comparison of Techniques for Hiv-1 Rna Detection and Quantitation in Cervicovaginal Secretions

As new interventions are developed to prevent transmission of HIV-1, accurate and reproducible techniques to measure genital HIV-1 are necessary to provide surrogate markers of intervention effect. Genital tract HIV-1 load is likely a more direct measure of infectivity than plasma viral load, but it has been difficult to measure genital HIV-1 RNA levels in a standardized manner. A variety of techniques have been used to collect genital secretions for detection and quantitation of HIV-1. Studies of female genital HIV-1 have used swabs, filter paper Sno Strips, or cervicovaginal lavage (CVL) for specimen collection (1–8). Swabs and Sno Strips (Akorn, Inc., Buffalo Grove, IL) have been used for the separate collection of cervical and vaginal secretions, whereas CVL involves insertion of sterile saline into the vaginal vault with subsequent aspiration of lavage fluid (6,8). Little is known about the comparability of these methods. CVL may have the advantage of increased sampling surface area, in that the lavage fluid may come into contact with both the ectocervix and much of the vaginal wall. Swab and Sno Strip collection, conversely, offer the ability to determine compartment-specific changes in shedding unique to either the endocervix or the vagina. Sno Strips wick up a standardized volume of secretions and enable estimation of HIV-1 concentration per ml of genital fluid. Swabs and lavage specimens, however, can also be used to obtain estimates of concentration using a standardized denominator (i.e., per swab or per ml of lavage fluid), and these denominators may be more relevant to issues of infectivity. As perinatal and sexual HIV-1 intervention studies are designed, it remains important to determine the optimal method for genital HIV-1 sampling. For international studies, it is particularly important to identify collection techniques that are feasible for field conditions in developing country settings and lead to sensitive, reproducible measurement of genital HIV-1 RNA, even after storage and transport. We conducted a study to compare the prevalence, quantity, and reproducibility of HIV-1 RNA detection using three collection techniques (swabs, Sno Strips, CVL) and three storage methods (no medium, freezing medium, TriReagent) for genital specimens obtained from HIV-1 seropositive women in Nairobi, Kenya.