Hepatitis B virus s protein enhances sperm apoptosis and reduces sperm fertilizing capacity in vitro

Integration of hepatitis B virus into patients' sperm genome and its clinical risks

BACKGROUND

Like the coronavirus disease 2019, the hepatitis B virus is also wreaking havoc worldwide, which has infected over 2 billion people globally. Using an experimental animal model, our previous research observed that the hepatitis B virus genes integrated into human spermatozoa can replicate and express after being transmitted to embryos. However, as of now, this phenomenon has not been confirmed in clinical data from patients.

OBJECTIVES

To explore the integration of the hepatitis B virus into patients' sperm genome and its potential clinical risks.

MATERIALS AND METHODS

Forty-eight patients with chronic hepatitis B virus infection were categorized into two groups: Test Group-1 comprised 23 patients without integration of hepatitis B virus DNA within the sperm genome. Test Group-2 comprised 25 patients with integration of hepatitis B virus DNA within the sperm genome. Forty-eight healthy male donors were included as control. The standard semen parameter analysis, real-time polymerase chain reaction, quantitative real-time polymerase chain reaction, sperm chromatin structure assay, fluorescence in situ hybridization, and immunofluorescence assays were utilized.

RESULTS

The difference in the median copy number of hepatitis B virus DNA per mL of sera between Test Group-1 and Group-2 was not statistically significant. In Test Group-2, the integration rate of hepatitis B virus DNA was 0.109%, which showed a significant correlation with the median copy number of hepatitis B virus DNA in motile spermatozoa (1.18 × 103 /mL). Abnormal semen parameters were found in almost all these 25 patients. The integrated hepatitis B virus S, C, X, and P genes were detected to be introduced into sperm-derived embryos through fertilization and retained their function in replication, transcription, and translation.

CONCLUSION

Our findings suggest that hepatitis B virus infection can lead to sperm quality deterioration and reduced fertilization capacity. Furthermore, viral integration causes instability in the sperm genome, increasing the potential risk of termination, miscarriage, and stillbirth. This study identified an unconventional mode of hepatitis B virus transmission through genes rather than virions. The presence of viral sequences in the embryonic genome poses a risk of liver inflammation and cancer.

Update on known and emergent viruses affecting human male genital tract and fertility

Many viruses infect the male genital tract with harmful consequences at individual and population levels. In fact, viral infections may induce damage to different organs of the male genital tract (MGT), therefore compromising male fertility. The oxidative stress, induced during viral-mediated local and systemic inflammation, is responsible for testicular damage, compromising germinal and endocrine cell functions. A reduction in sperm count, motility, number of normal sperm and an increase in DNA fragmentation are all common findings in the course of viral infections that, however, generally regress after infection clearance. In some cases, however, viral shedding persists for a long time leading to unexpected sexual transmission, even after the disappearance of the viral load from the blood.The recent outbreak of Zika and Ebola Virus evidenced how the MGT could represent a reservoir of dangerous emergent viruses and how new modalities of surveillance of survivors are strongly needed to limit viral transmission among the general population.Here we reviewed the evidence concerning the presence of relevant viruses, including emergent and re-emergent, on the male genital tract, their route of entry, their adverse effects on male fertility and the pattern of viral shedding in the semen.We also described laboratory strategies to reduce the risk of horizontal or vertical cross-infection in serodiscordant couples undergoing assisted reproductive technologies.

The influence of male HBV infection on sperm quality, embryonic development, and assisted reproductive outcomes

STUDY QUESTION

What is the impact of male hepatitis B virus (HBV) infection on sperm quality, embryonic development, and assisted reproductive outcomes?

SUMMARY ANSWER

Male HBV infection did not affect assisted reproductive outcomes, but HBV is capable of impairing human sperm and embryo formation in the early stages following fertilization.

WHAT IS KNOWN ALREADY

HBV is found in germ cells and early embryos of patients with HBV. HBV may impair human sperm function via increasing reactive oxygen species.

