The 41 kDa protein shares epitopes with other microorganisms but is the first protein to appear in Lyme disease. It is important to know the background antibodies of the patient population when performing Western immunoblots. Cooke and Bartenhagen 16 found antibody to at least one protein of B. burgdorferi in more than 40 percent of patients who did not have Lyme disease. The authors suggested that the high frequency could be caused by antibodies to organisms that possess cross-reactive proteins. A convalescent sample should be obtained two to four weeks after the initial sample was obtained to confirm a suspected case of early Lyme disease in the absence of IgM. Only an IgG Western immunoblot is recommended for use beyond the first four weeks of disease, while IgM and IgG immunoblots are recommended for serodiagnosis of suspected cases within the first four weeks of disease onset.
Patients develop an IgG antibody response about four weeks after infection.
The level of IgG antibodies will rise during the next few weeks of infection and may persist at detectable levels for several years. Most test methods will produce a positive test result during the chronic stage of disease if the patient has developed a detectable IgG response. It is important to analyze any IgG response to B. burgdorferi for specific proteins and correlate it with clinical findings. The antigenic strain of B. burgdorferi also can have a significant effect on laboratorians ability to detect antibody to this pathogen. Strains that work well for detecting antibody to B. burgdorferi include 2591, low passage 297 and low passage B31.