Q.27 Arrange the events of virus replication in a host cell •
A. Attachment
B. Packing of viral genome with structural proteins
C. Release of genomic material in the host cytoplasm
D. Synthesis of viral genes and proteins
Choose the correct answer from the options given below :
1. A, B, C, D
2. A, C, D, B
3. B, A, C, D
4. C, D, B, A
Virus replication in host cells follows a precise sequence: attachment, entry/uncoating, biosynthesis, assembly, and release. For Q.27—”Arrange the events: A. Attachment, B. Packing of viral genome with structural proteins, C. Release of genomic material in host cytoplasm, D. Synthesis of viral genes and proteins”—the correct answer is option 2: A, C, D, B.
Option Analysis
Option 1: A, B, C, D
This sequence places packing (assembly) before genomic release and synthesis, which is impossible since structural proteins and genomes must exist before packaging can occur.
Incorrect; violates replication logic where biosynthesis precedes assembly.
Option 2: A, C, D, B
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A: Virus attaches to host receptors via glycoproteins.
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C: Penetration/uncoating releases viral genome into cytoplasm (e.g., endocytosis or fusion).
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D: Host machinery transcribes/translates viral mRNA into proteins and replicates genome.
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B: New genomes packaged with capsid proteins into virions.
Correct; matches standard lytic cycle (HIV, influenza, T4 phage).
Option 3: B, A, C, D
Packing first defies biology—intact virions cannot assemble before attachment or genome entry.
Wrong; assembly is penultimate step.
Option 4: C, D, B, A
Genomic release without prior attachment is impossible; viruses must bind first.
Incorrect; attachment initiates entire cycle.
Replication Cycle Steps
| Step | Event | Description |
|---|---|---|
| 1 | A: Attachment | Spike proteins bind cell receptors (specificity determines host range). |
| 2 | C: Genome Release | Fusion/endocytosis uncoats nucleic acid in cytoplasm. |
| 3 | D: Synthesis | Viral genes → mRNA → proteins; genome replication (host ribosomes/polymerases). |
| 4 | B: Packing/Assembly | Nucleocapsids form, envelope acquired (if applicable). |
| 5 | (Not listed) Release | Lysis or budding. |
Applies to most viruses; retroviruses add reverse transcription post-C.
Exam Relevance
CSIR NET/GATE Virology staple: Memorize A→C→D→B→Release. Variants exist (e.g., poxviruses replicate in cytoplasm), but this fits question phrasing. Understand eclipse phase (C to D).
