Pathogenesis (3) Flashcards
T/F: Infection is synonymous with disease
FALSE - is NOT
What is pathogenicity?
ability of the virus to cause disease
What is virulence?
relative measure of pathogenicity of the infecting virus
- one strain could be worse than another
What is a strain?
a well-characterized virus
What is an isolate?
the virus recovered from a specific host or location
What is a serotype?
subgroup of viruses that share antigens recognized by antibodies of the immune system
Give two ways you can be exposed to a virus (more than 2, just list 2)
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
The entry of a virus into the cell is dependent on an appropriate _______
cell receptor
What are some things viruses cause once infecting a host?
disease
acute clinical disease
subclinical disease
induction of cancer
induction of chronic progressive disease
All viruses are _______
obligate intracellular pathogens (cannot live outside host cell)
What is the first step in virus infection?
virus binds to receptors on cells = ADSORPTION
______, number, and ______ of host cell receptors determine the host range and the ______ of the virus
Nature
distribution
tissue tropism
After adsorption, the bound vision is taken into the cell through _____ or _______
endocytosis or
fusion to the plasma membrane
After endocytosis, the _____ is dismantled so that its _____ is released into the cytoplasm, which is a process called _______
capsid
nucleic acid
uncoating
What are the 4 major steps in virus infection?
adsorption
endocytosis
uncoating
replication
What are some host factors influencing pathogenesis?
genetic
age
hormonal influence
healthy living conditions
concurrent or mixed infections
exposure to vectors
immunity
What is tropism?
spread to SECONDARY site where its choice (target) cell is
some viruses have evolved to preferentially target certain cell types, tissues, or hosts
Rabies virus is _______
neurotropic (tending to attack the nervous system)
Malignant catarrhal fever targets the ______ system, and bovine virus diarrhea targets the ______
vascular system
lymphoid tissues
What are the types of tropism regarding preferred cells?
cellular tropism
host tropism
tissue tropism
What is neurotropic? It replicates at the [primary/secondary] site. What also occurs?
direct inoculation
replicates at primary site then spreads to secondary site where its target cell is
Systemic disease also occurs and sheds in secretions
What is epithelial tropic? It replicates at the [primary/secondary] site. What also occurs?
direct inoculation
replicate at primary site then spreads to secondary site where its choice cell is
Systemic disease usually occurs and sheds in secretions
What are other types of tropism?
gastrointestinal tract tropism (enteric viruses)
respiratory tract - maybe?
immune system cells - retroviruses - maybe?
lymphoid tissues
What are the two principal types of infection?
localized
systemic
What is a localized infection?
limited to the site of entry to the virus
- cattle warts
local spread and local inflammatory response
What is a systemic infection?
spread to various organ systems depending on viral tropism
- canine distemper
T/F: Rhinovirus is an example of a localized infection
TRUE
Systemic infections are caused by _______
viremia
When can systemic disease follow when a virus enters the bloodstream?
if the basement membrane is disrupted
What are some of the variations on the theme of localized and systemic infection?
inapparent infections
immunopathologic disease
congenital infections
persistent and latent infection
slow virus infections
oncogenicity
Slow virus infections occur where the incubation period is _______
prolonged
What is a congenital infection?
viral infection during pregnancy
can be infection in utero, during birth, congenital defects, fetal death
In congenital infections, the virus is usually transferred to the fetus during the _____ phase of the dam
viremic
What are peristent infections?
following a short incubation period with clinical recovery
usually result in serious disease and death
What are latent infections?
a persistent infection in which the latent virus is activated intermittently, resulting in a rapid viral replication and recurrent manifestation of disease
- herpes virus remain latent then reactivated by stress
- does not ever clear the infection
What are inapparent infections associated with?
infection of a reservoir species/host
low infectious dose
infection with virus of low virulence
host resistant
Which type of variation is epidemiologically important? (serve as an unrecognized source for the spread of viruses)
inapparent infections
What is an example of an oncogenic virus infection?
feline leukemia virus
feline sarcoma virus
murine leukemia and sarcoma viruses
avian reticuloendotheliosis virus
What are the DNA tumor viruses?
papovirus (warts)
hepadnavirus
herpesvirus
adenovirus
poxvirus
What are RNA tumor viruses?
retroviruses (oncovirinae)
COVID is a [systemic/localized] disease
systemic
Pathogenic viruses have different ______
virulences
Viruses have different sites of replication relative to _______, the preferred cells and tissue
tropism
Virus excretion occurs only at the site in [systemic/localized] infections, but may excrete from many organs in [systemic/localized]
localized
systemic
_______ is characteristic of some disease. The characteristics of the infection are related to virus transmission and perpetuation
Immunopathology
Herpesvirus moves [towards/away] the CNS
away
