Virus Cryptopathology and Culturing

Damage to Host Cell

Cytopathic Effects (CPEs)

• Virus Induced damage that alters appearance of Cell

• Cell become Disoriented, Change Shape / Size, Intracell Damage

• Inclusion Bodies → Compacted Masses of Viruses Damaged Cell Organelles in Nucleus or Cytoplasm

• Syncytia → Fusion of Multiple Host Cells → Multiple Nuclei

Cytopathic Changes From Virus

None → Single Layer

Poliovirus → Killed Completely

Adenovirus → Cells Clump

Respiratory Syncytial Virus → Cells Fuse with Multiple Nuclei

Rabies Virus → Inclusion Bodies

Teratogenic Viruses

Viruses that cause Defects during Embryonic Development

Persistent Infections

Carrier Relationship in some Cells

• Cell Harbors Viruses and isn’t Instantly Lysed

  • Latent in Cytoplasm OR

  • Viral DNA into Host DNA

    • Provirus

• Chronic Latent State → Periodic Reactivation

Chicken Pox and Shingles

Varicella-Zoster Virus (Herpes Viridae)

Viruses and Cancer

Oncogenes → Regular Cell Growth → If Altered becomes Cancerous

Oncogenic Viruses → Induce Tumors

Viral DNA into Host Cell DNA

Transformation

DNA Oncoviruses

• Herpesviridae → Epstein-Barr Virus

• Papovaviridae → Papillomavirus → Warts

• Hepadnaviridae → Hetatitis B Virus
  
  

RNA Oncoviruses

• Retroviridae → Human T-cell Leukemia Virus

Virus and Cancer Transformation

Transformation

• Virus carries Genes that Cause Cancer

• Virus Produce Proteins → Loss of Growth Regulation in Cell

Growing Bacteriophages in Lab

Plaque Method → Solid Media

• Bacteriophage + Host Phage + Liquid Agar in Petri Dish

• Few Cycles of Infection → Bacteria is Destroyed

• Clear Area → Plaque

• Each Plaque = 1 Virus

• Concentration in Plaque Forming Units

Techniques in Cultivating and Identifying Animal Viruses

In Vivo Methods → Viral Cultivation in Animal Tissue

In Vitro Methods → Viral Cultivation in Cell or Tissue Culture

Primary Purpose of Cultivation

• Isolate and Identify Viruses

• Prep Virus for Vaccine

• Research

Using Live Animal Inoculation

Specific Bred Strains of Animals for Cultivating Viruses

• White Mice

• Rats

• Hamsters

• Guinea Pigs

• Rabbits

Injection Sites

• Brain

• Blood

• Muscle

• Body Cavity

• Skin

• Footpads

Using Bird Embryos

Benefits

• Embryonic Development occurs in Protective Shell

• Intact and Self-Supporting Unit with own Sterile Environment and Nourishment

Cell Culture Techniques

Cell Culture or Tissue Culture → In Vitro Virus Cultivation System

• Grow Populations of Isolated Animal Cells

• Most Viruses are Propagated through Cell Culture

Virus and Human Health

Impossible to Measure Worldwide

Most Common cause of Acute Infections that don’t lead to Hospital

• Colds, Chickenpox, Influenza, Herpes, Wars

Some have High Death Rates

• Rabies, Ebola

Other lead to Long-Term Debility

• Polio, Neonatal, Rubella

Designing Therapies against Viruses

Viruses Mutate at Rapid Rates

Difficult to design Therapies

• They Replicate inside Human Cells

Scientists Focus on Vaccines

Interferons

• Natural Human Cell Product

• Somewhat Successful in Preventing Infection

Prions

Infectious Protein

Neurological Disorder → Spongiform Encephalopathies

• Large Vacuoles in Brain

• Mad Cow Disease (Bovine Spongiform / BSE)

• Sheep and Goat Scrapie

• Kuru → Cannibals

• Creutzfeldt - Jakob Disease → Genetic

From Contaminated Meat, Surgical Instruments, Transplants

May have Implications in Alzheimer’s and Parkinson’s

Pathogenesis of Prions

Normal Gene for Protein

Abnormal Form of this Protein changes Structures of the Normal Protein

• Folds into New Shapes

Fragments Accumulate forming Plaques → Somehow kills Cells

Satellite Viruses

Dependent on other Viruses for Replication

Adeno-associated Virus (AAV)

• Thought it could only Replicated in Cells with Adenovirus

• Now found to Infect Cells infected with Other Viruses

Viroid

Single Piece of RNA

Smaller than Viral RNA

• 300 - 400 Nucleotides

• No Protein Coat

Does not Code for Protein

Cause PLANT Diseases

• Chrysanthemum Stunt

• Cucumber Pale Fruit Disease

• Potato Spindle Tuber

May have Evolved from Introns → Pieces of RNA

Pathogenesis