New insights into the interaction between the gp120 and the HIV receptor in human sperm (human.sperm/gp120/galactoglycerolipid/antigalactosylceramide/seminolip id/spermatogonia)

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.

Properties, metabolism and roles of sulfogalactosylglycerolipid in male reproduction

Sulfogalactosylglycerolipid (SGG, aka seminolipid) is selectively synthesized in high amounts in mammalian testicular germ cells (TGCs). SGG is an ordered lipid and directly involved in cell adhesion. SGG is indispensable for spermatogenesis, a process that greatly depends on interaction between Sertoli cells and TGCs. Spermatogenesis is disrupted in mice null for Cgt and Cst, encoding two enzymes essential for SGG biosynthesis. Sperm surface SGG also plays roles in fertilization. All of these results indicate the significance of SGG in male reproduction. SGG homeostasis is also important in male fertility. Approximately 50% of TGCs become apoptotic and phagocytosed by Sertoli cells. SGG in apoptotic remnants needs to be degraded by Sertoli lysosomal enzymes to the lipid backbone. Failure in this event leads to a lysosomal storage disorder and sub-functionality of Sertoli cells, including their support for TGC development, and consequently subfertility. Significantly, both biosynthesis and degradation pathways of the galactosylsulfate head group of SGG are the same as those of sulfogalactosylceramide (SGC), a structurally related sulfoglycolipid important for brain functions. If subfertility in males with gene mutations in SGG/SGC metabolism pathways manifests prior to neurological disorder, sperm SGG levels might be used as a reporting/predicting index of the neurological status.

Monocytes but Not Lymphocytes Carrying HIV-1 on Their Surface Transmit Infection to Human Tissue Ex Vivo

Unprotected sexual intercourse with HIV-infected men is the major cause of new infections. HIV virions are released into semen by various cells of the male genital tract, as well as by infected monocytes and lymphocytes present in semen. Some of these virions may attach to the surfaces of cells, infected or uninfected. We investigated whether cells carrying attached HIV on their surfaces can transmit infection. We addressed this question in a model system of human tissue exposed ex vivo to monocytes and lymphocytes carrying HIV on their surfaces. We gamma irradiated the cells to prevent their productive infection. In spite of comparable amounts of HIV attached to monocytes and lymphocytes, only monocytes were capable of transmitting infection and triggering productive infection in tissue. This HIV-1 transmission was mediated by cell-cell contacts. Our experiments suggest that in vivo, HIV attached to infected or uninfected monocytes, which far outnumber lymphocytes in HIV-infected semen, may contribute to sexual transmission of HIV from men to their partners.

IMPORTANCE

The vast majority of new HIV infections occur through sexual transmission, in which HIV is transferred from the semen of an infected male to an uninfected partner. In semen, HIV-1 particles may exist as free-floating virions; inside infected cells; or attached to the surfaces of cells, whether they are infected or not. Here, we investigated whether HIV attached to the surfaces of monocytes or lymphocytes could transmit infection to human tissue. Incubation of human tissue with monocyte-attached HIV resulted in productive tissue infection. In contrast, there was no infection of tissues when they were incubated with lymphocyte-attached HIV-1. Our results highlight the important role that seminal monocytes may play in HIV transmission in vivo, especially since monocytes far outnumber lymphocytes in the semen of HIV-infected individuals.

Innate and adaptive immune responses in male and female reproductive tracts in homeostasis and following HIV infection

The male and female reproductive tracts are complex microenvironments that have diverse functional demands. The immune system in the reproductive tract has the demanding task of providing a protective environment for a fetal allograft while simultaneously conferring protection against potential pathogens. As such, it has evolved a unique set of adaptations, primarily under the influence of sex hormones, which make it distinct from other mucosal sites. Here, we discuss the various components of the immune system that are present in both the male and female reproductive tracts, including innate soluble factors and cells and humoral and cell-mediated adaptive immunity under homeostatic conditions. We review the evidence showing unique phenotypic and functional characteristics of immune cells and responses in the male and female reproductive tracts that exhibit compartmentalization from systemic immunity and discuss how these features are influenced by sex hormones. We also examine the interactions among the reproductive tract, sex hormones and immune responses following HIV-1 infection. An improved understanding of the unique characteristics of the male and female reproductive tracts will provide insights into improving clinical treatments of the immunological causes of infertility and the design of prophylactic interventions for the prevention of sexually transmitted infections.

