Assay detects antimalarial resistance in a drop of blood

Researchers from Vanderbilt University have developed an assay that uses a drop of whole blood to provide rapid access to critical information associated with resistance to antimalarial drugs at the point of care, avoiding the time, expense and effort of having the sample sent to a central laboratory and allowing clinicians to quickly re-evaluate treatment options. Their work has been published in The Journal of Molecular Diagnostics.

Blood contains a wealth of genetic information, but currently must undergo significant processing to remove components that interfere with molecular analyses. Gathering genetic information from a single drop of blood has thus proved elusive; yet this study, which analysed a single mutation in a malaria parasite, provides the first steps to do just that. A drop of blood can be used directly, without any additional processing, to assess a range of genetic data.

“Monitoring of antimalarial resistance is important to prevent its further spread, but the available options for assessing resistance are less than ideal for field settings,” said Dr Mindy Leelawong, co-lead investigator on the study. “Although molecular detection is perhaps the most efficient method, it is also the most complex because it requires DNA extraction and PCR instrumentation.

“Our strategy eliminates the most time- and labour-intensive step: DNA extraction. By creating a procedure that overcomes the obstacles presented by blood, we have developed a simple method to quickly identify mutations associated with drug resistance. As a consequence, higher throughput testing and more rapid sample-to-result turnaround will be possible.”

Dr Frederick R Haselton, also a co-lead investigator on the study, explained that the researchers redesigned the molecular tools used for DNA analysis in order to mitigate the inhibition by blood components. “We utilised reporter dyes that are more optically compatible with blood, which were combined with a specific type of DNA subunit to accurately pinpoint mutations. The end result is an assay in which blood is directly added to a reaction tube to detect mutations associated with antimalarial drug resistance.”

The researchers anticipate that the technique can be modified for assessing resistance to artemisinin, the current first-line therapy for malarial infection, or future drugs as they become available. The technique may also become a platform for evaluating other molecular targets found in blood, while the technology offers a potential platform to manage the spread of drug resistance on the ground.

“These drug-resistant parasites must not spread; we know from previous generations of drugs that the consequences can be catastrophic,” said co-lead investigator Dr David W Wright. “To prevent further spread, the geographic location of drug-resistant parasites must be known.”

Image credit: ©stock.adobe.com/au/bankerfotos

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