Real-time PCR assays for detection and quantification of early P. falciparum gametocyte stages

Gadalla, A. A. H., Siciliano, G., Farid, R., Alano, P., Ranford-Cartwright, L. , McCarthy, J. S., Thompson, J. and Babiker, H. A. (2021) Real-time PCR assays for detection and quantification of early P. falciparum gametocyte stages. Scientific Reports, 11, 19118. (doi: 10.1038/s41598-021-97456-4) (PMID:34580326) (PMCID:PMC8476600)

Abstract

The use of quantitative qRT-PCR assays for detection and quantification of late gametocyte stages has revealed the high transmission capacity of the human malaria parasite, Plasmodium falciparum. To understand how the parasite adjusts its transmission in response to in-host environmental conditions including antimalarials requires simultaneous quantification of early and late gametocytes. Here, we describe qRT-PCR assays that specifically detect and quantify early-stage P. falciparum gametocytes. The assays are based on expression of known early and late gametocyte genes and were developed using purified stage II and stage V gametocytes and tested in natural and controlled human infections. Genes pfpeg4 and pfg27 are specifically expressed at significant levels in early gametocytes with a limit of quantification of 190 and 390 gametocytes/mL, respectively. In infected volunteers, transcripts of pfpeg4 and pfg27 were detected shortly after the onset of blood stage infection. In natural infections, both early (pfpeg4/pfg27) and late gametocyte transcripts (pfs25) were detected in 71.2% of individuals, only early gametocyte transcripts in 12.6%, and only late gametocyte transcripts in 15.2%. The pfpeg4/pfg27 qRT-PCR assays are sensitive and specific for quantification of circulating sexually committed ring stages/early gametocytes and can be used to increase our understanding of epidemiological processes that modulate P. falciparum transmission.

• Item Type: Articles
• Additional Information: Amal Gadalla was supported by SQU scholarship and International Atomic Energy Agency (IAEA). Work at Istituto Superiore di Sanità was funded by the grant "Italy-South Africa Research Project ISARP2018 “New generation drugs against Plasmodium falciparum transmission for malaria eradication” to P.A. by the Italian Ministries of Health and of Foreign Affairs and International Cooperation.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ranford-Cartwright, Dr Lisa
• Authors: Gadalla, A. A. H., Siciliano, G., Farid, R., Alano, P., Ranford-Cartwright, L., McCarthy, J. S., Thompson, J., and Babiker, H. A.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Scientific Reports
• Publisher: Nature Research
• ISSN: 2045-2322
• ISSN (Online): 2045-2322
• Copyright Holders: Copyright © 2021 The Authors
• First Published: First published in Scientific Reports 11: 19118
• Publisher Policy: Reproduced under a Creative Commons License