HIV-1 chemokine co-receptor CCR5 is expressed on the surface of human spermatozoa

Characterization and distribution of HIV-infected cells in semen

Semen is a known vector for both human immunodeficiency virus (HIV) infection and transmission. However, the distribution and characteristics of HIV-infected cells in semen remain unclear. Investigating the possibility of transmission through the spermatozoon in semen is of great clinical significance to improve the strategies for exposure prevention and assisted reproduction for HIV-infected partners. Twenty-six HIV-infected patients, including twelve treatment-naïve (TN) patients and fourteen antiretroviral treated (ART) patients, were enrolled in this study. HIV p24 protein in spermatozoa was detected using imaging flow cytometry and immunohistochemistry, and HIV RNA was identified using next-generation RNAscope in situ hybridization. Additionally, we described the rates of HIV-positive spermatozoon and CD4⁺ T lymphocytes in semen, and found that p24⁺ spermatozoon were mainly CD4 negative regardless of whether the patients received ART. Of note, p24-positive cells in semen are predominantly spermatozoa, and we confirmed that motile spermatozoa carried HIV into peripheral blood mononuclear cells of healthy men in vitro. Our findings provide evidence regarding the risk of HIV-infected spermatozoa.

So Pathogenic or So What?-A Brief Overview of SIV Pathogenesis with an Emphasis on Cure Research

HIV infection requires lifelong antiretroviral therapy (ART) to control disease progression. Although ART has greatly extended the life expectancy of persons living with HIV (PWH), PWH nonetheless suffer from an increase in AIDS-related and non-AIDS related comorbidities resulting from HIV pathogenesis. Thus, an HIV cure is imperative to improve the quality of life of PWH. In this review, we discuss the origins of various SIV strains utilized in cure and comorbidity research as well as their respective animal species used. We briefly detail the life cycle of HIV and describe the pathogenesis of HIV/SIV and the integral role of chronic immune activation and inflammation on disease progression and comorbidities, with comparisons between pathogenic infections and nonpathogenic infections that occur in natural hosts of SIVs. We further discuss the various HIV cure strategies being explored with an emphasis on immunological therapies and "shock and kill".

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.

The role of infections and leukocytes in male infertility

Declining birth rates are one of the problems facing society today. Male counterparts are responsible for about half of the infertility cases, and genitourinary tract infections may play a contributing role in approximately 15% of male infertility cases. Leukocytospermia is an established indicator of infection in the male urogenital tract, although other microorganisms such as bacteria and virus may also be contributors to the etiology of male infertility. The pathophysiology of these infectious agents may be initiated by a local inflammatory reaction resulting in an increase in reactive oxygen species (ROS). This results in testicular injury, thereby affecting sperm morphology, sperm motility, sperm viability and elevation of the seminal leukocyte as a result of the genital tract infection. The infectious and inflammatory changes can result in male infertility. It is proposed that high concentrations of seminal leukocyte and infectious agents may affect sperm function resulting in clumping of motile spermatozoa, decreasing acrosomal functionality and also causing alterations in sperm morphology. However, the literature has poorly clarified the role of infection in male infertility, provoking further debate and research on this topic.

Comparisons of Human Immunodeficiency Virus Type 1 Envelope Variants in Blood and Genital Fluids near the Time of Male-to-Female Transmission

