Immunology CH 3.3 Infectious Diseases Flashcards by Kailea Boerste

which serum antibody response usually characterizes the primary (early stage) syphillis?

ab against syphillis are undetectable
detected 1 to 3 wk after appearance of the primary chancre
detected in 50% of cases before the primary chanchre disappears
detected within 2 weeks after infection

B, 90% of people develope ab between 1-3 wk after primary chancre

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what substance is detected in the sample bu RPR and veneral diease reasearch lab VDRL tests for syphillis?

cardiolipin
anticardiolipin antibody ACA
anti-trepronema pallidum antibody
T. pallidum

ACA or Reagin

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what type of antigen is used in the RPR card test?

live treponema organisms
killed suspension of treponemal organisms
cardiolipin
tanned sheep cells

cardiolipin

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which of the following is the most sensitive test to detect congenital syphillis?

VDRL
RPR
T. pallidujm agglut (TP-PA)
PCR

PCR will amplify very small amount of DNA to allow detection

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a biological false positive rxn is least likely with which test for syphillis?

VDRL
TP-PA
RPR
All results are equally likely to result a false positive

TP-PA is most specific for syphillis

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a 12yr old girl has sympt of fatigue and localized lymphadenopathy. Tests reveal peripheral blood lymphocytosis, positive RPR and positive spot test for IM. what test should be preformed next?

HIV screen
VDRL
EBV - specific antigen test
TP-PA test

TP-PA

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which test is most likely to be positive in the tertiary stage of syphillis?

trep-specific antibody
RPR
VDRL
RST (reagin screen test)

A: treponemal specific antibody

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what is the most likely interpretation of the following syphillis serological results?

RPR reactive; TP-PA nonreactive

neurosyphillis
secondary syphillis
syphillis that has been sucessfully treated
bio false positive

D bio false positive

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which specimen is the sample of choice to evaluate latent or tertiary syphillis?

serum sample
chancre fluid
CSF
joint fluid

CSF

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Interpret the following

RPR titer: weak reactive- 1:4 reactive 1:8 to 1:64

excess antibody: prozone
excess antigen: post zone
equivalence
impossible to interpret

excess antibody, prozone

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tests to ID infection with HIV fall into which three general classification types of tests?

tissue cultures, antigen and antibody tests
tests for antigens, antibodies and nucleic acid
DNA probe, DNA amp and western blot
ELISA, western blot and southern blot

tests for antigens, antibodies and nucleic acid

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which tests are considered screening tests for HIV?

ELISA, chemilum, and rapid antibody tests
IFA, western blot, radioimmunoprecip assay
culture, antigen capture, DNA amp
Reverse transcript and mRNA assay

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which tests are recommended confirmitory for HIV?

ELISA and rapid antibody test
HIV, 1-2 antibody ssay and qualitative PCR
Culture, antigen capture, quant PCR
Reverse transcript and mRNA assay

B. HIV 1-2 antibody assay and qual PCR

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how do fourth and fifth gen HIV tests reduce the time from infection to the test becoming positive?

they are PCR tests detecting viral RNA
they detect p24 ag in addition to HIV antigen
they detect proviral DNA
they detect ab to more ag than earlier HIV tests

B, p24 ag in addition to HIV ag

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a woman who has had five pregnancies test pos for HIV on fourth gen assay, and is negative on 1-2. Initial reactivity may be due to?

poss corss rxn with herpes/EBV
interference w medications
cross rxn of pregnancy antibodies
possible technical error, repeat specimen

cross rxn of pregnancy antibodies

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Interpret the following results for HIV testing:
Fourth Gen ELISA pos; repeat ELISA pos; HIV 1,2 assay negative; qual HIV RNA rt PCR pos

False pos fourth gen assay
false neg antibody diff assay
indeterminante, more testing needed
HIV p24 antigen detected on fourth gen ELISA

D, fourth gen HIV p24 antigen detected

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What is the most likely explanation when antibody tests for HIV are negative but the PCR test is positive?

probably not HIV infection
pt is in the “window phase” before ab production
tests were preformed incorectly
clinical signs misinterpreted

B, pt may be in the window phase and ab may not be produced yet

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what criteria constitutes the classification system for HIV infections?

