Host-Pathogen Interaction – Virulence and Pathogenicity
The host-pathogen interaction is defined as how microbes or viruses sustain themselves within host organisms on a molecular, cellular, organismal or population level. This term is most commonly used to refer to disease-causing microorganisms although they may not cause illness in all hosts. Microbes were thought to be primary aggressors that governed the host-pathogen interaction, resulting in disease. Host damage was the most relevant outcome of the host-pathogen interaction. Virulence is one of a number of possible outcomes of host-microbe interaction. As such, microbial virulence is dependent on host factors, as exemplified by the pathogenicity of avirulent microbes in immunocompromised hosts and the lack of pathogenicity of virulent pathogens in immune hosts. Although pathogens do have the capability to cause disease, they do not always do so. This is described as context-dependent pathogenicity.