Stages of viral replication and their main characteristics.

Virion

extracellular particle

Vegetative virus

replicative form (autonomous extrachromosomal element)

Permissive cell

a host cell that supports the complete viral replication cycle

Types of infection based on outcome

• Productive infection
• Proliferative infection
• Persistent infection

Stages of Infection

1. Adsorption (attachment)
2. Penetration (entry)
3. Decapsidation (uncoating)
4. Eclipse phase (synthesis)
5. Assembly of new virion
6. Maturation
7. Egress and Envelope Formation
8. Viral Specificity– Receptors

1. Adsorption

Binding to the adhesion receptor
Binding to the specific receptor

2. Penetration

• Non-enveloped viruses: entry via direct penetration or endocytosis

• Enveloped viruses: envelope derived from internal membranes; entry via receptor-mediated endocytosis

• Bacteriophages: transfection; only the nucleic acid enters the host cell

3. Decapsidation

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4. Eclipse phase - Synthesis

1. transcription - synthesis of mRNA from the viral genome to serve as a template for subsequent protein synthesis

2. Protein synthesis (Translation) using the viral mRNA

3. Nucleic acid synthesis (Replication) – replication of the viral genome and synthesis of capsid components

5. Assembly

mhm

6. Maturation and 7. Release

• Maturation
• Cell lysis
• Budding – paramyxoviruses, rhabdoviruses, togaviruses, and retroviruses
• Exocytosis