Question
Which of the following methods provides evidence of a recent viral infection and can be used for rapid diagnosis from a single serum specimen?
| A. | Detection of virus-specific IgM antibodies in a single serum specimen |
| B. |
Demonstration of viral antigens by indirect immunofluorescence assay in nasopharyngeal washings |
| C. |
Isolation of viruses using centrifugation-enhanced culture |
| D. |
Detection of viral hemagglutination-inhibiting (HAI) antibodies in a single serum specimen |
Show Answer
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Correct Answer » A Explanation |
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For serological diagnosis of an acute or recent viral infection, detection of virus-specific IgM antibodies in a single serum sample is highly useful.
- IgM is the first antibody produced after infection.
- Its presence usually indicates a recent or current infection.
- It eliminates the need for paired sera in many viral diseases.
Examples:
- Dengue IgM
- Hepatitis A IgM
- Rubella IgM
- Measles IgM
Option Analysis
A. Detection of virus-specific IgM antibodies in a single serum specimen
Correct.
- Indicates recent infection.
- Most commonly used serological marker of acute viral infection.
- Can be detected by ELISA, immunofluorescence, etc.
B. Demonstration of viral antigens by indirect immunofluorescence assay in nasopharyngeal washings
Incorrect in the context of the question.
- Useful for rapid viral diagnosis (e.g., RSV, Influenza).
- Detects viral antigen directly.
- Does not involve serum antibody detection.
C. Isolation of viruses using centrifugation-enhanced culture
Incorrect.
- Viral culture is a definitive diagnostic method.
- Time-consuming and technically demanding.
- Not the preferred method for rapid diagnosis from a single serum specimen.
D. Detection of viral hemagglutination-inhibiting (HAI) antibodies in a single serum specimen
Incorrect.
- HAI antibodies are usually IgG-based.
- A single serum titre is often difficult to interpret.
- Diagnosis typically requires a fourfold rise in titre between acute and convalescent sera.