Research shows efficacy of malarial drug Chloroquine in treating Zika infection

Zika virus remains a major global health risk. In most adults, Zika causes mild flu-like symptoms. But in pregnant women, the virus can cause serious birth defects in babies including microcephaly a neurological condition in which newborns have unusually small heads and fail to develop properly. There is no treatment or way to reverse the condition.

A new research study led by researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) and UC San Diego School of Medicine has found that chloroquine, a medication used to prevent and treat malaria may also be effective for Zika virus. The drug has a long history of safe use during pregnancy, and is relatively inexpensive. The research was published today in Scientific Reports.

Terskikh is co-senior author of a new study that examined the effect of chloroquine in human brain organoids and pregnant mice infected with the virus, and found the drug markedly reduced the amount of Zika virus in maternal blood and neural progenitor cells in the fetal brain. Pregnant mice received chloroquine through drinking water in dosages equivalent to acceptable levels used in humans.

Citation: Shiryaev, Sergey A., Pinar Mesci, Antonella Pinto, Isabella Fernandes, Nicholas Sheets, Sujan Shresta, Chen Farhy, Chun-Teng Huang, Alex Y. Strongin, Alysson R. Muotri, and Alexey V. Terskikh. “Repurposing of the anti-malaria drug chloroquine for Zika Virus treatment and prophylaxis.” Scientific Reports 7, no. 1 (2017).
doi:10.1038/s41598-017-15467-6.
Funding: California Institute for Regenerative Medicine, National Institutes of Health, NARSAD Independent Investigator Grant, International Rett Syndrome Foundation.
Adapted from press release by Sanford-Burnham Prebys Medical Discovery Institute.

Analysis of interactome of Zika virus infected neural cells shows altered expression of more than 500 proteins

Zika virus (ZIKV) interferes with the cellular machinery controlling cell division and alters the expression of hundreds of genes responsible for guiding the formation and development of brain cells, according to findings of research published in Scientific Reports.

Zika virus wikipedia
Zika virus structure. Credit: Wikipedia / David Goodwill

The association between Zika virus (ZIKV) infection and microcephaly has been previously established. Nevertheless, the cellular changes caused by the virus and leading to microcephaly are largely unknown. “Elucidating the foundations of Zika virus infection is crucial in order to develop tools against it”, says Stevens Rehen, the principal investigator of the study and a researcher working at the D’ Or Institute for Research and Education (IDOR) and at the Institute of Biomedical Sciences at Federal University of Rio de Janeiro (UFRJ) in Brazil.

In a previous study published by the group in Science magazine, researchers observed that the pool of human neural stem cells infected by the Brazilian strain of Zika virus was rapidly and completely depleted if compared to non-infected cells. This finding led the group to further investigate how Zika virus disrupts the interactome map (or molecular fingerprinting) of infected cells – which is the entire set of cellular and molecular interactions in a given cell group. The analysis of the interactome of Zika-infected cells may reveal the cellular targets and pathways with which the virus interacts or which it modulates, offering valuable opportunities for drug design.

To this end, human neural cells were infected by a strain of Zika virus (ZIKV) obtained from a Brazilian patient. These cells were then made into neurospheres, which are organized 3D aggregates of neural cells resembling fetal brain tissue that recapitulate many of the normal early and crucial processes that the brain undergoes through development and thus are a great model for studying the human brain. Next, the group identified the molecular fingerprinting of infected and non-infected cells by checking the expression level and status of innumerous genes and proteins.

The analysis revealed that more than 500 proteins in infected neurospheres had their expression level or status (upregulated vs downregulated) altered, if compared to non-infected neurospheres. A number of these altered proteins are normally involved with tasks such as fixing DNA damage or assuring chromosomal stability. Also, proteins that are normally required for cell growth were silent in infected neurospheres, which may explain why Zika-infected cells die much sooner than their non-infected counterparts. Interestingly, genes driving cell specialization were also silent in infected neurospheres, precluding that specialized brain cells were generated. On the other hand, proteins associated with viral replication were over-abundant, most likely the result of a strategy adopted by the virus to promote its own replication in the host cell. A complete list of all human proteins that have been found altered in Zika-infected neurospheres is available in the study entitled “Zika virus disrupts molecular fingerprinting of human neurospheres”, published in Scientific Reports this week. 

According to Patricia Garcez, Assistant Professor at the Federal University of Rio de Janeiro and the first author of the study: “these findings provide insights into the molecular mechanisms of Zika virus (ZIKV) infection over the course of brain development and may explain some of the consequences seen in the brain of newborns with microcephaly”.

