Mimivirus Research Yields Results Related To Larger Viruses

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Main Category: Biology / Biochemistry
Also Included In: Infectious Diseases / Bacteria / Viruses;  Genetics
Article Date: 13 May 2008 - 1:00 PST

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A large portal has been found in the mimivirus which is formed shortly after infection. This novel discovery in viral biology was reported on May 12, 2008 in the open access journal PLoS Biology, part of the Public Library of Science family.

Viruses generally consist of a protein shell containing genetic information but no means to replicate independently. The two main events in the viral life cycle entail the delivery of the viral genome into the host cell, and the further packaging of copies of these genomes into the more protein shells, known as capsids. In bacteriophages and herpes viruses these processes are linear, and occur in order, base pair after base pair beginning at a certain site in the genome.

The Acanthamoeba polyphaga mimivirus (usually referred to as simply "mimivirus") usually infects the amoeba Acanthamoeba polyphaga. It is considered one of the largest and most complicated known viruses. In viruses such as the mimivirus, with its large genome of 1.2 million base pairs, there has been some question about whether this process of linear replication is used.

In this study, Abraham Minsky and colleagues identified a large tunnel in the mimivirus using electron tomography and cryo-scanning electron microscopy, which is formed shortly after infection and following a large opening of the capsid itself. This tunnel makes it possible for the entire genome to exit in a rapid, one-step process. According to the authors, these large-scale modes of viral translocation imply that the mimivirus, and potentially others, could have evolved mechanisms that help them move their large genomes efficiently.

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Distinct DNA exit and packaging portals in the virus Acanthamoeba polyphaga mimivirus.
Zauberman N, Mutsafi Y, Ben Halevy D, Shimoni E, Klein E, et al
PLoS Biol 6(5): e114.
doi:10.1371/journal.pbio.0060114
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Written by Anna Sophia McKenney
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