The correct answer is (3) Neuraminidase. Influenza virus surface spikes feature this enzyme, crucial for viral release from host cells.

Option Analysis

(1) RNA Polymerase

RNA polymerase synthesizes RNA from DNA or RNA templates, vital for influenza’s replication inside cells as an RNA virus. However, it resides in the viral core, not on surface spikes.​

(2) DNA Polymerase

DNA polymerase replicates DNA, irrelevant to influenza—a negative-sense RNA virus lacking a DNA stage. It plays no role in the virus or its spikes.​

(3) Neuraminidase (Correct)

Neuraminidase (NA) forms mushroom-shaped spikes on influenza’s envelope. It cleaves sialic acid residues, enabling progeny virions to detach from host cells and spread infection.

(4) Hexokinase

Hexokinase phosphorylates glucose in glycolysis, a host metabolic enzyme absent from viruses. Influenza lacks metabolic machinery, so it cannot carry this.​

The influenza virus spikes enzyme, Neuraminidase, defines viral infectivity. Found on the envelope of influenza A and B viruses, these functional surface projections aid virus propagation.

Structure of Influenza Spikes

Influenza virions display two key glycoproteins: hemagglutinin (HA) for cell attachment and Neuraminidase for release. NA’s tetrameric spikes hydrolyze α-2,3/α-2,6 sialic acid linkages on host glycans.

Why Neuraminidase?

Post-replication, virions aggregate via sialic acid binding to HA. Neuraminidase acts as a receptor-destroying enzyme, desialylating the surface for efficient detachment—essential for pathogenesis.​

Common MCQ Confusions

• RNA polymerase: Internal, for vRNA transcription.​

• DNA polymerase: DNA-specific, irrelevant.​

• Hexokinase: Host glycolysis enzyme, not viral.​

This distinction is key for exams like GATE Life Sciences.

Therapeutic Relevance

NA inhibitors (e.g., oseltamivir) target spikes, blocking release and treating flu. Mutations confer resistance, highlighting NA’s evolutionary role.