BIO2060 Exam 3 - Viral Replication

Nucleocaspid

core of a virus, containing the genome and associated proteins

Virion

complete, infectious viral particle

Viral Envelope

lipid bilayer derived from the host cell membrane

Host specificity

only infect certain types of cells

Viral Attachment Protein

protein on the viral surface that binds to a specific host receptor

Host Receptor

molecule on the host cell surface that interacts with the viral attachment protein

Receptor Function

Host receptors often play crucial roles in cellular functions, making them targets for viral attachment

Strain Specificity

Some viruses can only infect specific strains within a species

Viral Entry

virus crossing the plasma membrane

Uncoating

removing the viral capsid to release the genome into the cell

Entry for Enveloped Viruses

Membrane fusion, where the viral envelope fuses with the host cell membrane

Entry for Non-Enveloped Viruses

Endocytosis, where the virus is engulfed by the host cell membrane

Entry for Bacteriophages

Injection of the genome through a pore in the bacterial cell wall

Entry for Plant Viruses

Entry through damaged cell walls or connections between cells

Genome Replication

process of making new copies of the viral genome

Protein Synthesis

production of viral proteins using the host cell's machinery

dsDNA Viruses

using the host cell's DNA polymerase

ssDNA Viruses

involves a dsDNA intermediate, which serves as a template for replication

dsRNA Viruses

requiring a viral RNA-dependent RNA polymerase (RdRP)

ssRNA (+) Viruses

functions directly as mRNA

ssRNA (-) Viruses

viral RdRP produces mRNA from the genome

ssRNA + RT Viruses

Reverse transcriptase (RT) converts the RNA genome to dsDNA

dsDNA + RT Viruses

mRNA is transcribed from the viral dsDNA template, and RT generates genomic DNA from an RNA intermediate

Assembly

process of assembling new viral particles from newly synthesized

Egress

release of new viral particles from the host cell

Assembly: Nucleocapsid Formation

genome is packaged into a capsid, often guided by specific proteins

Assembly: Envelope Acquisition (Enveloped Viruses)

nucleocapsid buds out of the host cell, acquiring a lipid bilayer and spike proteins from the host cell membrane

Egress: Enveloped

Budding, where the virus exits the host cell by wrapping itself in a portion of the host cell membrane

Egress: Non-Enveloped

Lysis, where the virus causes the host cell to burst, releasing new viral particles

Egress: Bacteriophage

Lysis of the bacterial cell wall, often facilitated by the enzyme lysozyme

Egress: Plant

Spread through damaged cell walls or connections between cell

Positive-sense RNA Viruses

genome functions directly as mRNA

Negative-sense RNA Viruses

genome is complementary to mRNA, requiring a viral RdRP to produce mRNA

ssRNA + RT Viruses (Retroviruses)

RNA genome is converted to dsDNA by RT

Bacteriophages

Can have lytic or lysogenic cycles

Fuzeon

Blocks viral entry by inhibiting membrane fusion

AZT

nucleoside analog that inhibits reverse transcription in HIV

Acyclovir

nucleoside analog that inhibits viral DNA replication in Herpes simplex virus (HSV)

Tamiflu

neuraminidase (NA) inhibitor that prevents the release of new influenza virus particles from infected cells