Citation: Patricia P. Garcez, Juliana Minardi Nascimento, Janaina Mota de Vasconcelos, Rodrigo Madeiro da Costa, Rodrigo Delvecchio, Pablo Trindade, Erick Correia Loiola, Luiza M. Higa, Juliana S. Cassoli, Gabriela Vitória, Patricia C. Sequeira, Jaroslaw Sochacki, Renato S. Aguiar, Hellen Thais Fuzii, Ana M. Bispo de Filippis, João Lídio da Silva Gonçalves Vianez Júnior, Amilcar Tanuri, Daniel Martins-de-Souza & Stevens K. Rehen. “Zika virus disrupts molecular fingerprinting of human neurospheres.” Scientific Reports 7, Article number: 40780 (2017).
DOI: 10.1038/srep40780
Research funding: Brazilian Development Bank, Funding Authority for Studies and Projects, National Council of Scientific and Technological Development, Foundation for Research Support – State of Rio de Janeiro, São Paulo Research Foundation.
Adapted from press release by D’ Or Institute for Research and Education (IDOR).

Zika virus research: Structure of immature virus revealed

Researchers at Purdue University have determined the high-resolution structure of immature Zika virus, a step toward better understanding how the virus infects host cells and spreads.

Purdue researchers have determined the high-resolution structure of the immature Zika virus. This composite image of the surface (left), and cross-sectional region (right), reflect the new findings. Research into a virus’s structure provides insights important to the development of effective antiviral treatments and vaccines.
Credit: Purdue University image courtesy of Kuhn and Rossmann research groups.

Zika belongs to a family of viruses called flaviviruses, which includes dengue, West Nile, yellow fever, Japanese encephalitis and tick-borne encephalitic viruses. Although only the mature forms of flaviviruses are considered infectious, the virus population secreted from host cells is a mixture of mature, partially mature and immature virus particles. “It is, therefore, probable that the immature form of Zika also plays a role in virus infection and spread,” said Michael Rossmann, Purdue’s Hanley Distinguished Professor of Biological Sciences.

The research team was led by Rossmann, with Richard Kuhn, both professors in Purdue’s Department of Biological Sciences, as well as postdoctoral research associate Vidya Mangala Prasad. Findings are detailed in a research paper published in the journal Nature Structural & Molecular Biology .

The researchers used a technique called cryo-electron microscopy to reconstruct the immature virus’s structure at 9 Ångstroms resolution, or about a thousand times better resolution than would be possible with a conventional light microscope.

The genome of the virus is housed inside a protective envelope that includes a lipid membrane, an envelope protein, a precursor membrane protein and a capsid protein. The Purdue researchers are the first to learn the position of the capsid protein in the immature virus, which plays the critical role of recognizing the virus’s genetic material and acts as a chaperone to guide these RNA strands into the virus for assembly. The envelope protein is essential for the virus’s binding, attachment and fusion to host cells during the infection process. The membrane protein cleaves from the mature virus as it is released from the host to infect other cells.

A map of the immature virus’s structure revealed details about the proteins, showing that the envelope and precursor membrane proteins are arranged in 60 spike-like features on the virus’s surface, whereas the capsid protein is located on the internal side of the lipid membrane. The structure differs from the mature Zika virus in that the membrane protein in the mature virus is covered by the envelope protein. Both proteins exist on the surface of the immature version of the virus. Findings also show differences between the immature Zika virus and immature versions of other flaviviruses. Notably, it contains a “partially ordered capsid protein shell” that is less prominent in other immature flaviviruses.

“I think these findings open the door to begin to explore the assembly process of the virus,” said Kuhn, director of the Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D). And researchers feel that the structure of the virus is likely to play a major role in the disease, transmission, and pathology.

Citation: Prasad, Vidya Mangala,  Andrew S Miller, Thomas Klose, Devika Sirohi, Geeta Buda, Wen Jiang, Richard J Kuhn & Michael G Rossmann. “Structure of the immature Zika virus at 9 Å resolution.” Nature Structural & Molecular Biology 2017.
DOI: 10.1038/nsmb.3352
Research funding: NIH
Adapted from press release by Purdue University.

Zika virus lineage and evolution

The Zika virus remains a mystery. Isolated from macaque monkeys in the Ziika Forest in Uganda in 1947, the virus was shown to infect humans not long after, but it was identified as a benign disease, with mild symptoms. For this reason, it was not heavily studied until almost 70 years later when it appeared to be associated with an unusual cluster of cases of microcephalic birth defects and Guillain-Barré Syndrome (GBS) paralysis in Brazil in 2015 and 2016.

