Cultivation of the Bacillus of Whipple's Disease

TLDR

Whipple’s disease is a systemic bacterial infection for which no isolate has yet been successfully subcultured, limiting laboratory study of the pathogen. The authors aim to enable serologic testing for Whipple’s disease by cultivating the bacterium. They isolated the organism from aortic valve tissue and propagated it in human HEL cells using a shell‑vial assay, established subcultures, generated polyclonal antibodies in mice, and deposited the strain in the French National Collection. The cultured bacterium elicited specific IgM responses in 7 of 9 patient sera versus 3 of 40 controls, reacted in indirect immunofluorescence, was confirmed by 16S rRNA sequencing, and was detectable in patient tissue using the generated antibodies.

Abstract

Whipple's disease is a systemic bacterial infection, but to date no isolate of the bacterium has been established in subculture, and no strain of this bacterium has been available for study.Using specimens from the aortic [corrected] valve of a patient with endocarditis due to Whipple's disease, we isolated and propagated a bacterium by inoculation in a human fibroblast cell line (HEL) with the use of a shell-vial assay. We tested serum samples from our patient, other patients with Whipple's disease, and control subjects for the presence of antibodies to this bacterium.The bacterium of Whipple's disease was grown successfully in HEL cells, and we established subcultures of the isolate. Indirect immunofluorescence assays showed that the patient's serum reacted specifically against the bacterium. Seven of 9 serum samples from patients with Whipple's disease had IgM antibody titers of 1:50 or more, as compared with 3 of 40 samples from the control subjects (P<0.001). Polyclonal antibodies against the bacterium were generated by inoculation of the microorganism into mice and were used to detect bacteria in the excised cardiac tissue from our patient on immunohistochemical analysis. The 16S ribosomal RNA gene of the cultured bacterium was identical to the sequence for Tropheryma whippelii identified previously in tissue samples from patients with Whipple's disease. The strain we have grown is available in the French National Collection.We cultivated the bacterium of Whipple's disease, detected specific antibodies in tissue from the source patient, and generated specific antibodies in mice to be used in the immunodetection of the microorganism in tissues. The development of a serologic test for Whipple's disease may now be possible.