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Table 2 Representation of the five classes of viral genes in three selected viruses with small, medium-size and large genomes

From: The ancient Virus World and evolution of cells

 

Genome size (kb)/number of annotated genes

Representation of the 5 classes of viral genes (number and brief description)

  

1. Recent acquisitions from cells

2. Ancient acquisitions from cells

3. ORFans

4. Conserved virus-specific genes

5. Hallmark genes

Virus

      

Poliovirus a

7.4/10

None

2: a duplication of a chymotrypsin-like protease (3C, 2A)

1: uncharacterized protein (3A)

1: genome-linked protein (VPg)

6: 4 diverged copies of JRC (VP1-4), S3H (3C), RdRp (3D)

Sulfolobus turreted icosahedral virus (STIV) b

17.6/36

3: two predicted transcription regulators and an uncharacterized protein

5: four predicted transcription regulators and an uncharacterized protein

26: uncharacterized proteins

None

2: JRC, packaging ATPase

Vaccinia virus c

194.7/~200

~48: primarily, proteins involved in virus-host interaction

~36: primarily, proteins involved in genome replication and expression

~24: poorly characterized proteins, possibly, involved in virus-host interactions

~84: primarily, structural components of the virion and some proteins involved in genome expression

5: JRC, S3H/primase, packaging ATPase, DNA polymerase(?)

  1. aThe classification is based on the analysis described in [87].
  2. bThe classification is based on the analysis described in [11].
  3. cThe classification is based on the analysis described in [108] and EVK, unpublished observations; the uncertainty in the number of genes is due to the pseudogenization of varying subsets of genes in different strains of vaccinia virus.
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Biology Direct

ISSN: 1745-6150

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