Ebola virus is of four types, three of which cause Ebola in humans. The habitat, exact origin, and locations of this virus are still unknown, but it is believed that it is native to the African continent and leave in animal hosts. The virus is transmitted from person-to-person through direct contact with the person who have Ebola, or direct contact with their body fluids.The ebola virus is an RNA virus that causes the disease known as Ebola hemorrhagic fever. The Ebola virus is one of the two members of RNA viruses called the Filoviridae.
The structure of Filovirus as such is very big and distinctive. There is a helix- shaped capsid and is present inside a membrane envelope, which is rich in viral proteins and glycoprotein. Nucleoprotein; the major capsid protein has got an N terminal that associates with the viral RNA. The frame appears in the form of a trophy and is formed by the wrapping around of three glycoprotein subunits (GP1) to form the bowl and three GP2 to form the base. The glycoprotein consists of a base, a head and a glycan cap. GP2 forms an internally fused loop consisting of hydrophobic deposits and are shown on a beta-sheet structure.
Four alternating and elongated units of the GP1 fold to form the GP1 base sub domain. A complex kind of oligosaccharides on the Ebola virus reveals the N-linked glycans forming a thick coating over the surface. This protects the virus from the immune responses and they neutralize the antibodies produced against them. Several lysine molecules present on the surface helps in their attachment to the host. The viral structure is cut into smaller pieces by cathepsin (proteases) thereby removing the mucus and glycan layers. This exposes the lysine molecules to the interacting cells. The combining of the host cell with the virus is helped by GP2.
Genome and Replication
The Ebola virus possesses a single molecule of single stranded RNA. There are 18959- 18961 nucleotides in it. The 3’ (3 prime) end does not have an adenylate sequence, which helps in the addition of adenine molecules and the 5’ (5prime) end is uncapped. vReplication is carried out by an interaction between the host and some enzymes produced by the virus. They produce multiple copies of themselves which later gets assembled to the complete virus particle.
It is helped in by the 472 nucleotides from the 3’ end and 731 nucleotides from the 5’ end. 7 structural proteins and 1 non-structural protein are coded by it. The genomic material on its own is non-infectious. The genome represents seven genes and seven diverse transcriptional elements are made into mRNA after establishment of infection.
1) Transmission is more in the later stages
2) It occurs by direct contact and through blood and other body secretions of the patient
3) Infected animals also spread the infection
4) Contact with infected surgical equipments
5) Improper sterilization or disposal methods
6) Transmitted to healthcare workers who have not used gloves, masks, etc. while nursing
7) It is not transmitted through food, water and air
8) Maintaining of proper hand hygiene prevents transmission
Even though Chimpanzees, fruit bats, antelopes, porcupines, dogs, pigs, gorillas, rodents and humans are identified hosts of Ebola virus, fruit bats are considered as the most focused one. Hypsignathus monstrosus, Epomops franqueti and Myonycteris torquata are the bat species under suspicion. Eating bat meat and eating of fruit bitten by bats transmits the infection to humans and primates respectively. Bat stool collected from certain areas tested positive for Ebola virion.
1. Zaire Ebola (EBOV)
2. Sudan Ebola virus (SUDV)
3. Reston Ebola virus (RESTV)
4. Cote d’lvoire Ebola virus (TAFV)
5. Bundibugyo Ebola virus (BDBV)