CD4 positive t cell count and clinical symptoms
clinical symptoms, condition, durnation, and strength of reactivity on fourth gen HIV test
presence/absence of lymphadenopathy
strong fourth gen HIV test reactivity and CD8 positive T cell count

A, CD4 positive t cell count and clinical symptoms

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what is the main difficulty associated with the development of an HIV vaccine?

the virus has been diff. to culture, antigen extraction and concentration are laborious
human trials cannot be preformed
different strains of the virus are genetically diverse
anti-idiotype antibodies cannot be developed

C, different strains of the virus are genetically diverse

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which CD4:CD8 ratio is most likely in a patient with AIDS?

2:1
3:1
2:3
1:3

inverted ratio is common, D is correct 1:3 ratio with more CD8

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what is the advantage of fourth gen rapid HIV tests over earlier rapid HIV tests?

they use recombinant antigens
they detect mult strains of HIV
they detect p24 antigen
they are quantitative

C, they detect p24 antigen

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which method is used to test for HIV infection in infants who are born to HIV pos mothers?

ELISA
western blot
PCR
viral culture

PCR is used, uses small amount of blood and do not rely on antibody response

what is the most likely cause when a fourth gen HIV assay is pos for all the controls and samples?

improper pippetting
improper washing
improper addition of sample
improper reading

improper washing may not remove unbound Ig

what constitutes a diagnosis of viral hepatitis?

abn tests for liver enzymes
clinical signs and sympt
pos results for hepatitis markers
all of these options

all of these options

which of the following statements regarding infection with Hep D (HDV) is true? occurs in pts with HIV infections does not progress to chronic hepatitis occurs in pts with HBV infection is not spread through the blood or sexual contact

HDV can only infect if it is cross reacted/coinfected with HBV, option C

all of the following hepatitis viruses are spread through blood or blood products except? Hepatitis A virus: HAV HBV HCV HDV

HAV is spread through fecal oral route, short incubation period

which hepatitis B marker is the best indicator of early acute infections? hep B surface ag (HBsAg) hep B e-antigen (HBeAg) hep B core antigen (HBcAg) hep B surface antibody (Anti-HBs)

HBsAg is the first to appear in HBV infections

which is the first antibody detected in serum after infection with HBV? Anti-HBs Anti-HBc IgM Anti-HBe all are detectable at the same time

HBcAg is the first detectable antibody , it presists for years after infection and is found in asymptomatic carriers

which antibody persists in low level carriers of HBV? IgM anti-HBc IgG anti-HBc IgM anti-HBe IgG anti-HBs

IgG anti HBc can be detected in carriers who are negative

what is the most likely explanation when a patient has clinical signs of viral hepatitis but tests negative for HAV IgM, HBsAg, and HCV antibody? tests were preformed improperly pt does not have hepatitis the patient may be in the core window clinical eval was improper

the pt may be in the core window when surface ag and ab are undetectable

which hepatitis marker should be preformed on blood products? HBsAg and Anti-HBc Anti-HBs and anti-HBc HBeAg and HBcAg Anti-HBs and HBeAg

HBsAg and Anti-HBc blood products are early indicators

which hepatitis antibody confers immunity against reinfection with HBV? Anti HBc IgM Anti HBc IgG Anti HBe Anti HBs

D, anti HBs used as a marker for immunity after infection or vaccination

which test, other than serological markers, is most consistently elevated in viral hepatitis? antinuclear ab alanine aminotransferase (ALT) absolute lymph count lactate dehydrogenase

ALT may be increased in hepatic disease, with highest in the acute viral

if only anti-HBs is positive, which of the following can be ruled out? HBV vaccination distant past infection with HBV hep B Ig injection (HBIG) chronic HBV infection

D, persons with chronic infection show a negative anti- HBs

interpret the following results for EBV infection: IgG and IgM antibodies to viral capsid antigen (VCA) are positive infection in the past infection with a mutual enhancer virus, such as HIV current infection impossible to interpret, need more info

current infection, igM will disappear after 4 months of infection resolving

rapid mono tests use latex particles coated with which of the following? guinea pig ag beef proteins horse proteins sheep proteins

heterophile antibody directed against beef proteins

Blood products are tested for which virus before being transfused to new borns? EBV Human T lymphotropic virus II (HTLV-II) CMV HDV