STUDY DESIGN, SIZE, DURATION

We conducted a retrospective cohort study of 1581 infertile couples, including 496 male patients clinically confirmed to have hepatitis B infection, and a laboratory study of effects of HBV proteins on early embryos, using human embryonic stem cells (hESCs), human sperm, and golden hamster oocytes.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 1581 infertile couples (24-40 years of age) who were admitted to a reproductive medicine center to undergo ART for the first time from January 2019 to November 2021 were selected as the study subjects. The case group was composed of 469 couples with hepatitis B surface antigen (HBsAg)-seropositive men and seronegative women (368 for IVF and 101 for ICSI treatment). The negative control group was composed of 1112 couples where both men and women were seronegative for hepatitis B antigen. We divided these couples into three comparison groups (IVF/ICSI, IVF, and ICSI). IVF of human sperm and hamster oocytes was used to evaluate the influence of the HBV HBs protein on formation of 2-cell embryos. Mitochondrial membrane potential (MMP) of hESCs was assayed via a fluorescence intensity system. Immunofluorescence staining of the phosphorylated histone H2A.X was applied to identify DNA damage to hESCs caused by the HBV X (HBx) protein.

MAIN RESULTS AND THE ROLE OF CHANCE

Sperm concentration, total sperm number, and sperm with normal morphology were decreased in the couples with HBV-infected males in couples who were undergoing IVF/ICSI (male HBV(+) vs control: 469 vs 1112 individuals; sperm number, P < 0.01; normal sperm morphology, P < 0.01), IVF (368 vs 792; sperm number, P < 0.01; normal sperm morphology, P ≤ 0.05), and ICSI (101 vs 306; sperm number, P < 0.01; normal sperm morphology, P < 0.001). There was no significant difference in the number of embryo cleavages, blastocyst formation, biochemical pregnancy rate, clinical pregnancy rate, and live-birth rate between case and control groups. The 2PN fertilization rate in IVF/ICSI (P < 0.01) and ICSI (P < 0.05) couples, and the number of 2PN-fertilized oocytes in IVF (P < 0.001) couples were lower in couples with male HBV infection compared to control couples. HBV HBs protein reduced the MMP of human sperm and decreased 2-cell embryo formation in IVF of human sperm and zona-free-hamster oocyte. A reduction in fluorescence intensity and immunofluorescence staining of phosphorylated histone H2A.X indicated that HBx caused MMP impairment and DNA damage in human early embryonic cells, respectively.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

HBV can be examined in samples of sperm or discarded IVF early embryos from HBsAg-seropositive men and seronegative women. The hESC model in vitro may not fully mimic the natural embryos in vivo.

WIDER IMPLICATIONS OF THE FINDINGS

This study furthers our understanding of the influence of male HBV infection on embryonic development. Our results suggest that a semen-washing process may be necessary for male patients with HBV undergoing ART to minimize the potential negative effects of HBV infection on the early embryo.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by grants from the National Natural Science Foundation of China, grant numbers 81870432 and 81570567 to X.Z., 81571994 to P.S., and 81950410640, the Natural Science Foundation of Guangdong Province, China (No. 2023A1515010660 to X.Z.), and the Li Ka Shing Shantou University Foundation (Grant No. L11112008). The authors have no conflicts of interest.

Viral tropism for the testis and sexual transmission

The mammalian testis adopts an immune privileged environment to protect male germ cells from adverse autoimmune reaction. The testicular immune privileged status can be also hijacked by various microbial pathogens as a sanctuary to escape systemic immune surveillance. In particular, several viruses have a tropism for the testis. To overcome the immune privileged status and mount an effective local defense against invading viruses, testicular cells are well equipped with innate antiviral machinery. However, several viruses may persist an elongated duration in the testis and disrupt the local immune homeostasis, thereby impairing testicular functions and male fertility. Moreover, the viruses in the testis, as well as other organs of the male reproductive system, can shed to the semen, thus allowing sexual transmission to partners. Viral infection in the testis, which can impair male fertility and lead to sexual transmission, is a serious concern in research on known and on new emerging viruses. To provide references for our scientific peers, this article reviews research achievements and suggests future research focuses in the field.

Human seminal virome: a panel based on recent literature

Background

The seminal virome and its implications for fertility remain poorly understood. To date, there are no defined panels for the detection of viruses of clinical interest in seminal samples.

