Terms in this set (27)
When the virus slips into a dormant existence
Are there symptoms during Latency?
No apparent clinical features since infectious virus can not be detected
How long does latency last?
Lasts life of the host, high stable
Why is latency asymptomatic?
Allows virus to escape from host defense
What are three basic characteristics of latency?
(1) Viral gene expression is silent or ineffective
(2) Immune surveillance of host cell harboring the latent viral genome is reduced or eliminated
(3) the viral genome remains intact
Lysogeny associated with?
Latency associated with?
Human or animal viruses
Prophage associated with?
Phage DNA is integrated into host chromosomal DNA
Provirus associated with?
Latency when viral DNA is integrated into host cell's chromosomal DNA (human, animal virus)
In lysogenic phage, DNA is always?
Always integrated into host cell's genome
In some latent virus, DNA do not get?
Do not get incorporated; genome maintains its identity
Prophage integration is?
Specific and is able to extricate itself.
Integration of prophage is normally between?
Biotin synthesizing enzyme gene and galactose metabolizing enzyme gene
Induction phase is?
Phase where prophage extricates itself to enter the lytic cycle
Provirus integration is?
Random in host cell genome; no induction
Lysogenic cells carry prophage until?
Future generations of latently infected cells will?
Carry provirus - permanent feature
Certain factors determine wheather lytic cycle is induced or lysogenic cycle is entered?
Lack of Nutrients
Provirus will remove itself form chromosome and lead to synthesis of new viral particles
Genome Maintenancy in Latency
(1) as non-replicating DNA in terminally differentiated non dividing cells
(2) Genome integrated into host chromosome and synchronized with host genome
(3) Genome becomes an autonomous, self-replicating chromosome in a dividing cell
Viruses that exist as non replicating DNA in terminally differentiated cells?
Herpes Simplex (HSV I and II)
Varicella-Zoster virus (VZV)
HSV I/II, VZV do not integrate DNA but...
Remain as an episome
Circular molecule of DNA that is independent of host chromosome
Where is episome found?
Where is plasmid found?
Viruses whose genome is integrated into host chromosome and synchronized with host genome?
Viruses whose genome becomes an autonomous self-replicating chromosome?
Epstein Barr Virus
What is unique of HPV?
HPV enteres as a mini-chromosome with histones