The IgG OspE test measures antibodies against Outer Surface Protein E (OspE) of Borrelia burgdorferi, one of the proteins that help the bacterium evade the immune system and persist in the body. OspE belongs to the Erp (OspE-related proteins) family, which plays a key role in protecting Borrelia from complement-mediated killing by binding to host factor H.
What IgG OspE Means
-
IgG antibodies against OspE typically develop weeks to months after infection and may remain detectable long after exposure.
-
A positive IgG OspE result indicates past immune recognition of Borrelia, which can support the diagnosis of later or persistent Lyme disease.
-
Because OspE helps Borrelia survive in the bloodstream, IgG detection may be especially relevant in patients with disseminated or chronic forms of infection.
Clinical Importance
Testing for IgG OspE may be most useful in patients with:
-
Persistent or late-stage Lyme symptoms such as arthritis, fatigue, or neurological complaints
-
Evidence of Borrelia dissemination, where immune evasion mechanisms are important
-
Chronic or relapsing illness following a history of tick exposure in endemic regions
-
Suspected co-infections, where broader immune profiling improves diagnostic accuracy
Patient Takeaway
A positive IgG OspE result suggests your immune system has previously recognized this Borrelia surface protein, pointing to past or ongoing exposure. However, IgG antibodies can remain in the body long after the initial infection, so the result does not confirm whether the infection is still active.
Your healthcare provider will interpret the result alongside your symptoms, clinical history, and additional Lyme disease markers (such as OspC, OspA, or VlsE/C6).
If your IgG OspE result is equivocal (borderline), antibody levels are near the cutoff and not clearly positive or negative. In such cases, repeat or confirmatory testing may be recommended.
IgG Outer Surface P. E
Every lab result you’ve ever had, charted and explained.
Healthmatters is a tracker for your lab results. Upload a report from any lab, any country — every marker charted and explained.
Start with my report →
All our content is backed by peer-reviewed studies, academic research, and trusted medical sources. We’re committed to accuracy and transparency — see our editorial policy for details.