Results

In this study, we characterized the human seminal virome based on more than 1,000 studies published over the last five years.

Conclusions

The number of studies investigating viruses that occur in human semen has increased, and to date, these studies have been mostly prospective or related to specific clinical findings. Through the joint analysis of all these studies, we have listed the viruses related to the worsening of seminal parameters and propose a new panel with the main viruses already described that possibly affect male fertility and health. This panel can assist in evaluating semen quality and serve as a tool for investigation in cases of infertility.

Hepatitis B Virus and Cytomegalovirus Infections Disrupt Sperm Parameters in Males through Decreasing Mitochondrial Membrane Potential: A Case-control Study

Background: Infertility is a global problem that affects more than 15% of couples. The occurrence of this problem is about 50% in males. Viral infections cause infertility in men by different mechanisms. Objectives: This study is designed to evaluate the effects of hepatitis B virus (HBV) and cytomegalovirus (CMV) infection on male fertility and determine the mechanisms involved. Methods: A total of 73 males were included in the present study. They were assigned to the groups healthy fertile (n = 22 volunteers) as the healthy controls, non-infected infertile (n = 27), HBV-infected infertile (n = 14), and CMV-infected infertile (n = 10). The sperm parameters, including count, morphology, progressive motility (PR), and progressive + non-progressive motility (PR + NP), were analyzed in their semen. The semen samples of all studied participants were subjected to polymerase chain reaction to determine the presence of HBV or CMV infection. Mitochondrial membrane potential (MMP) and tumor necrosis factor-alpha (TNF-α) were also assessed. Results: Our findings showed that all sperm parameters, including count, morphology, PR, and PR + NP, decreased in males with HBV and CMV infections compared to the healthy control group (P < 0.01 in all cases). MMP declined in HBV- and CMV-infected males compared to the healthy control group (P < 0.001). Conversely, the TNF-α level of semen in HBV- and CMV-infected men was significantly higher than in the healthy control group (P < 0.001). Conclusions: The results of the present study demonstrated that HBV and CMV infections lead to male infertility through increasing TNF-α and decreasing sperm MMP.

The Microbiome, an Important Factor That Is Easily Overlooked in Male Infertility

Humankind has been interested in reproduction for millennia. Infertility, in which male factors contribute to approximately 50%, is estimated to concern over 72 million people worldwide. Despite advances in the diagnosis, medical treatment, and psychosocial management of male infertility over the past few decades, approximately 30% of male infertility is still thought to be idiopathic. Despite emerging advances in the microbiome associated with male infertility have indicated that the microbiome may be a key factor to the management of male infertility, roles, and mechanisms of the microbiome remain ambiguous. Here, we mainly discussed the association between microbial infection in the genital tract and male infertility, effect of antimicrobial therapy on male reproduction, association between microbial dysbiosis and male infertility, and effect of probiotic intervention on male reproduction. This review made progress toward establishing a relationship between the microbiome and male infertility, and explored the role of the microbiome in male infertility. We call for more high-quality studies to focus on the relationship between microbes and male infertility, and strongly suggest increasing awareness among sterile males with microbial infection and/or microbial dysbiosis when they seek fertility help.

Viral Infections and Male Infertility: A Comprehensive Review of the Role of Oxidative Stress

Viral infections have been a part of human existence to date, though viruses have posed a huge threat with various outbreaks lately. These threats are associated with reproductive health challenges, especially male infertility. The prime focus of this review is to highlight the mechanisms associated with viral infection-induced male infertility/subfertility and identify new treatment strategies with the aim to preserve male fertility. The reviewed data showed that viral infections stimulate inflammatory responses, resulting in the release of proinflammatory cytokines, which induces oxidative stress. This oxido-inflammatory cycle could continue in a vicious cycle and threaten male fertility. Existing data from human and experimental studies show that viral infection-induced oxido-inflammatory response results in testicular damage, atrophy of the seminiferous tubules and Sertoli cells, and reduced Leydig cell mass. This is accompanied by reduced circulatory testosterone, impaired spermatogenesis, reduced sperm motility, lipid peroxidation, DNA fragmentation and apoptosis of the sperm cells. Based on the available pieces of evidence, antioxidant therapy, in vivo and in vitro, may be beneficial and protects against the potential risk of male infertility from viral infection. It is, however recommended that more clinical studies be conducted to demonstrate the possible protective roles of antioxidants used as adjuvant therapy in viral infections, and in the in vitro treatment of semen samples for those utilizing semen washing and artificial reproductive techniques.

