Research news in brief

Air travel responsible for spread of dengue through Asia

The spread of dengue to new areas is likely due in large part to trends in air travel, Chinese and British researchers report in PLOS Neglected Tropical Diseases. Dengue virus (DENV) affects an estimated 390 million people globally each year, and can cause symptoms ranging from a mild fever and headache to severe low blood pressure. The virus has mostly caused disease in tropical and subtropical areas of the world, but a 2014 outbreak in Japan broke that pattern. Overall, the geographic area affected by dengue has been growing in recent years. The researchers analysed the spread of DENVs in Asia from 1956 to 2015 using a phylogeographic approach to reconstruct historical virus movement and evaluate multiple potential predictors of the spatial spread of DENV among Asian countries. They used 2202 genetic sequences of DENVs, collected in 20 countries or regions of Asia over the 59 years, to determine how different strains were related. They also investigated trends in air travel, maritime mobility, migration, and socio-economics to determine what factors affect the spread of dengue. The spread of DENV serotypes 1, 2 and 3 was associated with air traffic more so than any other factors, the data revealed. The researchers found that large air traffic hubs such as Thailand and India helped seed dengue epidemics, whereas lower centrality hubs such as Vietnam were found to have limited role in dengue spread. China, Cambodia, Indonesia and Singapore may increasingly help diffuse the virus to other Asian countries over time. “Future trends in global mobility could potentially accelerate the appearance and diffusion of DENV worldwide,” the researchers wrote. “Prevention and control of dengue epidemics require a better understanding of its mode of geographic dissemination, especially for countries in the tropics.”

Human genome editing not for making babies, say experts

An international group of 11 organisations with genetics expertise has issued a policy statement on germline genome editing in humans, which recommends against genome editing that culminates in human pregnancy. The statement, however, supports publicly funded, in vitro research into its potential clinical applications, and outlines scientific and societal steps necessary before the implementation of such clinical applications is considered. Published in The American Journal of Human Genetics, the statement was jointly authored by the American Society of Human Genetics, the Association of Genetic Nurses and Counsellors, the Canadian Association of Genetic Counsellors, the International Genetic Epidemiology Society and the National Society of Genetic Counselors. It was also endorsed by the American Society for Reproductive Medicine, the Asia Pacific Society of Human Genetics, the British Society for Genetic Medicine, the Human Genetics Society of Australasia, the Professional Society of Genetic Counselors in Asia and the Southern African Society for Human Genetics. The CRISPR/Cas9 system — a genome editing tool introduced in 2013 — has quickly become widely used in genetics research due to the ease with which it can be customised and its effectiveness across cell types and species. There is considerable interest in using this tool in somatic cells – to develop cell-based therapeutics, for example – as well as in germline cells, which are the focus of this statement and an ethically more complex problem because of the potential effects on not just the treated individual but also on future generations. The statement authors agreed that at this time, it is inappropriate to perform germline gene editing that culminates in human pregnancy, and that there is currently no reason to prohibit in vitro (outside of a living organism) germline genome editing research, with appropriate oversight and consent, or to prohibit public funding for such research. Moreover, they agreed that before any future clinical application of germline genome editing takes place, there should be a compelling medical rationale to use this approach, an evidence base to support its clinical use, an ethical justification, and a transparent and public process to solicit and incorporate stakeholder input.

Targeting breast cancer’s Achilles heel may supercharge treatment

Research from Melbourne’s Walter and Eliza Hall Institute, in collaboration with pharmaceutical company Servier, shows that a new class of anticancer agents that target cancer cells’ “Achilles’ heel” may help to supercharge breast cancer treatment, improving outcomes for some of the most aggressive types of breast cancer. The study was published in Science Translational Medicine. MCL-1 is an anti-apoptotic protein that is amplified in many cancers, and is found at excessive levels in triple negative and HER2-positive breast cancers. It is often associated with poor outcomes for patients and is, therefore, an important anticancer therapeutic target. The researchers found that combining an MCL-1 inhibitor (compound S63845) with standard cancer therapy was more effective in killing triple negative breast cancers and HER2-positive breast cancers than standard therapy alone. The results are particularly important for triple negative breast cancers because, unlike other breast cancers, they have not seen substantial improvements in treatment or patient outcomes in the past 30 years. Around one in three Australian women with breast cancer have a triple negative or HER2-positive breast cancer. Triple negative breast cancers are particularly common in women with a faulty BRCA1 gene.

How early life affects the adult zebrafish brain

University of Queensland researchers have been investigating how different experiences early in life may affect the nature of  brain activity and, in turn, alter an individual’s behaviour. A study published in Current Biology used zebrafish as a model to investigate the origins of spontaneous neural activity – in the form of new thoughts. The researchers found that spontaneous activity in the part of the brain that processes visual images peaked when the zebrafish were 5 days old, and then declined. “Zebrafish in the larvae phase are transparent, so we can directly image their neural activity,” said Professor Geoffrey Goodhill, whose team included researchers from the UQ School of Mathematics and Physics and School of Biomedical Sciences. “We then used a branch of mathematics called graph theory to analyse the resulting patterns.” The study found that the visual environment the fish grew up in affected their spontaneous brain activity. Turning off the lights while the larvae developed – known as “dark rearing” – changed their brains’ patterns of spontaneous activity. “Dark rearing also reduced the larvae’s ability to catch their prey, a single-celled organism called paramecia, even after the lights were turned back on,” said Professor Goodhill. “This shows that the environment affects the way the zebrafish brain becomes wired up as it grows, and this wiring change affects the fish’s behaviour. It’s very exciting that there is a lot more brain plasticity in the zebrafish brain than we previously realised. This means that zebrafish can perhaps help us understand what happens to the brains of people who are deprived of the right kinds of input early in life.” The team now plans to investigate whether there are certain moments during the zebrafish’s early life when the right input is particularly critical for brain development, as has been shown in humans.

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