MCQ – 10319

Which of the following methods provides evidence of a recent viral infection and can be used for rapid diagnosis from a single serum specimen?

Correct Answer » A Explanation

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.