This microscopic 'worm' has killed the more than 4,500 people who have died from Ebola this year. It can reach 1,400 nanometers in length, inside it hides an RNA helix and its membrane is made of material stolen from the cell it infects. Russian designers have produced this 3D model of the dangerous virus, an infographic featured in Science magazine.
The elongated worm-like appearance of the Ebola virus already surprised Belgian scientists who discovered it in 1976, when they analyzed samples collected in their former colony, the Congo, near the Ebola River. Today much more information about its structure is known, and a team of infographics from Visual Science (Russia) has compiled it to create one of the most detailed 3D models of the microorganism.
The infectious virion or viral particle is about 80 nanometers (nm) in diameter - fairly constant - and a variable length of up to 1,400 nm long. It contains proteins encoded by the virus itself (drawn in the image in maroon tones) and structures captured from the host cell (in gray), such as the human proteins that the pathogen uses to form its own membrane. This is generated when the newly replicated virus buds out of the infected cell.
On its membrane, the ebolavirus manufactures glycoproteins (GP), molecular tufts that serve to fixate and enter its next victims. These GPs are similar to those of the AIDS virus and, as in this case, they are also the focus of numerous scientific studies to neutralize them with possible vaccines.
Several layers of proteins are distributed within the virion, such as VP40 and VP24, which act during budding; or VP35 and VP30, which activate transcription and fight the interferon produced by our immune system to fight against pathogens.
The spiral structure that appears in the center is a nucleocapsule made up of its RNA - the Ebola virus has no DNA - and the NP protein that helps pack it into a helix. The image also shows the polymerase or protein L, responsible for the synthesis of RNA, the real software that organizes the microorganism.
This 3D infographic, which received an honorable mention in 2012 by the journal Science and is now current again, includes 11 types of human and virus proteins, 18,900 nucleotides of their RNA genome and more than 2.5 million lipid molecules. The model is based on X-ray analysis and nuclear magnetic resonance spectroscopy, as well as virological information published in recent decades.
"The virus presents this form of worm and is strange in its length, but in reality it is like the others with respect to the functions of its proteins and constituents," says Professor Frederick A. Murphy of the University of Texas Medical Center. (USA), which was the first to photograph the virus when it was isolated in 1976. Their images have become so widespread that many people think that all Ebola virions are like this, but their length and degree of twist can vary greatly.
Multiplication power
Murphy believes that there is no structural component that explains how dangerous this microorganism is, although knowing it well helps fight it: "Possible vaccines target proteins on its surface, and other drugs try to interfere with any of its functions."
But while effective drugs and treatments for the Ebola virus are discovered, it continues to kill about 70% of the people it infects. The professor of Microbiology César Nombela explains to Sinc where its strength lies: “The virus has an intense multiplying capacity, which causes a pathological effect on the cells it affects, mainly those of the wall of blood capillaries, the liver and some white blood cells. This affectation leads to intravascular coagulation and generalized bleeding, causing multi-organ failure after a prolonged fever and other very serious symptoms ”.
To avoid its transmission, the expert insists that this occurs by contact, not by respiratory route, especially with the body fluids of patients in the symptomatic stage. Therefore, the recommendation is to isolate for observation and diagnosis those who have lived with or contacted patients who are already infected or who later reveal themselves as such.
"If positive, isolation, life support treatment and, if possible, compassionate treatment with means (serums, antiviral agents) of those that are currently in early stages of development should be established, as there are no consolidated treatments for this infection, neither preventive nor curative - Nombela recalls -, and the training and instruction of health personnel is also essential, which must be sufficient for strict monitoring of compliance with the protocols ”.
Regarding the initial origin of the pathogen, there is evidence that its natural reservoir is the African fruit bats, which at certain times can transfer it directly to man, or through other animals, such as antelopes and monkeys, although the mechanisms involved are little known.
Life cycle of ebolaviruses. / CDC
"Transmission to non-human primates seems to be like that which occurs between people, but in cases such as dogs, for example, we do not know anything", acknowledges Murphy, who comments: "The euthanasia of Excalibur in Spain was in the interest of having an extra precaution. Animal lovers may be upset, but you have to wonder what you would have done if you had to deal with that dog. "
Fortunately, the owner of the sacrificed animal, Teresa Romero, the nursing assistant infected with Ebola, seems to have overcome the disease. Somehow your body has discovered the mechanism to eliminate a virus that this year has already killed more than 4,500 people in West Africa. Teresa's antibodies and experience can hold the secret of how to fight and kill the dangerous 'worm'.
Five species of Ebola virus
The Ebola virus belongs to a viral family ( Filoviridae ) made up of three genera: Cuevavirus , Marburgvirus, and Ebolavirus . So far five species of ebolavirus have been identified: Zaire, Bundibugyo, Sudan, Reston, and Taï Forest. The first three ( Bundibugyo ebolavirus , Zaire ebolavirus, and Sudan ebolavirus ) are associated with the series of large Ebola outbreaks that have occurred in Africa since 1976.
The one with the current epidemic is Zaire, which according to data from the World Health Organization, dated October 17, has already caused the death of 4,555 people, in addition to 9,216 confirmed, probable and suspected cases in the seven affected countries. (Guinea, Liberia, Nigeria, Senegal, Sierra Leone, Spain and the United States).
For its part , Reston ebolavirus is a mutation of this microorganism first described in 1990 in a laboratory near Reston, Virginia (USA). It was discovered in macaques from the Philippines and, in principle, it is not pathogenic for man. And the fifth species, the Taï Forest virus, gets its name from the Taï forest of the Ivory Coast, where it has also been found in primates and a single case was recorded in humans in 1994.
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