Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda
Abstract Background Rapid diagnostic tests (RDTs) play a key role in malaria case management. The most widely used RDT identifies Plasmodium falciparum based on immunochromatographic recognition of P. falciparum histidine-rich protein 2 (PfHRP2). Deletion of the paralogous pfhrp2 and pfhrp3 genes le...
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| Format: | Article |
| Language: | English |
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BMC
2021-01-01
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| Series: | Malaria Journal |
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| Online Access: | https://doi.org/10.1186/s12936-020-03547-4 |
| _version_ | 1818959533158957056 |
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| author | Sam L. Nsobya Andrew Walakira Elizabeth Namirembe Moses Kiggundu Joaniter I. Nankabirwa Emmanuel Ruhamyankaka Emmanuel Arinaitwe Melissa D. Conrad Moses R. Kamya Grant Dorsey Philip J. Rosenthal |
| author_facet | Sam L. Nsobya Andrew Walakira Elizabeth Namirembe Moses Kiggundu Joaniter I. Nankabirwa Emmanuel Ruhamyankaka Emmanuel Arinaitwe Melissa D. Conrad Moses R. Kamya Grant Dorsey Philip J. Rosenthal |
| author_sort | Sam L. Nsobya |
| collection | DOAJ |
| description | Abstract Background Rapid diagnostic tests (RDTs) play a key role in malaria case management. The most widely used RDT identifies Plasmodium falciparum based on immunochromatographic recognition of P. falciparum histidine-rich protein 2 (PfHRP2). Deletion of the paralogous pfhrp2 and pfhrp3 genes leads to false-negative PfHRP2-based RDTs, and has been reported in P. falciparum infections from South America and Africa. However, identification of pfhrp2/pfhrp3 deletions has usually been based only on failure to amplify these genes using PCR, without confirmation based on PfHRP2 protein expression, and understanding of the true prevalence of deletions is incomplete. Methods Deletions of pfhrp2/pfhrp3 in blood samples were investigated from cross-sectional surveys in 2012-13 in three regions of varied malaria transmission intensity in Uganda. Samples with positive Giemsa-stained thick blood smears, but negative PfHRP2-based RDTs were evaluated by PCR amplification of conserved subunit ribosomal DNA for Plasmodium species, PCR amplification of pfhrp2 and pfhrp3 genes to identify deletions, and bead-based immunoassays for expression of PfHRP2. Results Of 3516 samples collected in cross-sectional surveys, 1493 (42.5%) had positive blood smears, of which 96 (6.4%) were RDT-negative. Of these 96 RDT-negative samples, P. falciparum DNA was identified by PCR in 56 (58%) and only non-falciparum plasmodial DNA in 40 (42%). In all 56 P. falciparum-positive samples there was a failure to amplify pfhrp2 or pfhrp3: in 25 (45%) pfhrp2 was not amplified, in 39 (70%) pfhrp3 was not amplified, and in 19 (34%) neither gene was amplified. For the 39 P. falciparum-positive, RDT-negative samples available for analysis of protein expression, PfHRP2 was not identified by immunoassay in only four samples (10.3%); these four samples all had failure to amplify both pfhrp2 and pfhrp3 by PCR. Thus, only four of 96 (4.2%) smear-positive, RDT-negative samples had P. falciparum infections with deletion of pfhrp2 and pfhrp3 confirmed by failure to amplify the genes by PCR and lack of expression of PfHRP2 demonstrated by immunoassay. Conclusion False negative RDTs were uncommon. Deletions in pfhrp2 and pfhrp3 explained some of these false negatives, but most false negatives were not due to deletion of the pfhrp2 and pfhrp3 genes. |
| first_indexed | 2024-12-20T11:43:09Z |
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| id | doaj.art-f47ea82463444c419018d31e5abc4629 |
| institution | Directory Open Access Journal |
| issn | 1475-2875 |
| language | English |
| last_indexed | 2024-12-20T11:43:09Z |
| publishDate | 2021-01-01 |
| publisher | BMC |
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| series | Malaria Journal |
