Virology
22-2-11
Diagnostic methods in virology
 Detection of virus
 Detection of viral antigen
 Detection of viral genome
 Detection of serological response
Detection of viral antigens
 Antisera (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 immunoassay must be used for each pathogen
 In contrast electron microscopy and culture are
catch all techniques which detect all pathogens
Methods
 Antigen 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 response
 IgM detection
 Detection of rising titre: ELISA, complement fixation
test, haemagglutination inhibition
Detection of serological response: Antigen
capture ELISA for HIV antibody
Case 1
 The 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 1
 What additional tests would you request?
 What your treatment options
Case 2
 You 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 2
Patient 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 4
 A 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 5
 A 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 5
 Shown 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?