years or older.
• Prior history of receptive anal intercourse.
• Laboratory values within the last 28 days:
• Negative for HIV antibodies
• Lymphocyte count within normal limits
• Neutrophil count > 1,000 cells/ml
• Cluster of Differentiation 4 (CD4) cell count > 500 cells/ml
• Platelet count ≥ 150,000 cells/mm3
• Prothrombin Time (PT) within normal limits
• Partial thromboplastin time (PTT) within normal limits.
• No childbearing intentions.

Exclusion criteria

• Active anorectal disease or recent (3 months) anorectal surgery;
• Diarrhea, defined as three or more loose stools per day, for at least three days prior to admission.
• History of sleep apnea, or airway problems with previous sedation procedures.
• History of significant adverse reaction to sedation medications.
• Other history, including significant occupational radiation exposure, history of inflammatory bowel disease or any other diseases and lab results, such that, in the judgment of the investigator, study procedures are not considered safe for the subject's participation.