Hepatitis B virus surface protein induces sperm dysfunction through the activation of a Bcl2/Bax signaling cascade triggering AIF/Endo G-mediated apoptosis

BACKGROUND

Hepatitis B virus (HBV) was found to exist in semen and male germ cells of patients with chronic HBV infection. Our previous studies demonstrated that HBV surface protein (HBs) could induce sperm dysfunction by activating a calcium signaling cascade and triggering caspase-dependent apoptosis. However, the relationship between sperm dysfunction caused by HBs and caspase-independent apoptosis has not been investigated.

OBJECTIVES

To evaluate the effects of HBs exposure on sperm dysfunction by activating caspase-independent apoptosis.

MATERIALS AND METHODS

Spermatozoa were exposed to HBs at concentrations of 0, 25, 50, and 100 μg/mL for 3 h. Flow cytometry, qRT-PCR, immunofluorescence assay, ELISA, and zona-free hamster oocyte penetration assays were performed.

RESULTS

With increasing concentrations of HBs, various parameters of the spermatozoa changed. The number of Bcl2-positive cells declined and that of both Bax-positive cells and Apaf-1-positive cells increased. The transcription level of Bcl2 increased and that of both Bax and Apaf-1 declined. The average levels of AIF and Endo G declined in mitochondria and increased in the cytoplasm and nucleus. The sperm DNA fragmentation index increased. The mean percentages of live spermatozoa declined and that of both injured and dead spermatozoa increased; and the sperm penetration rate declined. For the aforementioned parameters, the differences between the test and the control groups were statistically significant.

CONCLUSION

HBs exposure can activate the Bax/Bcl2 signaling cascade that triggers AIF/Endo G-mediated apoptosis, resulting in sperm DNA fragmentation, sperm injury, and death, and a decrease in the sperm fertilizing capacity. This new knowledge will help to evaluate the negative impact of HBV on male fertility in HBV-infected patients.

Host microRNAs regulate expression of hepatitis B virus genes during transmission from patients' sperm to embryo

Human sperm nucleus contains diverse RNA populations. This study aimed to screen and identify host microRNAs (miRs) that regulate gene expression of hepatitis B virus (HBV) during transmission from patients' sperm to sperm-derived embryos. Using microarrays, 336 miRs were found to be differentially expressed. After validation using real-time quantitative RT-PCR (RT-qPCR), four miRs were selected as targets. Using RT-qPCR and enzyme-linked immunosorbent assays, when patients' sperm were treated with mimics (or inhibitors) specific for hsa-miR-19a-3p and hsa-miR-29c-3p, the S gene transcription in sperm and translation in sperm-derived embryos was downregulated (or upregulated). There were significant differences in transcriptional and translational levels of the S gene between the test and control groups. These findings suggest that hsa-miR-19a-3p and hsa-miR-29c-3p significantly suppressed expression of the S gene, offering potential therapeutic targets for treating patients with HBV infection, and further reducing the negative impact of HBV infection on sperm fertilizing capacity.

Viral infections and implications for male reproductive health

Viral infections have haunted humankind since times immemorial. Overpopulation, globalization, and extensive deforestation have created an ideal environment for a viral spread with unknown and multiple shedding routes. Many viruses can infect the male reproductive tract, with potential adverse consequences to male reproductive health, including infertility and cancer. Moreover, some genital tract viral infections can be sexually transmitted, potentially impacting the resulting offspring's health. We have summarized the evidence concerning the presence and adverse effects of the relevant viruses on the reproductive tract (mumps virus, human immunodeficiency virus, herpes virus, human papillomavirus, hepatitis B and C viruses, Ebola virus, Zika virus, influenza virus, and coronaviruses), their routes of infection, target organs and cells, prevalence and pattern of virus shedding in semen, as well as diagnosis/testing and treatment strategies. The pathophysiological understanding in the male genital tract is essential to assess its clinical impact on male reproductive health and guide future research.