To better understand the transmission of human immunodeficiency virus type 1 (HIV-1), the genetic characteristics of blood and genital viruses from males were compared to those of the imputed founding virus population in their female partners. Initially serodiscordant heterosexual African couples with sequence-confirmed male-to-female HIV-1 transmission and blood and genital specimens collected near the time of transmission were studied. Single viral templates from blood plasma and genital tract RNA and DNA were sequenced across HIV-1 env gp160. Eight of 29 couples examined yielded viral sequences from both tissues. Analysis of these couples' sequences demonstrated, with one exception, that the women's founding viral populations arose from a single viral variant and were CCR5 tropic, even though CXCR4 variants were detected within four males. The median genetic distance of the imputed most recent common ancestor of the women's founder viruses showed that they were closer to the semen viruses than to the blood viruses of their transmitting male partner, but this finding was biased by detection of a greater number of viral clades in the blood. Using multiple assays, the blood and genital viruses were consistently found to be compartmentalized in only two of eight men. No distinct amino acid signatures in the men's viruses were found to link to the women's founders, nor did the women's env sequences have shorter variable loops or fewer N-linked glycosylation sites. The lack of selective factors, except for coreceptor tropism, is consistent with others' findings in male-to-female and high-risk transmissions. The infrequent compartmentalization between the transmitters' blood and semen viruses suggests that cell-free blood virus likely includes HIV-1 sequences representative of those of viruses in semen.IMPORTANCE Mucosal transmissions account for the majority of HIV-1 infections. Identification of the viral characteristics associated with transmission would facilitate vaccine design. This study of HIV strains from transmitting males and their seroconverting female partners found that the males' genital tract viruses were rarely distinct from the blood variants. The imputed founder viruses in women were genetically similar to both the blood and genital tract variants of their male partners, indicating a lack of evidence for genital tract-specific lineages. These findings suggest that targeting vaccine responses to variants found in blood are likely to also protect from genital tract variants.

A CCR5 antagonist-based HIV entry inhibitor exhibited potent spermicidal activity: Potential application for contraception and prevention of HIV sexual transmission

B07 is a small-molecule CCR5 antagonist-based HIV-1 entry inhibitor that is being developed as an anti-HIV microbicide for preventing sexual transmission of HIV. Here we evaluated its spermicidal and contraceptive potential, including sperm motility, plasma membrane integrity, and contraceptive efficacy tested in rabbits. We found that B07 inhibited sperm motility and movement patterns in a concentration- and time-dependent manner. Within 30 min, B07 induced sperm immobilization with the minimum 100% effective concentration and median effective concentration of 640.0 and 64.4 μg/mL, respectively. The hypo-osmotic swelling test showed that plasma membranes of B07-treated sperms exhibited slight disruption, as verified by electron micrographs. In both B07 gel and N-9 gel groups, not a single implantation site or embryo was observed based on the contraceptive efficacy test in rabbits, indicating that B07 could effectively block the potential of sperm to reach and/or fertilize oocytes. The safety profile of B07 in vivo was evaluated by use of an optimized rabbit vaginal irritation test. While the pathological scores of the N-9 gel group was 14.67 ± 1.21, those of the blank control and B07 gel groups were 2.17 ± 0.76 and 4.00 ± 0.89, respectively, which were within the clinically acceptable range (<8). The proportion of inflammatory cells and CD45⁺ cells in the cervicovaginal lavages of the B07 gel group showed no significant change compared to those of the control group. Therefore, our results confirmed that B07 exhibited significant spermicidal and contraceptive effects, suggesting its potential for development as a microbicidal spermicide for contraception and prevention of HIV sexual transmission.

The integrated HIV-1 provirus in patient sperm chromosome and its transfer into the early embryo by fertilization

Complete understanding of the route of HIV-1 transmission is an important prerequisite for curbing the HIV/AIDS pandemic. So far, the known routes of HIV-1 transmission include sexual contact, needle sharing, puncture, transfusion and mother-to-child transmission. Whether HIV can be vertically transmitted from human sperm to embryo by fertilization is largely undetermined. Direct research on embryo derived from infected human sperm and healthy human ova have been difficult because of ethical issues and problems in the collection of ova. However, the use of inter-specific in vitro fertilization (IVF) between human sperm and hamster ova can avoid both of these problems. Combined with molecular, cytogenetical and immunological techniques such as the preparation of human sperm chromosomes, fluorescent in situ hybridization (FISH), and immunofluorescence assay (IFA), this study mainly explored whether any integrated HIV provirus were present in the chromosomes of infected patients' sperm, and whether that provirus could be transferred into early embryos by fertilization and maintain its function of replication and expression. Evidence showed that HIV-1 nucleic acid was present in the spermatozoa of HIV/AIDS patients, that HIV-1 provirus is present on the patient sperm chromosome, that the integrated provirus could be transferred into early embryo chromosomally integrated by fertilization, and that it could replicate alongside the embryonic genome and subsequently express its protein in the embryo. These findings indicate the possibility of vertical transmission of HIV-1 from the sperm genome to the embryonic genome by fertilization. This study also offers a platform for the research into this new mode of transmission for other viruses, especially sexually transmitted viruses.

