Treponemal IgG and IgM response in experimentally infected chimpanzees.

The pattern of immunological responses at various stages of syphilis.

“…A possibly similar effect was seen by Duncan and Kuhn (1974) in experimentally infected chimpanzees where the production of anti-treponemal IgM antibodies ceased spontaneously in 10 out of 24 untreated animals.…”

The Immunology of Syphilis

“…Recent studies have shown that VDRL reactivity develops in chimpanzees which are infected experimentally with either 7. pallidum or 7. cun;-CU//. 26 Fluorescent treponemal antibody (FTA), especially when present following absorption with 7. reiter (FTA-ABS), is highly specific for infection with 7. pallidum.-^' 2« Both IgG and IgM have been shown to participate.2' 2fi. so ^ jj interesting to note that rheumatoid arthritis and systemic lupus erythematosus, which also cause falsely positive VDRL results, are occasionally associated with a false-positive FTA-ABS.-" -' -' The reaction produced by serum from patients with lupus is said to be distinguishable microscopically from that due to syphilis;-^' it may result from leakage of nuclear material from the treponeme during processing.-'2 FTA-ABS are detectable in nearly all syphilitic patients, except those whose primary chancre is in its earliest stages.^''^ ^^ Once present, these antibodies probably persist for life, although one recent study"" suggests that this may not be the case.…”