what is a virulence factor
Virulence factors are molecules produced by pathogens (bacteria, viruses, fungi and protozoa) that contribute to the pathogenicity of the organism and enable them to achieve the following: 1  colonization of a niche in the host (this includes attachment to cells).2  immunoevasion, evasion of the host's immune response.hese obtained bacterial virulence factors have two different routes used to help them survive and grow: 1  The factors are used to assist and promote colonization of the host. 2  The factors, including toxins, hemolysins, and proteases, bring damage to the host.