Ebola pathophysiology
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Ebola Microchapters |
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Ebola pathophysiology On the Web |
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American Roentgen Ray Society Images of Ebola pathophysiology |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Structure
Size and shape
Electron micrographs of members of Ebola virus show them to have the characteristic thread-like structure of a filovirus.[1] EBOV VP30 is around 288 amino acids long.[1] The virions are tubular and variable in shape and may appear as a "U", "6", coiled, circular, or branched shape, however, laboratory purification techniques, such as centrifugation, may contribute to the various shapes.[1] Virions are generally 80 nm in diameter.[1] They are variable in length, and can be up to 1400 nm long. On average, however, the length of a typical Ebola virus is closer to 1000 nm. In the center of the virion is a structure called nucleocapsid, which is formed by the helically wound viral genomic RNA complexed with the proteins NP, VP35, VP30 and L. It has a diameter of 40 – 50 nm and contains a central channel of 20–30 nm in diameter. Virally encoded glycoprotein (GP) spikes 10 nm long and 10 nm apart are present on the outer viral envelope of the virion, which is derived from the host cell membrane. Between envelope and nucleocapsid, in the so-called matrix space, the viral proteins VP40 and VP24 are located.
Genome
Each virion contains one minor molecule of linear, single-stranded, negative-sense RNA, totaling 18959 to 18961 nucleotides in length. The 3′ terminus is not polyadenylated and the 5′ end is not capped. It was found that 472 nucleotides from the 3' end and 731 nucleotides from the 5' end were sufficient for replication.[1] It codes for seven structural proteins and one non-structural protein. The gene order is 3′ - leader - NP - VP35 - VP40 - GP/sGP - VP30 - VP24 - L - trailer - 5′; with the leader and trailer being non-transcribed regions which carry important signals to control transcription, replication and packaging of the viral genomes into new virions. The genomic material by itself is not infectious, because viral proteins, among them the RNA-dependent RNA polymerase, are necessary to transcribe the viral genome into mRNAs, as well as for replication of the viral genome.