Pathogenesis of viral infections Flashcards
viral pathogenesis
concerned with the method by which viruses produce disease
pathogenecity
the ability of an organism to cause disease by overcoming the defenses of a host
virulence
the capacity of a microorganism, compared to other closely related microbes, to produce disease in the infected host
susceptible cells
virus infected cells whose infection may not be sufficient to cause clinically demonstrable disease
target cells
virus infected cells whose infection usually contributes to clinically demonstrable disease
clinical signs
any objective evidence or manifestation of an illness
clinical symptoms
any subjective evidence of disease
what are the three common portals of exit
- respiratory
- gastrointestinal
- urogenital
viremia
the presence of virus in the bloodstream
passive viremia
direct inoculation of virus into the bloodstream via the bit of an arthopod vector, through iatrogenic inoculation with a contaminated needle, or by the transfusion of contaminated blood products
primary viremia (active)
the release of progeny virons from the site of initial viral replication
secondary viremia
the release of virus from localized area of secondary viral multiplication into the bloodstream, which can lead to infection in other parts of the body
free in the plasma virus
usually short duration, with clearance of viruses coinciding with the appearance of neutralizing antibodies in the circulation
cell-associated viruses
they are not often cleared by antibodies and therefore tend to cause prolonged viremias
viruses breach the blood-tissue junction by:
- infecting endothelial cells
- passive transport across the vessel wall by leukocytes
- transcytosis
transcytosis
transport of virons in intracellular vesicles across the vessel wall and release of virons by exocytosis
localized
the lesions and multiplication are confined to portal of entry
generalized
- begin localized but do not stay there
- multiple organ systems involved
rash
a temporary skin eruption or viral exanthem
macule
virus replication in the dermis leads to a flat reddened lesion produced by a lasting local dilation of dermal blood vessels
papule
a raised macule due to localized edema and cellular infiltrates
vesicle
virus replication spreads from the dermis to the epidermis, resulting in a small circumscribed epidermal elevation that contains a clear fluid
pustule
a vesicle with copious neutrophil infiltration
neuronophagia
phagocytosis of neurons by glial cells
von Willebrand factor
is an adhesive glycoprotein synthesized in megakaryocytes and endothelial cells that circulates in blood complexed to factor 8
infertility
early death of fertilized ova, embryos, or fetus, followed by resorption or unseen expulsion
abortion
indicative of severe damage to the fetus or its placental membranes or both
teratogenesis
the abnormal development or arrests in development of the embryo or fetus
inapparent infection
one that does not cause a noticeable illness
chronic inflammation
can result in extensive tissue damage, fibrosis, and loss of organ or tissue function