Zika Virus. Credit: Wikipedia

If the at-least-70-year-old virus is responsible for the recently reported neurological diseases, why were the first serious effects not noticed until recently? And, why were these effects first in Brazil, very distant from its continent of apparent origin, Africa? The mysterious history of the virus matters because its details might tell us the backstory of how it came to be what it is where it is and from that, why it is doing so much damage.

But, how do you know the history of an invisible virus, which leaves no physical record? It is especially hard to know the history of Zika because the seemingly benign disease has been under-the-radar for most of its known time in human hosts.

This is where genetics can help, since single-strand RNA viruses like Zika tend to change rapidly over time and, with bioinformatics, researchers can deduce what the ancestral relationships are between different viruses collected at different places in different times from different hosts. While the first noted occurrence of the virus was in Africa, it was detected only a few years later in Asia, and separate lineages of the disease are known from both areas – a clue that the history hidden in the genes may be complicated.

“But sequence data on Zika is limited,” notes University of North Carolina at Charlotte Bioinformatics and Genomics Professor Daniel Janies. “People have made the assumption that it came out of Africa because that’s where it was discovered. However, it has not been easy to reconstruct the history of Zika with the data we have,” he said.

Janies heads a team of researchers who have recently completed a phylogenetic and geographic analysis of the available collection of Zika’s genetic sequences. The analysis provides the most complete study of the virus’s history to date and reveals specific genetic changes that occurred as the virus crossed the Pacific Ocean on its way to the Americas. An analysis of the genes involved also suggests new hypotheses to explain the virus’s association with microcephaly and GBS.

A report by Janies, Adriano de Bernardi Schneider, Jun-tao Guo, Gregorio Linchangco, Zachary Witter, Dylan Vinesett and Lambodhar Damodaran from the department of Bioinformatics and Genomics at UNC Charlotte, Robert Malone from Atheric Pharmaceutical, and Jane Homan from IoGenetics LLC appears in the issue of Cladistics.

“Our results indicate that Zika may have deep ancestry in Asia that has been under-recorded,” Janies said. “For example, not all the recent global outbreaks of Zika appear to result from a simple linear chronology of travel from the most recent past outbreak.”

“Recently there has been an outbreak of Zika in Singapore in parallel to the one in the Americas. We have updated our analyses and the Singapore Zika virus is distantly related to the viral lineage in the Americas. This lends support for the hypothesis that there are yet-to-be-discovered reservoirs of Zika virus in Asia,” Janies said.

The Cladistics report traces Zika’s phylogenetic tree through analysis of genetic sequences, combining it with the chronology and geographic information from the samples, and allows the researchers to detail the virus’ probable historical path as well as specific genetic and structural changes in the virus as it traveled to the Americas.

The researchers noted, in particular, some new mutations that began appearing in the virus as it traveled from island to island across the Pacific. Not long after these mutations appear, there are records in French Polynesia of an increase in both microcephaly and GBS. The specific nature of the new mutations in the virus also suggest to the team some possible relationships between viral infection and the severe symptoms associated with the virus in the Americas.

“We looked at the viral changes that correspond to the first reports of microcephaly and we saw the origins of these changes in the Pacific lineages,” Janies noted. “There are mutations that occurred in the part of the viral genome that codes the viral envelope protein and the ends of the viral genome that are called ‘untranslated regions.’ We focused on the envelope protein because that’s the part responsible for the entry of the virus to host’s cells. We studied the untranslated regions since they mediate the types of tissues the virus attacks and viral replication.”

Both sets of mutations suggested potential relationships to the virus’s new association with neurological and developmental problems in adults and infants.

“Members of our team found that Zika has recently started making its envelope proteins with features, called epitopes, that are similar to human proteins, which could cause a human host immune response to the virus to be diluted,” Janies said. “The theory underlying this idea is called ‘epitope mimicry.’ The similarity is advantageous to the virus because it confuses the host’s immune system and blunts the immune reaction to the virus.”

However, the researchers suspect that the human proteins being mimicked may be significant for reasons besides providing immune system “cover” for the attacking virus.

An important element of the envelope protein mutation, Janies points out, is not only in the mimicry itself, but also, in the specific genes being mimicked: “Our team members found that two of the human proteins that Zika is mimicking are involved in the signaling that goes on when the sensory organs are being formed in the fetus. These genes are called ‘Neuron Navigator Protein 2’ and ‘Human Neurogenic Differentiation Factor 4’, ” he said.

