Genomic surveillance elucidates Ebola virus

origin and transmission during the 2014 outbreak

Report

Presented by: Trixia M. GonzalesSubmitted to: Prof. Krystelle Angelique Santiago

What is Ebola virus?

 Ebola was named after the Ebola River in

Zaire

It first emerged in Sudan and Zaire in1976 First Major Outbreak (ZEBOV)1976- Sudan (SEBOV)

Where does Ebola hide?

• 2002- Fruit Bats• Antibodies

against Ebola• Ebola Gene

sequences in liver and spleen

• Fruit bats do not show any symptoms

• Best candidate to be the reservoir

The link between human infection by the Ebola virus and their proximity to primates and some with the outbreaks in wild

animals is clear. Outbreaks occurred in countries that house 80 percent of

the world’s remaining wild gorilla and chimpanzee populations.

EBOLA ALSO FOUND IN PHILIPPINES!BUT the virus from the Philippines does not cause illness in humans. EBOR-ebola reston never developed into a Ebola Hemorrhagic fever

EBOLA AS A HEMORRHAGIC VIRUS

FIVE SUBTYPES OF EBOLA VIRUS

•Ebola-Zaire (EVD) 78% fatality rate

•Ebola-Sudan•Ebola-Ivory Coast•Ebola-Bundibugyo•Ebola-Reston

EVD Outbreak

Largest known outbreakFebruary 2014 Guinea March Liberia May Sierra Leone July-Nigeria

Kenema Government

Hospital (KGH)•KGH Established an EBOV surveillance in Kenema Sierra Leone•On May 25,2014 First case of EVD in Sierra Leone•This incident is connected to the burial tradition in Guinea•Tracing 13 female attended the burial

Deep sequencing

method• Deep sequencing is the

sequencing done many times to generate high confidence for a clearer and accurate results.

Deep sequencing

(results)•They sequenced 99 Ebola virus genomes collected from 78 patients confirmed with bola virus in Sierra Leone.•Combined the 78 sequences with 3 Guinean samples•341 fixed substitution from all previous published EBOV

Deep sequencing

(results)•Identification of 263 iSNVs•With 73 nonsynonymous.,108 nonsynonynous,70 non coding and 12 frame shift.•Intrahost Variation RNA editing site of Glycoprotein(GP)

Phylogenetic Comparison

Traced the transmission path and evolutionary relationships of the samples. To find the lineage responsible for the current outbreak diverged from the Middle African outbreak.

Phylogenetic Comparison

(results)• Strong correlation • And that the three

most recent out breaks all diverged from a common ancestor

Findings•Substitution rate was twice as high between 2014 outbreaks and previous outbreaks.

•There were also mutations the no synonymous mutation rate suggest that this could cause of viral adaptation.

Findings•They found more than 395 mutations or genetic changes that make the 2014 Ebola virus genomes distinct from the viral genomes tied to previous outbreaks. Including 50 fixed no synonymous and 8 high level of conservation.

Unanswered

• They were unable to identify whether these differences are related to the severity of the current outbreak.

FindingsThey also found sequence variations indicating that the present outbreak started from a single introduction into humans, subsequently spreading from person to person over many months

ConclusionThat the variations they identified were frequently in parts of the genome that encode proteins such as the Glycoprotein. Some of the variation detected may affect the primers, or starting points for DNA synthesis, used in polymerase chain reaction (PCR)-based diagnostic tests, emphasizing the importance of genomic surveillance and the need for vigilance

SourcesGire, SK, Goba, A et al. Genomic surveillance

elucidates Ebola virus origin and transmission during the 2014 outbreak. Science. DOI:

10.1126/science.1259657

Websitehttp://www.broadinstitute.org/news/6017

http://www.who.int/mediacentre/factsheets/fs103/en/http://web.stanford.edu/group/virus/filo/history.html

http://www.who.int/mediacentre/factsheets/fs103/en/