In vitro human immunodeficiency virus and sperm cell interaction mediated by the mannose receptor

Leukocytes are considered to be the main source of HIV-1 infection in semen. However, HIV-1 interaction with spermatozoa has also been demonstrated, suggesting that both spermatozoa and leukocytes might play a role during sexual transmission of HIV-1. The purpose of the present study was to evaluate if HIV-1 particles interact with sperm cells through the mannose receptor (MR), and then to determine the ability of "infected" sperm cells to transmit the virus to susceptible targets. The expression of classical HIV-1 receptor and co-receptors and the MR by sperm cells was determined by flow cytometry; the interaction in vitro between sperm and HIV-1 was evaluated by fluorescence microscopy. Additionally, the in vitro interaction of sperm cells and HIV-1 was determined detecting viral nucleic acids by PCR. D-Mannose was used to block HIV-1-sperm cell interaction. Sperm cells preincubated with HIV-1 particles and activated mononuclear cells were co-cultured to determine viral transmission. The presence of viral RNA was detected in 28% of the samples in which sperm cells were preincubated with HIV-1 particles. Mannose was able to block interaction in 75% of the cases. Finally, we demonstrated that "infected" sperm cells were able to transmit the HIV-1 infection to susceptible targets. In conclusion, these results indicate that the MR is involved in sperm cell-HIV-1 interaction. Our results also suggest that sperm cells could be an important source of infection.

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.

Spermatozoa capture HIV-1 through heparan sulfate and efficiently transmit the virus to dendritic cells

Semen is the main vector for HIV-1 dissemination worldwide. It contains three major sources of infectious virus: free virions, infected leukocytes, and spermatozoa-associated virions. We focused on the interaction of HIV-1 with human spermatozoa and dendritic cells (DCs). We report that heparan sulfate is expressed in spermatozoa and plays an important role in the capture of HIV-1. Spermatozoa-attached virus is efficiently transmitted to DCs, macrophages, and T cells. Interaction of spermatozoa with DCs not only leads to the transmission of HIV-1 and the internalization of the spermatozoa but also results in the phenotypic maturation of DCs and the production of IL-10 but not IL-12p70. At low values of extracellular pH (∼6.5 pH units), similar to those found in the vaginal mucosa after sexual intercourse, the binding of HIV-1 to the spermatozoa and the consequent transmission of HIV-1 to DCs were strongly enhanced. Our observations support the notion that far from being a passive carrier, spermatozoa acting in concert with DCs might affect the early course of sexual transmission of HIV-1 infection.

Reproductive assistance for infected couples with bloodborne viruses

During the past 15 years Assisted Reproduction has been facing a new demand from patients requiring ART: couples at risk of partner to partner, and mother to child transmission of viral infections, mainly HIV-1, HCV and HIV-HCV co-infected partners. The general conditions and life expectancy of many patients with HIV infection are very good, and three-quarters of these individuals are in their reproductive years. For these reasons, a large number of young couples are expected to make future plans to have children. This desire is not easy to realize for serodiscordant couples, if we consider that, in order to avoid HIV virus transmission, it is necessary to encourage the condom use in vaginal and anal contacts. On the other hand infertile discordant HCV couples need to be included in protocols of controlled assisted reproduction procedures to avoid any risk of HCV transmission to the partner. In this paper we consider assisted reproduction in discordant couples for HIV or HCV-positive men.

Reproductive assistance in HIV-1 discordant couples

PURPOSE OF REVIEW

The total number of people living with HIV has reached 39.5 million. In developed countries, the major risk for HIV transmission is by heterosexual intercourse. The general condition and life expectancy of many patients with HIV infection is very good, and three-quarter of these individuals are in their reproductive years. For these reasons a large number of young couples are expected to make future plans to have children. Assisted reproduction in HIV-1 discordant couples has become important for clinicians in preventing HIV-1 transmission.

RECENT FINDINGS

The main theme covered in this article is epidemiology of HIV-1 in the world, the biology of the virus present in the sperm, the recently published guidelines from the American Society for Reproductive Medicine and ethics recommendations concerning assisted reproduction in people infected by virus, and all clinical aspects and scientific data published that have been modified to allow assisted reproduction in HIV-serodiscordant couples.

