Sperm can act as vectors for HIV-1 transmission into vaginal and cervical epithelial cells

Functional characteristics of 3'-azido-3'-deoxythymidine transport at the blood-testis barrier

3'-Azido-3'-deoxythymidine (AZT), an antiretroviral drug, is often adopted in the therapy for human immunodeficiency virus (HIV) infection, and the characteristics of AZT transport at the blood-testis barrier (BTB) were investigated in this study. In the integration plot analysis that evaluates the transport activity in vivo, the apparent influx clearance of [³H]AZT was significantly greater than that of [¹⁴C]D-mannitol, a non-permeable paracellular transport marker. In the uptake study in vitro with TM4 cells derived from mouse Sertoli cells, [³H]AZT uptake exhibited a time- and concentration-dependent manner, of which K_m and V_max values being 20.3 µM and 102 pmol/(min·mg protein), respectively. In the inhibition analysis, [³H]AZT uptake was not affected by extracellular inorganics and some substrates of transporters putatively involved in AZT transport. In the further inhibition analyses to elucidate the characteristics of AZT transport, [³H]AZT uptake was strongly reduced in the presence of several nucleosides, that are categorized as 2'-deoxynucleosides with pyrimidine, whereas little effect on [³H]AZT uptake was exhibited in the presence of other nucleosides, nucleobases, and antiretrovirals. These results suggest the influx transport of AZT from the circulating blood to the testis, and the involvement of carrier-mediated process at the BTB, which selectively recognizes 2'-deoxynucleosides with a pyrimidine base.

ESHRE guideline: medically assisted reproduction in patients with a viral infection/disease

STUDY QUESTION

What is the recommended management for medically assisted reproduction (MAR) in patients with a viral infection or disease, based on the best available evidence in the literature?

SUMMARY ANSWER

The ESHRE guideline on MAR in patients with a viral infection/disease makes 78 recommendations on prevention of horizontal and vertical transmission before, during and after MAR, and the impact on its outcomes, and these also include recommendations regarding laboratory safety on the processing and storage of gametes and embryos testing positive for viral infections.

WHAT IS KNOWN ALREADY

The development of new and improved anti-viral medications has resulted in improved life expectancy and quality of life for patients with viral infections/diseases. Patients of reproductive age are increasingly exploring their options for family creation.

STUDY DESIGN SIZE DURATION

The guideline was developed according to the structured methodology for the development of ESHRE guidelines. After the formulation of nine key questions for six viruses (hepatitis B virus, hepatitis C virus, human immunodeficiency virus, human papilloma virus, human T-lymphotropic virus I/II and Zika virus) by a group of experts, literature searches and assessments were performed. Papers published up to 2 November 2020 and written in English were included in the review. Evidence was analyzed by female, male or couple testing positive for the virus.

PARTICIPANTS/MATERIALS SETTING METHODS

Based on the collected evidence, recommendations were formulated and discussed until consensus was reached within the guideline group. There were 61 key questions to be answered by the guideline development group (GDG), of which 12 were answered as narrative questions and 49 as PICO (Patient, Intervention, Comparison, Outcome) questions. A stakeholder review was organized after the finalization of the draft. The final version was approved by the GDG and the ESHRE Executive Committee.

MAIN RESULTS AND THE ROLE OF CHANCE

This guideline aims to help providers meet a growing demand for guidance on the management of patients with a viral infection/disease presenting in the fertility clinic.The guideline makes 78 recommendations on prevention of viral transmission before and during MAR, and interventions to reduce/avoid vertical transmission to the newborn. Preferred MAR treatments and interventions are described together with the effect of viral infections on outcomes. The GDG formulated 44 evidence-based recommendations-of which 37 were formulated as strong recommendations and 7 as weak-33 good practice points (GPP) and one research only recommendation. Of the evidence-based recommendations, none were supported by high-quality evidence, two by moderate-quality evidence, 15 by low-quality evidence and 27 by very low-quality evidence. To support future research in the field of MAR in patients with a viral infection/disease, a list of research recommendations is provided.

LIMITATIONS REASONS FOR CAUTION

Most interventions included are not well-studied in patients with a viral infection/disease. For a large proportion of interventions, evidence was very limited and of very low quality. More evidence is required for these interventions, especially in the field of human papilloma virus (HPV). Such future studies may require the current recommendations to be revised.

WIDER IMPLICATIONS OF THE FINDINGS

The guideline provides clinicians with clear advice on best practice in MAR for patients with a viral infection/disease, based on the best evidence currently available. In addition, a list of research recommendations is provided to stimulate further studies in the field.

STUDY FUNDING/COMPETING INTERESTS

The guideline was developed and funded by ESHRE, covering expenses associated with the guideline meetings, with the literature searches and with the dissemination of the guideline. The guideline group members did not receive any financial incentives, all work was provided voluntarily. A.D. reports research fees from Ferring and Merck, consulting fees from Ferring, outside the submitted work. C.P. reports speakers fees from Merck and MSD outside the submitted work. K.T. reports speakers fees from Cooper Surgical and Ferring and consultancy fees as member of the advisory board BioTeam of Ferring, outside the submitted work. The other authors have no conflicts of interest to declare.

