Borrelia Afzelii OspC
Description
Introduction to Borrelia afzelii OspC
Borrelia afzelii OspC (Outer Surface Protein C) is a 22-kDa surface-exposed lipoprotein critical for the transmission and virulence of Borrelia afzelii, a causative agent of Lyme borreliosis in Europe and Asia . This protein is encoded by the ospC gene, which exhibits high genetic diversity across Borrelia species and strains, contributing to adaptive strategies during host infection . OspC is transiently expressed during tick feeding and early mammalian infection, enabling spirochetes to evade innate immunity and establish disseminated infections .
Key Features:
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High Variability: ospC sequences are classified into distinct groups (e.g., A1–A8 for B. afzelii) based on nucleotide divergence (<2% within groups, >8% between groups) .
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Host Adaptation: Specific ospC genotypes are linked to host tropism. For example, ospC group A1 is associated with human acrodermatitis chronica atrophicans (ACA), while A5 and A6 are linked to bloodstream dissemination .
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Co-Feeding Dynamics: Co-infection with multiple ospC genotypes in ticks is common, with co-feeding larvae and nymphs enhancing strain diversity in nature .
Table 1: Clinically Relevant ospC Groups in B. afzelii
| ospC Group | Clinical Manifestation | Host Association |
|---|---|---|
| A1 | ACA, Neuroborreliosis | Humans, Rodents |
| A3/A4 | ACA | Rodents |
| A5/A6 | Disseminated Infection | Blood, CSF |
| A7/A8 | Skin Lesions | Rodents |
| Data compiled from . |
Immune Evasion and Transmission:
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Complement Inhibition: OspC binds complement component C4b, blocking the classical and lectin pathways to resist serum killing .
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Tick-to-Host Transmission: OspC expression peaks in nymphal ticks during feeding (48–72 hours), correlating with spirochete migration to salivary glands and mammalian infectivity .
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Strain-Specific Efficiency: Strains with higher nymphal spirochete loads (e.g., ospC type A3) exhibit 1.5× higher transmission rates than low-load strains (e.g., ospC type A10) .
Table 2: Nymph-to-Host Transmission (NHT) Efficiency by ospC Type
| ospC Type | Spirochete Load (Mean) | NHT Success Rate |
|---|---|---|
| A3 (Fin-Jyv-A3) | 1.9× higher | 79% |
| A10 (NE4049) | Baseline | 53% |
| Data from . |
Recombinant OspC Production:
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Expression Systems: B. afzelii OspC is recombinantly produced in E. coli as a 22,151-Da polypeptide with a 10xHis tag for purification .
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Diagnostic Use: OspC-enriched antigen preparations are used in ELISA to detect anti-Borrelia antibodies, with sensitivity validated across IgG/IgM panels .
Vaccine Development Challenges:
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Antigenic Variation: Limited cross-protection between OspC classes (e.g., A, B, M) due to sequence heterogeneity complicates broad-spectrum vaccine design .
Evolutionary and Ecological Insights
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Host Specialization: ospC allele U is exclusive to chipmunks (Tamias striatus), suggesting niche adaptation and competitive exclusion of other alleles in mixed infections .
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Priority Effects: The first ospC allele infecting a host often dominates, reducing co-infection likelihood due to antibody-mediated or resource competition .
Product Specs
Product Science Overview
Borrelia afzelii is one of the primary causative agents of Lyme disease in Europe. This bacterium belongs to the Borrelia burgdorferi sensu lato complex, which includes several species responsible for Lyme disease. One of the critical factors in the pathogenicity of Borrelia afzelii is the expression of outer surface proteins (Osp), particularly Outer Surface Protein C (OspC).
OspC is a major surface lipoprotein produced by Borrelia species during the early stages of infection. It plays a crucial role in the bacterium’s ability to establish infection in the host. OspC is highly variable among different Borrelia strains, which helps the bacteria evade the host’s immune system .
OspC is upregulated in response to a blood meal taken by the tick vector, facilitating the transmission of Borrelia from the tick to the mammalian host . Once inside the host, OspC helps the bacteria evade the immune system by binding to human fibrinogen and other blood components . This interaction is essential for the bacteria’s survival and dissemination within the host.
Recombinant OspC refers to the protein produced through recombinant DNA technology, typically in a bacterial expression system like E. coli. This recombinant protein is used in various research and diagnostic applications. For instance, it can be used to study the protein’s structure and function, develop diagnostic tests for Lyme disease, and potentially create vaccines .
- Research: Recombinant OspC is used to study the molecular mechanisms of Borrelia infection. By understanding how OspC interacts with host proteins, researchers can develop strategies to block these interactions and prevent infection.
- Diagnostics: OspC is a target for serological tests used to diagnose Lyme disease. Recombinant OspC can be used to produce antigens for these tests, improving their sensitivity and specificity .
- Vaccine Development: There is ongoing research into developing vaccines against Lyme disease. Recombinant OspC is a potential candidate for such vaccines, as it is a key antigen involved in the early stages of infection .
