Implications of RNA Viruses in the Male Reproductive Tract: An Outlook on SARS-CoV-2

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.

Effects of COVID-19 Infection on Spermatogenesis, Oxidative Stress and Erectile Function

BACKGROUND

Our aim was to evaluate the effect of COVID-19 infection on male fertility and sexual function.

METHODS

Thirty-one patients were investigated over a mean follow-up of 90 days (22-527) after a COVID-19 infection. Erectile dysfunction (ED), blood tests for sexual hormones, semen analysis including analysis of oxidative stress (OS), as well as COVID-19 antibody titer and the nasal COVID-19 PCR test were evaluated pre- and post-infection.

RESULTS

Five patients reported a mild de novo ED (16.13%). One patient had a de novo positive mixed antiglobulin reaction test after the infection. We found no significant difference between pre-COVID-19 and post-COVID-19 spermiogram parameters (p = 0.815). OS showed no significant association with COVID-19 infection, but with pathological spermiogram categories, sperm concentration, total sperm count, testis volume, FSH and testosterone.

CONCLUSION

COVID-19 infection does not appear to affect sperm quality and OS negatively in the intermediate term. Further investigations will be needed to assess the potential long-term effects of the infection and vaccination on male sexual function and fertility.

Influence of body mass index and waist-hip ratio on male semen parameters in infertile men in the real world: a retrospective study

Background

It is suggested that body mass index (BMI) can affect male semen quality; however, the results remain controversial. In addition, most studies have focused on the effect of obesity on semen quality. Evidence on the relationship of underweight or waist-hip ratio (WHR) with semen quality is rare. This study aimed to assess the association of BMI and WHR with semen quality.

Methods

Data, including BMI and WHR, was collected from 715.00 men who underwent a fertility evaluation. BMI (kg/m²) was categorized as <18.50 (underweight), 18.50-24.90 (normal), 25.00-27.90 (overweight), and ≥28.00 (obese) kg/m² for analysis. WHR was categorized as <0.81 (normal) and ≥0.81 (high). Semen volume, sperm concentration, progressive motility, and total motile sperm count were detected by experienced clinical technicians.

Results

Spearman's correlation showed that BMI was weakly associated with sperm progressive motility (r = 0.076, P < 0.05), while WHR showed no relationship with semen parameters. The azoospermia rate was significantly higher (33.33% vs. 2.10%, P < 0.001) and the sperm concentration was lower (P < 0.05) in the underweight group. The nonlinear correlation analysis showed that BMI was negatively associated with sperm concentration while BMI was more than 22.40 kg/m² (P < 0.05), while WHR was negatively related to sperm progressive motility within 0.82 to 0.89 (P < 0.05). Furthermore, the multivariate logistic analysis showed that follicular stimulating hormone (FSH) was an independent risk factor for normal sperm concentration (odds ratio [OR]: 0.791, P = 0.001) and morphology (OR: 0.821, P = 0.002), BMI was an independent risk factor for normal sperm progressive motility, and testosterone was an independent risk factor for sperm morphology (OR: 0.908, P = 0.023).

Conclusion

BMI and WHR were significantly associated with semen parameters, while BMI was an independent risk factor for normal sperm progressive motility. Reproductive hormones, including FSH and testosterone, had a significant influence on sperm concentration and sperm morphology.

The role of glial cells in Zika virus-induced neurodegeneration

Zika virus (ZIKV) is a strongly neurotropic flavivirus whose infection has been associated with microcephaly in neonates. However, clinical and experimental evidence indicate that ZIKV also affects the adult nervous system. In this regard, in vitro and in vivo studies have shown the ability of ZIKV to infect glial cells. In the central nervous system (CNS), glial cells are represented by astrocytes, microglia, and oligodendrocytes. In contrast, the peripheral nervous system (PNS) constitutes a highly heterogeneous group of cells (Schwann cells, satellite glial cells, and enteric glial cells) spread through the body. These cells are critical in both physiological and pathological conditions; as such, ZIKV-induced glial dysfunctions can be associated with the development and progression of neurological complications, including those related to the adult and aging brain. This review will address the effects of ZIKV infection on CNS and PNS glial cells, focusing on cellular and molecular mechanisms, including changes in the inflammatory response, oxidative stress, mitochondrial dysfunction, Ca²⁺ and glutamate homeostasis, neural metabolism, and neuron-glia communication. Of note, preventive and therapeutic strategies that focus on glial cells may emerge to delay and/or prevent the development of ZIKV-induced neurodegeneration and its consequences.

