The Zika virus (ZIKV) is an arbovirus from the Flaviviridae family and is primarily transmitted via infected mosquitoes.  However, ZIKV has also been isolated in semen and so the virus can be transmitted sexually through infected partners. The recent on-going outbreak of ZIKV, which originated in Bahia in Brazil in 2015, has spread rapidly across the Americas and has resulted in more than 1.5 million cases worldwide.

The recent epidemic in the Americas has dominated the headlines due to the high incidence of babies born with microcephaly to ZIKV-infected mothers. Indeed this outbreak has been characterised by an increased prevalence of neurological syndromes such as microcephaly and Guillain-Barre syndrome. In February 2016 the World Health Organisation (WHO) declared the current epidemic to be a global public health emergency, due to the accelerated rate at which ZIKV is spreading, bringing its associated neurological conditions.

Once a relatively obscure virus, the recent devastating outbreaks have thrust ZIKV into the scientific spotlight. Recent research, led by the MRC-University of Glasgow Centre for Virus Research, has uncovered how the current strain of ZIKV is spreading so quickly. The team have used high-throughput sequencing to determine the ZIKV full genome sequence, importantly including the non-coding regions. The genome sequence was derived from a viral isolate taken from a patient from the Brazilian city of Recife who displayed classic symptoms of infection.

By studying the non-coding regions of the ZIKV genome, the team discovered that, typical of a flavivirus, ZIKV is able to produce non-coding subgenomic RNA (sfRNA) in infected cells. sfRNA allows the virus to evade the host’s immune system by counteracting the host’s interferon response.

Dr. Alain Kohl, of the MRC-University of Glasgow Centre for Virus Research said, “We have used the information from a Brazilian isolate, which we obtained from our colleagues in Brazil and fully characterised it in collaboration with them, to identify a virus-derived molecule that inhibits a very important part of the host antiviral response system. This information is important for understanding the pathogenesis of Zika virus infection but may also be useful for the design of attenuated viruses for vaccine studies in the future.”

Vickie Flint, PhD

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