“Because these are the proteins are being mimicked, a hypothesis is that the developmental pathways that rely on the proteins may be being disrupted by the immune system,” Janies said.

The other mutations, on the untranslated regions, suggest other possible effects that might change where Zika virus infects in the body.

Although epitope mimicry hypothesis helps clarify the protein-immune interaction, the mutations in the untranslated regions may explain the types of tissues Zika attacks” UNC Charlotte Bioinformatics and Genomics graduate student Adriano de Bernardi Schneider said. “The presence of specific binding regions on untranslated regions of the Zika viral genome, called “Musashi Binding Elements” provides bases for the study of changes in tissue preference of the virus.”

In this part of the study, the authors evaluated the changes in the virus’ Musashi Binding Elements and found that they increased the efficiency of the Zika virus that is circulating in the Americas in hijacking human cells.

Musashi is a family of RNA-binding proteins in the host cells that control gene expression and the development of stem cells. The finding that Zika has mutated to be better at binding to human Musashi proteins, leads to the hypothesis that Zika is adapting to be more efficient at attacking human cells. Moreover, the role of Musashi proteins in stem cells provides another possible target for the study of developmental defects in the fetus associated with Zika infection in pregnancy.

Both the autoimmune effect and changes in the virus’ tissue specificity are working hypotheses suggested by computational models and will require further study to verify.

In contrast, the information gained from studying Zika’s phylogenetic history is of immediate importance to medicine and public health response, as this work puts the mutations in specific time and place context, at a time when the virus has nearly circled the planet, changing from place to place in its travels and leaving different variants. Many versions of the virus currently exist globally and these variants have different capabilities and effects.

“We’re tracing the lineages and the geographic links in a very rigorous way and pulling it all together, pinpointing Zika’s molecular changes in time and space – showing what actually is going on in different places,” Janies said. “Why does it matter? Well, when Zika arrives someplace is it going to be benign or dangerous? It has been both — it depends on where it is coming from.”

Citation: Adriano de Bernardi Schneider, Robert W. Malone, Jun-Tao Guo, Jane Homan, Gregorio Linchangco, Zachary L. Witter, Dylan Vinesett, Lambodhar Damodaran and Daniel A. Janies. “Molecular evolution of Zika virus as it crossed the Pacific to the Americas”. Cladistics 2016.
DOI: 10.1111/cla.12178
Research funding: Defense Advanced Research Projects Agency.
Adapted from press release by the University of North Carolina at Charlotte. 

Zika virus infection can cause Glaucoma in infants

A team of researchers in Brazil and at the Yale School of Public Health has published the first report demonstrating that the Zika virus can cause glaucoma in infants who were exposed to the virus during gestation.

Cross-section of Zika virus, with capsid layer (pink),
membrane layer (purple), and RNA genome (yellow)
Credit: Wikipedia, David Goodwill
Exposure to the Zika virus during pregnancy causes birth defects of the central nervous system, including microcephaly. Brazilian and Yale School of Public Health researchers had reported early during the microcephaly epidemic that the virus also causes severe lesions in the retina, the posterior portion of the eye. However, until now, there has been no evidence that Zika causes glaucoma, a condition that can result in permanent damage to the optic nerve and blindness.
“We identified the first case where Zika virus appears to have affected the development of the anterior chamber or front portion of the eye during gestation and caused glaucoma after birth,” said Albert Icksang Ko, M.D., professor at the Yale School of Public Health and co-author of the study published in the journal Ophthalmology. Ko has longstanding research collaborations in Brazil and has worked with local scientists since Zika first appeared in the Americas to better understand the birth defects that are caused by the virus and the risk factors for Zika Congenital Syndrome.

While conducting their investigations of the microcephaly epidemic in Salvador in Northeast Brazil, the researchers identified a three-month-old boy who was exposed to Zika virus during gestation. While no signs of glaucoma were present at the time of birth, the infant developed swelling, pain, and tearing in the right eye. The research team diagnosed glaucoma as the cause of symptoms and together with local ophthalmologists, performed a trabeculectomy, an operation that successfully alleviated the pressure within the eye.

While this is the first known incidence of glaucoma in an infant with the Zika virus, clinicians treating patients with Zika should be aware that glaucoma is another serious symptom of the disease that should be monitored, said the investigators. Additional research is needed to determine if glaucoma in infants with Zika is caused by indirect or direct exposure to the virus, either during gestation or postpartum.