CMV can be life threatening to newborns in blood products

what is the end point for the antistreptolysin O (ASO) latex agg assay? highest serum dilution that shows no agglut highest serum dilution that shows agglt lowest serum dilution that shows agglut lowest serum dilution that shows no agglut

highets dilution showing agglutination

A streptozyme test was preformed but the result was negative, even though the pt showed clinical signs of a strep throat infection. what should be done next? ASO or anti-deoxyrib B (anti-DNase B) test another test but diluted antihyaluronidase test wait for 3 - 5 days and repeat the test

A, ASO or Anti-DNase B test

rapid assays for influenza that utilize specimens obtained from nasopharyngeal swabs detect: IgM anti-Influenza IgA anti-influenza IgA - influenza antigen immune complexes influenza nucleoprotein antigens

D, influenza nucleoprotein antigens

how can interferring cold agglut be removed from a test sample? centrifuge the serum and remove the top layer incubate the clot at 1deg to 4 deg for several hours then remove the serum incubate at 56deg in water bath for 30 min use an anticoag sample

B, incubate the clot at 1deg to 4deg for several hours then remove the serum

all tubes (dilutions) except the negative controls are positive for cold agglutinins. this indicates: contaminanted RBCs a rare antibody against RBC antigens the sample was stored at 4deg prior to separating serum and cells further serial dilution is neccessary

D, further serial dilution is neccessary

all pos cold agglut tubes remain positive after 37deg incubation except the positive control. what is the most likely explination for this situation? high titer cold agglut contamination of test system antibody other than cold agglut faulty bath water

C, antibody such as warm auto or allo antibody is present

which of the following positive antibody tests may be indicated of recent vaccination or early primary infection for rubella in patients with no clinical symptoms? Only IgG antibodies positive only IgM antibodies positive Both IgM and IgG positive fourfold rise in titer for IgG antibodies

B, only IgM

which increase in antibody titer (dilution) best indicates an acute infection? from 1:2 to 1:8 1:4 to 1:16 1:16 to 1:256 1:64 to 1:128

C, shows a 16 fold rise in titer and is most difinitive

why is laboratory diagnosis difficult in cases of lyme disease? clinical respose may not be apparent upon initial infection: IgM antibody may not be detected until 3 to 6wk after infection lab tests may be designed to detect whole B. bordoferii, not flagellar antigen found in early detection most labs are technically demanding and lack specificity antibodies formed initially to b.bugdorferi may cross rxn in antigen tests for autoimmune diseases

A, IgM antibody may not be detected until 3-6wk after infection/bite from tick

serological tests for which disease may give a false pos result if the pt has lyme disease? HIV Syphillis EBV Hep C

B, may test pos with some treponemal antibody tests with syphillis

in monitoring HIV infections, which parameter may be expected to be the most sensitive indicator of the effectiveness of the antiretroviral treatment? HIV antibody titer CD4:CD8 ratio HIV viral lode absolute total t cell count

C, HIV viral load, will rise and fall

a renal transplant is found to have a rising creatinine level and reduce urine output. Dr orders a Urine PCR assay. when you call out which organism the dr wants to ID, you are told: HCV Legionella pneumophila EBV BK virus

BK virus can cause renal and urinary tract infections

A newborn is tested for vertically transmitted HIV. which of the following test is most useful? HIV PCR CD4 count rapid HIV antibody test HIV IgM antibody test

A neonatal test HIV PCR

which of the following fungal organisms is best diagnosed by antigen detection as opposed to antibody detection? Histoplasma cryptococcus candida aspergillus

B, cryptococcus

you are referred a papanicolaou smear specimen for you to assay to detect the presence of a virus associated with cervical cancer: you preform: an ELISA for anti-huma simplex virus 2 antibodies a molecular assay for HSV-2 an ELISA for HPV antibodies a molecular assay for HPV

D a molecular assay for HPV

a pt has unexplained anemia.m Dr suspects a parvovirus B19 Infection. the parvovirus IgM test result is negative. next steps is: the pt does not have parvovirus a convelecent sample is recommend in 4wk to determine if fourfold titer rise has occured a parvovirus PCR is reccom a recent transfusion for pt anemia may have resulted the false neg result and the pt should be retested in 4 wks

C a parvovirus PCR is recommended