Define pathogenesis
the manner of development of a disease
Infection is or is not synonymous with disease?
is NOT
_________ is the ability of the virus to cause disease.
Pathogenicity
________ is a relative measure of the pathogenicity of the infecting virus.
Virulence
What is a ‘strain’?
well characterized virus
An _____ refers to the virus recovered from a specific host or location.
isolate
A ______ -sub-group of viruses that share antigens recognized by antibodies of the immune system; however, antibodies do not confer immunity a different type of sterotype.
serotype
The outcome of viral exposure/infection is influences by what things?
- method of transmission
- number of infecting particles (dose)
- virulence of infecting particles (genetics)
- speed of viral replication and spread
- degree of cellular damage
- effectiveness of host defenses
In a virus-infected host, it is the result of the cumulative effects of the virus infection at the cellular level. What is this the definition of?
disease
What are some effects of viruses on the host animal?
- direct damage to cells due to cell death/apoptosis ( paralysis and immune deficiency)
- disruption of normal cell functions
- immune responses to virus infected cells
- immune cell release of cytokines
- virus hijacking/expressing host genes
All viruses are ________ _________ pathogens.
obligate intracellular
What is adsorption?
virus binds to receptors on cells
Bound viron is taken into the cell through ______ or fusion to the plasma membrane
endocytosis
Capsid is dismantled so that its nucleic acid is releasing into the cytoplasm by a process called ________.
uncoating
Once the viral genome is uncoated, _______ begins.
replication
List the 7 host factors that influence pathogenesis.
1) Genetic- species, breed, organ/tissue, susceptibility, intracellular hospitality
2) Age- neonate vs. geriatric
3) Hormonal influence- pregnancy
4) Healthy living conditions- temp, crowding, nutrition, air flow, etc.
5) Concurrent or mixed infections
6) Exposure to vectors
7) Immunity (innate, passive, acquired)
List the steps of the viral infection process.
1) Entry into host and primary virus replication
2) Local or generated spread in the host, cell and tissue tropism, and secondary virus infection
3) Evasion of host inflammatory and immune defenses
4) Shedding from host
5) Cause damage to host
What is tropism?
Some viruses have evolved to preferentially target certain cell types, tissues, or hosts
What are some characteristics of neurotropic viruses?
- direct inoculation
- replication at the primary site
- Tromism- spread to secondary site where its choice cell is
- systemic disease usually occur
- shed in secretions
What are some characteristics of epithelial tropic viruses?
- direct inoculation
- replicate at primary site
- tropism
- systemic disease usually occurs
- shed in secretions
What are the two principal types of infection?
- localized virus: limited to the site of entry of the virus
- systemic: spread to various organ systems depending on viral tropism
What are some variations on the theme of localized and systemic infections?
- inapparent infections
- immunopathologic disease
- congenital infections
- persistent and latent infection
- slow virus infections occur where the incubation period is prolonged
- oncogenicity (cancer)
What are some examples of types of congenital infections?
- infections in utero
- infection during birth
- congenital defects
- fetal death
What are some characteristics of persistent infections?
- long incubation periods
- a protracted clinical course
- usually result in serious disease and death
