A qPCR to quantify Wolbachia from few Onchocerca volvulus microfilariae as a surrogate for adult worm histology in clinical trials of antiwolbachial drugs

• Published in: Parasitology research (1987) Vol. 121; no. 4; pp. 1199 - 1206
• Main Authors: Schlabe, Stefan, Korir, Patricia, Lämmer, Christine, Landmann, Frederic, Dubben, Bettina, Koschel, Marianne, Albers, Anna, Debrah, Linda Batsa, Debrah, Alexander Yaw, Hübner, Marc P., Pfarr, Kenneth, Klarmann-Schulz, Ute, Hoerauf, Achim
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2022; Springer; Springer Nature B.V; Springer Verlag (Germany)
• Subjects: Animals; Antibiotics; Bacteriology; Biomedical and Life Sciences; Biomedicine; Biopsy; Blindness; Clinical trials; Filarioidea; Humans; Immunology; Intestinal Volvulus; Intestines; Life Sciences; Medical Microbiology; Microbiology; Microbiology and Parasitology; Microfilariae; Nematoda; Obstructions; Onchocerca; Onchocerca volvulus; Onchocerca volvulus - genetics; Onchocerciasis; Onchocerciasis - drug therapy; Parasitology; Plasmids; Reproducibility of Results; Sterilization; Treatment and Prophylaxis - Short Communication; Tropical diseases; Wolbachia; Wolbachia - genetics; Germany; qPCR; Onchocerca volvulus; Litomosoides sigmodontis; Wolbachia
• ISSN: 0932-0113; 1432-1955
• DOI: 10.1007/s00436-021-07411-5

The filarial nematode
Onchocerca volvulus
causes onchocerciasis (river blindness), a neglected tropical disease affecting 21 million people, mostly in Sub-Saharan Africa. Targeting the endosymbiont
Wolbachia
with antibiotics leads to permanent sterilization and killing of adult worms. The gold standard to assess
Wolbachia
depletion is the histological examination of adult worms in nodules beginning at 6 months post-treatment. However, nodules can only be used once, limiting the time points to monitor
Wolbachia
depletion. A diagnostic to longitudinally monitor
Wolbachia
depletion from microfilariae (MF) at more frequent intervals < 6 months post-treatment would accelerate clinical trials of antiwolbachials. We developed a TaqMan qPCR amplifying the single-copy gene
w
Ov
ftsZ
to quantify
Wolbachia
from as few as one MF that had migrated from skin biopsies and compared quantification using circular and linearized plasmids or synthetic dsDNA (gBlock®). qPCR for MF from the rodent nematode
Litomosoides sigmodontis
was used to support the reproducibility and validate the principle. The qPCR using as few as 2 MF from
O. volvulus
and
L. sigmodontis
reproducibly quantified
Wolbachia
. Use of a linearized plasmid standard or synthesized dsDNA resulted in numbers of
Wolbachia
/MF congruent with biologically plausible estimates in
O. volvulus
and
L. sigmodontis
MF. The qPCR assay yielded a median of 48.8 (range 1.5–280.5)
Wolbachia
/
O. volvulus
MF. The qPCR is a sensitive tool for quantifying
Wolbachia
in a few MF from skin biopsies and allows for establishing the qPCR as a surrogate parameter for monitoring
Wolbachia
depletion in adult worms of new antiwolbachial candidates.