February 24, 2019

Research Roundup: Pregnant women in DRC to be given Ebola vaccine, releases of genetically modified mosquitoes in high-security lab, and CRISPR may help against viruses for which no vaccine exists

Ansley Kahn
Program Assistant
PATH/Algy Amad

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Pregnant and breastfeeding women in Ebola-affected areas in the Democratic Republic of Congo (DRC) will now be able to receive the experimental Ebola vaccine—marking a reversal of a previous World Health Organization (WHO) decision. Due to the severity of the current Ebola outbreak in the DRC, the WHO Strategic Advisory Group of Experts (SAGE) on immunization recommended that pregnant and breastfeeding women should now be included in the vaccination campaign as long as they and their babies are monitored. Pregnant women have historically been excluded from similar immunization campaigns because vaccines against infectious diseases are rarely tested or approved for use in pregnant women. SAGE advised that the use of the experimental Ebola vaccine in pregnant and breastfeeding women should be continuously evaluated based on emerging data on its safety and efficacy—the review of which will inform vaccine recommendations for future outbreaks.

For the first time, scientists have begun large-scale releases of genetically modified mosquitoes in a high-security laboratory in Terni, Italy. Using the powerful gene-editing technique known as CRISPR, scientists aim to see if they can eventually help to eradicate malaria by altering a gene in mosquitoes, known as “doublesex,” which impacts sexual development. This alteration causes the mouth of female mosquitoes to resemble that of a male—meaning they can’t bite and spread the malaria parasite—as well as deforms female mosquitoes’ reproductive organs so they cannot lay eggs. As more female mosquitoes inherit these modifications, more and more become sterile, which could eventually crash or drastically reduce populations of the Anopheles gambiae mosquito that spreads malaria. Researchers hope to know within six months whether these modified mosquitoes would be able to efficiently spread their lethal modifications in the wild, though a better understanding of the possible environmental impacts of their existence is necessary before any release would be permitted.

Researchers at a half dozen universities are using the genome editing tool CRISPR to try to turn the immune system against viruses for which no vaccine exists. Vaccines work by inducing the immune system’s B cells to produce specific matching antibodies that bind to antigen molecules on a virus, setting the immune system into motion. However, to develop a vaccine, scientists have to identify the exact piece of an antigen that will trigger production of an effective antibody—an often challenging task. Researchers are trying to skip part of this process by instead using CRISPR to directly genetically reprogram B cells to produce the needed antibodies against viruses. CRISPR is used to splice open the DNA of B cells and then a harmless virus is used to introduce DNA for certain antibodies into the cells. The goal is for the cells to repair themselves and then start continuously producing the antibody. While the science still has a long way to go, researchers have achieved some promising early results in reprogramming mouse B cells against respiratory syncytial virus and human cells against HIV.