The Zika virus, which is primarily transmitted through infected mosquitoes, has reached epidemic levels in several areas worldwide, and is of particular concern in Brazil, where the Pan American Health Organization reports more than 200,000 suspected cases and 109,000 confirmed cases of the disease. Since the outbreak began in 2015, Zika has now reached the United States, with more than 4,000 travel-related cases reported, and 139 locally acquired mosquito-borne cases confirmed, according to the CDC. There is currently no vaccine for the Zika virus.

Citation: “Glaucoma and Congenital Zika Syndrome”. Bruno de Paula Freitas, Albert I. Ko, Ricardo Khouri, Monica Mayoral, Daniele Freitas Henriques, Maurício Maia, Rubens Belfort Jr. Ophthalmology 2016 vol: 0 (0) pp: 529-535.
DOI: 10.1016/j.ophtha.2016.10.004

Adapted from press release by Yale University.

Understanding how Zika virus interacts with human antibody C10 paves way for new therapeutic target

As Zika virus spreads throughout the world, the call for rapid development of therapeutics to treat Zika virus rings loud and clear. Taking a step further in identifying a possible therapeutic candidate, a team of researchers at Duke-NUS Medical School (Duke-NUS), in collaboration with scientists from the University of North Carolina, have discovered the mechanism by which C10, a human antibody previously identified to react with the Dengue virus, prevents Zika virus infection at a cellular level.

C10 antibody (purple) visualized to be interacting with
the Zika virus coat (green). Credit:Victor Kostyuchenko,
Duke-NUS Medical School
Previously, C10 was identified as one of the most potent antibodies able to neutralize Zika virus infection. Now, Associate Prof Lok Shee-Mei and her team at the Emerging Infectious Disease Programme of Duke-NUS have taken it one step further by determining how C10 is able to prevent Zika virus infection.
To infect a cell, virus particles usually undergo two main steps, docking and fusion, which are also common targets for disruption when developing viral therapeutics. During docking, the virus particle identifies specific sites on the cell and binds to them. With Zika virus infection, docking then initiates the cell to take the virus in via an endosome – a separate compartment within the cell body. Proteins within the virus coat undergo structural changes to fuse with the membrane of the endosome, thereby releasing the virus genome into the cell, and completing the fusion step of infection.

Using a method called cryoelectron microscopy, which allows for the visualization of extremely small particles and their interactions, the team visualized C10 interacting with the Zika virus under different pHs, so as to mimic the different environments both the antibody and virus will find themselves in throughout infection. They showed that C10 binds to the main protein that makes up the Zika virus coat, regardless of pH, and locks these proteins into place, preventing the structural changes required for the fusion step of infection. Without fusion of the virus to the endosome, viral DNA is prevented from entering the cell, and infection is thwarted.

“Hopefully, these results will further accelerate the development of C10 as a Zika virus therapy to combat its effects of microcephaly and Guillain-Barré syndrome. This should emphasise the need for further studies of the effect of C10 on Zika virus infection in animal models,” commented Dr Lok.

“By defining the structural basis for neutralization, these studies provide further support for the idea that this antibody will protect against Zika virus infection, potentially leading to a new therapy to treat this dreaded disease,” says Ralph Baric, PhD, professor in the Department of Epidemiology at UNC’s Gillings School of Global Public Health.

These findings suggest that C10 may be developed as a therapy for Zika virus infection, and should be further explored. In addition, disrupting fusion with C10 may prove to be more effective in preventing Zika virus infection compared with therapies that attempt to disrupt docking. This is because the fusion step is critical for Zika virus infection, while the virus may develop other mechanisms to overcome disruptions to the docking step. With the call for rapid development of Zika therapies, C10 has emerged as a front runner to answer this call.

Citation: “Neutralization mechanism of a highly potent antibody against Zika virus”. Shuijun Zhang, Victor A. Kostyuchenko, Thiam-Seng Ng, Xin-Ni Lim, Justin S. G. Ooi, Sebastian Lambert, Ter Yong Tan, Douglas G. Widman, Jian Shi, Ralph S. Baric & Shee-Mei Lok. Nature Communications 2016 vol: 7 pp: 13679.
DOI: 10.1038/ncomms13679
Research funding: Singapore Ministry of Education, National Research Foundation, Singapore Ministry of Health, National Institutes of Health.
Adapted from press release by Duke-NUS Medical School.

