viral detection tests&measures
TRANSCRIPT
A Viral presentation by S.Vigneshwaran
Topics to be discussed
• Objectives
• Lab safety
• Specimen collection
• Routine Lab diagnosis
• Newly developed techniques
OBJECTIVES
Screening
Diagnosis
Identification
Control of outbreaks
• Homogenization of infected tissues
• Centrifugation
• Ultrasonic vibration
• Broken glasswares
Common Hazards…
ingestion..
Skin penetration..
Eye
To be followed….
Collection of Specimens….
Oropharyngeal swab
Collection of blood
Nasal swab
Stool collection kit
Routine lab diagnosisto be carried
M – MicroscopyS – Serological diagnosisV – Viral antigen identification
Microscopy
• Virus elementary bodies – Stained smears..
• Electron microscopy efficacy increased
• Viral diarrhea – Electron microscopy only
• Inclusion bodies – Rabies
Vira
l anti
gens
in c
ultu
re
Diag
nosis
Fluo
resc
ent a
ntibo
dy te
chni
que
Direct
Indirect
Examination
Earlydemonstration
Scope
Speed
Demonstration of virus antigens….
• Precipitation of gel• Immunofluorescence
• Counterimmunoelectrophoresis• Radioimmunoassay• Enzyme linked immunosorbentassay
• Probe’s method• Polymerase chain reaction
Serological tests
Highly sensitive serological test
Molecular methods
Sero Diagnosis..
• Rise in titre of antibodies – evidence for causative agent
• For it is essential to examine ‘ A paired sera’
• Collected early in course of disease
Acute sample
• Collected 10 to 14 days later
Convalescent sample
Serological tests
Employed
depend on….
VirusType of
Generally..• Neutralisation• Complement fixation• ELISA• Haemagglutination inhibition tests
Molecular diagnosis
availability
Enlarging the scope
sensitivity
specificity Viral
disease
diagnosis
Newly developed techniques
ELVIS
Herpes simplex virus
ᵝ galactosidase production
lac 2 gene gets activated
Activates UL97 Promoter
Hamster kidney cell
HSV
Nucleic acid amplification• Commercial kits – rapid diagnosis• Amplified NA – easy for detection• Standard technique• Methods: 1)PCR 2)Reverse transcriptase• Viruses like 1)HIV-1 2)Cytomegalovirus 3)Hepatitis virus B and C can be detected
Nucleic acid hybridization• Sensitive and Selective• Spotted – Nitrocellulose membrane & Viral NA• Denatured – alkali • Hybridized – labelled viral NA fragment• Rota virus – dot hybridization technique
Measuring the immune response to viral infection
Immunity
Cell mediated
Dermal hypersensitivity
cytotoxicity
Humoral mediated IgG,IgM
Thank u..