Arch Virol (2002) 147: 1077–1089
The nucleolus – a gateway to viral infection?
J. A. Hiscox
School of Animal and Microbial Sciences, University of Reading, U.K.
Received August 24, 2001; accepted December 26, 2001
Published online March 18, 2002, © Springer-Verlag 2002
Summary. A number of viruses and viral proteins interact with a dynamic sub-
nuclear structure called the nucleolus. The nucleolus is present during interphase
in mammalian cells and is the site of ribosome biogenesis, and has been implicated
in controlling regulatory processes such as the cell cycle.Viruses interact with the
nucleolusanditsantigens;viralproteinsco-localisewithfactorssuch as nucleolin,
B23 and ﬁbrillarin, and can cause their redistribution during infection. Viruses
can use these components as part of their replication process, and also use the
nucleolus as a site of replication itself. Many of these properties are not restricted
to any particular type of virus or replication mechanism, and examples of these
processes can be found in DNA, RNA and retroviruses. Evidence suggests that
viruses may target the nucleolus and its components to favour viral transcription,
translation and perhaps alter the cell cycle in order to promote virus replication.
Autoimmunity to nucleolin and ﬁbrillarin have been associated with a number of
diseases, and by targeting the nucleolus and displacing nucleolar antigens, virus
infection might play a role in the initiation of these conditions.
The eukaryotic nucleus contains a number of domains or subcompartments, which
include nucleoli, nuclear Cajal bodies, nuclear speckles, transcription and replica-
tion foci, and chromosome territories . For many years the exclusive function
of the nucleolus was thought to be ribosomal rRNA synthesis and ribosome bio-
genesis. Recently, however, the nucleolus has been implicated in many aspects
of cell biology that include functions such as gene silencing, senescence, and cell
cycle regulation [8, 50, 51].
The nucleolus is the site where 5.8S, 18S and 28S rRNAs are transcribed,
processed, and assembled into ribosome subunits . The nucleolus is composed