A no film slot blot for the detection of developing P. falciparum oocysts in mosquitoes

PLoS One. 2017 Apr 21;12(4):e0174229. doi: 10.1371/journal.pone.0174229. eCollection 2017.

Abstract

Non-microscopy-based assays for sensitive and rapid detection of Plasmodium infection in mosquitoes are needed to allow rapid and high throughput measurement of transmission intensity and malaria control program effectiveness. Here, we report on a modified enhanced chemiluminescence-based slot blot assay for detection of Plasmodium falciparum (Pf) circumsporozite protein (PfCSP) expressed on parasite oocysts developing inside the mosquito midgut. This modified assay has several novel features that include eliminating the need for exposure to autoradiography (AR) film, as well as utilizing a novel high affinity anti-CSP antibody, and optimizing assay procedures resulting in significant reduction in the time required to perform the assay. The chemiluminescent signal for the detection of PfCSP in mosquito samples was captured digitally utilizing the C-Digit blot scanner that, allowed the detection of 0.01 pg of recombinant P. falciparum CSP and as few as 0.02 P. falciparum oocysts in a little over two hours. The earlier ECL-SB detected rCSP and oocysts and took approximately 5 h to perform. Whole mosquito lysates from both high and low prevalence-infected mosquito populations were prepared and evaluated for PfCSP detection on the ECL-SB by both AR film and digital data capture and analysis. There was a 100% agreement between the AR film and the C-Digit scanner methods for PfCSP detection in randomly sampled mosquitoes. This novel "No Film" Slot Blot assay obviates the need for AR film exposure and development and significantly reduces the assay time enabling widespread use in field settings.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / analysis
  • Culicidae / parasitology*
  • Female
  • Mice
  • Mice, Inbred BALB C
  • Oocysts / growth & development*
  • Plasmodium falciparum / growth & development*
  • Protozoan Proteins / analysis
  • Protozoan Proteins / immunology
  • Reproducibility of Results

Substances

  • Antibodies, Monoclonal
  • Protozoan Proteins
  • circumsporozoite protein, Protozoan

Grants and funding

Work on this study was supported through PATH. Representatives of PATH listed as coauthors on this manuscript contributed to the preparation of this manuscript.