The IgG VmpE test measures antibodies against Variable Major Protein E (VmpE), a surface protein produced by Borrelia burgdorferi, the bacterium that causes Lyme disease. VmpE belongs to a family of variable major proteins (Vmps) that the bacteria can change through a process called antigenic variation. This ability allows Borrelia to evade immune detection and sometimes persist in the body.
What IgG VmpE Means
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IgG antibodies generally appear weeks after infection and remain detectable long-term as part of immune memory.
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A positive IgG VmpE result suggests past or ongoing immune recognition of Borrelia. Because VmpE changes its structure to avoid the immune system, IgG reactivity may reflect exposure during persistent or relapsing stages of infection.
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This test complements other Borrelia markers (such as OspC and VlsE) by giving additional insight into how the immune system responds to Borrelia’s evasion strategies.
Clinical Importance
Testing for IgG VmpE may be useful in patients with:
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Chronic or relapsing Lyme symptoms, such as fatigue, joint pain, or neurological issues
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Suspected persistent infection, where Borrelia may continue to vary its surface proteins
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Unexplained immune activity after a history of tick exposure in endemic areas
Patient Takeaway
A positive IgG VmpE result means your immune system has previously recognized this variable Borrelia protein. This points to prior or ongoing exposure, but IgG antibodies alone cannot confirm an active infection, since they may persist long after the illness.
Your healthcare provider will interpret the result together with your symptoms, medical history, and other Lyme disease markers.
If the IgG VmpE result is equivocal (borderline), antibody levels are close to the cutoff and not clearly positive or negative. In this case, repeat or confirmatory testing is usually recommended.
IgG Variable Major Pro. E
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