Zika virus: Future reproductive concerns

John R. A human rights-based framework to assess gender equality in health systems: the example of Zika virus in the Americas

BACKGROUND

The right to health was enshrined in the constitution of the World Health Organization (WHO) in 1946 and in the Universal Declaration of Human Rights in 1948. The latter Declaration, which also guaranteed women's rights, was signed by almost all countries in the world. Subsequent international conventions reinforced these rights, requiring that women be able to realize their fundamental freedoms and dignity. Although the value of incorporating gender into health systems has been increasingly acknowledged over the years, gender inequalities in health persist.

OBJECTIVE

To introduce a tool to help countries assess their performance in addressing gender inequalities in their health systems, using the example of the Zika virus (ZIKV) in countries of the Americas.

METHODS

This paper is based on comprehensive reviews of the literature on the links between gender equality, health systems and human rights, and available scientific evidence about an adequate response to ZIKV.

RESULTS

The authors present a simple two-part framework from the human rights perspectives of the health system as duty bearer, incorporating WHO's six health system building blocks, and of its clients as rights holders. The authors apply the framework to ZIKV in the Americas, and identify strengths and weaknesses at every level of the health system. They find that when considering gender, health systems have focused mainly on dichotomous sex differences, failing to consider broader gender relations and processes affecting access to services, quality of care, and health outcomes.

CONCLUSIONS

The authors' framework will permit countries to assess progress toward gender equality in health, within the context of their human rights commitments, by examining each health system building block, and the degree to which clients are realizing their rights. By applying the framework to specific health conditions, gender-related achievements and shortcomings can be identified in each health system component, fostering a more comprehensive and gender-sensitive response.

Cellular Targets and Receptor of Sexual Transmission of Zika Virus

STUDY QUESTION

What is the mechanism of sexual transmission of Zika virus (ZIKV)?

SUMMARY ANSWER

By utilizing exquisite reverse transcriptase-initiated in situ polymerase chain reaction (RT-in situ PCR), which enables an improved visualization of spermatozoa's subcellular compartment, we precisely localized the mid-piece of sperm that carry receptors for ZIKV.

WHAT IS ALREADY KNOWN

ZIKV is transmitted sexually and recent studies have verified ZIKV presence in semen of previously Zika-infected patients for >6-month postinfection when ZIKV had disappeared from blood, saliva, and urine. Strong serial analyses of various body fluids suggest that ZIKV can be transmitted between sexual partners. Currently, there is limited information on the association of the virus with human semen cell types that may carry the virus.

STUDY DESIGN, SIZE, DURATION

Analyses were carried out to localize ZIKV for subcellular localization of ZIKV on cell types. The Tyro3 receptor for ZIKV was colocalized by dual immunocytochemistry with specific monoclonal antibodies.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Three semen specimens were purchased from a commercial sperm bank. Motile sperm was separated from nonmotile cells by the "swim-up" technique. Each of the semen fractions was infected with ZIKV at the multiplicity of infection of 0.1.0 and 1.0 and evaluated for the primary targets of ZIKV in the semen cells by RT-in situ PCR and confirmed by real-time RT-PCR.

MAIN RESULTS AND THE ROLE OF CHANCE

ZIKV was present primarily at the mid-piece of mature spermatozoa in about 30% of the sperm. In addition, we determined that Tyro3 receptors, primarily expressed on mid-piece of human spermatozoa, play a role in ZIKV-binding and entry into spermatozoa. Our data strongly suggest a potential sexual/horizontal route of transmission for ZIKV primarily via infected sperms; most likely ZIKV enters the sperm via the Tyro3 receptor found at the mid-piece of the mature spermatozoa.

LIMITATIONS, REASONS FOR CAUTION

We are uncertain as to what phase of spermatogenesis, that in human takes about 120 days, sperms are permissive to ZIKV. If permissiveness was very early during spermatogenesis males could be infectious for ∼120 days after the disappearance of viremia in an infected man.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings bring a new focus on the current affords to develop ZIKV vaccine. Why in the presence of anti-ZIKV antibodies infected men are still able to transmit the virus sexually? We suggest that only certain subclass of immunoglobulin (Ig)G (ie, IgG4) can cross the blood-Sertoli barrier therefore, a successful vaccine must provoke a subclass of IgG can quell ZIKV inside the seminiferous tubules.

The non-canonical Notch signaling is essential for the control of fertility in Aedes aegypti

The Notch signaling pathway is a highly evolutionarily-conserved cell-cell signaling pathway that regulates many events during development. It plays a pivotal role in the regulation of fundamental cellular processes, such as cell proliferation, stem cell maintenance, and differentiation during embryonic and adult development. However, functions of Notch signaling in Aedes aegypti, the major mosquito vector for dengue, are largely unknown. In this study, we identified a unique feature of A. aegypti Notch (AaNotch) in the control of the sterile-like phenotype in female mosquitoes. Silencing AaNotch with a reverse genetic approach significantly reduced the fecundity and fertility of the mosquito. Silencing AaNotch also resulted in the prevention of micropyle formation, which led to impaired fertilization. In addition, JNK phosphorylation (a signaling molecule in the non-canonical Notch signaling pathway) was inhibited in the absence of AaNotch. Furthermore, treatment with a JNK inhibitor in the mosquito resulted in impaired fecundity and fertility. Taken together, our results demonstrate that non-canonical Notch signaling is essential for controlling fertility in the A. aegypti mosquito.

Human Zika and West Nile virus neurological infections: What is the difference?

The recent epidemic of West Nile Virus (WNV) infection in the United States was associated with severe neurological disease in immunocompromised hosts, while the emergence of Zika virus infection in the Americas has been notable for an association with increased microcephaly in the fetuses of infected mothers. Rare autopsies of WNV infected humans have shown multiple organ involvement with a clear neurotropism. We have recently had the opportunity to examine the distribution of Zika virus in autopsies of newborns from infected pregnancies. While both viruses infect multiple organs, Zika appears to cause neurological disease in the fetus through two different mechanisms. Infection during the first trimester showed the potential to infect neural progenitor cells causing severe developmental abnormalities, while infection later in gestation was associated with meningeal infection and destructive ischemic lesions of the brain. Both viruses infect kidney tubules but Zika shares a prominent hepatotropism characteristic of other flaviviruses (e.g., Dengue). Limited transplacental Zika infection would be consistent with restriction to primary maternal infections with high viremia. In the absence of a vaccine, restriction of travel by immunosuppressed and pregnant non-immune individuals to endemic regions seems prudent.