Relationship between infectivity and OspC expression in Lyme disease Borrelia

Area of Science:

• Microbiology
• Infectious Diseases
• Immunology

Background:

• Borrelia burgdorferi is the causative agent of Lyme disease.
• Outer surface protein C (OspC) is a key virulence factor in Borrelia species.
• In vitro culture conditions can alter bacterial gene expression and virulence.

Purpose of the Study:

• To investigate the effect of in vitro serial subculturing on OspC expression in Borrelia burgdorferi.
• To determine the relationship between OspC expression and the infectivity of Borrelia burgdorferi in a mouse model.

Main Methods:

• Serial subculturing of Borrelia burgdorferi sensu stricto strain 297 and B. garinii strains HP1 and 12-92 for 36-50 passages in vitro.
• Analysis of OspC expression using SDS-PAGE and Western blotting.
• Inoculation of outbred ddY mice with low- and high-passage strains to assess infectivity.
• Isolation and characterization of Borrelia from infected mice.

Main Results:

• Low-passage Borrelia strains exhibited abundant OspC expression, while high-passage strains showed reduced or lost OspC expression.
• Low-passage strains were highly infectious in mice, whereas high-passage strains had low infectivity.
• Borrelia isolates from infected mice regained significant OspC expression, irrespective of the initial passage level.

Conclusions:

• OspC expression is significantly reduced during prolonged in vitro cultivation of Borrelia burgdorferi.
• Reduced OspC expression correlates with decreased infectivity of Borrelia burgdorferi in a murine model.
• OspC expression is regained in vivo, highlighting its critical role in establishing Borrelia infection.