Chemokine expression and control of muscle cell migration during myogenesis

Adult regenerative myogenesis is vital for restoring normal tissue structure after muscle injury. Muscle regeneration is dependent on progenitor satellite cells, which proliferate in response to injury, and their progeny differentiate and undergo cell-cell fusion to form regenerating myofibers. Myogenic progenitor cells must be precisely regulated and positioned for proper cell fusion to occur. Chemokines are secreted proteins that share both leukocyte chemoattractant and cytokine-like behavior and affect the physiology of a number of cell types. We investigated the steady-state mRNA levels of 84 chemokines, chemokine receptors and signaling molecules, to obtain a comprehensive view of chemokine expression by muscle cells during myogenesis in vitro. A large number of chemokines and chemokine receptors were expressed by primary mouse muscle cells, especially during times of extensive cell-cell fusion. Furthermore, muscle cells exhibited different migratory behavior throughout myogenesis in vitro. One receptor-ligand pair, CXCR4-SDF-1alpha (CXCL12), regulated migration of both proliferating and terminally differentiated muscle cells, and was necessary for proper fusion of muscle cells. Given the large number of chemokines and chemokine receptors directly expressed by muscle cells, these proteins might have a greater role in myogenesis than previously appreciated.

HIV infection of the male genital tract--consequences for sexual transmission and reproduction

Despite semen being the main vector of human immunodeficiency virus (HIV) dissemination worldwide, the origin of the virus in this bodily fluid remains unclear. It was recently shown that several organs of the male genital tract (MGT) are infected by HIV/simian immunodeficiency virus (SIV) and likely to contribute to semen viral load during the primary and chronic stages of the infection. These findings are important in helping answer the following questions: (i) does the MGT constitute a viral reservoir responsible for the persistence of virus release into the semen of a subset of HIV-infected men under antiretroviral therapy, who otherwise show an undetectable blood viral load? (ii) What is the aetiology of the semen abnormalities observed in asymptomatic HIV-infected men? (iii) What is the exact nature of the interactions between the spermatozoa, their testicular progenitors and HIV, an important issue in the context of assisted reproductive techniques proposed for HIV-seropositive (HIV+) men? Answers to these questions are crucial for the design of new therapeutic strategies aimed at eradicating the virus from the genital tract of HIV+ men--thus reducing its sexual transmission--and for improving the care of serodiscordant couples wishing to have children. This review summarizes the most recent literature on HIV infection of the male genital tract, discusses the above issues in light of the latest findings and highlights future directions of research.

Vaginal microbicides and the prevention of HIV transmission

Worldwide, nearly half of all individuals living with HIV are now women, who acquire the virus largely by heterosexual exposure. With an HIV vaccine likely to be years away, topical microbicide formulations applied vaginally or rectally are being investigated as another strategy for HIV prevention. A review of preclinical and clinical research on the development of microbicides formulated to prevent vaginal HIV transmission yielded 118 studies: 73 preclinical and 45 clinical. Preclinical research included in-vitro assays and cervical explant models, as well as animal models. Clinical research included phase I and II/IIb safety studies, and phase III efficacy studies. Whereas most phase I and phase II clinical trials have found microbicide compounds to be safe and well tolerated, phase III trials completed to date have not demonstrated efficacy in preventing HIV transmission. Topical microbicides are grouped into five classes of agents, based on where they disrupt the pathway of sexual transmission of HIV. These classes include surfactants/membrane disruptors, vaginal milieu protectors, viral entry inhibitors, reverse transcriptase inhibitors, and a fifth group whose mechanism is unknown. The trajectory of microbicide development has been toward agents that block more specific virus-host cell interactions. Microbicide clinical trials face scientifically and ethically complex issues, such as the choice of placebo gel, the potential for viral resistance, and the inclusion of HIV-infected participants. Assessment of combination agents will most likely advance this field of research.