Current vaccination trials using Zika Purified Inactivated Virus (ZPIV) vaccine

The first of five early stage clinical trials to test the safety and ability of an investigational Zika vaccine candidate called the Zika Purified Inactivated Virus (ZPIV) vaccine to generate an immune system response has begun at the Walter Reed Army Institute of Research (WRAIR) Clinical Trial Center in Silver Spring, Maryland.

The experimental Zika Purified Inactivated Virus (ZPIV) vaccine is based on the same technology WRAIR used in 2009 to successfully develop a vaccine for another flavivirus called Japanese encephalitis. The Zika Purified Inactivated Virus (ZPIV) vaccine contains whole Zika virus particles that have been inactivated, meaning that the virus cannot replicate and cause disease in humans. However, the protein shell of the inactivated virus remains intact so it can be recognized by the immune system and evoke an immune response. The National Institute of Allergy and Infectious Diseases (NIAID) partially supported the preclinical development of the Zika Purified Inactivated Virus (ZPIV) vaccine candidate, including safety testing and non-human primate studies that found that the vaccine induced antibodies that neutralized the virus and protected the animals from disease when they were challenged with Zika virus. WRAIR, NIAID and the Biomedical Advanced Research and Development Authority (BARDA) part of the HHS Office of the Assistant Secretary for Preparedness and Response (ASPR) have established a joint Research Collaboration Agreement to support the development of this vaccine.

Led by WRAIR principal investigator Maj. Leyi Lin, M.D., the new study aims to enroll 75 people ages 18 to 49 years with no prior flavivirus infection. Flaviviruses include Zika virus, yellow fever virus, dengue virus, Japanese encephalitis virus and West Nile virus. Participants will be randomly divided into three groups: the first group (25 participants) will receive two intramuscular injections of the Zika Purified Inactivated Virus (ZPIV)  test vaccine or a placebo (saline) 28 days apart; the other two groups (25 participants each) will receive a two-dose regimen of a Japanese encephalitis virus vaccine or one dose of a yellow fever vaccine before beginning the two-dose Zika Purified Inactivated Virus (ZPIV) vaccine regimen. Investigators chose to administer additional flavivirus vaccines because U.S. service members are often vaccinated against these diseases before deploying to Zika-endemic areas.

Additionally, a subgroup of 30 of the participants who receive the two-dose Zika Purified Inactivated Virus (ZPIV) regimen will receive a third dose one year later. All participants in the trial will receive the same Zika Purified Inactivated Virus (ZPIV) vaccine dose at each injection (5 micrograms). A DoD Research Monitor, an independent physician not associated with the protocol, will monitor the conduct of the trial and report any safety issues to the WRAIR Institutional Review Board. Another independent group, the Safety Monitoring Committee, will also monitor participant safety, review data and report any issues to NIAID. As the regulatory sponsor, NIAID ensures the trial follows the study protocol and informs the FDA of any significant adverse events or risks. NIAID also maintains the Investigational New Drug (IND) application (link is external) for the candidate vaccine. The WRAIR study is expected to be completed by fall 2018.

Four additional Phase 1 studies to evaluate the Zika Purified Inactivated Virus (ZPIV) investigational vaccine are expected to launch in the coming months. These include

A trial enrolling 90 adults ages 18-49 years at the Center for Vaccine Development at the Saint Louis University School of Medicine. This site is an NIAID-funded Vaccine and Treatment Evaluation Unit, and Sarah George, M.D., will serve as principal investigator. All participants will receive either two injections of Zika Purified Inactivated Virus (ZPIV) or a placebo 28 days apart. Participants will be randomly assigned to receive either a high, moderate or low dose at both injections to evaluate the optimal dose for use in larger future studies.

A trial enrolling 90 adults ages 21-49 years at the clinical research center CAIMED, part of Ponce Health Sciences University in Puerto Rico. The site is supported by NIAID via a subcontract from the Saint Louis University School of Medicine. This trial will examine the vaccine’s safety and immunogenicity in participants who have already been naturally exposed to dengue virus. Participants will be randomly assigned to receive either a high dose, moderate dose or a placebo. Elizabeth A. Barranco, M.D., will lead the trial.

NIAID’s Vaccine Research Center (VRC) will test the Zika Purified Inactivated Virus (ZPIV) vaccine candidate as a boost vaccination to its DNA Zika vaccine candidate, which entered Phase 1 clinical trials in August. The next part of the study, which will enroll 60 additional participants ages 18-50 years, will take place at the NIH Clinical Center in Bethesda, Maryland, the Center for Vaccine Development at the University of Maryland School of Medicine’s Institute for Global Health in Baltimore, and Emory University in Atlanta. Half of the participants will receive the NIAID Zika virus investigational DNA vaccine followed by a Zika Purified Inactivated Virus (ZPIV) vaccine boost four or 12 weeks later. The remaining participants will receive only two doses of Zika Purified Inactivated Virus (ZPIV) vaccine four or 12 weeks apart. Julie Ledgerwood, D.O., chief of the VRC’s clinical trials program, will serve as principal investigator.

