The Leeuwenhoek Lecture, 1991. The influence of the host on microbes that cause disease

Area of Science:

• Microbiology
• Pathogenesis
• Host-Pathogen Interactions

Background:

• Microbial pathogenicity, or virulence, is the capacity to cause disease.
• Virulence depends on microbial gene products that facilitate infection, multiplication, and host defense interference.
• Microbial gene product formation is influenced by the host's in vivo environment, which differs from laboratory cultures.

Purpose of the Study:

• To highlight the increasing importance of studying microorganisms grown in vivo.
• To emphasize the need to dissect complex in vivo conditions to understand specific host factor influences on virulence determinant production.
• To identify specific host factors responsible for producing identified virulence determinants.

Main Methods:

• Review of studies investigating microbial growth and virulence factor production in vivo.
• Analysis of specific host-derived factors influencing microbial virulence, including iron limitation, erythritol, and CMP-NANA.
• Examination of how these factors impact microbial survival and pathogenicity.

Main Results:

• Iron limitation in vivo induces bacterial siderophores, outer membrane receptors, and toxins.
• Erythritol acts as a growth stimulant for brucellae, leading to placentitis and abortion in livestock.
• CMP-NANA modifies gonococcal lipopolysaccharide (LPS), conferring resistance to complement-mediated killing.

Conclusions:

• Specific host factors significantly influence microbial virulence determinant production.
• Understanding these host-pathogen interactions is crucial for controlling infectious diseases.
• The principles discussed apply to bacterial, viral, and fungal pathogenicity.