Therapeutics ID Santanello Flashcard

Properties of Viruses not seen in Cells

  • Acellular
  • Viruses cannot metabolize on their own
  • Don’t divide or grow
  • Contain DNA or RNA
  • Proteinaceous capsid around genome
  • 10 nm to 300 nm

Characteristics of Viruses

  • Extracellular State: Virion — infective
  • Intracellular State: Virus
  • Consists of protein coat (capsid) that is made of protein subunits (capsomeres)
  • The nucleic acid and capsid together are called nucleocapsid

How are viruses spread?

  • Oral-Fecal (rotavirus, hepatitis A)
  • Airborne (influenza, orthomyxovirus)
  • Sexual (HIV, HPV, HSV)
  • Direct Inoculation (hepatitis B, west nile virus)
  • Congenital (CMV)

Picornaviridae

Cold

Hep A

Togaviridae

Rubella

Encephalitis

 

Flavaviridae

Yellow Fever

Hepatitis

Coronaviridae

Cold

SARS

Retroviridae
HIV
Paramyxoviridae

Cold

Measles

Mumps

Orthomyxoviridae
Influenza
Rhabdoviridae
Rabies
Poxviridae

Small pox

 

Papillomaviridae

Warts

Cervical Cancer

Hepadnaviridae
Hep B
Adenoviridae

Upper Respiratory Infections

Conjunctivitis

Herpesviridae

Mononucleosis

Chicken pox

Fever blisters

Cytomegalovirus

Genital herpes

5 Different Stages of Viral Replication

  1. Attachment of the virion to the host cell
  2. Entry of the virion or its genome into the host cell
  3. Synthesis of new nucleic acids and viral proteins by the host’s enzymes, ribosomes
  4. Assembly of new viruses within the host cell
  5. Release of new virions from the host cell

Advantages of Prescription Bacteriophages over Antibiotics

  • No resistance development
  • Less C. difficile
  • Selective for bacteria
  • No deleterious effects

Replication of Animal Viruses: Similarities/Differences with Bacteriophages

1.  Attachment: animal viruses lack tails and tail fibers — has glycoprotein spikes or other attachment molecules
2.  Entry

  • Direct Penetration
  • Membrane fusion
  • Phagocytosis

3.  Release

  • Enveloped viruses often released via budding which allows infected cells to remain intact
  • Naked viruses extruded by exocytosis or causes lysis and cell death

 

Interferon’s Role as an Antiviral

  • Most nucleated cells make IFN-β and IFN-α
  • They bind to specific receptors on adjacent cells to protect them from viral infection
  • They enhance expression of MHC Class I (Cytotoxic T-Cells) and Class II (T-Helper Cells) molecules, which then increases viral antigen presentation to specific T-cells
  • Cells develop an antiviral state — replication of virus is inhibited
  • Restrict growth at: penetration, uncoating, synthesis of mRNA, protein synthesis and assembly

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