Brazil has been struggling with the worst outbreak of yellow fever, resulting in 300 deaths so far this year. Last Tuesday, the government announced it’ll vaccinate its entire population.
We wonder what else has to be done to avoid future outbreaks. So, we spoke with Jair Siqueira-Neto, a Brazilian Researcher and Professor at University of California, San Diego, dedicated to find cures for devastating tropical diseases. Jair’s work is committed to investigate drugs to treat Zika-infected adults. In our interview, he also talks about new technologies that are reshaping the process of drug discovery and the synergy of biotech startups, academic groups, and the pharmaceutical industry.
BayBrazil: The Zika research is testing potential treatments using a drug-screening platform. Has this procedure been done before for any tropical disease?
Jair: A drug-screening platform is a set of automated instruments that permit testing large numbers of chemical compounds to identify the ones that can be effective to treat a particular disease. Microplates the size of an iPhone Plus containing up to 1536 wells are used and in each well, a different chemical compound is tested. A screening assay is a biological model of the disease prepared in those plates. To be considered high-throughput, the assay has to be able to test at least 10,000 compounds per day. In the case of Zika virus, we can screen more than 12,000 compounds per day. We infect human-derived neural stem cells with the virus and treat with candidate compounds for 3 days. After that time we use an automated microscope to take pictures of each well. If a given compound is inactive, the virus induces cell death. Therefore, we look for wells with live cells, which means compounds in those wells are likely to have antiviral activity. We developed a software that can automatically evaluate each image and quantify cell protection, which correlates with antiviral activity. Those compounds able to protect the cells are selected as “hits” in the screening process, which is the first step in the drug discovery pipeline. Screening of compounds is an efficient way to discover new drugs and the pharmaceutical industry applies this method since the 80’s. In general, pharmaceutical companies do not prioritize tropical diseases due to the lack market incentive. That is why these diseases are collectively called Neglected Tropical Diseases (NTDs). We are one of the very few academic groups equipped with the automated infrastructure to test compounds in large scale. I am a member of the Center for Discovery and Innovation in Parasitic Diseases (www.cdipd.org), focused on drug discovery and development to treat NTDs. I am also the director of the UCSD Screening Core, where we offer screening services and infrastructure to academic and non-academic organizations (https://uccore.org/node/68).
BayBrazil: Volunteers can offer their computers and Android devices and help the virtual drug-screening platform. How are you gathering people to contribute? How does the virtual drug-screening platform work?
Jair: The OpenZika project led by Prof. Carolina Horta, Dr. Sean Ekins, and Dr. Alexander Perryman was an amazing initiative to advance the drug discovery process. IBM makes available a network infrastructure that allows a virtual screening for drug candidates, called World Community Grid. In this case, instead of testing 60,000 in my platform, several million compounds are being tested virtually. First, they used all the computational power from people’s devices to predict the tridimensional structure of the virus’ proteins. Then, they used the structure of the chemical compounds and the software tried to “fit” them one by one in the vulnerable sites of the predicted viral proteins. This entire process requires enormous computational power, that could only be achieved through this initiative. My participation in the project is to take the candidates identified by the software predictions and test them in the actual cell-based assay for activity confirmation.
BayBrazil: Besides US and Brazil, which countries are interested and investing in the Zika’s treatment? And why do you believe the US is so committed to the research?
Jair: There are many published scientific articles coming from China, Singapore, and some European countries as well, which means these countries are investing in research to treat or prevent Zika virus. In a more idealistic view, science should be borderless. Zika was announced by the World Health Organization as a public health emergency of international concern in March/2016. The rapid spread of the virus through the American continent was a reason for concern, hence the international scientific community interest in it. The United States National Institute of Health (NIH), Center for Disease Control (CDC) and the Department of Defense (DoD) are all very interested in methods to predict and address any pandemic disease. That is why specific funds were made available to investigate Zika virus.
BayBrazil: Zika was discovered seventy years ago. Is there any explanation of why suddenly we had so many cases and alarming symptoms in 2016?
Jair: Zika virus was first identified infecting a sentinel rhesus monkey in Uganda when scientists were studying yellow fever in 1948. The first human case was reported in 1952, the clinical symptoms were mild and the virus was not considered medically relevant. The first outbreak happened in the Yap Islands in 2007 followed by French Polynesia in 2014 and Brazil in 2016. The Brazilian scientist Celina Turchi from Oswaldo Cruz Foundation (Fiocruz) was the first one to correlate the increased number of babies born with microcephaly and the Zika virus circulating in Recife. Another group of Brazilian scientists later confirmed using animal models that the virus was indeed capable of infecting neural progenitor cells impairing the proper intra-uterine development of the brain. One hypothesis to explain why the original African virus could not cause microcephaly and the new virus circulating in American continent can rely on mutations in the genetic material of the virus. Two key factors contributed to the rapid spread of the virus: 1. Intense population migration (international travels); 2. Multiple transmission routes: vectorial (Aedes aegypti), sexual and congenital. The virus is very stable and can stay at immune privileged sites for months, even if the infected individual has no symptoms. As a matter of fact, 80% of the human cases are asymptomatic. That means these people can spread the disease, even not knowing they are infected themselves. So, the number of alarming symptomatic cases really correspond to only 20% of all infected population. In areas where the insect vector is abundant (like Brazil and Latin America), with a very favorable climate and lack of public policies to control these insects, the virus encountered perfect conditions to spread.
