Lec 33 CMV EBC other Herpes Flashcards
What are 3 drugs used to treat CMV?
- ganciclovir
- valganciclovir
- cidofovir
What are the common characteristics of herpes viruses?
- large
- enveloped
- double strand DNA
- ubiquitous [except HHV 8]
- chronic/latent infection follows acute
- reactivations common
- mostly transmitted by close contact during asymptomatic reactivation and shedding [except varicella]
What is the one herpes virus that is not ubiquitous?
HHV8
Who is at higher risk for getting herpes viruses?
- immunocompromised particularly with CMI deficiency
What are clinical symptoms of EBV?
causes mononucleosis syndrome
- fever
- pharyngitis
- lymphadenopathy
- hepatosplenomegaly + mild hepatitis
- rash
- atypical lymphocytes
- rarely also: upper airway obstruction, splenic rupture
- resolves in 2-3 wks –> fatigue/malaise may last longer
What causes mononucleosis syndrome?
EBV
What is pathogenesis of mono syndrome?
- resolves in 2-3 wks –> fatigue/malaise may last longer
Who gets mono?
- early childhood usually asymptomatic
- adolescence/early adult hood
- 70% of US population infected by age 30
What happens if you give amoxicillin to pt with EBV?
can trigger a non-allergic rash
What is pathogenesis of EBV?
acute
- get EBV infection from saliva of infected person
- EBV infects resting memory B lymphocytes and establishes latency = main target
- host mounts immune response [humoral and cell mediated]
chronic
- EBV transforms/immortalizes B cells
- cell mediated immunity [EBV-specific cytotoxic T] keep B cells from proliferating out of control
- from time to time: virus can reactivate and enter lytic replication and be shed in saliva
What is pathogenesis of EBV in immunocompromised?
- balance is lost of im
- B cells proliferate out of control –> get lympho-proliferative disorders and cancers
How is EBV transmitted?
- through saliva from subject with acute disease or with asymptomatic reactivation
- through organ transplantation
What is the receptor for EBV infection? where is it located?
CD21 receptor –> on B cells and epithelial cells of oral mucosa and salivary glands
What is immune response to EBV?
- specific cytotoxic T cells control immortalized B cell proliferation
- expansion of this T cell population causes
- – atypical lymphocytosis
- – hyperplasia of lymphatic organs
What is basis of monospot test? who is is sensitive test for?
sensitive for: adolescents/adults, not young children
- basis of test = heterophile antibodies
==== non-specific IgM antibodies that sometimes stick to red blood cells and don’t play a role in controlling the infection
What antibodies initially present in EBV infection? later? after months of time?
initially: high IgM and IgG against viral capsid antigen
later: antibodies against early antigen appear, IgG persists, IgM decreases
fast forward: IgG persists, IgM goes away, EBNA [antibody against epstein barr nuclear antigen] starts to appear
What does a positive EBNA tell you?
patients had mono previously [months or years ago] but it is now resolved
What cancers associated with EBV?
- African [endemic] Burkitt’s lymphoma
- sporadic burkitt’s lymphoma [less closely associated]
- nasopharyngeal carcinoma
- hodgkins lymphoma
- primary CNS lymphoma in AIDS
- post transplant lymphoproliferative disease
What are two symptoms/diseases associated with EBV and HIV co-infection?
- oral hairy leukoplakia [white patch on side of tongue, non-malignant]
- CNS lymphoma
What is chronic active EBV? what types of antibodies do you find?
- begins with infectious mononucleosis but acute infection is not adequately cleared
- high titers of EA and VCA antibodies, lack of appropriate EBNA response
- major organ involvement, persists for months
- high mortality
What is treatment for EBV?
- supportive treatment
- reduce immunosuppression in transplant recipients
- rituximab [anti-CD20] for some EBV related malignancies
What is rituximab? mech of action
- an anti-CD20 monoclonal antibody
- CD20 = a B cell surface receptor
- acts by: directly causing B cell apoptosis, activating complement-dependent cytotoxicity, activating antibody-dependent cell mediated cytotoxicity
- used to treat some EBV related malignancies
What percentage of population of young adults has CMV?
70-90%
How is CMV transmitted?
- through secretions of acutely and chronically infected
- saliva, vaginal fluid, semen, urine
- through blood transfusion, organ transplantation, mother –> infant
