(1)Virology and Viral Hepatitis Notes

Basic building blocks of a virus

Viral Nucleic Acid (ssDNA, dsDNA, RNA), Protein Coat (Capsid), Envelope (in some viruses)

Benefits of virus particle structure

Protection of nucleic acid, Specificity in host cell interaction, Genome delivery

Basic steps in virus replication cycle

1. Attachment/Entry 2. Replication/Transcription 3. Virion Assembly 4. Virion Release

How a plaque assay works

Quantifies cytotoxic viruses by measuring plaque-forming units

pfu and MOI

Plaque forming units (pfu): Measure of infectious virus particles. Multiplicity of infection (moi): Average number of virus particles infecting each cell. Multiplicity \ of \ infection \ (moi) = \frac{Plaque \ forming \ units \ (pfu) \ of \ virus \ used \ for \ infection}{number \ of \ cells}

HBV and HDV relationship

HDV requires HBV for transmission and exacerbates HBV infections; HBV vaccine protects against HDV

Hepatitis viruses: vaccines and treatments

HAV: Vaccine available. HBV: Vaccine available, treatments available. HCV: Treatments available, no vaccine. HDV: HBV vaccine works on HDV, no specific antiviral treatment. HEV: No vaccine, no available treatment.

Hepat

HAV: Fecal-oral route. HBV: Bloodborne, perinatal. HCV: Intravenous drug use, transfusions, tattooing. HDV: Requires HBV for transmission. HEV: Fecal-oral route via contaminated water.

Genome

Genetic material of a virus

Virion Structure Advantages

Protect nucleic acid, specificity in host cell interaction, genome delivery.

Virus Replication Cycle Steps

Attachment/Entry, Replication/Transcription, Virion Assembly, Virion Release

Antibodies

Neutralize foreign objects (antigens). IgG (majority of response), IgM (early stages).

Antigens

Recognized by T cell receptors or antibodies. Proteins, polysaccharides, lipids, small molecules.

Passive Immunization

Antibodies transferred (no memory)

Active Immunization

Body responds to antigens (memory)

Plaque forming units (pfu)

Measure of infectious virus particles.

Multiplicity of infection (moi)

Average number of virus particles infecting each cell.

HAV

Fecal-oral route; mild, acute; vaccine available.

HBV

Parenteral; severe, 5-10% chronic; vaccine available.

HCV

Parenteral; subclinical, 70% chronic; no vaccine.

HDV

Parenteral; exacerbates HBV, chronic with HBV; HBV vaccine works.

HEV

Fecal-oral route; mild in normal patients, severe in pregnant women, acute; no vaccine.

HDV and HBV Relationship

Requires HBV for transmission; HBV vaccine protects against it.