RANTES and human sperm fertilizing ability: effect on acrosome reaction and sperm/oocyte fusion

Beta-chemokine, regulated on activation and normally T-cell expressed and presumably secreted (RANTES), is present in both the male and female genital tract fluids where its levels increase in diseases related to infertility, such as endometriosis and male genital tract infections. beta-Chemokine receptors (CCR3 and CCR5) are expressed on freshly ejaculated human sperm cells and a sperm chemoattractant effect for RANTES has been reported. No information exists on other possible roles of RANTES on sperm functions involved in the fertilization process. In the present study, the exposure of sperm suspensions to high concentrations of the chemokine, comparable to those observed in inflammatory diseases, significantly decreased the stimulatory effect exerted by progesterone on sperm/oocyte fusion, evaluated by means of the hamster egg penetration test. Accordingly, a large proportion of spermatozoa preincubated under capacitating conditions with high concentrations of RANTES underwent a premature acrosome reaction (AR) that prevented subsequent progesterone-induced AR. Finally, sperm samples exposed to the same high levels of chemokine showed a significant increase in the intracellular levels of cAMP, which is involved in capacitation and AR dynamics. These results indicate a negative interference of high levels of RANTES on the sperm fertilizing ability, thereby suggesting a potential contribution of this chemokine to subfertility associated with endometriosis and genital tract inflammatory diseases.

[The male genital tract: A host for HIV]

Despite semen being the main vector of human immunodeficiency virus (HIV) dissemination worldwide, the origin of the virus in this bodily fluid remains unknown. Of particular significance is the persistence of virus release in the semen of HIV-infected men under antiretroviral therapy, who otherwise show an undetectable blood viral load. It is therefore considered critical to identify the sources of virus shedding in semen for the more efficient control of HIV transmission. A number of studies indirectly suggest that the free viral particles and infected cells contaminating semen are produced within the male genital tract. Our recent findings indicate HIV infection of several semen-producing organs, including the testis (which represents a pharmacological sanctuary for several antiretroviral drugs), thus reinforcing the hypothesis of the local origin of the seminal contamination. Whether one or several of these organs constitute a viral reservoir seeding semen despite antiviral therapies, remains to be determined. In addition, the detection of virus within the testicular germ cells should be taken into account in the context of assisted reproductive techniques using these cells from HIV positive men.

Beta‐chemokine receptors 5 and 3 are expressed on the head region of human spermatozoon

Induction of human sperm chemotaxis is an established phenomenon, though signaling systems physiologically involved have not been identified. Recently, it has been demonstrated that RANTES is present in the follicular fluid and that this molecule is a chemoactractant for human spermatozoa. However, the presence of beta-chemokine receptors on human spermatozoa has never been reported. By cytometric, Western blotting and immunofluorescence analysis, we demonstrate the presence of CCR5 and CCR3 on ejaculated spermatozoa from healthy subjects. CCR5 was detected in the periacrosomal region of the sperm surface, whereas CCR3 was also present in the postacrosomal cap. Individual variability was observed on CCR5 and CCR3 positive sperm percentages. Presence of Delta32+/-) mutation was demonstrated in two subjects expressing CCR5 in half of the ejaculated spermatozoa. Our findings represent the missing information in favor of the possibility that beta-chemokines and their receptors are involved in sperm chemotaxis. Identification of molecular mechanisms of sperm chemotaxis may allow us to identify predictive parameters of sperm fertilizing ability in hypofertile or infertile subjects. Finally, both CCR5 and CCR3 expressed on the sperm cell surface may be involved in HIV-1 adhesion to spermatozoa, thus allowing these cells to perform as virion cellular carriers during sexual transmission of HIV-1 infection.