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Nature: Genetic diversity and evolutionary dynamics of Ebola virus in Sierra Leone

tetano

tetano

Editor, Senior Moderator
[h=1]Nature | Letter

Genetic diversity and evolutionary dynamics of Ebola virus in Sierra Leone[/h]
Nature (2015) doi:10.1038/nature14490 Received 30 January 2015 Accepted 23 April 2015 Published online 13 May 2015 [h=2]Article tools[/h]

A novel Ebola virus (EBOV) first identified in March 2014 has infected more than 25,000 people in West Africa, resulting in more than 10,000 deaths[SUP]1, 2[/SUP]. Preliminary analyses of genome sequences of 81 EBOV collected from March to June 2014 from Guinea and Sierra Leone suggest that the 2014 EBOV originated from an independent transmission event from its natural reservoir[SUP]3[/SUP] followed by sustained human-to-human infections[SUP]4[/SUP]. It has been reported that the EBOV genome variation might have an effect on the efficacy of sequence-based virus detection and candidate therapeutics[SUP]5, 6[/SUP]. However, only limited viral information has been available since July 2014, when the outbreak entered a rapid growth phase[SUP]7[/SUP]. Here we describe 175 full-length EBOV genome sequences from five severely stricken districts in Sierra Leone from 28 September to 11 November 2014. We found that the 2014 EBOV has become more phylogenetically and genetically diverse from July to November 2014, characterized by the emergence of multiple novel lineages. The substitution rate for the 2014 EBOV was estimated to be 1.23 ? 10[SUP]−3[/SUP] substitutions per site per year (95% highest posterior density interval, 1.04 ? 10[SUP]−3[/SUP] to 1.41 ? 10[SUP]−3[/SUP] substitutions per site per year), approximating to that observed between previous EBOV outbreaks. The sharp increase in genetic diversity of the 2014 EBOV warrants extensive EBOV surveillance in Sierra Leone, Guinea and Liberia to better understand the viral evolution and transmission dynamics of the ongoing outbreak. These data will facilitate the international efforts to develop vaccines and therapeutics.


http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14490.html
 
[h=1]Latest Ebola data rule out rapid mutation[/h] Genetic-sequence haul shows that the virus evolved differently ? but no faster ? than in previous epidemics.
13 May 2015
[h=2]Article tools[/h] Rights & Permissions
1.17554.jpg
Bryan Denton/Corbis
Sierra Leone is one of the countries hardest hit in the current Ebola epidemic.


The Ebola virus evolved as it spread through West Africa last year ? but its mutation rate did not accelerate, as some had thought, according to an analysis of genetic sequence data published on 13 May in Nature[SUP]1[/SUP]. The data offer reassurance that the scope of the current epidemic did not make it possible for the virus to evolve into a more virulent or deadlier form.
The virus's evolution rate during the current epidemic, and whether it is changing in ways that make it easier to transmit, or more or less lethal, has been hotly debated. To address these questions, a team led by Wu-Chun Cao, an epidemiologist at the State Key Laboratory of Pathogen and Biosecurity in Beijing, sequenced 175 Ebola virus genomes from people who were infected with the virus, including some who died.

...


http://www.nature.com/news/latest-ebola-data-rule-out-rapid-mutation-1.17554
 
Press release

PHE study finds Ebola virus mutated slower than first thought

From:Public Health EnglandFirst published:17 June 2015

Scientists find Ebola virus' mutation rate only slightly higher than previous outbreaks.

The Ebola virus responsible for the outbreak in West Africa mutated at a similar rate to previous outbreaks, according to a new international study led by Public Health England (PHE) and published today (18 June 2015) in Nature.

Early in the outbreak, research suggested the virus’ mutation rate was twice that of previous Ebola outbreaks. However, PHE’s study has established that the mutation rate was only slightly higher than previous outbreaks, which is reassuring to public health experts around the world.

Granted unprecedented access to data covering a period of almost a year, the scientists analysed 179 patient samples obtained by the European Mobile Laboratory (EMLab), which was deployed to the epicentre of the outbreak in Guinea, to reveal how the Ebola virus mutated and spread.

