Ebolavirus

Ebolavirus

Electron micrograph of an Ebola virus virion

Ebolavirus is a genus of RNA viruses in the family Filoviridae, order Mononegavirales. The members of this genus are known to cause Ebola virus disease (EVD) in humans and other primates, a severe and often fatal illness characterized by fever, bleeding, and organ failure.

Virology

Structure of an Ebola virus virion

Ebolaviruses are enveloped viruses with a single-stranded, negative-sense RNA genome. The virions are filamentous, often appearing in a characteristic "shepherd's crook" shape. The genome encodes seven structural proteins: nucleoprotein (NP), viral proteins VP35, VP40, glycoprotein (GP), VP30, VP24, and the RNA-dependent RNA polymerase (L).

Genome

The genome of ebolaviruses is approximately 19 kb in length and is organized into seven genes. These genes encode the structural proteins necessary for the virus's replication and assembly. The glycoprotein (GP) is responsible for binding to host cell receptors and mediating entry into the cell.

Replication

Ebolavirus replication occurs in the cytoplasm of infected cells. The virus attaches to host cells via its glycoprotein, enters through macropinocytosis, and releases its RNA genome into the cytoplasm. The viral RNA polymerase transcribes the genome into mRNA, which is then translated into viral proteins. New virions are assembled at the host cell membrane and released by budding.

Pathogenesis

Ebola virus proteins

Ebolavirus infection leads to a severe hemorrhagic fever characterized by fever, vomiting, diarrhea, and bleeding. The virus targets endothelial cells, liver cells, and immune cells, leading to vascular leakage, coagulopathy, and immune system dysregulation.

Transmission

Ebolavirus is transmitted through direct contact with the bodily fluids of infected individuals or animals. The virus can also be spread through contaminated surfaces and materials. Human-to-human transmission occurs primarily through contact with blood, secretions, or other bodily fluids.

Immune Response

The immune response to ebolavirus infection is complex. The virus can evade the immune system by inhibiting the production of interferons and other antiviral responses. However, survivors of EVD often develop strong antibody responses that can neutralize the virus.

Epidemiology

Phylogenetic tree of filoviruses

Ebolavirus outbreaks have occurred primarily in Central Africa and West Africa. The largest outbreak occurred in West Africa from 2014 to 2016, affecting multiple countries and resulting in thousands of deaths. The natural reservoir of ebolaviruses is believed to be fruit bats, which can harbor the virus without showing symptoms.

Prevention and Treatment

Ebola virus particles

Preventive measures include infection control practices, such as wearing protective clothing and isolating infected individuals. Vaccines, such as the rVSV-ZEBOV vaccine, have been developed and shown to be effective in preventing EVD. Treatment is primarily supportive, focusing on maintaining fluid and electrolyte balance, and managing symptoms.

Related pages

• Ebola virus disease
• Filoviridae
• Viral hemorrhagic fever