Ebola is a viral disease that gained notoriety for its high fatality rate and devastating impact on communities. It is caused by the Ebola virus, which belongs to the Filoviridae family of viruses. The virus has five known subtypes, named after the regions in which they were discovered: Zaire, Sudan, Bundibugyo, Tai Forest, and Reston. Of these, the Zaire strain is considered the most deadly, with a mortality rate of 50 to 90 percent.
Understanding the Ebola Virus
To understand how to combat a virus, it is essential to understand its unique structure. Like all viruses, Ebola is very small and cannot be seen with a high-powered light microscope. Instead, it is visible using an electron microscope. The virus particle, also known as a virion, is filament-shaped and studded with small proteins on its surface. These proteins allow the virus to bind to and enter into cells, leading to infection.
Ebola virus is spread through direct contact with bodily fluids, including blood, semen, feces, or vomit, of infected persons or animals. Infection can also spread through contaminated needles and syringes, clothing, and bedding. Unlike some other viruses, such as influenza or SARS, Ebola virus is not spread through the air, water, mosquitoes, or other insects.
Visualizing the Ebola Virus
To study the Ebola virus and the proteins on its surface, researchers have used a version of cryo-electron tomography, a technique originally developed to study similar proteins in HIV. This technique involves imaging single virions at various angles, creating a 3D image of the virion. To achieve higher resolution of individual proteins, researchers then average the images of many of these proteins together.
In 2014, researchers published the first structure of the envelope glycoprotein spike from the Zaire strain of Ebola, using cryo-electron tomography. The envelope glycoprotein spike is a trimeric protein complex that protrudes from the virus's surface and plays a crucial role in the virus's entry into cells. However, determining the structure of the Ebola spike has been challenging because a significant portion of the protein complex is composed of poorly ordered carbohydrates (sugar molecules). The structure revealed that the carbohydrates are located in a cap at the apex of the spike.
Understanding the structure of the Ebola virus is essential in developing effective therapies and vaccines. Cryo-electron tomography has been a valuable tool in studying the virus and the proteins on its surface, such as the envelope glycoprotein spike. As research continues, we may be able to better understand the virus's mechanisms and develop new treatments to combat this deadly disease.