Is monkeypox a new, emerging sexually transmitted disease? A rapid review of the literature

Monkeypox, a milder disease compared to smallpox, is caused by a virus initially discovered and described in 1958 by the prominent Danish virologist von Magnus, who was investigating an infectious outbreak affecting monkey colonies. Currently, officially starting from May 2022, an outbreak of monkeypox is ongoing, with 51 000 cases being notified as of September 1, 2022-51 408 confirmed, 28 suspected, and 12 fatalities, for a grand total of 51 448 cases. More than 100 countries and territories are affected, from all the six World Health Organization regions. There are some striking features, that make this outbreak rather unusual when compared with previous outbreaks, including a shift on average age and the most affected age group, affected sex/gender, risk factors, clinical course, presentation, and the transmission route. Initially predominantly zoonotic, with an animal-to-human transmission, throughout the last decades, human-to-human transmission has become more and more sustained and effective. In particular, clusters of monkeypox have been described among men having sex with men, some of which have been epidemiologically linked to international travel to nonendemic countries and participation in mass gathering events/festivals, like the "Maspalomas (Gran Canaria) 2022 pride." This review will specifically focus on the "emerging" transmission route of the monkeypox virus, that is to say, the sexual transmission route, which, although not confirmed yet, seems highly likely in the diffusion of the infectious agent.

Microbial and human transcriptional profiling of coronavirus disease 2019 patients: Potential predictors of disease severity

The high morbidity of patients with coronavirus disease 2019 (COVID-19) brings on a panic around the world. COVID-19 is associated with sex bias, immune system, and preexisting chronic diseases. We analyzed the gene expression in patients with COVID-19 and in their microbiota in order to identify potential biomarkers to aid in disease management. A total of 129 RNA samples from nasopharyngeal, oropharyngeal, and anal swabs were collected and sequenced in a high-throughput manner. Several microbial strains differed in abundance between patients with mild or severe COVID-19. Microbial genera were more abundant in oropharyngeal swabs than in nasopharyngeal or anal swabs. Oropharyngeal swabs allowed more sensitive detection of the causative SARS-CoV-2. Microbial and human transcriptomes in swabs from patients with mild disease showed enrichment of genes involved in amino acid metabolism, or protein modification via small protein removal, and antibacterial defense responses, respectively, whereas swabs from patients with severe disease showed enrichment of genes involved in drug metabolism, or negative regulation of apoptosis execution, spermatogenesis, and immune system, respectively. Microbial abundance and diversity did not differ significantly between males and females. The expression of several host genes on the X chromosome correlated negatively with disease severity. In this way, our analyses identify host genes whose differential expression could aid in the diagnosis of COVID-19 and prediction of its severity via non-invasive assay.

Cellular and Molecular Mechanisms of In Vivo and In Vitro SARS-CoV-2 Infection: A Lesson from Human Sperm

Despite the major target of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, being the respiratory system, clinical evidence suggests that the male reproductive system may represent another viral target organ. Revealing the effect of SARS-CoV-2 infection on testis and sperm is a priority for reproductive biology, as well as for reproductive medicine. Here, we confirmed that the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) is highly expressed on human testis and ejaculated sperm; moreover, we provide evidence for the expression of the co-receptors transmembrane protease/serine (TMPRSS2), Basigin (BSG), and Catepsin L (CTSL). Human sperm were readily infected, both in vivo and in vitro, by SARS-CoV-2, as demonstrated by confocal and electron microscopy. The demonstration that the seminiferous epithelium and sperm support SARS-CoV-2 viral replication suggests the possibility that the spermatogenetic process may be detrimentally affected by the virus, and at the same time, supports the need to implement safety measures and guidelines to ensure specific care in reproductive medicine.

Effects of mild/asymptomatic COVID-19 on semen parameters and sex-related hormone levels in men: a systematic review and meta-analysis

Coronavirus disease 2019 (COVID-19) has yet to be proven to alter male reproductive function, particularly in the majority of mild/asymptomatic patients. The purpose of this study was to explore whether mild/asymptomatic COVID-19 affects semen quality and sex-related hormone levels. To find suitable comparative studies, a systematic review and meta-analysis was done up to January 22, 2022, by using multiple databases (Web of Science, PubMed, and Embase). Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to identify and choose the studies. Meta-analysis was used to examine the semen parameters and sex-related hormones of mild/asymptomatic COVID-19 patients before and after infection. The effects of semen collection time, fever, and intensity of verification on semen following infection were also investigated. A total of 13 studies (n = 770) were included in the analysis, including three case-control studies, six pre-post studies, and four single-arm studies. A meta-analysis of five pre-post studies showed that after infection with COVID-19, sperm concentration (I² = 0; P = 0.003), total sperm count (I² = 46.3%; P = 0.043), progressive motility (I² = 50.0%; P < 0.001), total sperm motility (I² = 76.1%; P = 0.047), and normal sperm morphology (I² = 0; P = 0.001) decreased. Simultaneously, a systematic review of 13 studies found a significant relationship between semen collection time after infection, inflammation severity, and semen parameter values, with fever having only bearing on semen concentration. Furthermore, there was no significant difference in sex-related hormone levels before and after infection in mild/asymptomatic patients. Mild/asymptomatic COVID-19 infection had a significant effect on semen quality in the short term. It is recommended to avoid initiating a pregnancy during this period of time.