Question

The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as

Answer 1

The answer is lethal dose 50 or LD50.

LD50 is a measure of a lethal dose of a substance that can be toxin, radioactive or pathogenic. The value of LD50 for that substance is the dose required to kill half of the animal population. For example, in a population of 100 rats, the dose necessary to kill 50 of them is the lethal dose.