Sex and shedding of human immunodeficiency virus.

To the Editor—By distinguishing between women who ovulated during the menstrual cycle and those who did not ovulate, Green-blat et al. [1] found that sex, contrary to generally accepted opinion , influences circulating human immunodeficiency virus (HIV) type 1 RNA levels. In ovulating women, the virus load fell during the early follicular phase through the midluteal phase. Furthermore , cervicovaginal shedding of HIV among pregnant women was higher than it was among nonpregnant women with more-advanced HIV disease [2]. Since the hormonal balances of pregnant and nonpregnant women differ, the effects of ovulation and of pregnancy on HIV RNA levels seem to point to a connection with reproductive hormones. However, the mechanisms of both phenomena are not wholly understood. It may, therefore, be of interest to investigate similar phenomena in animals. In sheep infected experimentally with Chlamydia psittaci, shedding of the microorganism occurs only during the periovicular phase of the estrous cycle [3]. Detectable levels of chlamydiae obtained by vaginal swabs collected during different stages of the ewe's estrous cycle were restricted to the day of ovulation until ∼4 days later. Of note, a persistent chlamydial infection of the ewe's reproductive tract occurred after the experimental infection. The periovicular, increased shedding of C. psittaci in sheep and the influence of ovulation in women on the fluctuation in plasma HIV RNA level [1] seem to support the significance of changes related to reproductive ability. Another comparison relates to birds. In some of 19 orders of birds examined over 4 years in Israel, shedding of C. psittaci was higher in the summer than it was in the winter [4]. A more-detailed follow-up was done in pigeons (Columbia livia domestica) during 12 consecutive months [5]. Examination by immunofluorescence of cloacal swabs revealed that C. psittaci affected a large percentage of these birds without causing clinical symptoms. Chlamydial shedding reached a nadir in December, increased regularly until it peaked in August, and then decreased, again reaching a low near December, thus demonstrating an annual cycle. The seasonal variations of chlamydial antibodies in the pigeons were similar to the seasonal variations of the shedding of the C. psittaci microorganisms, which also peaked in July–August. The ubiquitous synchronizer of cyclic variations is the pho-toperiod [6]. Among vertebrate animals, the most highly evolved photoperiodic mechanisms occur in birds and regulate central life functions, including migration, reproduction, and molt [7]. In pigeons, for instance, size of the gonads …