SUMMARY

To evaluate in clinical practice the safety of HIV-1 assisted reproduction with sperm washing and the outcome of assisted reproductive technologies offered to HIV-1 serodiscordant couples counselled for the prevention of HIV transmission.

[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.

Elimination of HIV-1 from semen and application of the processed semen to assisted reproductive technology

As HIV infection is becoming a controllable chronic infection after the introduction of the highly active antiretroviral therapy (HAART), patients with this infection are now able to make plans for the future. Numerous serodiscordant (HIV-positive men and HIV-negative women) couples seek medical assistance to have a child with minimum risk to the HIV-negative female partner and the child using processed (washed) sperm. HIV-1 elimination from the semen using density gradient centrifugation and the swim-up procedure, which is a standard processing procedure, depends on both sperm motility and the physical properties of the virus-containing particles. To establish a simple method for recovering sperm from poor quality semen, we developed the tilted-tube rotation method to generate a continuous density gradient, and using this continuous density gradient we have succeeded in recovering motile sperm, even from the semen of seropositive males with severe male factors. This review aims to summarize the recent progress in the underlying principles and technical aspects of semen processing for elimination of HIV-1. (Reprod Med Biol 2007; 6: 151-156).

The thermotropic phase behaviour and phase structure of a homologous series of racemic β-d-galactosyl dialkylglycerols studied by differential scanning calorimetry and X-ray diffraction

The thermotropic phase behaviour of aqueous dispersions of some synthetic 1,2-di-O-alkyl-3-O-(beta-D-galactosyl)-rac-glycerols (rac-beta-D-GalDAGs) with both odd and even hydrocarbon chain lengths was studied by differential scanning calorimetry (DSC), small-angle (SAXS) and wide-angle (WAXS) X-ray diffraction. DSC heating curves show a complex pattern of lamellar (L) and nonlamellar (NL) phase polymorphism dependent on the sample's thermal history. On cooling from 95 degrees C and immediate reheating, rac-beta-D-GalDAGs typically show a single, strongly energetic phase transition, corresponding to either a lamellar gel/liquid-crystalline (L(beta)/L(alpha)) phase transition (N< or =15 carbon atoms) or a lamellar gel/inverted hexagonal (L(beta)/H(II)) phase transition (N> or =16). At higher temperatures, some shorter chain compounds (N=10-13) exhibit additional endothermic phase transitions, identified as L/NL phase transitions using SAXS/WAXS. The NL morphology and the number of associated intermediate transitions vary with hydrocarbon chain length. Typically, at temperatures just above the L(alpha) phase boundary, a region of phase coexistence consisting of two inverted cubic (Q(II)) phases are observed. The space group of the cubic phase seen on initial heating has not been determined; however, on further heating, this Q(II) phase disappears, enabling the identification of the second Q(II) phase as Pn3 m (space group Q(224)). Only the Pn3 m phase is seen on cooling. Under suitable annealing conditions, rac-beta-D-GalDAGs rapidly form highly ordered lamellar-crystalline (L(c)) phases at temperatures above (N< or =15) or below (N=16-18) the L(beta)/L(alpha) phase transition temperature (T(m)). In the N< or =15 chain length lipids, DSC heating curves show two overlapping, highly energetic, endothermic peaks on heating above T(m); corresponding changes in the first-order spacings are observed by SAXS, accompanied by two different, complex patterns of reflections in the WAXS region. The WAXS data show that there is a difference in hydrocarbon chain packing, but no difference in bilayer dimensions or hydrocarbon chain tilt for these two L(c) phases (termed L(c1) and L(c2), respectively). Continued heating of suitably annealed, shorter chain rac-beta-D-GalDAGs from the L(c2) phase results in a phase transition to an L(alpha) phase and, on further heating, to the same Q(II) or H(II) phases observed on first heating. On reheating annealed samples with longer chain lengths, a subgel phase is formed. This is characterized by a single, poorly energetic endotherm visible below the T(m). SAXS/WAXS identifies this event as an L(c)/L(beta) phase transition. However, the WAXS reflections in the di-16:0 lipid do not entirely correspond to the reflections seen for either the L(c1) or L(c2) phases present in the shorter chain rac-beta-D-GalDAGs; rather these consist of a combination of L(c1), L(c2) and L(beta) reflections, consistent with DSC data where all three phase transitions occur within a span of 5 degrees C. At very long chain lengths (N> or =19), the L(beta)/L(c) conversion process is so slow that no L(c) phases are formed over the time scale of our experiments. The L(beta)/L(c) phase conversion process is significantly faster than that seen in the corresponding rac-beta-D-GlcDAGs, but is slower than in the 1,2-sn-beta-D-GalDAGs already studied. The L(alpha)/NL phase transition temperatures are also higher in the rac-beta-D-GalDAGs than in the corresponding rac-beta-D-GlcDAGs, suggesting that the orientation of the hydroxyl at position 4 and the chirality of the glycerol molecule in the lipid/water interface influence both the L(c) and NL phase properties of these lipids, probably by controlling the relative positions of hydrogen bond donors and acceptors in the polar region of the membrane.