DISCLAIMER

This guideline represents the views of ESHRE, which were achieved after careful consideration of the scientific evidence available at the time of preparation. In the absence of scientific evidence on certain aspects, a consensus between the relevant ESHRE stakeholders has been obtained. Adherence to these clinical practice guidelines does not guarantee a successful or specific outcome, nor does it establish a standard of care. Clinical practice guidelines do not replace the need for application of clinical judgment to each individual presentation, nor variations based on locality and facility type. ESHRE makes no warranty, express or implied, regarding the clinical practice guidelines and specifically excludes any warranties of merchantability and fitness for a particular use or purpose. (Full disclaimer available at  www.eshre.eu/guidelines.).

Vaginal Epithelium Transiently Harbours HIV-1 Facilitating Transmission

Vaginal transmission accounts for majority of newly acquired HIV infections worldwide. Initial events that transpire post-viral binding to vaginal epithelium leading to productive infection in the female reproductive tract are not well elucidated. Here, we examined the interaction of HIV-1 with vaginal epithelial cells (VEC) using Vk2/E6E7, an established cell line exhibiting an HIV-binding receptor phenotype (CD4-CCR5-CD206+) similar to primary cells. We observed rapid viral sequestration, as a metabolically active process that was dose-dependent. Sequestered virus demonstrated monophasic decay after 6 hours with a half-life of 22.435 hours, though residual virus was detectable 48 hours' post-exposure. Viral uptake was not followed by successful reverse transcription and thus productive infection in VEC unlike activated PBMCs. Intraepithelial virus was infectious as evidenced by infection in trans of PHA-p stimulated PBMCs on co-culture. Trans-infection efficiency, however, deteriorated with time, concordant with viral retention kinetics, as peak levels of sequestered virus coincided with maximum viral output of co-cultivated PBMCs. Further, blocking lymphocyte receptor function-associated antigen 1 (LFA-1) expressed on PBMCs significantly inhibited trans-infection suggesting that cell-to-cell spread of HIV from epithelium to target cells was LFA-1 mediated. In addition to stimulated PBMCs, we also demonstrated infection in trans of FACS sorted CD4+ T lymphocyte subsets expressing co-receptors CCR5 and CXCR4. These included, for the first time, potentially gut homing CD4+ T cell subsets co-expressing integrin α4β7 and CCR5. Our study thus delineates a hitherto unexplored role for the vaginal epithelium as a transient viral reservoir enabling infection of susceptible cell types.

Immunocompetent Human 3D Organ-Specific Hormone-Responding Vaginal Mucosa Model of HIV-1 Infection

The lack of appropriate experimental models often limits our ability to investigate the establishment of infections in specific tissues. To reproduce the structural and spatial organization of vaginal mucosae to study human immunodeficiency virus type-1 (HIV-1) infection, we used the self-assembly technique to bioengineer tridimensional vaginal mucosae using human cells extracted from HIV-1-negative healthy pre- and postmenopausal donors. We produced a stroma, free of exogenous material, that can be adapted to generate near-to-native vaginal tissue with the best complexity obtained with seeded epithelial cells on the organ-specific stroma. The autologous engineered tissues had mechanical properties close to native mucosa and shared similar glycogen production, which declined in reconstructed tissues of the postmenopausal donor. The in vitro-engineered tissues were also rendered immune competent by adding human monocyte-derived macrophages (MDMs) on the epithelium or in the stroma layers. The model was infected with HIV-1, and viral replication and transcytosis were observed when immunocompetent reconstructed vaginal mucosa tissue has incorporated MDMs into the stroma and infected with free HIV-1 green fluorescent protein (GFP) viral particles. These data illustrate a natural permissiveness of immunocompetent untransformed human vaginal mucosae to HIV-1 infection. This model offers a physiological tool to explore viral load, HIV-1 transmission in an environment that may contribute to the virus propagation, and new antiviral treatments in vitro. Impact statement This study introduces an innovative immunocompetent three-dimensional human organ-specific vaginal mucosa free of exogenous material for in vitro modeling of human immunodeficiency virus type-1 (HIV-1) infection. The proposed model is histologically close to native tissue, especially by presenting glycogen accumulation in the epithelium's superficial cells, responsive to estrogen, and able to sustain a monocyte-derived macrophage population infected or not by HIV-1 during ∼2 months.

Viruses in the reproductive tract: On their way to the germ line?

Studies of vertebrate genomes have indicated that all species contain in their chromosomes stretches of DNA with sequence similarity to viral genomes. How such 'endogenous' viral elements (EVEs) ended up in host genomes is usually explained in general terms such as 'they entered the germ line at some point during evolution'. This seems a correct statement, but is also rather imprecise. The vast number of endogenous viral sequences suggest that common routes to the 'germ line' may exist, as relying on chance alone may not easily explain the abundance of EVEs in modern mammalian genomes. An increasing number of virus types have been detected in human semen and a growing number of studies have reported on viral infections that cause male infertility or subfertility and on viral infections that threaten in vitro fertilisation practices. Thus, it is timely to survey the pathway(s) that viruses can use to gain access to the human germ line. Embryo transfer and semen quality studies in livestock form another source of relevant information because virus infection during reproduction is clearly unwanted, as is the case for the human situation. In this review, studies on viruses in the male and female reproductive tract and in the early embryo will be discussed to propose a plausible viral route to the mammalian germ line.