Timing of intermittent seminal HIV-1 RNA shedding in patients with undetectable plasma viral load under combination antiretroviral therapy.

It was demonstrated that combination antiretroviral therapy (cART) reduces the HIV-1 viral load (VL) in the blood and the seminal compartment. Some studies have reported that the seminal HIV-1 VL is undetectable in individuals with an undetectable blood plasma viral load (bpVL) under cART. However, some recent studies have demonstrated that seminal HIV-1 RNA may still be detected, and potentially infectious, even in the case of an undetectable bpVL. The aim of this retrospective study was to determine the detection rate of a seminal VL and whether shedding could be intermittent over a very short time. From January 2006 to December 2011, 88 HIV-1 infected men, enrolled in an Assisted Reproduction program, provided 306 semen samples, corresponding to 177 frozen sperm samples (two samples delivered at a one-hour interval (n = 129) or one sample (n = 48)). All enrolled men were under cART, with an undetectable bpVL for more than 6 months. HIV-1 RNA was quantified in seminal plasma using a Roche COBAS Ampliprep COBAS TaqMan HIV-1 test. Seminal HIV-1 RNA was detected in 23 samples (7.5%) from 17 patients (19.3%). This detection rate was stable over years. With regards to the freezing of two samples delivered at a one-hour interval, the proportion of discordance between the first and second samples was 9.3% (12/129). Our results confirm the intermittent shedding of HIV-1 in semen. While this finding has been shown by studies examining longer time intervals, to our knowledge, this has never been demonstrated over such a short time interval.

[The process of X inactivation in the mouse]. / Le modèle de l'inactivation du chromosome X chez la souris.

X chromosome inactivation (XCI) is an excellent model for studying how epigenetic marks are initiated during early embryogenesis. XCI is an essential process that takes place in females, leading to dosage compensation between males and females. In mouse, it occurs in two waves: the first one is paternally imprinted, during the preimplantation period and the second one occurs in a random fashion. We provide here an update of the main molecular steps and hypothesis underlining this complex process.

Physiopathology of human embryonic implantation: clinical incidences.

Embryo implantation consists of a series of events promoting the invasion of the endometrium and then the uterine arterial system by the extra-embryonic trophoblast. In order for this semi-heterologous implantation to succeed, the endometrium has to first undergo a number of structural and biochemical changes (decidualization). The decidua's various constituents subsequently play a role in the embryonic implantation. The third step is the transformation of the uterine vascular system and the growth of the placenta, which will provide the foetoplacental unit with nutrients. Several physiopathological aspects will be discussed: 1) the implantation window, regulated by maternal and embryonic hormonal secretions and thus influenced by any defects in the latter: dysharmonic luteal phase, 21-hydroxylase block, abnormal integrin expression, 2) the successive trophoblast invasions of uterine vessels which, when defective, lead to early embryo loss or late-onset vascular pathologies, as preeclampsia, 3) the pregnancy's immunological equilibrium, with a spontaneously tolerated semi-allogeneic implant, 4) the impact of pro-coagulant factors (thrombophilia) on the pregnancy's progression, 5) the environment of the uterus, ranging from hydrosalpinx to uterine contractions. In summary, the least anatomical or physiological perturbation can interfere with human embryonic implantation - a very particular phenomenon and a true biological paradox.