The document discusses shingles, which is caused by the varicella zoster virus (VZV) that also causes chickenpox. After a chickenpox infection, the VZV virus remains dormant in the body's nerves. Approximately 30% of people who had chickenpox will later develop shingles. The VZV replicates within cells and can be classified as a varicellovirus within the Herpesviridae family. While related to herpes simplex viruses 1 and 2, VZV is thought to have diverged from a common ancestral virus. Genomic sequencing has identified nine genotypes of VZV that are globally distributed.

1. 1
GENERAL VIROLOGY
SHINGLES
Date: 29-09-15
Muhammad Saad Mughal
SP13-BTY-006
Dr. Sidra Rehman

2. Shingles
Both chickenpox and shingles are caused by the same virus, (VZV). After a person has had
chickenpox, the virus rests in the body’s nerves permanently. Approximately 30% of all
people who have been infected with chickenpox will later develop herpes zoster, commonly
known as zoster or shingles. VZV only affects humans, and commonly causes chickenpox in
children, teens and young adults and herpes zoster (shingles) in adults and rarely in children.
Common names
VZV is known by many names, including chickenpox virus, varicella virus, zoster virus, and
human herpesvirus type 3 (HHV-3).
Scientific name of virus
Varicella zoster virus
Classification
Order: Herpesvirales
Family: Herpesviridae
Subfamily: Alphaherpesvirinae
Genus: Varicellovirus
Species: Human herpesvirus 3

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Viral Replication
Fig: Model of VZV replication. Enveloped VZV particles attach to cell membranes, fuse and release
tegument proteins. Uncoated capsids dock at nuclear pores, where genomic DNA is injected into the
nucleus and circularizes. On the basis of events that have been documented in herpes simplex virus 1
(HSV-1) replication, immediate-early genes are expressed, followed by early and late genes.
Nucleocapsids are assembled and package newly synthesized genomic DNA, move to the inner
nuclear membrane and bud across the nuclear membrane. Capsids enter the cytoplasm, and virion
glycoproteins mature in the trans-Golgi region and tegument proteins assemble in vesicles; capsids
undergo secondary envelopment and are transported to cell surfaces, where newly assembled virus
particles are released.
Phylogenetic Ancestor

4. 4
Commonality with HSV1 and HSV2 indicates a common ancestor, five genes do not have
corresponding HSV genes. Relation with other human herpes viruses is less strong, but many
homologues and conserved gene blocks are still found.
There are five principle clades (1-5) and four genotypes that do not fit into these clades. The
current distribution of these clades is Asia (clades 1,2,and 5) and Europe (clades 1, 3 and 4).
Allocation of VZV strains to clades required sequence of whole virus genome. Practically all
molecular epidemiological data on global VZV strains distribution obtained with targeted
sequencing of selected regions.
Phylogenetic analysis of VZV genomic sequences resolves wild-type strains into 9 genotypes
(E1, E2, J, M1, M2, M3, M4, VIII and IX). Complete sequences for M3 and M4 strains are
unavailable, but targeted analyses of representative strains suggest they are stable, circulating
VZV genotypes.
Refrences
https://en.wikipedia.org/wiki/Varicella_zoster_virus#Evolution
www.immunize.org/catg.d/p4221.pdf
http://www.nature.com/nrmicro/journal/v12/n3/fig_tab/nrmicro3215_F1.html
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