BayBrazil: World Health Organization declared Zika a public health emergency and Zika was an international concern. Do you think the international interest about Zika was increased because it happened in Brazil during the 2016 Olympics?
Jair: The fact that the outbreak happened just before the Olympic Games raised some concerns about the risk of exposing both athletes and tourists coming to the event and possibility of spreading the virus to new countries. But I don’t believe the international concern would have been different despite the event. In fact, some specialists said the risk of infecting during the games was low because the event happened during the Brazilian winter, where the abundance of mosquito vector is significantly reduced. And indeed, there were no cases reported during the Olympic Games.
BayBrazil: Recently, there was a sharp decrease in cases of Zika. Does it mean the transmission is controlled or another crisis may happen in the future?
Jair: Unfortunately, we cannot say that transmission is controlled. It has never been the case. The probability of a future outbreak is still in debate by the academic community. There is a hypothesis of post-exposure auto-protection. Something like a natural vaccine. The immune system of an infected individual would learn to recognize the virus, and would immediately fight in case of a future infection. If that is true, most likely populations that have been exposed to the virus would be considered protected and a new outbreak would only happen if the virus mutates enough that our immune system would no longer recognize it. We have to keep in mind that Zika is a single-stranded RNA virus. RNA viruses mutate a lot faster than DNA viruses. So, it is likely that a new outbreak will happen in the future after some virus mutations occur.
BayBrazil: How much have new technologies, like machine learning and artificial intelligence, been used in drug discoveries? Can these technologies make improvements in the research´s time and cost?
Jair: The drug discovery field is constantly evolving. The increase in computing power aligned with machine learning and artificial intelligence have helped to reshape the process of drug discovery, not only in the early steps of identifying new candidates, but also in the process of optimizing these candidates through medicinal chemistry, by predicting which modifications could achieve better selectivity towards the target of interest, minimizing possible adverse effects, anticipating the way the molecule will behave inside a live organism, how it will be distributed, metabolized, excreted, etc. Other recent technologies, such as the CRISPR/Cas9, allow scientists to perform specific genetic alterations with relative simplicity. These represent great tools to better understand disease fundamentals, which will contribute to the identification of new targets to be used in the treatment of diseases. All these new technologies improve not only the time and cost of the research but can also generate results and knowledge that was simply impossible few years ago.
BayBrazil: Do you think Pharmaceutical Startups can be more efficient to drug discovery process or academic centers and big pharmaceutical companies are more suitable for the task?
Jair: I see the field moving in a direction where biotech startups, academic groups, and the pharmaceutical industry are interacting with each other in a more synergistic way. The big pharmaceutical industry has been shifting their business model over the years, reducing their internal processes in the early discovery stage. Instead, they have been partnering and collaborating with experts from academic groups or biotech companies or startups. This strategy decreases the risks of an early investment in a phase that is still at a high probability of failure. Many biotech companies are founded as spin-offs from academic discoveries, often times having professors or post-docs as founders. Once a new drug has demonstrated safety and proof-of-concept efficacy in humans, the pharmaceutical industry gets very interested in licensing the intellectual property of those drug candidates. Then when it gets to clinical studies, the most expensive part of the drug development process, the pharmaceutical industry usually takes over the projects.
BayBrazil: Although there are vaccine and public vaccination campaigns available, a Yellow Fever outbreak is happening in Brazil and has led to many deaths. Any other measure could be done to avoid this kind of crisis?
Jair: The Yellow Fever outbreak in Brazil is, unfortunately, a consequence of a number of mistakes: misinformed anti-vaccination campaigns, poor control of the insect vector (which is, by the way, the same that transmits Zika and dengue), lack of adequate environmental policies and political engagement in public health. It is simply unacceptable that a disease that has a very effective vaccine and the damaging potential of Yellow Fever returns with such high number of cases. The best strategy to contain the spread of the disease is to vaccinate population at risk and control the mosquito vector. Hence, educate the population about the importance of the vaccine is of utmost importance and regarding vector control, there are innovative methods beyond spraying insecticides/larvicides. One company has genetically engineered mosquitos that generate sterile offspring, efficiently reducing its population. Another strategy takes advantage of a bacteria (Wolbachia) that impair virus multiplication in the insect cells, therefore reducing the transmission potential. Further tests are now taking place with both strategies and preliminary data seems promising. All these methods could be combined and implemented in endemic areas, as a mean to control the spread of Aedes aegypt borne viral diseases. I hope to see the local responsible entities taking quick actions to fight possible outbreaks in the future.
BayBrazil: Is it important for anyone planning to travel to Brazil in the next few months to take the yellow fever vaccine or it is necessary only for those who are going to the most infected area?
Jair: It is absolutely important for anyone older than 9 months going to Brazil to take the yellow fever vaccine, even if not traveling to an infected area. The vaccine is actually recommended for anyone traveling to Latin America since it is hard to predict when/if the virus will spread to other countries as well. So, for those traveling, take your shot and enjoy your trip!