From the Research
Lipopolysaccharide (LPS) is the virulence feature best at evading complement. LPS forms the outer layer of the outer membrane in Gram-negative bacteria and provides significant protection against complement-mediated killing, as supported by a recent study in 2022 1. The structure of LPS, particularly the O-antigen component, creates a physical barrier that prevents complement proteins from accessing the bacterial cell membrane where they would form the membrane attack complex. Additionally, LPS can bind regulatory proteins that inhibit complement activation or accelerate the decay of complement components. Some bacteria modify their LPS structure to reduce binding of complement proteins or increase resistance to antimicrobial peptides generated during complement activation. This evasion mechanism is particularly important for pathogens that encounter complement in the bloodstream, allowing them to avoid destruction by this key component of innate immunity and establish successful infections.
Key points to consider:
- LPS is a major component of Gram-negative bacterial outer membranes and plays a crucial role in virulence and pathogenesis, as described in a study from 2012 2.
- The O-antigen component of LPS is involved in attachment to host cells and provides protection from complement-mediated killing, as noted in a study from 2013 3.
- Modifications of the LPS structure, such as changes in the O-antigen composition or the addition of capsular polysaccharides, can enhance complement resistance, as discussed in a study from 2000 4.
- The surface architecture of Gram-negative bacteria is profoundly affected by the activities of surface polymer:lipid A-core ligase and by molecular determinants of polymer chain length, which can impact virulence, as reviewed in a study from 1997 5.
Overall, the evidence suggests that LPS is the most effective virulence feature at evading complement, and its structure and modifications play a critical role in this process.