The analysis confirmed that the Ebola virus was introduced into the Guinean population in December 2013 at a single source, supporting theories from epidemiologists (scientists who investigate the spread of disease). Scientists believe the virus was initially transmitted from a bat to a 2 year old boy in Guinea.

The team also established how the virus spilled into Sierra Leone from Guinea in April or early May 2014. Notably, a large number of the early cases in different regions of Sierra Leone can be linked to a single funeral.

Lead author Professor Miles Carroll, Head of Research Microbiology Services for PHE, said:
Our analysis shows the Ebola virus responsible for the current outbreak mutated at a similar rate to the earlier outbreaks in Uganda and the Democratic Republic of Congo. The results are good news for the scientists working to develop long-term solutions for Ebola, such as vaccines and treatments, as it means these new interventions should still work against the mutated strains of the virus. Currently, rehydration and replacement of critical elements appear to be the best way to improve a patient’s chances of surviving Ebola.
Following this study, we have theorised that one of the key factors in whether Ebola kills someone is the host’s genetic makeup rather than changes in the virus itself. Our next study will investigate this theory which may lead to improved treatment options.
We would like to acknowledge the collaborative efforts of a great many colleagues who worked on this study here in the UK and across the European Union and in Africa. In particular, this work was an opportunity to transfer skills and knowledge to our colleagues in Guinea as an investment in the public health infrastructure of the region.​
Professor David Heymann, PHE Chairman and of Infectious Disease Epidemiology at the London School of Hygiene and Tropical Medicine, said:
This project, funded by the European Commission, illustrates how international collaboration is the most effective way to progress our understanding of new emerging diseases and develop innovative public health treatments and vaccines.

PHE are supporting global efforts to find the best diagnostic, vaccine and treatment options for Ebola. This research is reassuring to scientists and the public that the recent work on Ebola has been worthwhile and could soon lead to a better state of preparedness and response for the future.​
Background
  1. The article reference is: Carroll et al. (2015). Temporal and spatial analysis of the 2014-2015 Ebola virus outbreak in West Africa. Nature.
  2. The study involved 132 scientists from 50 organisations across the UK and European Union, and included scientists based at the EMLab in Guinea, Liberia and Sierra Leone. In addition to personnel from the Health Guinean Authorities, World Health Organisation (WHO) and M?decins Sans Fronti?res (MSF).
  3. PHE exists to protect and improve the nation’s health and wellbeing, and reduce health inequalities. It does this through world-class science, knowledge and intelligence, advocacy, partnerships and the delivery of specialist public health services. PHE is an operationally autonomous executive agency of the Department of Health. www.gov.uk/phe. Twitter:@PHE_uk, Facebook: www.facebook.com/PublicHealthEngland
  4. The EMLab is a consortium of laboratories located throughout the EU that specialise in working with dangerous viruses like Ebola. They received a grant from the EC in 2012 to develop three mobile units for the diagnosis of outbreak diseases in Africa and Europe. In March 2014EMLab scientists were the first to be deployed to the epicentre of the Ebola outbreak in Gueckedou. EMLab worked closely with MSF for 1 year until the Gueckedou region was declared free from Ebola. The EMLab is co-ordinated by Prof Stephan Gunther from the Bernard Nocht Institute in Hamburg. This study was supported by a research grant from the EC that funds the subsequent analysis of the diagnostics material. The research arm of EMLab is called EVIDENT.
  5. The genetic fingerprinting capability for Ebola virus has been in development for several years in collaboration with the study co-authors; Prof. Julian Hiscox and colleagues at the University of Bristol led by Dr David Matthews. The genetic analysis component of the study was led by Dr Mike Elmore (PHE), Dr Georgios Poliakis (Liverpool University) and Prof Andrew Rambaut (Edinburgh University).
  6. The financial support for the study was provided by a €1.8 million grant awarded by the European Union to the research arm of the EMLab, EVIDENT, which is co-ordinated by Professor Stephan Gunther from the Bernard Nocht Institute in Germany. For more information, visit: evident-project.eu
PHE Press Office, infections


https://www.gov.uk/government/news/p...-first-thought
 
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