Draw the morphological structure of influenza virus
Q102 marksShort Notes
Answer
Morphological structure of influenza virus (described, since a diagram cannot be rendered in this text-based answer — the description below covers the key labelled features that would appear in the diagram):
Influenza virus is a spherical to pleomorphic, enveloped, single-stranded, negative-sense, segmented RNA virus (8 gene segments for types A/B), approximately 80–120 nm in diameter.
Structure (outside to inside):
Lipid envelope — derived from the host cell membrane during budding, studded with two glycoprotein spikes:
Haemagglutinin (HA) — rod-shaped spikes, mediate attachment to host sialic acid receptors and membrane fusion.
Neuraminidase (NA) — mushroom-shaped spikes, cleave sialic acid to facilitate release of progeny virions.
Matrix (M1) protein — lines the inner surface of the envelope, providing structural support; M2 protein — a minor ion channel protein embedded in the envelope (target of the older adamantane antivirals).
Nucleocapsid — a helical ribonucleoprotein complex; each of the 8 individual RNA segments is separately encapsidated by nucleoprotein (NP) and associated with the viral RNA-dependent RNA polymerase complex (PA, PB1, PB2 subunits).
Key labelling points for a diagram: outer envelope with HA and NA spikes clearly differentiated by shape; M1 protein beneath the envelope; segmented helical nucleocapsid with associated polymerase complex at the core — the segmented genome structure is the critical feature enabling genetic reassortment (antigenic shift) when two strains co-infect a cell.
