Breakthroughs Blog: Zika

In this regular feature on Breakthroughs, we highlight some of the most interesting reads in global health research from the past week. Scientists have identified a gene that stops tuberculosis (TB) from mutating and becoming resistant to antibiotics. Researchers at Centro Nacional de Biotecnología in Madrid and the University of Sussex in Brighton individually deactivated each of the 11,000 genes that make up the TB bacterium, and tested the modified strains against an antibiotic commonly used to treat the disease. The study revealed that the NucS gene, which produces an enzyme that repairs DNA, significantly reduces the frequency of genetic mutations, and consequently, the development of antibiotic resistance. As drug-resistant strains of TB have been reported in more than 100 countries, this discovery could pave the way for improved diagnosis and treatment, making it easier for clinicians and researchers to predict which cases of TB will develop resistance. The US Agency for International Development (USAID) is the largest donor of food aid worldwide, spending US$1.5 billion on wheat, sorghum, rice, and other edible commodities annually. As the food travels around the world, an estimated 1 percent is lost to spoilage, which amounts to 10,000 tons of food worth $15 million. Now, researchers at the Massachusetts Institute of Technology are exploring new ways to package the food to avert spoilage and are testing eight different bags of varying sizes and materials to determine their ability to protect against humidity, water damage, and pests. One model has a completely airtight liner that resists moisture, while another uses a biopesticide that stops insects from reproducing, rather than killing them. The research team is also investigating the use of an airtight liner for the shipping containers, rather than the bags themselves. The final results and recommendations will be available this summer. Gene drives, a promising technique for eliminating mosquitoes and eradicating mosquito-borne diseases, may be stymied by evolution. The novel method involves genetically modifying mosquitoes by introducing an unusually dominant genetic mutation that is passed on to the insects’ offspring, overtaking an entire population of mosquitoes within a few generations. To combat malaria, Zika, and other mosquito-borne diseases, scientists have engineered mosquitoes whose offspring are infertile, and initial trials suggest that gene drives could be a breakthrough in vector control. However, additional research indicates that as these manmade genetic mutations spread through a population, so too do natural mutations that counteract the effect. Furthermore, there is an immense amount of genetic variation among mosquitoes, which limits the potential targets for gene drives. To overcome this, some researchers are introducing multiple genetic mutations at once, however, it remains to be seen whether the manmade or natural mutations will be more powerful.

2016 was a year that ushered in significant shifts in the global health landscape. We witnessed the waning of the Ebola epidemic and the waxing of the Zika outbreak; important leadership changes among the biggest institutional players in global health; and the development and introduction of new innovations that could turn the tide against leading infectious disease killers. As the year comes to an end, GHTC is reflecting on the top stories in global health innovation that made news in 2016. Here are seven of those top moments: 1. Scientists mobilize against Zika A vial of the National Institute of Allergy and Infectious Diseases (NIAID) Zika Virus Investigational DNA Vaccine (Photo: NIAID).Once considered an obscure virus responsible for a mild illness, Zika took the world by storm in 2016. As the virus gained a foothold in more than 60 countries, its association with devastating birth defects and neurological conditions was firmly established. Prior to Zika’s emergence in the Americas, only 25 research papers had been published on the virus. As the epidemic grew, scientists around the world joined the fight against Zika, often sharing their data and research in real time to speed progress. Thanks to the efforts of these researchers, over the past year our scientific understanding of Zika has grown exponentially, and we have advanced a robust pipeline of new tools to prevent, detect, and treat Zika. Today, there are more than 35 Zika vaccine candidates under development; 13 Zika diagnostics have been authorized for use by the US Food and Drug Administration; and researchers are screening novel compounds and evaluating existing drugs to advance treatments for the disease. 2. The world commits to the fight against antimicrobial resistance United Nations General Assembly (Photo: GHTC/Matthew Robinson). 2016 marked the year the world finally got serious about tackling antimicrobial resistance. On the heels of several major analyses examining the potentially devastating health and economic impact of antimicrobial resistance, the United Nations (UN) General Assembly convened global leaders for a high-level summit on antimicrobial resistance—the fourth time such a meeting has been held on a health-related topic during the UN’s 71-year history. At the close of the summit, UN member states unanimously endorsed and adopted a political declaration committing to developing action plans and policies; mobilizing resources; and supporting public awareness, surveillance, and R&D efforts to combat antimicrobial resistance. It is our hope that 2017 will mark the year political commitment translates to concrete action to advance the development of new antibiotics. 