2023-11-10 23:15:25
It has been a total surprise. No one had ever seen a virus clinging to another virus, until the anomalous results of sequencing during an investigation put scientists on the trail, who finally obtained a revealing image. What was discovered explains the results of the sequencing (it is about two beings, not one) and also clearly shows two viruses, one clinging to the other, instead of a single virus.
It was already known that some viruses, called satellites, not only depend on their host organism to complete their life cycle, but also on another virus, known as “helper.” The satellite virus needs the helper to build its capsid, a protective shell that encloses the virus’s genetic material, or to help it replicate its DNA. These viral relationships require the satellite and the auxiliary to be very close to each other, at least temporarily, but there were no known cases of a satellite actually attaching to an auxiliary… until now.
The discovery is the work of a team made up of, among others, Ivan Erill, Tagide deCarvalho, Elia Mascolo and Julia López-Pérez, all four from the University of Maryland in Baltimore County (UMBC) in the United States.
Researchers have specifically observed a satellite-type bacteriophage (a virus that infects bacterial cells), which systematically binds to an auxiliary bacteriophage. The attachment point in question is the “neck”, where the capsid attaches to the tail of the virus.
In detailed electron microscopy images taken by Tagide deCarvalho, 80 percent (40 of 50) of the auxiliaries had a satellite clutched to their necks. Some of those who did not have it had satellite tendrils remaining on the neck. Erill describes them as “bite marks.”
The satellite virus clinging to the helper virus. The photo has been taken using an electron microscope and has then been processed and colored to make the details better perceptible. (Image: Tagide deCarvalho. CC BY-NC-ND)
Following the initial observations, the satellite, helper and host genomes were analyzed, revealing more clues about this never-before-seen viral relationship. Most satellite viruses contain a gene that allows them to integrate into the genetic material of the host cell after entering it. This allows the satellite to reproduce whenever a helper virus enters the cell thereafter. The host cell also copies the satellite’s DNA along with its own when it divides.
The discovery suggests that there are many more similar systems to be discovered.
The study is titled “Simultaneous entry as an adaptation to virulence in a novel satellite-helper system infecting Streptomyces species.” And it has been published in the academic journal The ISME Journal. (Source: NCYT from Amazings)
#observe #time #virus #clinging