Leptospirosis diagnosis by immunocapture polymerase chain reaction: a new tool for early diagnosis and epidemiologic surveillance

The aim of this study was to develop an immunocapture polymerase chain reaction (IC-PCR) protocol for leptospirosis. For the standardization of IC-PCR, polyclonal (AS) and monoclonal (MAb) antibodies against different serogroups and serovars of Leptospira were coupled to polystyrene plates. Human sera were artificially contaminated with leptospires and incubated on plates. The bacterial DNA was obtained and used in a multiplex PCR. Sensitivity was tested using sera contaminated with crescent concentrations of leptospires, while specificity was established using sera contaminated with different bacterial genera and sera obtained from patients positive for viral infections. IC-PCR using AS was able to recognize specific serogroups, although some cross-reactions have been observed. No cross-reactions were observed when MAbs were used; however, the sensitivity in this case was lower than that of IC-PCR using AS. IC-PCR proved to be specific to Leptospira and is a promising tool for early diagnosis of leptospirosis, providing additional information about the infecting serovar or serogroup.