3. New strategies deployed to stymie mosquito-borne diseases Mosquito-borne diseases remain an age-old scourge, but 2016 saw the advancement of several novel strategies to combat these tiny foes. Efforts to combat mosquito-borne diseases with the transmission blocking–bacteria Wolbachia took an important leap forward this year. Past studies have shown that when the Wolbachia bacteria is introduced to Aedes aegypti mosquitos—which carry viruses like Zika and yellow fever—it prevents the viruses from replicating and blocks further transmission. Because the bacteria can be passed from one generation of mosquitoes to the next, the bacteria offers hope for eliminating a virus’s presence within a local mosquito population. After several years of conducting small-scale tests of this method, the Eliminate Dengue Program announced in 2016 it would begin conducting two large-scale trials in South America to determine whether this approach is effective in halting the spread of mosquito-borne diseases in large urban settings. This year the biotech company Oxitec also advanced efforts to test the use of genetically modified mosquitoes to reduce mosquito populations and disease transmission. The company has engineered mosquitoes that mate with A. aegypti mosquitoes, producing offspring that are unable to mature to adulthood. Early last year, Oxitec introduced the mosquitoes into the Brazilian city of Piracicaba, resulting in an 82 percent decrease in the population of A. aegypti mosquitoes in just nine months. Now, Oxitec has expanded the trial to a larger geographical area and is also initiating trials in the Florida Keys and the Cayman Islands. 4. World’s first kid-friendly TB medicine launches Children who receive tuberculosis (TB) medicines require a different dose than adults, yet until this year, there were no TB medicines designed specifically for children, so parents were forced to split or crush adult pills in an attempt to administer the right dose to their child. This year, that all changed with the launch of the world’s first kid-friendly TB medication. Developed by TB Alliance, the medicine is designed with the unique needs of children in mind: It is fruit-flavored, dissolvable in water, easy to administer, and appropriately-dosed. Already, more than 30 countries have adopted the new medicines, and enough orders have been placed to treat half of childhood TB cases worldwide. 5. Unique HIV prevention option for women reaches important development milestone Image captionMonthly vaginal dapivirine ring helps protect women against HIV (Photo: International Partnership for Microbicides). Women may soon have a powerful new tool at their disposal to prevent HIV infection. Earlier this year, the International Partnership for Microbicides (IPM) announced the results of two large phase 3 clinical trials demonstrating that a monthly vaginal ring containing the antiretroviral drug dapivirine can help protect women from HIV. While initial results indicated that the dapivirine ring reduced HIV risk by approximately 30 percent, further analysis revealed that the ring reduced infection rates by 75 percent in women who used the ring consistently. Now, IPM is seeking regulatory approval for the dapivirine ring and is conducting open-label studies, enabling trial participants to continue using the ring as IPM collects additional data. The dapivirine ring is the only long-acting, female-initiated HIV prevention tool to have proven successful in phase 3 clinical trials. Young women in sub-Saharan Africa are more than twice as likely to be infected with HIV than their male counterparts, and thus female-centered prevention tools are needed stem the epidemic. 6. Roll out begins of world’s first malaria vaccine candidate After decades of development and testing, the world’s first malaria vaccine candidate will soon be introduced in several communities in sub-Saharan Africa. The vaccine—RTS,S—was developed by PATH and GlaxoSmithKline and received a positive opinion from the European Medicines Agency last year following completion of phase 3 clinical trials. In November, the World Health Organization (WHO) announced it would pilot and evaluate the vaccine in real-life settings, thanks to funding from The Global Fund; UNITAID; and Gavi, the Vaccine Alliance. Pending results of these pilot tests, WHO will determine whether to deploy the vaccine on a wider scale. 7. New global health technologies advance through the pipeline PATH launches an easy-to-use, rapid diagnostic for onchocerciasis (Photo: PATH/Dunia Faulx) Over the past year, several other promising new health innovations have moved through the development pipeline and one step closer to reaching the hands of patients: Two important health tools—a novel, affordable oral cholera vaccine developed by the International Vaccine Institute, and the Woman’s Condom developed by PATH and partners—received WHO prequalification this year, paving the way for their procurement by UN agencies and other international procurement organizations. Two new rapid diagnostic tests for the neglected tropical diseases onchocerciasis (river blindness) and lymphatic filariasis were launched this year. Developed by PATH, these tests provide results in just 30 minutes and can be stored at a wide range of temperatures. Development has begun for an affordable therapy for hepatitis C. In 2013, the world’s first cures for hepatitis C hit the US market, however, treatment remains out of reach for many patients due to the high price tag. This year, the Drugs for Neglected Diseases initiative announced it would begin testing an alternative therapy in phase 2 and 3 clinical trials, with a guarantee from the manufacturer that, if successful, the entire regimen will be sold for no more than US$294.  As 2016 draws to a close and 2017 begins, it is time for the global health community to redouble our efforts to make sure this vital progress in global health innovation continues to ensure that people around the world will have access to lifesaving and life-improving health technologies.

