Simultaneous Quantification of Plasmodium Antigens and Host Factor C-Reactive Protein in Asymptomatic Individuals with Confirmed Malaria by Use of a Novel Multiplex Immunoassay

Abstract

Malaria rapid diagnostic tests (RDTs) primarily detect Plasmodium falciparum antigen histidine-rich protein 2 (HRP2) and the malaria-conserved antigen lactate dehydrogenase (LDH) for P. vivax and other malaria species. The performance of RDTs and their utility is dependent on circulating antigen concentration distributions in infected individuals in a population in which malaria is endemic and on the limit of detection of the RDT for the antigens.

Quantification of malaria antigens PfHRP2 and pLDH by quantitative suspension array technology in whole blood, dried blood spot and plasma

“…The qSAT allows the determination of protein concentrations as low as 6.0, 56.1 and 1042.7 pg/ml, respectively. Hence, the assay provides increased sensitivity compared to commercially available ELISA kits, which have LODs of approximately 400 pg/ml and 1000 pg/ml for PfHRP2 and pLDH, respectively [27,37]. The assay shows good levels of dilution linearity, accuracy and precision, and can be used to effectively and rapidly quantify malaria antigens in large quantities of different biosamples.…”

“…ELISAs are however costly, time and sample consuming, and generally only allow for the detection of one analyte at the time. The recent release of a highly-sensitive RDT for PfHRP2 (Alere ™ Malaria Ag P.f ), with two to ten-fold higher sensitivity than other currently available RDTs [22,23], as well as the work in progress to develop new generation pLDH-based RDTs, underpins the need for new highly-sensitive, laboratory-based, reference immunoassays than can provide lower limit of detection than classical ELISAs [24][25][26][27]. Highly sensitive quantitative assays should not only be a more suitable tool for validation of new-generation RDTs, but could also be used to better understand antigen kinetics, particularly that of PfHRP2, and to support malaria surveillance.…”

Quantification of malaria antigens PfHRP2 and pLDH by quantitative suspension array technology in whole blood, dried blood spot and plasma

“…Additionally, the assay can also quantify Pv pLDH down to 1211.6 pg/ml. The assay analytical sensitivity to detect PfHRP2 is comparable to that of a recently developed bead suspension assay based on Luminex technology (25), as well as to other immunoassays that use different technologies (20,28). This suggests that with the current technology available for the quantification of PfHRP2 using antibodies, the lowest limit of detection achievable is in the range of 0.5 to 10 pg/ml.…”

“…This suggests that with the current technology available for the quantification of PfHRP2 using antibodies, the lowest limit of detection achievable is in the range of 0.5 to 10 pg/ml. The limit of detection for pLDH is more divergent across assays, ranging from approximately 10 pg/ml (28) up to 4000 pg/ml (25), but in all assays it is always higher than that for PfHRP2. This underpins the need to further improve the sensitivity of pLDH-based diagnostics.…”

“…ELISAs are however costly, time and sample consuming, and generally only allow for the detection of one analyte at the time. The recent release of a highly-sensitive RDT for PfHRP2 (Alere™ Malaria Ag P.f), with two to ten-fold higher sensitivity than other currently available RDTs (22,23), as well as the work in progress to develop new generation pLDH-based RDTs, underpin the need for new highly-sensitive laboratory based reference immunoassays than can provide lower limit of detection than classical ELISAs (24–28). Highly sensitive quantitative assays should not only be a more suitable tool for validation of new-generation RDTs, but could also be used to better understand antigen kinetics, particularly that of PfHRP2, and to support malaria surveillance.…”