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7. Viral serology


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What 4 viruses are within the Herpes virus group?
1. EBV
2. CMV
3. Herpes Simplex
4. Varicella-Zoster
What is the herpes group characterized by?
What diseases does EBV cause?
1. Infectious mono
2. Chronic active EBV (chronic fatigue syndrome)
3. Burkitt's lymphoma
4. Nasopharyngeal carcinoma
How is EBV transferred?
Blood transfusions
What 3 things are used to diagnose infectious mono?
1. Clinical features
2. Relative/abs lymphocytosis with >10% reactive lymphs.
3. Demonstration of heterophile antibody
In what populations is the heterophile more demonstrated?
Adults: 90-98% seropositive
Children: <50%; less spcfc.
What is a heterophile antibody?
Ab stimulated by 1 Ag which reacts w/a completely unrelated antigen of different mammal.
How does heterophile Ab relate to EBV?
The EBV antigen cross reacts with RBCs from horse, sheep, and ox.
What are 3 methods used to detect heterophile antibody?
1. Paul and Bunnell
2. Davidsohn
3. Rapid slide tests
What is the Paul-Bunnell screening test?
-Hemagglutination test
-Mix inactivated Pt serum + Sheep RBCs.
-Look for agglutination
What are the drawbacks of the Paul-Bunnel test?
Does not distinguish btwn Ab against EBV, serum sickness, or Forssman; NOT SPECIFIC.
What is the Davidsohn differential etst?
Modified Paul-bunnell test;
-guinea pig RBCs absorb out the Forssman antigen.
-horse RBCs absorb out CMV antigen.
-absorbed serum then tested.
What are drawbacks of the davidsohn test?
What is the monoslide test?
a faster alternative to davidsohn test.
-Reagent A has both guinea pig and horse RBCs.
-Horse cells are 'suped up' so the test is more senstive.
Cite 4 situations when specific EBV antibody testing is done:
1. Confirm heterophile neg adult case of infectious mono.
2. In cases of childhood mono.
3. Cases w/out classic symptoms
4. Immunocompromised patients
What are the 4 types of eBV antibodies?
1. Anti-EB viral capsid Ag
2. Anti-EBV early Ag
3. Anti-EBV nuclear Ag
4. Anti-EBV membrane Ag
When do EBV antibodies appear?
Viral capsid:
-IgG is 4-7 days; lifelong
-IgM indicates acute infection.
Early Ag:
-Indic. acute inf, gone in 3mo
Nuclear Ag:
not there in acute, appears in convalescent stage.
What antibodies would be positive in Burkitt's lymphoma and Nasopharyngeal carcinoma?
-IgG Anti-VCA
What antibodies are present during the reactivation phase?
Anti-VCA (IgG)
What type of testing is used to test for specific EBV Abs?
In whom is Cytomegalovirus life-threatening?
Immature infants
What can congenital CMV progress to?
Cytomegalic inclusions disease.
What causes congenital CMV infection in infants? (2 things)
1. Primary infection of mom
2. Reactivation of mom
What 3 methods are usually used to diagnose CMV?
1. Urine or blood culture in shell vial assay, with DFA for confirmation.
2. Serological methods - ELISA
3. PCR
What specimen should serology methods be done on? What spcf methods?
Paired sera; there are no good IgM assays.
ELISA, C' fixatn, IFA, RIA, LA.
What is the most common test for CMV?
When is IgM preferred over paired sera?
I don't know yet
What 4 serology assays are used to detect herpes simplex virus?
1. Elisa
2. Compl. fixation
3. Indirect IFA
4. Indirect hemagluttination
What antibodies are detected in HSV?
Paired sera or IgM
Why is serology used to test for Varicella-Zoster virus?
To detect immune status.
What types of tests are done for VZV?
1. Elisa (mostly)
2. Complement fixation (insensitive)
What types of tests are done for Rotavirus?
-EIA - for antigen in stool; VERY sensitive!!
-PCR in ref labs
-EM in research
Why do the MMR, and how?
for immune status
ELISA, HAI, Compl. fix, IFA
What types of tests are done for Rubella?
-Comp fix
What does a torch panel test for?
If the ToRCH is done on an infant, what would indicate infection?
IgM; if IgG is found, that's impossible, must be mom's.
What viruses are included in a normal respiratory panel?
1. RSV (resp synct virus)
2. Parainfluenza (croup)
3. Adenoviruses
5. Coxsackie virus
What tests are used to detect RSV?
-Comp fix
what tests are used to detect parainfluenza?
-Comp fix
What test are used to detect adenoviruses?
-Comp fix
what does a nasal wash specimen screening test for?
-Influenza A/B
-Parainfluenza 1,2,3
What are 5 types of HIV screening tests?
1. ELISA (best)
2. Rapid - OraQuick and UniGold
3. Orasure EIA on oral mucosal transudate
4. Urine tests
5. Home tests
what are 3 types of confirmatory tests for HIV?
1. Western blot (gold standard)
2. Indirect Immunofluorescent Ab
3. Radioimmunoprecipitin (RIPA)
what type of testing for HIV is done on babies? Why?
PCR; b/c antibody from the mother will affect ELISA/Western blots.
What data is used to monitor HIV status?
-CD4 lymph count
-Viral load testing
What testing is used to distinguish fresh vs. old infection of HIV?
-RNA and p24 assays; detects the virus before seroconversion.
What is the decreased sensitivity EIA used for?
to indicate a nonreactive recent infection; would be negative in recent infection.
How does West Nile virus normally present?
80% Asymptomatic
20% symptoms of flu
Who are we really concerned about contracting WNV?
Immunocomp, older, infants
what is the gold standard for WNV diagnosis?
serological testing
what 2 serological tests are used to diagnose WNV?
1. IgM capture ELISA (MAC)
2. Plaque reduction neutralization tests (PRNT)
what specimens are used for these tests?
1. serum
2. CSF
3. maybe urine

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