By: David Warmflash
Over the winter, the World Health Organization (WHO) published a list of twelve bacterial families, against which new antibiotics are needed urgently, based on current and emerging global health issues. Humanity also is in the midst of a WHO Action Plan for global vaccine development, with strong emphasis on eradicating polio with available vaccines, along with the creation of new vaccines against other diseases, such as malaria.
Most of the challenges are technical; priming the immune system against the malaria parasite, for instance, has proven difficult, because the organism has evolved numerous tricks to evade the immune system, but social and political challenges also come into the picture. The latter is illustrated in the case of polio, which U.S. President John F. Kennedy highlighted in a statement on the importance of vaccines in 1961. Yet today his nephew, Robert F. Kennedy Jr., leads an anti-vaccine movement that misrepresents science and plays into the fears of privileged people who don’t see the need for immunization—ironically, because they have grown up in places where vaccination has been a success.
People in North America, Western Europe, and other developed areas aren’t worried about the same diseases that worry people elsewhere, because they don’t see those diseases around them. But they get scared the minute that somebody within their own society gets infected. That’s what happened last year when the Zika virus—which created a scare in Brazil during the buildup to the Olympic Games—started showing up in Florida. And that’s when American pharmaceutical companies started investing in Zika research.
There has been significant progress in understanding the pathogenesis of insect-borne diseases in recent years. Like malaria and dengue fever, Zika is a mosquito-borne illness that presents a challenge for vaccine and drug development, because of tricks that the causative agent has evolved to infect cells. On penetrating a cell, the Zika virus surrounds itself with an armored coat that shields against the enzymes produced by the host cell. The viral genome is stored as RNA, which is protected when the coating of the virus fuses with the membrane of endosomes, compartments within the cell. This allows the RNA genome to replicate, and is one reason why the virus can penetrate the placenta, which otherwise provides very good protection for a fetus against viruses. Although the Zika virus has been around for a long time, it has a capability to penetrate the uterus and placenta that depends partly on various mutations in the viral genome that have developed during modern times. This capability makes Zika a major risk for pregnant women, whereas malaria and other mosquito-borne illnesses are problematic for anyone who gets bitten. So how might the growing understanding of such diseases improve management of their spread throughout the world?
In the United States, there are many research efforts aimed at understanding diseases of consequence in developing countries, including mosquito-borne illnesses. As one example, the U.S. National Institutes of Health is funding a project to create a kind of universal vaccine against all mosquito-borne illnesses. This is fascinating, since one genus of mosquito (Anopheles) spreads malaria, whereas a totally different genus (Aedes) spreads Zika and dengue. U.S. pharmaceutical companies should be interested in global health because Americans are in jeopardy as they travel to tropical areas, but how long will it be until these companies develop treatments for diseases, regardless of whether our own people are directly affected?