7) IFA Flashcards
main purposes of serological testing
- monitor course of infection
- detect past infection
- assess immune status
IgM in a newborn indicates…
congenital infection
(not mom’s)
molecular assays for viral nucleic acids are especially valuable for infections of the…
CNS
small amts of organism
IFA uses —— to detect ———
fluorochrome-labelled conjugate
Ab in pt serum
most common fluorochrome
FITC
direct IFA
pt tissue on slide + conjugate Ab + fluorochrome
indirect IFA
substrate with Ag on slide + pt serum (Ab) + conjugate + fluorochrome
IFA is (more/less) sensitive than EIA
less
disadvantages of IFA
- background fluorescence
- nonspecific binding to substances in serum
- fluorochromes sensitive to pH, light
- reading must be done frequently to maintain competency
advantages of IFA
- fairly sensitive
- no hazardous materials
fluorescent method developed to overcome IFA’s problems, but requires expensive instrumentation
fluorescent polarization immunoassay (FPIA)
lamp in fluroescent microscope must emit…
proper wavelength to excite fluorochrome
exciter filter in fluroescent scope
removes wavelengths other than one needed
barrier/emission filter in fluorescent scope
screens out light other than that produced by fluorochrome
complications associated with EBV
- Burkitt’s lymphoma
- nasopharyngeal carcinoma
- B-cell lymphomas
- chronic fatigue syndrome (not proven)
EBV-EA indicates…
active infection
EBV-M indicates…
acute infection
disappears after 3 months
EBV-G indicates…
current or past infection
90% pop has it by adulthood
EBNA detectable in….
convalescent stage of EBV
rapid mono detects…
heterophile Ab
produced by 40% EBV pts by week 1, and 90% by week 4
heterophile Ab
heterophile Ab sensitivity low in…
children <12 yo
negative heterophile Ab reflex
EBV-M serology
autoAb that EBV can trigger
- cold agg
- RF
- ANA
most of pop exposed by elderly years, majority are asymptomatic or have mono-like illness
CMV
CMV life-threatening for…
newborns
immcomp
most common congenital viral infection
CMV
50% newborns with CMV develop…
sequelae (visual impairments, hearing loss, mental retardation)
immcomp patients especially vulnerable to CMV
aids
transplant
CMV in immcomp pts can affect…
eyes
liver
lungs
GI
CNS
identifies risk for disseminated CMV
CMV-DNA by PCR
method of choice for CMV serology
EIA
utility of CMV-G
documenting past infection in organ or blood donors
utility of CMV-M
limited
false negative and positives
primary infection occurs as gingivostomatotitis in children
HSV-1
retreats to nerve ganglia as dormant infection (can be fatal)
HSV-1