A molecular laboratory is validating two nucleic acid assays: one for herpes simplex virus from CSF and one for influenza A from nasopharyngeal swab. Which statement about the required enzymatic steps is correct?
- A Only the influenza assay requires reverse transcription, since its RNA genome must first be copied into complementary DNA ✓
- B Neither assay requires reverse transcription because both are amplified by thermostable DNA polymerase alone
- C Both assays require a reverse transcription step because both genomes are RNA
- D Only the HSV assay requires reverse transcription, since latency transcripts must be converted before amplification
Correct answer: A. Only the influenza assay requires reverse transcription, since its RNA genome must first be copied into complementary DNA
Explanation
Influenza C has a segmented single-stranded RNA genome, so Taq polymerase cannot copy it directly and a reverse transcription step generating cDNA must precede PCR. HSV is a double-stranded DNA virus, so conventional thermostable DNA polymerase amplifies it without reverse transcription. Recognising whether the target is RNA or DNA determines whether RT is needed, a standard validation point in molecular labs.
Reference: Koneman's Color Atlas and Textbook of Diagnostic Microbiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.