Science

Link strengthens between Zika virus and defects

By Madeleine Banfield

Scientists have taken one step closer to establishing a concrete link between the Zika virus and microcephaly in babies, with a study showing that the virus can infect cells similar to those involved in brain development.

The Zika Virus has been a topic of discussion since the increase in cases grew rapidly in North America in 2015. Since the outbreak, the disease has spread to over 37different countries. The mosquito carried virus places pregnant woman at risk, because it can lead to babies being born with abnormally small heads, known as microcephaly, resulting in an increased risk of brain damage.

The Zika Virus is carried by Aedes Aegypti in tropical climates, which is the same mosquito that carries dengue, chikungunya and yellow fever. The infection was first observed in monkeys in Uganda in the 1940s, with the first human case being reported in the 1950s. What has been so unnerving about this virus, is our lack of knowledge. However, a new study has shed some light on this subject.

The study was conducted by John Hopkins University and Florida State University. Scientists used stem cells and stimulated them to develop into human cortical neural progenitor cells. These, otherwise known as human NPCs, are similar to cells that result in the development of the cortex, an area of the brain. These lab-grown neuronal cells were integral to use, because this part of the brain remains underdeveloped when affected by microcephaly. After the cells were exposed for 56 hours, 65 to 90 per cent of the cells were infected with the Zika Virus. It was discovered that these infected cells could reproduce rapidly. Additionally, the virus affected cell processes, limited cell growth and increased the chance of cell death.

Dr Zhexing Wen, one of the authors of this study, stresses that, “We don’t have the direct evidence to show that this will link the Zika virus to microcephaly.” However, he acknowledges that “it is telling that the human NPCs are very susceptible to the Zika virus and the Zika virus can cause the disruption of the human NPC growth and this may potentially correlate to the disrupted brain development in the foetus.”

Scientists, such as Professor Jonathan Ball from the University of Nottingham, argues that “there are still a number of unknowns” in regards to the virus, and is sceptical of the similarity between the artificially grown cells and human ones, because “we are complex organisms and lots of factors can affect how a virus infection pans out.”

Wen realistically recognises that further research needs to take place, stating: “Maybe different strains of the Zika virus have different effects or maybe different people in different areas of the world may have a different response to the same Zika virus.”

The virus is not fully understood, especially why these cells are significantly affected. Dr Anthony Fausi, the director of the National Institute of Allergy and Infectious Diseases asserts that, “It’s all accumulating complementary evidence,” and confirms that phase one of trials for a vaccine will begin around September 2016. This is important because it has been noted that more pregnant women are being diagnosed with the virus, suggesting that there is going to be another spike in cases in around 8-9 months. This study suggests a potential correlation between the Zika virus and microcephaly and is an important step towards understanding the mechanisms of this virus.

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