CMV, EBV, & KSHV Flashcards
EBV, CMV and KSHV are all?
Herpes viruses.
What is is the Genomic structure of KSHV, CMV, and EBV?
Double Stranded DNA.
What is the structure of these viruses?
Each has an icosahedral core surrounded by a lipoprotein envelope
Where does replication of these viruses take place?
The genome is replicated and viruses assembled in the nucleus in the nucleus
What type of infections do these bugs produce?
Self-limiting infections
What are some of the possible complications from these bugs?
Life threatening infections or cancers can occur especially in immuno-compromised patients
What kind of replication do herpes viruses undergo?
Lytic replication in a variety of cell types.
What is important about the primary infection of these herpes viruses?
The primary infection is usually asymptomatic
How do the viruses invade a host cell?
Attachment and penetration happens via virus glycoprotein-mediated fusion of envelope and plasma membrane
How does the released nucleocapsid migrate to the nuclear envelope of the host cell?
Via microtubules
What are the (IE) Immediate Early genes?
Virus specific transcription factors.
What is the function of the Immediate early genes?
- Use host RNA Polymerase II
2. STimulate transcription at virus early promoters
What are early genes?
Genes expressed after IE genes that encode many nonstructural proteins and enzymes.
What is the function of the early genes?
- The generate DNA replication machinery including viral DNA polymerase
- Generate Thymidine kinase (tk) which phosphorylates a variety of nucleotides besides thymidine
- Encode many nonstructural proteins
What are the functions of late genes?
- Encode structural proteins (capsids & Glycoproteins)
What is the cause of syncytia formation?
Viral encoded glycoproteins
Where does virus assembly occur?
In the nucleus, nucleocapsids bud first into the perinuclear space
As an alternative to lytic infection what do all herpes viruses undergo?
Latency.
What happens to Herpes viruses during latency?
Entire viral genome is maintained extrachromosomally in the host but no virus particles are produced.
What are the three stages of latency?
- Establishment
- Maintenance
- Reactivation
Under what circumstances does reactivation occur?
- Lapse in immunity (AIDS=KSHV)
- Stress
- Sunlight
- Menstration
What are the Betaherpesvirnae?
- CMV
- HHV-6
- HHV-7
What are the Gammaherpesvirinae?
- EBV
2. HHV-8
How are the Betaherpesvirnae and Gammaherpesvirinae different from Alphaherpesvirinae?
More isidious (less aggressive)
Is CMV highly contagious?
No
What is a huge determining factor in the age at which one may be infected with CMV?
Socioeconomic status. (THE LOWER THE STATUS THE EARLY ONE TENDS TO BE INFECTED)
Where is CMV usually found?
Saliva, urine, breast milk, semen, cervical secretions,blood, and transplanted organs
Who are the most at risk populations?
Neonates, Gay men, day care workers, pregnant workers, immunocompromised patients
How is infection of CMV spread?
Through direct contact with secretions, NOT BY AEROSOL
Where does primary replication of CMV take place?
Epithelial cells followed by spread to lymphoid tissue
What cells does CMV latently infect?
B-cells, T-cells, monocytes, and lymphocytes.
What is a common characteristic of CMV infected cells?
CMV causes Large puffed up cells
What are the symptoms of neonatal in utero infections by CMV?
Usually asymptomatic but can result in retardation and deafness
What are the symptoms of adult infection?
Mostly asymptomatic but mononucleosis accompanied by fever can occur
What subset of patients are particular at risk?
Immunocompromised