A WRAIR-funded trial enrolling 48 adults ages 18-50 years will be conducted at the Center for Virology and Vaccine Research, part of Beth Israel Deaconess Medical Center and Harvard Medical School in Boston. One group of participants will receive a single dose of the Zika Purified Inactivated Virus (ZPIV)  vaccine and all other participants will receive two doses of the Zika Purified Inactivated Virus (ZPIV) vaccine at varying intervals. Kathryn Stephenson, M.D., M.P.H., of Beth Israel Deaconess Medical Center, will lead the trial.

Scientists with Walter Reed Army Institute of Research, part of the U.S. Department of Defense (DoD), developed the vaccine. The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), is co-funding the Phase 1 clinical trial with Walter Reed Army Institute of Research, serving as the regulatory sponsor and providing other support. BARDA is funding the advanced development of the Zika Purified Inactivated Virus (ZPIV) vaccine candidate through a six-year contract with Sanofi Pasteur, which established a collaborative research and development agreement with WRAIR to accelerate further development of the vaccine.

Adapted from press release by NIH and Walter Reed Army Institute of Research

Mathematical model suggests increase in Zika virus outbreaks following Dengue fever vaccination

Vaccinating against dengue fever could increase outbreaks of Zika, suggests new research out of York University and Xi’an Jiaotong University in China. The research identifies a potentially serious public health concern. More than a third of the world’s population lives in areas where dengue is endemic and cases of co-infection with Zika have already been reported.

Conducted at York University’s Laboratory for Industrial and Applied Mathematics using mathematical modelling, the research was led by Biao Tang, an exchange PhD student from Xi’an Jiaotong University, in collaboration with York Professor Jianhong Wu and Tang’s supervisor, Professor Yanni Xiao at Xi’an Jiaotong University. As dengue and Zika are both part of the Flaviviridae family transmitted through a common mosquito host, the researchers wanted to know how vaccinating for one would affect the incidence of the other.

“Vaccinating against one virus could not only affect the control of another virus, it could in fact make it easier for the other to spread,” says Wu. “Recent evidence suggests that dengue virus antibodies can enhance the Zika virus infection. For that reason, we developed a new math model to investigate the effect of dengue vaccination on Zika outbreaks.”  The paper, “Implication of vaccination against dengue for Zika outbreak,” was published in Scientific Reports.

The team’s model shows that vaccinations for dengue increase the number of people contracting Zika. It also shows that the more people in a particular population that are vaccinated against dengue, the earlier and larger the Zika outbreak. The research also found that the most effective way to minimize the unintended effect of dengue vaccinations on Zika outbreaks is through an integrated strategy that includes mosquito control.

The researchers note their findings do not discourage the development and promotion of dengue vaccine products, however, more work needs to be done to understand how to optimize dengue vaccination programs and minimize the risk of Zika outbreaks.

Citation: Tang, Biao, Yanni Xiao, and Jianhong Wu. “Implication of vaccination against dengue for Zika outbreak.” Scientific Reports 6 (2016).
DOI: http://dx.doi.org/10.1038/srep35623
Adapted from press release by York University and Xi’an Jiaotong University

Research finds effects of Zika virus on male reproductive system in mice

But a new study in mice suggests that Zika infection also may have worrisome consequences for men that interfere with their ability to have children. The research indicates that the virus targets the male reproductive system. Three weeks after male mice were infected with Zika, their testicles had shrunk, levels of their sex hormones had dropped and their fertility was reduced. Overall, these mice were less likely to impregnate female mice. The study is published Oct. 31 in Nature.

The virus is known to persist in men’s semen for months. The Centers for Disease Control and Prevention recommend that men who have traveled to a Zika-endemic region use condoms for six months, regardless of whether they have had symptoms of Zika infection. It is not known, however, what impact this lingering virus can have on men’s reproductive systems.

To find out how the Zika virus affects males, Diamond, co-senior author Kelle Moley, MD, the James P. Crane Professor of Obstetrics and Gynecology, and colleagues injected male mice with the Zika virus. After one week, the virus had migrated to the testes, which bore microscopic signs of inflammation. After two weeks, the testicles were significantly smaller, their internal structure was collapsing, and many cells were dead or dying.

