CMV, EBV, KSHV Flashcards
What type of replication cycle does the herpes virus undergo?
Lytic replication
Describe structure of herpesvirus?
Icosahedral, enveloped, tegument contains the bad stuff (viral proteins)
Describe the attachment phase of the lytic replication cycle
herpes virus envlope fuses with the plasma membrane of the cell, nucleocapsid released and it goes to the nucleus
What are the 3 phases of the lytic replication cycle
Immediate early, Early, Late
What occurs during the immediate early phase?
viral transcription factors are transcribed.
Is the host RNA polymerase II used for this?
Yes.
What occurs during the early phase?
Replication proteins such as the viral DNA polymerase are transcribed. Thymidine kinase becomes thymidine
Late Phase
Structural proteins (capsids, glycoproteins) Viral glycoproteins are incorporated into virus envelope and transported to cell surface.
SUmmarize herpes lytic replication
IE- transcrption factors E- Replcation machinery (DNA poly) L- Structural Assembly occurs in nucleus. Process is refered to as cascade regulation
Where are gnomes maintained during herpesvirus latency
extrachromosomally
Is virus produced during latency?
No
Three stages of latency
Establishment, Maintenance, Reactivation
When does reactivation occur?
During a lapse in immunity, results in the production of virus and recurrent infection
How is CMV spread?
STI, through anything liquid in the body….also THROUGH TRANSPLANTS
At risk populations?
neonates, day care workers, pregnant workers, gay men, immunocompromised patients
WHere does the primary replication of CMV occur?
Epithelial cells of throat then spreads to lymphoid tissue
Where does CMV become latent?
B and T cells, monocytes, lymphocytes.
What are the symptoms?
In neonates, mostly asymptomatic but can cause deafness and retardation
In adults, mostly asymptomatic but can cause mono.
Do most transplant patients develop CMV?
Yes.
What is a serious aspect of transplant acquired CMV
pneumonitis can be life-threatening.
How is it treated?
CMV Ig and Ganciclovir
Diagnosis of CMV
PCR of ELISA….old way was SHell assay
Three most common anti-virals for herpesvirus?
Acyclovir, Ganciclovir, Foscarnet
WHich is most commonly used for CMV?
Ganciclovir- Guanosine analog, side effects are neutropenia and GI bleeds
Is epstein barr virus common?
Yes
What is one related symptom of EBV seen in AIDS patients
Oral hairy leukoplakia
How is oral hairy leukoplakia caused by EBV treated?
Acyclovir.
What two cancers is EBV associated with?
Nasopharyngeal carcinoma and Burkitts lymphoma
How is EBV spread?
Saliva
WHere does it lay latent?
Originally in the oropharyngeal epithehelium then moves to lymphocytes and then to liver and spleen
Symptoms?
most asymptomatic. Some get mono.
How is it diagnosed?
Monospot test or by symptoms and the appearance of 50% large lymphocytes with lobulated nuclei
What is EBNA
Epstein barr nuclear antigen
When does EBNA appear?
early in infection
COnversion to what signals the end of primary infection?
Anti EBNA Ig
What does VCA stand for
Viral capsid antigen
Describe how VCA can help with diagnosis
Presence of Anti VCA IgM means primary infection
Presence og anti vca IgG without Anti EBNA indicates primary infection
Presence of anti vca IgG with anti EBNA IgG signals the end of primary infection.
What does the monospot test look for?
Heterophile antibodies that agglutinate sheeps blood. This is the best test to differentiate EBV mono from CMV mono
What is PTLD
Post transplant lymphoproliferative disorder
What causes PTLD?
EBV modification of B cells causes them to proliferate out of control and in a post transplant patient taking immunosuppressive drugs, there is no immune response to these B cells.
How do we treat PTLD
Take pt off immunosuppressive therapy…risky
Burkitts lymphoma, describe it
Neoplasm of B cells that affects jaw bones. ENdemic in Central Africa and New Guinea. Three causes: EBV, Malaria, C-myc activation.
Nasopharyngeal carcinoma affects what cells?
Epithelial cells. Most common insouth china. presents as painless lump in neck. very poor survival
What is the role which KSHV plays in kaposi’s sarcoma
It is necessary but not sufficient to cause KS.
Where is KSHV latent?
B cells and endothelial cells
Where do KS tumors arise?
lining of lymphatic system.
Most KS patients in US are aids pts?
True
How is it spread?
Not quite sure. Its an STI but the virus is present in saliva
What other B cell abnormalities does KSHV cause?
Primary Effusion Lymphoma
Castelemans disease
HBow does Ganciclovir work?
Inhibits viral polymerase
How does Foscarnet work?
Inhibits DNA polymerase, does not have to be phosphorylated.
Where does EBV lay latent?
CMV
KSHV
EBV- Throat epithelial and B
CMV- B,T, mono, lymph
KSHV- lining of lymphoid