In this regular feature on Breakthroughs, we highlight some of the most interesting reads in global health research from the past week. Earlier this year, the World Health Organization released a list of the eight pathogens most likely to cause the next pandemic. All eight are caused by viruses, and all eight are zoonotic—originating in animals. To experts, this came as no surprise: viruses are able to rapidly evolve to infect different species or become more virulent, and nearly three-fourths of new and emerging diseases are zoonotic. Now, researchers are proposing the Global Virome Project, an initiative to characterize every virus in the world (well, 99 percent of them). Tracking down the estimated 1.3 million viruses in the world would cost nearly US$3.4 billion, however, proponents of the project argue that it would unearth insights into viruses en masse and ensure a basic scientific understanding of potential pandemic threats. New research suggests that nearly half of women infected with Zika during pregnancy will have adverse pregnancy outcomes, including miscarriages and birth defects. The study, which enrolled 125 women in Rio de Janeiro, Brazil, is the first to quantify the frequency of these complications among pregnant women who test positive for the virus. Overall, 46 percent of women experienced significant adverse outcomes, however, the true impact may be even higher. The study only followed infants for the first three months of life, but emerging research indicates that neurological and physical defects may develop throughout the first year of life. Further, the study reveals that risk is greatest for women who are infected during the first trimester (55 percent), though adverse outcomes remain common among women infected during the second (51 percent) and third (29 percent) trimester. Antibiotics and immune cells can only target bacteria when they are growing and dividing. Consequently, bacteria often become inactive to evade detection. Many bacteria rely on a toxin antitoxin system to achieve this. A pernicious environmental factor will prompt the bacteria to produce a toxin that puts themselves to sleep, and the abatement of that factor triggers the release of an antitoxin to wake the bacteria back up. Now, an international team of researchers has discovered that the toxin antitoxin system for E. coli, and potentially other bacteria, relies on oxygen to wake up the bacteria. When E. coli cells are dormant, both the antitoxin and oxygen must be present to destroy the original toxin. These findings suggest that oxygen could be the key to developing antibiotics that can wake up and consequently attack dormant bacteria.

Scientists at University of California, San Francisco have identified several drugs that block the Zika virus from infecting brain cells. After determining the types of brain cells susceptible to Zika, the researchers screened more than 2,000 Food and Drug Administration–approved medicines for their ability to protect these cells from the virus. The project revealed that azithromycin, a commonly used antibiotic, could provide protection against Zika in laboratory-grown brain cells. Not only is azithromycin widely available, it is also safe for use in pregnant women, an important characteristic as Zika infection during pregnancy can impede fetal development and result in devastating birth defects. An existing drug for gastrointestinal disorders has shown promise in treating and potentially even curing HIV in monkeys. Existing treatment—antiretroviral therapy (ART)—suppresses HIV, making the virus nearly undetectable in the blood, however, adherence is critical as just a few weeks off of treatment can result in a resurgence of the virus. Due to the demands of adherence and the expensive and toxic nature of many of these medicines, only one third of patients in the United States manage to keep the virus at these undetectable levels. Now researchers may have found a “functional cure” for HIV. The drug—vedolizumab—is approved to treat ulcerative colitis and Crohn's disease in more than 50 countries. In preclinical trials, vedolizumab kept the virus at bay in monkeys for up to two years after cessation of treatment. The National Institutes of Health recently initiated human clinical trials in which people living with HIV and AIDS will receive infusions of vedolizumab every four weeks. After several months, patients will stop taking ART, and their HIV viral load will be closely monitored to determine if the same curative effect is seen in humans. An experimental vaccine against Middle East Respiratory Syndrome (MERS) has successfully combatted the virus in mouse models and offers new insights into the design of subunit vaccines. Vaccines prompt the immune system to develop antibodies that recognize and attack a specific pathogen. Different proteins on the surface of a virus can elicit the production of distinct antibodies that vary in their ability to mobilize a robust immune response. Rather than using the entire virus, subunit vaccines contain specific proteins found on the surface of the virus. Consequently, scientists are able to include only the proteins that elicit the strongest immune response. However, this approach exposes the immune system to certain parts of the virus (i.e., the underside of these surface proteins) that wouldn’t normally be visible, and this can distract the immune system, prompting it to produce ineffective antibodies. In developing a subunit vaccine against MERS, researchers at New York Blood Center overcame this challenge by masking the spot on the vaccine that was distracting the immune system. The slightly tweaked vaccine has proved to be much more effective in protecting mice from MERS. Not only does this finding offer promise for the MERS vaccine, but this technique could be used to increase the efficacy of other subunit vaccines.