| spelling | doaj.art-f47ea82463444c419018d31e5abc46292022-12-21T19:41:56ZengBMCMalaria Journal1475-28752021-01-012011610.1186/s12936-020-03547-4Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from UgandaSam L. Nsobya0Andrew Walakira1Elizabeth Namirembe2Moses Kiggundu3Joaniter I. Nankabirwa4Emmanuel Ruhamyankaka5Emmanuel Arinaitwe6Melissa D. Conrad7Moses R. Kamya8Grant Dorsey9Philip J. Rosenthal10Infectious Diseases Research CollaborationInfectious Diseases Research CollaborationInfectious Diseases Research CollaborationInfectious Diseases Research CollaborationInfectious Diseases Research CollaborationInfectious Diseases Research CollaborationInfectious Diseases Research CollaborationDepartment of Medicine, University of CaliforniaInfectious Diseases Research CollaborationDepartment of Medicine, University of CaliforniaDepartment of Medicine, University of CaliforniaAbstract Background Rapid diagnostic tests (RDTs) play a key role in malaria case management. The most widely used RDT identifies Plasmodium falciparum based on immunochromatographic recognition of P. falciparum histidine-rich protein 2 (PfHRP2). Deletion of the paralogous pfhrp2 and pfhrp3 genes leads to false-negative PfHRP2-based RDTs, and has been reported in P. falciparum infections from South America and Africa. However, identification of pfhrp2/pfhrp3 deletions has usually been based only on failure to amplify these genes using PCR, without confirmation based on PfHRP2 protein expression, and understanding of the true prevalence of deletions is incomplete. Methods Deletions of pfhrp2/pfhrp3 in blood samples were investigated from cross-sectional surveys in 2012-13 in three regions of varied malaria transmission intensity in Uganda. Samples with positive Giemsa-stained thick blood smears, but negative PfHRP2-based RDTs were evaluated by PCR amplification of conserved subunit ribosomal DNA for Plasmodium species, PCR amplification of pfhrp2 and pfhrp3 genes to identify deletions, and bead-based immunoassays for expression of PfHRP2. Results Of 3516 samples collected in cross-sectional surveys, 1493 (42.5%) had positive blood smears, of which 96 (6.4%) were RDT-negative. Of these 96 RDT-negative samples, P. falciparum DNA was identified by PCR in 56 (58%) and only non-falciparum plasmodial DNA in 40 (42%). In all 56 P. falciparum-positive samples there was a failure to amplify pfhrp2 or pfhrp3: in 25 (45%) pfhrp2 was not amplified, in 39 (70%) pfhrp3 was not amplified, and in 19 (34%) neither gene was amplified. For the 39 P. falciparum-positive, RDT-negative samples available for analysis of protein expression, PfHRP2 was not identified by immunoassay in only four samples (10.3%); these four samples all had failure to amplify both pfhrp2 and pfhrp3 by PCR. Thus, only four of 96 (4.2%) smear-positive, RDT-negative samples had P. falciparum infections with deletion of pfhrp2 and pfhrp3 confirmed by failure to amplify the genes by PCR and lack of expression of PfHRP2 demonstrated by immunoassay. Conclusion False negative RDTs were uncommon. Deletions in pfhrp2 and pfhrp3 explained some of these false negatives, but most false negatives were not due to deletion of the pfhrp2 and pfhrp3 genes.https://doi.org/10.1186/s12936-020-03547-4pfhrp2pfhrp3Plasmodium falciparumHRP2Rapid diagnostic test |
| spellingShingle | Sam L. Nsobya Andrew Walakira Elizabeth Namirembe Moses Kiggundu Joaniter I. Nankabirwa Emmanuel Ruhamyankaka Emmanuel Arinaitwe Melissa D. Conrad Moses R. Kamya Grant Dorsey Philip J. Rosenthal Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda Malaria Journal pfhrp2 pfhrp3 Plasmodium falciparum HRP2 Rapid diagnostic test |
| title | Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda |
| title_full | Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda |
| title_fullStr | Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda |
| title_full_unstemmed | Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda |
| title_short | Deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test-negative Plasmodium falciparum isolates from Uganda |
| title_sort | deletions of pfhrp2 and pfhrp3 genes were uncommon in rapid diagnostic test negative plasmodium falciparum isolates from uganda |
| topic | pfhrp2 pfhrp3 Plasmodium falciparum HRP2 Rapid diagnostic test |
| url | https://doi.org/10.1186/s12936-020-03547-4 |
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