Introduction to virology is about viral taxonomy, morphology, sensitivity and parts.

1. VETERINARY VIROLOGY
INTRODUCTION

2. • A virus is an obligate intracellular parasite containing genetic material
surrounded by protein
• Virus particles can only be observed by an electron microscope

5. Importance of Virology in Veterinary
Medicine
• Viruses causes diseases in animals of economic and welfare
importance.
• Diagnose viral disease (clinical/lab tests)
• Advise clients control (risk to other animals)
• Animal viruses may pose risk to human health (zoonosis)
• Can act as important models for human disease

6. Treatment of Viral disease
• Husbandry – Fluids, comfort
• Antibiotics – to prevent secondary bacterial infection
• Antiviral drugs (interferons/virus specific inhibitors)
• Immune System modulators
• Post exposure vaccination (e.g. rabies)

7. Control of Viral disease
• Vaccination
• Hygiene and Sanitation – good management
• Isolation/Quarantine
• Eradication of reservoir/vector and possibly virus
• Legislation – movement, exportation (+products)
• Disease Surveillance – Clinical and Laboratory diagnosis

8. Virus Classification
• Who decides the Virus classification
• Taxonomy of Viruses
• What are the things to consider when classifying viruses?
• Chemical characteristics
• Genome
• Replication strategy
• Diseases
• Vectors
• Geographical distribution
• Host species
• Nucleotide sequence

9. Taxonomy
• Order
• Virales
- Mononegavirales
• Family
• Viridae
- Paramyxxoviridae
- Herpesviridae
• Subfamily
• Virinae
- Paramyxovirinae
- Alphaherpesvirinae
• Genus
• Virus
- Morbilivirus
- Varicellovirus
• Species/strain/type
• Virus
- Canine distemper virus
- Equid herpesvirus 1

10. DNA Viruses

11. RNA Viruses

12. Basics of Virology
• What are viruses?
• How do viruses replicate?
• What effects do viruses have?
• How do viruses change?
• What are the consequences of change?

13. What are Viruses
• Submicroscopic particles
• Nucleic acid contained within a protective protein coat
• Infect bacteria, plants, animals and humans
• Differences from bacteria
• Viruses Cannot replicate without a cellular environment
• Viruses ARE NOT affected by antibiotics

14. Virion Structure
• Virion means a complete,
fully developed, infectious
viral particle.
• Nucleocapsid
• Genome
• Capsid
• Envelope
• Envelope Glycoproteins

15. VIRAL Nucleic Acids
• DNA or RNA
• SS or DS (Single Stranded of Double Stranded)
• SS Negative or SS Postive sence (mRNA = +sense)
• Linear or Circular
• Segmented/Non Segmented
• Genetic heritage
• Codes for Virus proteins
• Controls virus protein production
• Promoters, transcriptional enhancers, splice signals
• Contains elements necessary for replication and genome packaging

17. Viral Proteins
• Structural
• Components of capsid (protective coat) and other components of the virion.
• Non-Structural
• Required for viral replication and interaction with host

18. Nucleocapsid
• Capsid is a protein coat that protects the nucleic acid from:
• Physical, chemical, enzymatic attack
• Nucleocapsid comprises the capsid and enclosed nucleic acid
• Facilitates entry into the cell and delivery of the nucleic acid
• Exposed to immune system

19. Shapes and Sizes
• Viruses come in a variety of shapes and sizes dictated by their protein
and nucleic acid composition
• But there are common elements in their structure due to symmetry.

21. Examples

23. Virus Envelope
• Envelopes are Lipid Bilayers acquired from cellular membranes.
• Examples: endoplasmic reticulum, nuclear membrane and plasma membrane.
• Viral proteins are associated with insertion into membrane – Surface
proteins often glycosylated
• Adsorption and entry of virus into cells (and Exit)
• Access to target cells
• Binding to receptors
• Fusion of envelope with cellular membranes to release genome
• Interaction with immune system components
• Binding of antibody
• Targets of immune system

24. Complex Virus Structures
• Most animal viruses fall into three structural classes.
• Helical capsid (enveloped)
• Icosahedral capsid (non-enveloped)
• Icosahedral enveloped
• And there are more complex structures exist example: Pox Virus

25. Stability of Viruses
• Non enveloped viruses more hardy than enveloped viruses
(e.g. foot and mouth disease hardier than influenza virus)
• Different viruses have differential ability to survive
• sensitive to temperature, pH, desiccation, lipid solvents,
detergents
• Most inactivated at 55-60 Celsius
• Detergents used to disrupt viral envelopes
• Rotavirus survives pH of stomach