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Better Detection of Malaria Strains Targeted by Multiplex Tool From PATH, Quansys Bio


NEW YORK (360Dx) – PATH and Quansys Biosciences said they have developed a multiplex diagnostic tool that's enabling the development of tests to detect malaria infections being missed by the most sensitive point-of-care lateral flow assays.

After developing the tool with Seattle-based PATH, Quansys last month launched the multiplex diagnostic tool for use by researchers looking to develop more sensitive and reliable rapid diagnostic tests to detect different strains of malaria. The tool, called the Q-Plex Human Malaria Array (5-Plex), can also be used by organizations looking to more accurately detect malarial species, Chris Lyman, vice president of R&D at Quansys, said in an interview.

Logan, Utah-based Quansys anticipates marketing Q-Plex Human Malaria Array (5-Plex) as an alternative to single-plex lateral flow assays being used to detect malaria. The Quansys platform uses sandwich-based immunoassays that employ capture and detection antibodies and chemiluminescence detection. Using a single blood sample, the multiplex assay measures HRP2 and pLDH at low concentrations and quantifies LDH epitopes specific to P. vivax and P. falciparum to distinguish between malaria species. The multiplex test measures five markers — HRP2, panLDH, pvLDH, pfLDH, and CRP as a general inflammation marker.

With more than 200 million cases of malaria annually, global health organizations have ratcheted up efforts to not only control malaria but to try to eradicate it.

New markers and lateral flow tests that PATH, FIND, and the Bill and Melinda Gates Foundation are developing and evaluating with diagnostic industry partners need the five-marker Quansys multiplex immunoassay because its performance can be used as a benchmark through which PATH can evaluate new tests, Gonzalo Domingo, scientific director and lead of malaria diagnostics at PATH, said in an interview. The project to develop the Q-Plex Human Malaria Array (5-Plex) tool was supported by a grant of an undisclosed amount from the Bill & Melinda Gates Foundation.

"When you're trying to eliminate malaria, you need to know who is infected in your community so that you can target treatment strategies accordingly," Domingo said.

As organizations achieve greater levels of control over malaria's prevalence, they encounter infections with lower levels of the diagnostic markers associated with the condition and need more sensitive tests to find out who is infected, he noted.

Using the Q-Plex Human Malaria Array (5-Plex), developers can evaluate how well the new tests are likely to fare in the field and whether existing tests are up to the task, Domingo said.

Further, the product is likely to help health organizations better understand the prevalence of new malaria disease markers in different communities associated with different levels of control or elimination, he noted.

PATH is using the tool "to ascertain whether some tests are no longer going to be applicable because they're not sensitive enough for different reasons…and we can see how much better new diagnostic tests need to be," Domingo said.

PATH, a nonprofit global health organization once known as the Program for Appropriate Technology in Health, does extensive in-country work with malaria programs in evaluating new technologies, interventions, and strategies. It's Malaria Control and Elimination Partnership in Africa (MACEPA), for example, has been working with national governments since 2005.

The organization currently uses the Quansys tool to benchmark RDTs for several undisclosed diagnostic companies and to help them understand whether their products are meeting competitive performance standards, a process that helps companies decide whether to pursue WHO prequalification, Domingo said.

In evaluating existing technologies used for malaria detection, PATH has seen that lateral flow tests, most of which are single-plex assays and don't require instruments, are doing a good job of detecting the most predominant malarial strains, Domingo said. However, they are missing other malarial strains that are less prevalent and are, nonetheless, an important part of mitigating the presence and spread of the disease, he said.

Current RDTs function by detecting HRP2, or histidine rich protein 2, to identify P. falciparum malaria and the plasmodium lactate dehydrogenase (pLDH) antigen to diagnose P. vivax malaria and all other human malaria species.

P. falciparum malaria is most prevalent in Africa and is associated with the greatest overall disease burden among malarial species. The most advanced commercial RDTs detect P. falciparum malaria in the field within about 30 minutes, and they are cheap and sensitive enough to be effective, Domingo said. 

In some regions, however, the parasite that causes malaria is no longer expressing P. falciparum. "If you run an RDT in that region you won't detect people with infections simply because the parasite isn't expressing that protein," he said.

As a result, tests with greater sensitivity and additional markers are needed to ensure that infections are not being missed, and that's where the Q-Plex Human Malaria Array comes into play. Researchers can use the five-plex array to develop tests that address the challenge of diagnosing P. falciparum malaria parasite strains that do not produce HRP2 and therefore are not detected by RDTs designed to identify the antigen, Domingo said.

Further, the assay can help in the development of tests to detect P. vivax-based malaria, which is a barrier to many countries achieving malaria elimination, he said. As countries approach elimination, P. vivax becomes the most prevalent species because it's harder to detect.

Quansys was founded in 2005 leveraging funding from a research endowment established by Rex Spendlove, a microbiologist and founder of San Angelo, Texas-based culture media firm Hyclone Laboratories.

Quansys develops customizable multiplex and single-plex assay technologies in collaboration with pharmaceutical companies, clinical laboratories, government institutions, and universities.

Its Q-Plex Array Technology makes it possible to measure up to 18 analytes at one time, helping researchers to better understand disease and improve their biological sample testing, the firm said.

Quansys' collaboration with PATH in the malaria diagnostics space represents a new phase of an ongoing partnership. PATH had previously used the Quansys platform to qualify the performance of the Abbott ultrasensitive point-of-care test, the Alere Malaria Ag P.f, which was launched outside the US in 2017 for the detection of P. falciparum HRP-II antigen. The organizations have also collaborated to develop a product that enabled testing for markers of malnutrition.

The Quansys project with PATH is emblematic of other projects in which the firm participates with customers to solve diagnostics challenges using the Quansys multiplex immunoassay platform, Lyman said. The projects often involve development of algorithm-based prognostic tests or diagnostic tests that incorporate cytokine-based inflammation kits that address immune system disorders, he added.

The firm is evaluating whether to pursue marketing clearance of its Q-Plex Human Malaria Array (5-Plex) with the US Food and Drug Administration, which would enable it to distribute the test as a commercial in vitro diagnostic kit, Lyman said.

He said that while the multiplex test cannot compete on price with inexpensive lateral flow technology, it will nonetheless be among the most cost-competitive testing options that uses an alternate technology, and because of its multiplexing capabilities, it beats all lateral flow tests on performance.

The test, which is currently available for research use only, is sensitive enough to detect not only symptomatic, active cases of malaria but also infections in people who aren't presenting with symptoms, Lyman said.

Other companies and investigators are developing new technologies for more effective detection of malaria. Mologic recently said it has developed devices that could be visually read and attained a sensitivity of 1 picogram per milliliter, a 1,000-fold improvement in sensitivity over its current technology.

In partnership with Wiesbaden, Germany-based distributor Human Diagnostics Worldwide and FIND, Eiken Chemical has developed a new loop-mediated isothermal amplification molecular assay that can detect P. vivax.

And preliminary data from infected children in Malawi has suggested a breath-based test for malaria is feasible.