After three weeks, the mice’s testicles had shrunk to one-tenth their normal size and the internal structure was completely destroyed. The mice were monitored until six weeks, and in that time their testicles did not heal, even after the mice had cleared the virus from their bloodstreams.

“We don’t know for certain if the damage is irreversible, but I expect so, because the cells that hold the internal structure in place have been infected and destroyed,” said Diamond, who is also a professor of pathology and immunology, and of molecular microbiology.

The structure of the testes depends on a type of cell called Sertoli cells, which maintain the barrier between the bloodstream and the testes and nourish developing sperm cells. Zika infects and kills Sertoli cells, the researchers found, and Sertoli cells don’t regenerate.

The testes normally produce sperm and testosterone, and as the mice’s testes sustained increasing levels of damage, their sperm counts and testosterone levels plummeted. By six weeks after infection, the number of motile sperm was down tenfold, and testosterone levels were similarly low.
When healthy females were mated with infected and uninfected male mice, the females paired with infected males were about four times less likely to become pregnant as those paired with uninfected males.

No reports have been published linking infertility in men to Zika infection, but, Moley said, infertility can be a difficult symptom to pick up in epidemiologic surveys.

“People often don’t find out that they’re infertile until they try to have children, and that could be years or decades after infection,” Moley said. “I think it is more likely doctors will start seeing men with symptoms of low testosterone, and they will work backward to make the connection to Zika.”
Men with low testosterone may experience a low sex drive, erectile dysfunction, fatigue and loss of body hair and muscle mass. Low testosterone can be diagnosed with a simple blood test.

Diamond and Moley said human studies in areas with high rates of Zika infection are needed to determine the impact of the virus on men’s reproductive health.

Citation: Zika virus infection damages the testes in mice. Authors: Jennifer Govero, Prabagaran Esakky, Suzanne M. Scheaffer, Estefania Fernandez, Andrea Drury, Derek J. Platt, Matthew J. Gorman, Justin M. Richner, Elizabeth A. Caine, Vanessa Salazar, Kelle H. Moley & Michael S. Diamond
DOI: http://dx.doi.org/10.1038/nature20556
Journal: Nature
Research Funding: NIH/National Institute of Allergy and Infectious Diseases
Adapted from press release by Washington University in St Louis

Zika virus evolution and spread

In a study published in Pathogens and Global Health, researchers have modelled the evolutionary development and diversity of the Zika virus to better understand how infection spreads between populations and how the virus reacts with the immune system. Such an understanding is essential if an effective vaccine is to be developed.

First found in Uganda in 1947, Zika is the newest discovery among a group of mosquito-transmitted viruses known as flaviviruses. It is an emerging threat in South and Central America and the Caribbean, with the recent Brazilian epidemic resulting in 440,000-1,300,000 cases and spreading to more than thirteen other countries.

While infected people usually show no symptoms, these can include fever, rash, joint pain or conjunctivitis. In addition, the Brazilian outbreak indicated Zika might cause fetal losses in pregnant women or microcephaly in infants born to infected women.

Dr. Silvia Angeletti from the University Campus Bio-Medico, Rome, and colleagues, carried out evolutionary analysis of the virus combined with homology (shared ancestry) modelling and T- and B-cells epitope prediction, which aims to determine how immune system responses cause the virus to react and change.

Their analysis revealed two distinct genotypes of the virus, African and Asiatic, and two separate clades (biological groupings that include a common ancestor and all the descendants of that ancestor). Clade I represented African gene sequences and Clade II, sequences of Asiatic and Brazilian origin.

The Brazilian sequences were found to be closely related to a sequence from French Polynesia. This lends support to the hypothesis that the virus might have been introduced to Brazil during the Va’a World Sprint Canoeing Championship in Rio de Janeiro in 2014, which included a team from French Polynesia, rather than the World Cup in which no teams from Pacific countries participated.

Among the factors that influence Zika infection, ‘antigenic variability’ (the way the virus alters its surface proteins to evade the host’s immune response) and pre-existing immunity caused by cross-reactions with other viruses might play an important role. Such cross-reactions also make diagnosis of Zika infection unreliable, and could thus facilitate the spread of the virus.

“Understanding the differences and similarities between Zika and other flaviviruses, such as the dengue fever and chikungunya viruses, is essential if effective drugs, vaccines and Zika-specific immunological tests for large population screening are to be designed,” the authors say.

Adapted from press release by Taylor & Francis