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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.

The HIV virus is rapidly developing resistance to common antiretroviral drugs. In low- and middle-income countries (LMICs), 10 percent of patients starting antiretroviral therapy (ART) and 40 percent of patients restarting treatment are infected with drug-resistant strains. The leading contributor to drug resistance is failure to adhere to treatment—a problem that plagues nearly three-fourths of patients in LMICs. In low-resource settings, many patients only have access to older, more toxic drugs, and more than one third of clinics report stock outs of HIV medicines. If action is not taken to improve treatment for these patients, drug-resistant strains of HIV-1 could result in 300,000 new infections and 425,000 deaths over the next five years. Last week, the US Congress overwhelmingly approved the nearly 1000-page 21st Century Cures Act, a massive initiative that channels new funding into the US National Institutes of Health and alters the way the US Food and Drug Administration (FDA) regulates certain medicines and devices. While some advocates argue that it weakens the FDA’s regulatory review process, others have applauded the legislation for its potential impact on the development and approval of new antibiotics. One provision—the limited population approval pathway—would allow the FDA to approve antimicrobials and other drugs for serious or life-threatening infections based on smaller clinical trials, addressing the challenge of identifying an adequate number of clinical trial participants (i.e., patients who are infected with drug-resistant pathogens). Another component addresses the FDA’s approach to updating antimicrobial susceptibility interpretative criteria, which informs the development of diagnostics that help physicians prescribe the best antibiotics for a given infection. The provision enables the agency to rely on other organizations’ research and update its criteria accordingly, rather than reviewing the research in house—a time consuming and costly process. While the legislation will likely be signed into law by President Obama, it could take years to fully implement. Scientists have long known that the tuberculosis vaccine offers protection against a number of pathogens and even treats certain conditions (i.e., bladder cancer and asthma), and a recent study in Cell Reports may explain why. Studies in mice and humans revealed that the Bacillus Calmette-Guerin vaccine increased glycolysis—the process of breaking down glucose—in monocytes, a type of immune cell. The effect, which lasts long after vaccination, enhances monocytes’ immunological memory—their ability to remember pathogens they have previously encountered—improving their disease detection and response capabilities. These findings could help scientists devise new strategies for boosting the immune system or its response to certain diseases. The European Medicines Agency (EMA) released a statement last week indicating that patients treated with certain hepatitis C medicines may experience a resurgence of previously latent hepatitis B. The phenomenon applies to a new class of drugs known as direct-acting antivirals and includes Daklinza, Exviera, Harvoni, Olysio, Sovaldi, and Viekirax. While there have only been 30 reported cases, the EMA is recommending patients be tested for hepatitis B before starting treatment.

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.