Virology

Virology22-2-11

Diagnostic methods in virology

Detection of virus

Detection of viral antigen

Detection of viral genome

Detection of serological response

Detection of viral antigensAntisera (mono or polyclonal) are used to

detect viral antigen

These assays can be sensitive as they can detect antigens of disrupted viral particles

They are pathogen specific - separate immuno-assay must be used for each pathogen

In contrast electron microscopy and culture are catch all techniques which detect all pathogens

MethodsAntigen capture ELISA - eg rotavirus, HBsAg, HIV

Latex particle agglutination (LPA) eg rotavirus

Immunoflouresence - eg RSV, influenza,

Viral antigen detection: ELISA for rotavirus

ELISA for Hep C antibody

Virus antigen detection: Latex particle agglutination for rotavirus

Virus antigen detection: Immunofluorescence - direct

Virus antigen detection: Immunofluorescence of RSV-infected

nasopharyngeal cells

Detection of viral genome

Genome amplification eg. PCR (polymerase chain reaction)

Viral genome detection: qPCR

Viral genome detection: PCR

Detection of serological responseIgM detection

Detection of rising titre: ELISA, complement fixation test, haemagglutination inhibition

Detection of serological response: Antigen capture ELISA for HIV

antibody

Case 1The following is a report from a lady with a

10-year history of fatigue, anorexia and elevated LFTs.

Hepatitis B surface antigen: negative

Hepatitis C antibody: positive

Hepatitis C antibody immunoblot confirmation: positive Banding pattern: c100 c33 c22 NS5

3+ 3+ 4+4+

Case 1What additional tests would you request?

What your treatment options

Case 2You are given the following results on two

different patients.

Are there any differences between the profiles?

What implications (if any) are there for these differences?

Case 2

Patient 1:

Tests Results

EIA for HBsAg Positive

***Infection Risk***

Hepatitis B e antigen Negative

Hepatitis B e antibody Positive

Hepatitis B core IgM antibody Negative

Report comment: Hepatitis B result profile consistent with

chronic hepatitis B infection.

Case 2Patient 2:

Tests Results

EIA for HBsAg Positive

***Infection Risk***

Hepatitis B e antigen Positive

***High Infection Risk***

Hepatitis B e antibody Negative

Hepatitis B core IgM antibody Positive: 250 IU/ml.

Report comment: Hepatitis B result profile consistent with

chronic hepatitis B infection.

Case 2

Do you agree with the comments?

What additional test(s) would you request for after a discussion with the microbiologist?

Case 3

You have vaccinated 2 patients against hepatitis B virus for the purpose of foreign travel.

What test would you request to assess the vaccination status?

Comment on the following results.

Case 3

Patient 1:

Hepatits B surface antibody: >1000 mIU/ml

Patient 2:

Hepatitis B surface antibody: <10 mIU/ml

Case 4A patient presents with malaise, elevated

LFTs and a history of intravenous drug abuse. You are given the following result:

Hepatitis B surface antigen: Positive

Hepatitis B surface antibody: Negative

Report comment: If this is the first positive serological test on this patient, please repeat to confirm.

Case 4

Comment on the above report.

What additional tests would you request?

Case 4

Hepatitis B surface antigen: Positive

***Infection Risk***

Hepatitis B e antigen: Positive

***High Infection Risk***

Hepatitis B e antibody: Negative

Hepatitis B core IgM antibody: Negative

Hepatitis B core total antibody: Positive

Report comment: ………..

What is your report comment?

Case 5A 23 year old female patient presents to the A/E

department with malaise, lymphadenopathy, malaise and a rash. She has a history of unsafe sexual activity.

What investigations would you request?

Case 5Shown below is one of the patient’s

laboratory results:

Tests Results

EIA for anti-HIV 1 (Organon) Positive

EIA for anti-HIV 1+2 (Murex) Positive

Report comment: ***confirmed anti-HIV 1 positive***

What additional tests would you require?

What would you advise the patient?