From Ancient to Emerging Infections: The Odyssey of Viruses in the Male Genital Tract

The male genital tract (MGT) is the target of a number of viral infections that can have deleterious consequences at the individual, offspring, and population levels. These consequences include infertility, cancers of male organs, transmission to the embryo/fetal development abnormalities, and sexual dissemination of major viral pathogens such as human immunodeficiency virus (HIV) and hepatitis B virus. Lately, two emerging viruses, Zika and Ebola, have additionally revealed that the human MGT can constitute a reservoir for viruses cleared from peripheral circulation by the immune system, leading to their sexual transmission by cured men. This represents a concern for future epidemics and further underlines the need for a better understanding of the interplay between viruses and the MGT. We review here how viruses, from ancient viruses that integrated the germline during evolution through old viruses (e.g., papillomaviruses originating from Neanderthals) and more modern sexually transmitted infections (e.g., simian zoonotic HIV) to emerging viruses (e.g., Ebola and Zika) take advantage of genital tract colonization for horizontal dissemination, viral persistence, vertical transmission, and endogenization. The MGT immune responses to viruses and the impact of these infections are discussed. We summarize the latest data regarding the sources of viruses in semen and the complex role of this body fluid in sexual transmission. Finally, we introduce key animal findings that are relevant for our understanding of viral infection and persistence in the human MGT and suggest future research directions.

Assisted conception does not increase the risk for mother-to-child transmission of hepatitis B virus, compared with natural conception: a prospective cohort study

OBJECTIVE

To determine whether assisted conception increases the risk for mother-to-child transmission of hepatitis B virus (HBV) infection compared with natural conception.

DESIGN

Prospective cohort study.

SETTING

Research laboratory.

PATIENT(S)

A total of 305 children, 176 born with assisted conception and 129 born with natural conception, were born to a total of 251 hepatitis B surface antigen- (HBsAg-) positive women.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The seropositive rates of HBsAg in children at birth and HBV infection rates at 9-15 months of age.

RESULT(S)

Overall, 7.5% (23/305) of children were HBsAg-positive at birth. The rate of HBsAg-positive children at birth did not significantly differ between children in the assisted conception group compared with those in the natural conception group (6.3% [11/176] vs. 9.3% [12/129]). Multivariate logistic regression analysis showed that conception method is not related to the rate of HBsAg-positive children at birth. All children who were positive for HBsAg at birth and were followed up for 9-15 months became negative for HBsAg after hepatitis B immunization.

CONCLUSION(S)

Assisted conception does not increase the risk for mother-to-child transmission of HBV compared with natural conception.

Transcription and regulation of hepatitis B virus genes in host sperm cells

To investigate whether transcription of hepatitis B virus (HBV) gene occurs in human sperm, total RNA was extracted from sperm of patients with chronic HBV infection (test-1), from donor sperm transfected with a plasmid containing the full-length HBV genome (test-2), and from nontransfected donor sperm (control), used as the template for reverse transcription-polymerase chain reaction (RT-PCR). Positive bands for HBV DNA were observed in the test groups but not in the control. Next, to identify the role of host genes in regulating viral gene transcription in sperm, total RNA was extracted from 2-cell embryos derived from hamster oocytes fertilized in vitro by HBV-transfected (test) or nontransfected (control) human sperm and successively subjected to SMART-PCR, suppression subtractive hybridization, T/A cloning, bacterial amplification, microarray hybridization, sequencing and the Basic Local Alignment Search Tool (BLAST) search to isolate differentially expressed genes. Twenty-nine sequences showing significant identity to five human gene families were identified, with chorionic somatomammotropin hormone 2 (CSH2), eukaryotic translation initiation factor 4 gamma 2 (EIF4G2), pterin-4 alpha-carbinolamine dehydratase 2 (PCBD2), pregnancy-specific beta-1-glycoprotein 4 (PSG4) and titin (TTN) selected to represent target genes. Using real-time quantitative RT-PCR (qRT-PCR), when CSH2 and PCBD2 (or EIF4G2, PSG4 and TTN) were silenced by RNA interference, transcriptional levels of HBV s and x genes significantly decreased (or increased) (P < 0.05). Silencing of a control gene in sperm did not significantly change transcription of HBV s and x genes (P > 0.05). This study provides the first experimental evidence that transcription of HBV genes occurs in human sperm and is regulated by host genes.

