Lecture 4: Virology Flashcards
Virology
The study of viruses and viral diseases
Virologist
someone who studies viruses
3 reasons why vet virology is important
- Cause high rates of mortality and morbidity
- In animals and birds cause tremendous financial losses to livestock and poultry industries, which hampers the economic development of a country
- Zoonosis
Are viruses living?
Nope
Structure of viruses
- Contain nucleic acid genome (RNA or DNA) surrounded by a protein coat (capsid) and in some cases other layers of material such as a lipid envelope
- Do not possess standard cellular organelles
What do viruses need host cells for?
- Make energy and proteins
- To multiply
Viruses can be described as _____ ______ parasites
obligate intracellular
The process of viral replication resembles an
assembly line in which various parts of the virus come together from different parts of the host cell to form new virus particles
Capsid
- protein shell of the virus that encases/envelopes the viral nucleic acid or genome
- Made up of capsomeres held together by non-covalent bonds
Nucleocapsid
Capsid + virus nucleic acid/genome
The lipid envelope is usually
a lipid bilayer derived from the host cell
Glycoproteins
present on the surface of the envelope and often appear as spikes
Naked viruses
have only a protein capsid enclosing nucleic acid
Enveloped viruses
have an additional lipid layer enclosing the nucleic acid
Pleomorphism
The ability of some viruses to alter their shape or size
6 stages of virus replication
- Attachment
- Penetration
- Uncoating
- Synthesis of viral nucleic acid and protein
- Assembly and maturation
- Release in large numbers
Impacts of virus replication in host cell (4)
- Cell death
- Fusion of cells
- Transformation of cell to malignant one
- No apparent changes
International Committee on Taxonomy of Viruses Classification System
-Only body charged by the International Union of Microbiological Societies with the task of developing, refining, and maintaining a universal virus taxonomy
What three things are considered for the classification of viruses
- Nature of virus genome for classification of viruses
- Virus replication strategies
- Morphology
7 types of transmission
- Direct contact
- Indirect contact
- Common Vehicle
- Airborne transmission
- Vector-borne
- Zoonotic transmission
- Vertical transmission
Indirect contact
Contaminated inanimate objects (fomites)
Common vehicle
Fecal contamination of water or food
Vertical transmission
Infection that is transferred from mother/dam to embryo, fetus, or newborn before, during, or shortly after partrution
Three ways to diagnose viral diseases
Clinical signs
Necropsy
Histopathology
Serology
Detection of viral antigen or host antibody against virus
Three types of serology detection
- Elisa
- Fluorescent antibody staining
- Immunohistochemical staining
Detection of viral nucleic acid
- RT-PCR/PCR
- Quantitative PCR
- Virus genome sequencing
Three ways of treatment
- Anti-viral drugs
- Immune system stimulation
- Synthesize antibodies or administration of natural antiserum
Anti-viral 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 system stimulation
Interferons, class of proteins that has antiviral effects and modulate functions of the immune system
Three types of vaccinations
- Live-attenuated virus
- Non-replicating virus
- Vaccines produced by recombinant DNA and related technologies
4 ways to prevent/control viruses
- Vaccines
- Proper hygiene/sanitation
- Eliminating arthropod vectors
- Quarantine and Culling
