LESSON 4- Laboratory diagnosis of viral disease Flashcards
Viral etiology of disease for which are available
antiviral chemotherapeutic agent
- demonstration of virus-induced cytopathic effects (CPEs) in the cells: production of
characteristic morphological changes in the cells they infect by:
(a) change in cell morphology,
such as rounding of cells or rounding and aggregation of cells, (b) syncytia formation, and (c)
inclusion bodies formation.
These changes can be demonstrated on staining by l
light microscopy
Screen blood donors for blood-borne viral pathogens, such as —
to prevent transmission of infection by transfusion of
blood and blood-borne products contaminated by viruses
hepatitis B and C,
HIV
- direct detection of viruses: through
electron microscopy (EM), fluorescence microscopy
(FM), and light microscopy (LM
These tests use specific monoclonal or
monospecific antibodies that are raised against specific viral antigens.
The enzyme-linked immunosorbent assay(ELISA),
direct immunofluorescence assay, RIA, etc
Tissue culture:
organ culture, explant culture, cell culture
DNAprobes:
:
(1) used in studying the expression of specific viral genomes on the
different cell types;
(2) detecting, in clinical specimens, viral genomes that do not
provide any CPE or for which no serological test are available; and
(3) detecting
slowly replicating or nonproductive viruses, such as human papilloma virus or CMV.
detecting
slowly replicating or nonproductive viruses, such as
human papilloma virus or CMV.
It is a
DNAamplification system that allows a millionfold amplification of a target sequence
of nucleic acids, at least 100,000-folds in a few hour
polymerase chain reaction (PCR), and reverse transcriptase PCR (RT PCR)
:
used for detection of viruses
(orthomyxoviruses) that agglutinate red blood cells of chickens, guinea pigs, human,
or other mammals
Hemagglutination inhibition (HI) test
:
detect specific viral antibodies in serum of the infected host; it is used to
identify the virus and its strain or serotype; it is used to determine whether viral infection is
an acute or chronic infection, or primary infection or reinfection;
viral serology
- detection of viral genome
-DNAprobes
-dot blot or Southern blot analysis
-northern blot or RNA:DNA probe hybridization
-polymerase chain reaction
based on inhibition of infection by the antibody and that of
CPEs of the viruses in tissue culture cells.
neutralization test (NT)
:
viral serology
Hemagglutination inhibition (HI) test
neutralization test (NT)
c) indirect fluorescent antibody (IFA) test
ELISA; RIA; latex agglutination test (LAT); and Western blot
