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As a result, the minimum infective dose is exactly equal to one bacterial cell, deviating from the traditional notion of the MID. Proportionality has a second consequence: when the dose is divided by ten, the probability of observing the effect is also divided by ten. Additionally, it is a relationship without threshold.
The TCID 50 (50% tissue culture infectious dose) assay is the measure of infectious virus titer. This endpoint dilution assay quantifies the amount of virus required to kill 50% of infected hosts or to produce a cytopathic effect in 50% of inoculated tissue culture cells. This assay may be more common in clinical research applications where the ...
Viral load is often expressed as viral particles, (virions) or infectious particles per mL depending on the type of assay. A higher viral burden, titre, or viral load often correlates with the severity of an active viral infection. The quantity of virus per mL can be calculated by estimating the live amount of virus in an involved fluid.
Virulence can also be transferred using a plasmid. The noun virulence (Latin noun virulentia) derives from the adjective virulent, meaning disease severity. [5] The word virulent derives from the Latin word virulentus, meaning "a poisoned wound" or "full of poison". [5] [6] The term virulence does not only apply to viruses.
Bacteria, like plants, have strong cell walls that a virus must breach to infect the cell. Given that bacterial cell walls are much thinner than plant cell walls due to their much smaller size, some viruses have evolved mechanisms that inject their genome into the bacterial cell across the cell wall, while the viral capsid remains outside.
A viral infection does not always cause disease. A viral infection simply involves viral replication in the host, but disease is the damage caused by viral multiplication. [5] An individual who has a viral infection but does not display disease symptoms is known as a carrier. [17] Mechanisms by which viruses cause damage and disease to host cells
In epidemiology, infectivity is the ability of a pathogen to establish an infection. More specifically, infectivity is the extent to which the pathogen can enter, survive, and multiply in a host. It is measured by the ratio of the number of people who become infected to the total number exposed to the pathogen. [1]
Gram-negative bacteria secrete a variety of virulence factors at host–pathogen interface, via membrane vesicle trafficking as bacterial outer membrane vesicles for invasion, nutrition and other cell-cell communications. It has been found that many pathogens have converged on similar virulence factors to battle against eukaryotic host defenses ...