Structure and Genome of Human Cytomegalo Virus 5/5 (8)

Structure and Genome of Human Cytomegalo Virus


Structure of Human Cytomegalo Virus

  • Cytomegalovirus (CMV) is a member of the herpes virus family which fall under the beta herpes subfamily.
  • CMV is spherical in shape with icosahedral symmetry.

Structure of Human Cytomegalo Virus



Figure: Structure of Human Cytomegalo Virus, Source: Dr. Marko Reschke, Marburg, Germany


  • The icosahedral protein capsid with average diameter 100 nm consists of 162 hollow hexagonal and pentagonal capsomeres with an electron-dense core containing the double stranded DNA genome with 230 kbp nucleotides together forming the nucleocapsid.
  • The nucleocapsid is surrounded by an envelope which is lipoprotein in nature.
  • Lipid part is derived from the nuclear membrane of the infected host cell.
  • Projecting from the trilaminar lipid host-derived envelope are spikes of viral glycoproteins which bind to specific host receptor and mediate virus entry.
  • gB is one of the major surface glycoproteins in CMV which influences virus binding to and entry into the cell and cell to cell transmission.
  • gH is second relatively abundant glycoprotein which is a target for complement independent neutralizing antibodies.
  • In mature virus particles, outside the capsid is an amorphous proteinaceous layer, the tegument, surrounded by a lipid envelope derived from host cell membranes.
  • Atleast 25 proteins are located in the tegument layer.
  • The tegument consist of enzymes such as VP16 which is responsible for subverting cellular proteins and enzymes to involve in viral nucleic acid replication and VHS (Virion Host Shut off ) protein which shut off the host cell protein synthesis in the cytoplasm.

Genome of Human Cytomegalo Virus

  • The CMV genome consists of approximately 230kb of linear double stranded DNA.
  • The genome is monopartite and contains terminal and internal reiterated sequences.

Genome of Human Cytomegalo Virus

Figure: Genome of Human Cytomegalo Virus, Source: https://doi.org/10.3390/v4112448



  • The genome is split into a unique long (UL) and a unique short (US) region, both flanked by inverted sequences.
  • It contains approximately 150 open reading frames (ORFs) that encode proteins.
  • Out of these, it has been found that 41 are essential and 117 are nonessential for CMV replication.

Structure and Genome of Human Cytomegalo Virus

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