Complete removal of HIV-1 RNA and proviral DNA from semen by the swim-up method: assisted reproduction technique using spermatozoa free from HIV-1

BACKGROUND

Use of antiretroviral drugs has reduced the mortality rate for HIV infection and many HIV-discordant couples wish to have children. It is possible for an HIV-infected man to father children without risk of HIV transmission if HIV-free spermatozoa can be obtained from his semen.

METHODS

An improved swim-up method was used to collect HIV-free spermatozoa from the semen of HIV-positive males. Diluted semen was layered over a Percoll solution with a continuous density gradient of 30-98%, and then centrifuged. The bottom layer was collected by cutting the end from the tube and the sperm suspension was collected using the swim-up method. Spermatozoa were tested by nested polymerase chain reaction (PCR) for HIV-1 RNA and DNA, with a detection limit of one copy. Spermatozoa were used for assisted reproduction in 43 couples.

RESULTS

HIV-1 RNA and proviral DNA were not detected by nested-PCR assay in all 73 of the collected spermatozoa samples from 52 patients. The HIV-1-negative sperm was used for in vitro fertilization in 12 couples and for intracytoplasmic sperm injection in 31 couples. No detection of HIV-1 RNA or proviral DNA in the culture medium of the fertilized eggs was confirmed again before embryo transfer. Of the 43 female partners, 20 conceived and 27 babies were born. HIV antibodies, HIV RNA and proviral DNA were negative in all of the females and babies.

CONCLUSIONS

HIV-negative spermatozoa could be obtained from semen of HIV-positive men. The method involves no risk of HIV transmission to female partners and their children.

Exploiting common targets in human fertilization and HIV infection: development of novel contraceptive microbicides

The continued high rates of unintended pregnancies and the unrelentless expansion of the acquired immune deficiency syndrome (AIDS) epidemic, especially in less developed countries, warrant the development of novel strategies to help individuals avoid these risks. Dually active compounds displaying contraceptive and microbicidal anti-human immunodeficiency virus (anti-HIV) properties constitute one such strategy. Sharing the same anatomical and functional context, sperm fertilization and genital infection by HIV offer an opportunity for simultaneous intervention. Some of the molecules and mechanisms used by sperm to fertilize the oocyte are similar, if not identical, to those used by HIV while infecting host cells. An example of common structures is the lipid membrane surrounding the spermatozoon and the HIV core. Disruption of its architecture by surface-active compounds exerts both spermicidal and virucidal activity. A more specific alteration of lipid rafts [membrane microdomains enriched in cholesterol and glycosylphosphatidylinositol (GPI)-anchored proteins] by beta-cyclodextrins also results in similar effects. During fertilization and infection, both sperm and HIV interact with their target cell receptors through chemical charges, hydrophobic forces and carbohydrate recognition. Anionic polymers such as cellulose sulphate and polystyrene sulphonate (PSS) inhibit sperm and HIV cell binding. Because some of the molecules involved in this interaction, e.g. heparin sulphate proteoglycan, are also used by other pathogens to infect their target tissues, polyanions exert broad antimicrobial activity as well. During fertilization and infection, sperm and HIV, as well as other microbes, use signal transduction molecules and mechanisms such as adenyl cyclase/cyclic adenosine monophosphate (cAMP)-dependent kinase, calcium and tyrosine phosphorylation, whose inhibition has been shown to impair sperm function and HIV replication. These commonalities at the level of sperm and HIV structure, cell binding and fusion processes, and signalling pathways therefore provide the biological framework to develop bifunctional inhibitors with both antimicrobial and contraceptive properties.

