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

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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..