Host genes regulate transcription of sperm-introduced hepatitis B virus genes in embryo

Hepatitis B virus (HBV) can invade the male germline, and sperm-introduced HBV genes could be transcribed in embryo. This study was to explore whether viral gene transcription is regulated by host genes. Embryos were produced by in vitro fertilization of hamster oocytes with human sperm containing the HBV genome. Total RNA extracted from test and control embryos were subjected to SMART-PCR, SSH, microarray hybridization, sequencing and BLAST analysis. Twenty-nine sequences showing significant identity to five human gene families were identified, with CSH2, EIF4G2, PCBD2, PSG4 and TTN selected to represent target genes. Using qRT-PCR, when CSH2 and PCBD2 (or EIF4G2, PSG4 and TTN) were silenced by RNAi, transcriptional levels of HBV s and x genes decreased (or increased). This is the first report that host genes participate in regulation of sperm-introduced HBV gene transcription in embryo, which is critical to prevent negative impact of HBV infection on early embryonic development.

Hepatitis B surface antigen in oocytes and embryos may not result in vertical transmission to offspring of hepatitis B virus carriers

OBJECTIVE

To investigate the vertical transmission of hepatitis B virus (HBV) via embryos to children and whether HBV in embryos has an effect on the development of the fetus and pregnancy outcomes of in vitro fertilization and embryo transfer (IVF-ET).

DESIGN

Long-term follow-up study.

SETTING

Research laboratory.

PATIENT(S)

Thirty-one couples with a hepatitis B surface antigen (HBsAg)-negative woman and HBsAg-positive man, and 41 couples with a HBsAg-positive woman and HBsAg-negative man, whose unfertilized oocytes and nonviable embryos were tested for HBV DNA, RNA, or HBsAg.

INTERVENTION(S)

HBV DNA, RNA, or HBsAg analyses in unfertilized oocytes and nonviable embryos.

MAIN OUTCOME MEASURE(S)

HBV serologic markers analyses.

RESULT(S)

We obtained follow-up data for 71 couples. A total of 24 babies were born, and no newborns exhibited defects at birth. Twelve babies were born to couples with HBV-positive oocytes and/or embryos. The pregnancy outcomes were not associated with the presence of HBV in oocytes and embryos. Three patterns of HBV serologic markers were screened. Twenty babies were anti-HBs-positive. Three babies were negative for HBsAg, antibody to hepatitis B surface antigen (anti-HBs), antibody to hepatitis B core antigen (anti-HBc), HBeAg, and antibody to hepatitis B e antigen (anti-HBe). One baby was seropositive for anti-HBs, anti-HBc, and anti-HBe at 6 months of age but seroconverted from anti-HBe-positive to anti-HBe-negative at 9 months of age.

CONCLUSION(S)

The presence of HBsAg in oocytes and embryos may not result in the vertical transmission of HBV in the offspring of HBV carriers.

Oxidative damage of DNA induced by X-irradiation decreases the uterine endometrial receptivity which involves mitochondrial and lysosomal dysfunction

X irradiation may lead to female infertility and the mechanism is still not clear. After X irradiation exposure, significantly morphological changes and functional decline in endometrial epithelial cells were observed. The mitochondrial and lysosomal dysfunction and oxidative DNA damage were noticed after X irradiation. In addition, pretreatment with NAC, NH4Cl or Pep A reduced the X irradiation induced damages. These studies demonstrate that the oxidative DNA damage which involved dysfunctional lysosomal and mitochondrial contribute to X irradiation-induced impaired receptive state of uterine endometrium and proper protective reagents can be helpful in improving endometrial function.