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

Viruses adhering to the sperm surface are described in the semen of HIV-1-infected individuals, although viral adhesion mechanisms have yet to be fully understood. We demonstrate, by cytometric analysis and immunofluorescence microscopy, the presence of beta-chemokine receptor 5 (CCR5) on the periacrosomal region of ejaculated spermatozoa. CCR5 expressed on the sperm cell surface may allow sperm to act as virion cellular carriers during the sexual transmission of HIV-1 infection.

ICSI for treatment of human immunodeficiency virus and hepatitis C virus-serodiscordant couples with infected male partner

BACKGROUND

Assisted reproductive technology with semen washing can offer a significant reduction in risk of sexual and vertical transmission of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) in serodiscordant couples with infected male partner.

METHODS

Among couples coming to our centre for reproductive problems from January 2001 to December 2003, we selected 43 couples with seropositive male and seronegative female: 25 couples with HIV-seropositive males, 10 couples with HIV/hepatitis C virus (HCV)-seropositive males and eight couples with HCV-seropositive males. Sperm samples were washed and used for ICSI.

RESULTS

Seventy-eight cycles of ICSI were performed. The mean fertilization rate was 70.34 +/- 20.14% (mean +/- SD). A mean number of 3.55 +/- 1.11 (range: 1-5) embryos of good quality was transferred for each patient. We obtained 22 pregnancies (21 singletons and one twin), with a pregnancy rate per transfer of 28.2% and an implantation rate per transfer of 15.2%. The cumulative pregnancy rate was 51.2%. At follow-up, no seroconversion was detected in any patient.

CONCLUSIONS

Our data suggest that sperm wash and ICSI could be useful for reducing the risk of HIV and/or HCV transmission in serodiscordant couples with infected male wishing to have a child, irrespective of their fertility status.

Sperm washing techniques address the fertility needs of HIV-seropositive men: a clinical review

It is estimated that nearly 40 million people worldwide are infected with HIV. HIV/AIDS prevalence among young people is high, with youth under age 25 years accounting for approximately half of all new infections. Nearly 1 million Americans are HIV-seropositive. Today, HIV-seropositive individuals live active and productive lives despite their illness, largely a result of prescribed highly active antiretroviral therapy (HAART). Most individuals are of reproductive age, and many desire to have children. Various assisted reproductive techniques have been used to reduce or eliminate infectious elements known to be present in semen so that isolated spermatozoa can be safely inseminated or used for intracytoplasmic sperm injection into oocytes. Presently, several European centres and a few US groups offer assistance to HIV seropositive men and their seronegative partners by performing either intrauterine insemination (IUI) or IVF. Since 1987, more than 3600 published attempts have been reported in which processed spermatozoa from HIV-seropositive men were used to establish pregnancy in HIV-seronegative women. Although the data remain observational, sperm washing techniques appear to be relatively safe and effective, offering HIV-serodiscordant couples an opportunity to have children.

Semen activates the female immune response during early pregnancy in mice

Insemination elicits inflammatory changes in female reproductive tissues, but whether this results in immunological priming to paternal antigens or influences pregnancy outcome is not clear. We have evaluated indices of lymphocyte activation in lymph nodes draining the uterus following allogeneic mating in mice and have investigated the significance of sperm and plasma constituents of semen in the response. At 4 days after mating, there was a 1b7-fold increase in the cellularity of the para-aortic lymph node (PALN) compared with virgin controls. PALN lymphocytes were principally T and B lymphocytes, with smaller populations of CD3(+) B220(lo), NK1.1(+) CD3(-) (NK) and NK1.1(+) CD3(+) (NKT) cells. CD69 expression indicative of activation was increased after mating and was most evident in CD3(+) and NK1.1(+) cells. Synthesis of cytokines including interleukin-2, interleukin-4 and interferon-gamma was elevated in CD3(+) PALN cells after exposure to semen, as assessed by intracellular cytokine fluorescence-activated cell sorting, immunohistochemistry and quantitative reverse transcriptase polymerase chain reaction. Matings with vasectomized males indicated that the lymphocyte activation occurs independently of sperm. However, in contrast, males from which seminal vesicle glands were surgically removed failed to stimulate PALN cell proliferation or cytokine synthesis. Adoptive transfer experiments using radiolabelled lymphocytes from mated mice showed that lymphocytes activated at insemination home to embryo implantation sites in the uterus as well as other mucosal tissues and lymph nodes. These findings indicate that activation and expansion of female lymphocyte populations occurs after mating, and is triggered by constituents of seminal plasma derived from the seminal vesicle glands. Moreover, lymphocytes activated at insemination may help mediate maternal tolerance of the conceptus in the implantation site.

