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Flashcards in Virology- overview Deck (17):

Morphology of Viruses

Morphology of Viruses

Enveloped vs. naked viruses

  • enveloped= lipid layer enclosing nucleocapsid
  • naked= just nucleocapsid

Different shapes of viruses



Structure of Viruses

Viruses contain nucleic acid genome (DNA or RNA) surrounded by a protein coat (capsid) and, in some cases, other layers of material, such as a lipid envelope (a bubble of fat).

  • Capsid- protein shell that encases the nucleic acis/genome
  • Nucleocapsid = Capsid + Nucleic acid
  • Lipid envelope=outside of nucleocapsid
  • Glycoproteins= on surface of envelope



Chemical composition of Viruses

Chemical composition of Viruses


Replication of Viruses (5)

1.) Attachment


3.)Uncoating- removal of protein coat (release genetic material)

4.)Synth of viral nucleic acid (genetic material of virus hijacks synth)

5.)Assembly and Maturation-viral particles assembled and released



Epidemiology of viral infections

(7 modes of transmission)


  • Direct-Contact Transmission: Direct physical contact with infected/Susceptible Host
  • Indirect-Contact Transmission:Contaminated inanimate objects (Fomites)
  • Common-Vehicle Transmission: Fecal contamination of Water or Food and Virus contamination of Meat or Meat products
  • Airborne Transmission
  • Vector (Arthropod)-Borne Transmission
  • Zoonotic Transmission
  • Vertical Transmission- embryonic


Diagnosis of viral infections (7)

Diagnosis of viral infections

1.) Clinical signs- visible in physical exam ex.bluetongue virus in sheep

2.) Necropsy- post mortem investigation (internal signs)

3.) Histopathology- looking at tissue 

4.) isolation and cultivation- cultures

5.)Electron Microscopy- can see shape of virus

6.) Serology- detection of viral antigen or host antibody (ELISA)

7.)PCR- process that amplifies nucleic material of virus so it is ealily detected/identified



Treatment of viral infections (3)

Treatment of viruses

  • Antiviral drugs-Interfere with the ability of a virus to infiltrate a target cell or target different stages of replication/Synthesis of components required for replication of the Virus.
  • Immune stimulation-Interferons, class of proteins that has antiviral effects and modulate functions of the immune system.
  • Synthesize antibodies/administration of natural antibodies



Prevention of viral infections (4)

Prevention of viral infections

  • Vaccination
  • Proper Hygiene
    • disinfectants
  • Eliminating Arthropod Vectors
    • using biological or chemical methods
  • Quarantine & Culling
    • separate/restrict movement of animals


Zoonotic virus

Zoonotic viruses can be transmitted between animals and humans


Virus Facts

Virus facts

“A Virus is a Piece of Bad News Wrapped up in a Protein”

  • non-living entities
  • no cellular organelles
  • cannot make energy for itself
  • obligate intracellular parasite (depends on other cells to survive)
  • cannot multiply by division (use pieces and parts of host cell)



Effect of viral replication on host cells

Effect of viral replication on host cells

Cell death

fusion of cells

transformation to malignant cell




Types of Vaccines

Types of Vaccines

  • Live-Attenuated Virus Vaccines:
    • produced from other viruses
  • Non-Replicating Virus Vaccines
    • made from inactivated virons or viral proteins
  • Vaccines Produced by Recombinant DNA and Related Technologies
    • made from viral proteins or genetic matrial


in an enveloped virus, the lipid bilayer is kept under the capsid. 



lipid bilayer outside- helps facilitate entry into new cells


genetic material inside


Step after uncoating in viral replication...?

synthesis of viral DNA


Viruses can be cultured the same way as bacteria?



viruses have to have a living cell to replicate 


how do elisa test work?

elisa tests use antigens, antibodies and a marker to identify virus.


pathogenicity vs. virulence

pathogenicity= ability to cause disease (yes or no) (qualitative)

virulence= quantitative measure of disease