Research Roundup: Ebola treatment, black widow virus, and Zika syndrome
In this regular feature on Breakthroughs, we highlight some of the most interesting reads in global health research from the past week.
During the recent Ebola epidemic in West Africa, an experimental drug, ZMapp, showed promise in treating the disease, but with only enough doses to treat seven people, the drug’s true impact remained unknown. Now, results of a randomized control trial conducted during the outbreak indicate that ZMapp likely increases a patient’s chance of survival, but fall just short of statistical significance. The researchers hoped to enroll 200 patients across Liberia, Sierra Leone, and Guinea, however, as the number of new cases waned, so too did eligible participants for the trial. Ultimately, the team recruited only 72 participants, all of whom received the standard care for Ebola and half of whom also received ZMapp. Further complicating the results, many of the patients were enrolled after the virus had already caused irreparable tissue damage and did not survive long enough to receive all three doses of ZMapp. The results suggest high probability—91.2 percent—that ZMapp is effective against the virus and confirm the drug’s safety. ZMapp is composed of three antibodies against Ebola, and research is underway to develop improved antibodies which could enhance the drug’s efficacy.
Viruses are constantly mutating, and often incorporate genes from the organisms they infect—viruses that infect bacteria often have bacterial DNA and viruses that infect animals often have animal DNA. The WO virus targets the bacteria Wolbachia, which in turn targets spiders and insects. Consequently, when researchers at Vanderbilt University sequenced the genome of WO, they expected to find snippets of Wolbachia DNA. Instead, they found that one third of WO’s genes came from the arthropods that Wolbachia infects. Further, WO contains genes for latrotoxin, the chemical cornerstone of the venom found in black widow spiders, a particularly surprising discovery as latrotoxin has never been reported outside of spiders. The scientists suspect WO’s unique evolution relied on the way Wolbachia intertwines itself with animal cells, requiring WO to drill through the animal cell membranes to reach the bacteria.
Zika virus, first discovered in 1947, was long considered innocuous, rarely reported in humans and associated with a mild infection. The virus raised concern, however, when scientists discovered its connection to microcephaly—a birth defect in which an infant’s brain does not develop properly, resulting in an abnormally small head. Now, one year after a spike in microcephaly cases in Brazil led to this important discovery, infants with what’s been deemed congenital Zika syndrome are coping with a range of devastating symptoms not usually reported in infants with microcephaly, including seizures, impaired vision and hearing, difficulty swallowing, and arm and leg deformities. Additionally, some infants have presented with neurological and physical defects despite having normal-sized heads and others still have developed microcephaly after birth, as the growth of the head has not kept up with that of the body.