Identification of CD4-independent HIV Receptors on Spermatozoa

PROBLEM

Human immunodeficiency virus (HIV) has been demonstrated to bind and enter into the spermatozoa facilitating the transmission into urogenital cells. However, spermatozoa has been reported to be devoid of the conventional CD4 receptors for HIV. This suggests that there exists an alternate modality of HIV entry into spermatozoa using receptors other than CD4. Present communication describes the identification of HIV receptors on the spermatozoa.

METHOD OF STUDY

The sperm proteins were solubilized using Triton X-100 and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western blot analysis, using cell-free HIV or gp120 envelope glycoprotein as a probe. HIV or gp120 bound protein band was then visualized by using alkaline phosphatase (AP) labeled anti-gp120 antibody as well as by using anti-gp120 antibody and subsequently by AP-labeled anti-rabbit gamma globulin.

RESULTS

The results obtained demonstrate for the first time that cell-free HIV and gp120 protein bind specifically to 160 kDa sperm protein that could be the receptor for HIV entry into spermatozoa.

CONCLUSION

A 160 kDa sperm protein could be the CD4-independent HIV receptor for HIV to bind and enter into the spermatozoa. Further characterization of this 160 kDa HIV receptor on sperm will provide an insight in understanding the mechanism and probable mode of intervention or prevention of HIV transmission at the initial stage of infection.

Human immunodeficiency virus receptor and coreceptor expression on human uterine epithelial cells: regulation of expression during the menstrual cycle and implications for human immunodeficiency virus infection

Human immunodeficiency virus-1 (HIV-1) is primarily a sexually transmitted disease. Identification of cell populations within the female reproductive tract that are initially infected, and the events involved in transmission of infection to other cells, remain to be established. In this report, we evaluated expression of HIV receptors and coreceptors on epithelial cells in the uterus and found they express several receptors critical for HIV infection including CD4, CXCR4, CCR5 and galactosylceramide (GalC). Moreover, expression of these receptors varied during the menstrual cycle. Expression of CD4 and CCR5 on uterine epithelial cells is high throughout the proliferative phase of the menstrual cycle when blood levels of oestradiol are high. In contrast, CXCR4 expression increased gradually throughout the proliferative phase. During the secretory phase of the cycle when both oestradiol and progesterone are elevated, CD4 and CCR5 expression decreased whereas CXCR4 expression remained elevated. Expression of GalC on endometrial glands is higher during the secretory phase than during the proliferative phase of the menstrual cycle. Because epithelial cells line the female reproductive tract and express HIV receptors and coreceptors, it is likely that they are one of the first cell types to become infected. The hormonal regulation of HIV receptor expression may affect a woman's susceptibility to HIV infection during her menstrual cycle. Moreover, selective coreceptor expression could account for the preferential transmission of R5-HIV-1 strains to women. In addition, these studies provide evidence that the uterus, and potentially the entire upper reproductive tract, are important sites for the initial events involved in HIV infection.

Analysis of HIV-1 viral load in seminal plasma samples

BACKGROUND

With HIV-1-infected individuals now facing the prospect of relatively long and healthy lives, many discordant couples (where the male is HIV-1 seropositive) are seeking to have children. To assist reducing the risks of heterosexual and subsequent vertical transmission in this situation, quantification of HIV-1 viral load in seminal plasma may be effective as one of several measures to reduce the risk of infecting the mother during insemination, potentially providing a better indication of infectivity than blood plasma analysis.

OBJECTIVE(S)

To modify existing molecular methods for the purpose of analysing HIV-1 viral load in seminal plasma.

METHODS

Two commercial assays for HIV-1 RNA quantification were used to assess their sensitivity, specificity and precision for quantification of seminal plasma samples. Seminal plasma samples were prepared with an additional centrifugation step to aid removal of inhibitors to molecular assays.

RESULTS

Seminal plasma samples exhibited specificity of >95%, equivalent to that reported by the manufacturers of the commercial assays. With additional centrifugation, complete inhibition of 2/19 (10%) seminal plasma samples was observed using the RT-PCR assay, and inhibition was not apparent in the bDNA assay. Quantification of HIV-1 RNA in seminal plasma samples in both assays was equivalent to that observed in plasma samples and did not appear to be affected by the additional centrifugation step.

