Genetics of Ebola virus:
Ebola virus belongs to a genus of Ebola which contains five of these viruses. Its genome is 19000 long nucleotide chain which is a single-stranded RNA. That encode seven protein polymerase cofactor (VP35), VP24, nucleoprotein, RNA-dependant RNA polymerase (L), transcription activator (VP30), VP40, GP. Because of its very high mortality rate of 83-90% world health organization (WHO) has ranked this as the biosafety level pathogen.
The name Ebola virus was given to this genus after Zaire (Democratic Republic of Congo). Because it was first described here. To avoid confusion the virus was renamed as Ebola virus in 2010. Four of these viruses cause a very destructive hemorrhagic fever in mammals and humans, including EBOV, which is known as Ebola virus disease. Ebola virus has caused an Ebola virus epidemic in West Africa, which caused 11,310 deaths among humans.
The route of transmission of this virus is through body fluids transmission and is transmitted from animals to humans. The natural host for these viruses is bats particularly fruit bats.
Ebola virus is negative sense-stranded RNA virus that is kept in virions. That is cylindrical and contain nucleocapsid components, viral envelope, and matrix. The complete cylinder of a virus is 80nm in diameter approximately. That has viral encoding glycoprotein GP, which is projected as 7-10 nm long spikes from the lipid bilayer surface. The cylinders are of variable size mostly they are 800nm long but sometimes it extends to 1000nm long. Virion the outer envelope is derived from the host domain of cell membrane by its biosynthesis when the GP inserts its spike in the host membrane. VP40 and Vp24 viral proteins are located between the nucleocapsid and the envelope in the matrix space. The nucleocapsid is at the center of the virion structure which has a series of viral proteins structure that is linked to the negative-sense strand RNA that is 18-19 kb fragment.
There are two candidate host cell proteins for the entry. The essential protein for the entry of Ebola virus into the host is cholesterol transporter protein (NPC1). In an experiment, a mouse whose one copy of NPC1 protein was removed showed 80% of survival after the 15 days exposure. In another experiment, the host cells were able to inhibit Ebola virus by preventing the binding of viral envelope glycoprotein to the host NPC1 protein. The second protein was present to enhance the binding of the viral glycoprotein to the receptor domain, TIM-1 is the second candidate protein. The infection of Vero cells can be prevented by silencing through siRNAs to TIM-1.
In 2016 a vaccine named VSV-EBOV was found to be effective 70-100% against the viral disease. It is the first success against the virus. Many candidate vaccines against the Ebola virus were developed before 2014. But none of these were approved by the United States Food and Drug Authority (FDA).