Varicella structure, genome and pathogenesis

1. INDIAN INSTITUTE OF TECHNOLOGY ROORKEE
Structure, Genomic Information and
Pathogenesis of Herpes Zoster Virus
Submitted by:-
Sourik Dey
18610023
Vaccine Development and Production
M.Sc. Biotechnology (IInd Year)
Submitted to :
Prof. R.P. Singh

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Varicella Zoster Virus (VZV)
• Varicella-zoster virus (VZV) causes
chickenpox and herpes zoster (shingles).
• Chickenpox follows initial exposure to the
virus and is typically a relatively mild, self-
limited childhood illness with a characteristic
exanthem, but can become disseminated in
immunocompromised children.
• Reactivation of the dormant virus results in
the characteristic painful dermatomal rash of
herpes zoster, which is often followed by
pain in the distribution of the rash
(postherpetic neuralgia). Electron micrograph of a Human
alphaherpesvirus 3 virus

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Structure of Varicella Zoster Virus

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Genome of Varicella Zoster Virus
Image Source: DOI: 10.1128/CMR.00031-09

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Genome Distribution
• The virus contains a double-stranded DNA genome and is linear measuring 125
kbp in length.
• The genome consists of a unique long region (UL) bounded by terminal long
(TRL) and internal long (IRL) repeats, and a unique short region (US) bounded
by internal short (IRS), and terminal short (TRS) repeats.
• The varicella-zoster virus (VZV) genome contains at least 70 genes.
• VZV encodes at least 3 immediate-early (IE) proteins that are located in the
tegument of virions and regulate virus transcription.
• The VZV genome contains about 41 “core genes” that are conserved with each
of the three subfamilies of herpesviruses, alphaherpesvirus, betaherpesvirus, and
gammaherpesvirus.
• Core genes include IE4, the VZV DNA polymerase, helicase-primase
components, single-stranded DNA-binding protein, ribonucleotide reductase,
uracil-DNA glycosylase, dUTPase, DNase, ORF47 protein kinase, major capsid
protein, protease, assembly protein, several tegument proteins, gB, gH, gL, gM,
and gN.

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Pathogenesis of Virus
VZV is transmitted in the following ways:-
• by spread - oropharyngeal secretion.
• through direct contact - fluid of skin lesions.

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Primary Infection
Secondary Infection

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Mechanism of Viral Infection
Image Source: DOI: 10.1128/CMR.00031-08

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Shingles Development

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Course of Pathogenesis

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