CONCLUSION

Minor modification of the RT-PCR assay procedure by additional centrifugation of seminal plasma improved the sensitivity of the assay. Inhibition was not apparent with the bDNA assay.

The role of semen in induction of maternal immune tolerance to pregnancy

Successful pregnancy requires a state of maternal immune 'tolerance' to accommodate antigens expressed by the conceptus. Implantation failure and placental pathologies largely reflect insufficiencies in maternal immune adaptation, but progress in devising therapeutic strategies to treat these conditions is stalled because the mechanisms underlying the induction and maintenance of maternal tolerance are unknown. Increasingly, clinical and experimental data support the proposal that insemination has consequences for the reproductive process beyond delivery of male gametes. An emerging hypothesis, based mainly on clinical observations and experiments in mice, is that insemination is causally linked to the activation and expansion of populations of lymphocytes mediating forms of 'active' immune tolerance in the implantation site. This review examines existing evidence for a role for semen in the immunology of pregnancy, highlighting the limitations of our existing knowledge and the prospects for future research and its clinical application.

The physical properties of glycosyl diacylglycerols. Calorimetric, X-ray diffraction and Fourier transform spectroscopic studies of a homologous series of 1,2-di-O-acyl-3-O-(beta-D-galactopyranosyl)-sn-glycerols

We have synthesized a homologous series of saturated 1,2-di-O-n-acyl-3-O-(beta-D-galactopyranosyl)-sn-glycerols with odd- and even-numbered hydrocarbon chains ranging in length from 10 to 20 carbon atoms, and have investigated their physical properties using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The DSC results show a complex pattern of phase behaviour, which in a typical preheated sample consists of a lower temperature, moderately energetic lamellar gel/lamellar liquid-crystalline (L(beta)/L(alpha)) phase transition and a higher temperature, weakly energetic lamellar/nonlamellar phase transition. On annealing at a suitable temperature below the L(beta)/L(alpha) phase transition, the L(beta) phase converts to a lamellar crystalline (L(c1)) phase which may undergo a highly energetic L(c1)/L(alpha) or L(c1)/inverted hexagonal (H(II)) phase transition at very high temperatures on subsequent heating or convert to a second L(c2) phase in certain long chain compounds on storage at or below 4 degrees C. The transition temperatures and phase assignments for these galactolipids are supported by our XRD and FTIR spectroscopic measurements. The phase transition temperatures of all of these events are higher than those of the comparable phase transitions exhibited by the corresponding diacyl alpha- and beta-D-glucosyl glycerols. In contrast, the L(beta)/L(alpha) and lamellar/nonlamellar phase transition temperatures of the beta-D-galactosyl glycerols are lower than those of the corresponding diacyl phosphatidylethanolamines (PEs) and these glycolipids form inverted cubic phases at temperatures between the lamellar and H(II) phase regions. Our FTIR measurements indicate that in the L(beta) phase, the hydrocarbon chains form a hexagonally packed structure in which the headgroup and interfacial region are undergoing rapid motion, whereas the L(c) phase consists of a more highly ordered, hydrogen-bonded phase, in which the chains are packed in an orthorhombic subcell similar to that reported for the diacyl-beta-D-glucosyl-sn-glycerols. A comparison of the DSC data presented here with our earlier studies of other diacyl glycolipids shows that the rate of conversion from the L(beta) to the L(c) phase in the beta-D-galactosyl glycerols is slightly faster than that seen in the alpha-D-glucosyl glycerols and much faster than that seen in the corresponding beta-D-glucosyl glycerols. The similarities between the FTIR spectra and the first-order spacings for the lamellar phases in both the beta-D-glucosyl and galactosyl glycerols suggest that the headgroup orientations may be similar in both beta-anomers in all of their lamellar phases. Thus, the differences in their L(beta)/L(c) conversion kinetics and the lamellar/nonlamellar phase properties of these lipids probably arise from subtly different hydration and H-bonding interactions in the headgroup and interfacial regions of these phases. In the latter case, such differences would be expected to alter the ability of the polar headgroup to counterbalance the volume of the hydrocarbon chains. This perspective is discussed in the context of the mechanism for the L(alpha)/H(II) phase transition which we recently proposed, based on our X-ray diffraction measurements of a series of PEs.