42. Which one of the following components of an enveloped virus particle is NOT encoded
by the viral genome?
(a) Capsid proteins ,
(b) Envelope lipids ,
(c) Non- structural proteins ,
(d) Structural proteins

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Which Component of an Enveloped Virus Is Not Encoded by the Viral Genome?

Enveloped viruses are characterized by their lipid bilayer envelope, which surrounds the viral capsid. This envelope contains several components, but not all of them are produced from the virus’s own genetic material. Let’s break down the choices.

(a) Capsid proteins

These proteins form the protein shell that encases the viral genome. They are encoded by the viral genome and are essential for protecting viral RNA or DNA.

(b) Envelope lipids

Correct Answer: Envelope lipids are not encoded by the viral genome. Instead, they are derived from the host cell’s membrane during the budding process. When the virus exits the host cell, it wraps itself in a portion of the host’s lipid bilayer, which becomes the viral envelope.

(c) Non-structural proteins

These are viral proteins that assist in replication, regulation, and other non-structural roles. They are encoded by the viral genome.

(d) Structural proteins

These include capsid proteins, matrix proteins, and glycoproteins embedded in the envelope. They are encoded by the virus to form the physical structure of the virus.

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Why Envelope Lipids Are Host-Derived

Enveloped viruses such as influenza, HIV, and SARS-CoV-2 acquire their lipid envelope from the host cell during budding. This process allows them to:

• Avoid immune detection (by mimicking host membranes),

• Easily enter other host cells via membrane fusion,

• Remain flexible in shape and composition.

Since lipids are not synthesized by the virus but instead come from the host, they are not encoded in the viral genome.

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Final Answer:

(b) Envelope lipids

These are not encoded by the viral genome; they are acquired from the host cell membrane.