Herpesvirus Genome: Important Properties
Linear, double-stranded DNA
DNA wrapped around a fibrillar spool which makes up the core
*A unique feature*: reiterated DNA sequences
(i) At the ends
(ii) Some herpesviruses have internal repeats which divide the genome
into unique short (US) and unique long (UL) sequences.
(iii) These repeats can invert to give rise to up to four different
isomers of a genome, which present in equimolar proportions.
*Another unique feature*: Herpesviruses themselves encode most of the
enzymes that they require to replicate viral DNA.
Scientists hypothesize that this allows the virus to replicate in
slowly-dividing or non-dividing cells such as neurons.
e.g. For HSV, about 50% of its 73 genes are not critical for viral
replication in vitro. The other genes may encode regulatory
proteins and virokines to help with in vivo pathogenesis.
Size of Genomes
|HSV (type 1 and type2)||152 kilobases|
|VZV ||125 kb|
|EBV ||172 kb|
|CMV ||229 kb|
|HHV-6 ||162 kb|
Created: March 4, 1999
Last modified: March 4, 1999