Viral Replication Flashcards
What is the first step of viral replication?
Attachment
Capsid or envelope proteins bind to the receptors
What is cell tropism?
Specificity of cells based on their receptors and a virus’s ability to bind
What is viropexis?
Phagocytic engulfment of the virus attached to a receptor
pH of the endocytic vacuole is important for uncoating
What is fusion?
Type of penetration pertaining to enveloped viruses
Cell membrane fuses with viral envelope, dependent upon viral proteins which mediate fusion
What is uncoating?
Removal of some or all capsid proteins,, release genome in nucleus or cytoplasm
What occurs after uncoating?
Transcription and translation of parental nucleic acid to form early mRNAs and early proteins
Occurs before viral nucleic acid synthesis
Describe the synthesis of viral nucleic acids.
NA synthesis may occur either in the cytoplasm (polio) or nucleus (herpes) or both
This stage is the dividing line between early and late events for DNA viruses
What occurs after NA synthesis?
Transcription and translation of progeny NA to form late mRNAs and late proteins
What is maturation?
Assembly of viral components to form intact virions, occurs at specific site within the cells
NA and capsid come together to form progeny virus
Envelopment - budding at cytoplasmic or nuclear membrane
What can cause viral progeny to be noninfectious?
Empty capsids formed by aggregation of excess capsid proteins
Improper maturation - no proteolytic cleavage of envelope proteins
How can viruses become drug resistant?
Mutation in viral NA that yields viral proteins that are not affected by drugs or the NA themselves are not directly affected
What are defective interfering particles?
Produced after high MOI of cells
Lack portions of their NA, and can’t replicate on their own, requiring help from infectious virus
May initiate persistent infections
What are inclusion bodies?
Localized areas within infected cells containing viral components
Can be nuclear or cytoplasmic
