Researchers from Integrated Diagnostics and the California Institute of Technology have won a $500,000 Gates Foundation grant to develop a protein capture-based point-of-care device for HIV diagnosis.
Caltech professor and Integrated co-founder Jim Heath will lead the project, which aims to use the Integrated Diagnostics' Protein-Catalyzed Capture Agents, or PCCs, a click chemistry-based class of protein affinity reagents it introduced several months ago (PM 10/28/2011).
The diagnostic will determine HIV status by detecting anti-HIV antibodies in patients. This is currently a common method of detecting the virus, Health told ProteoMonitor, but, he noted, existing tests – which typically use a peptide made from an immunogenic epitope on HIV to detect these antibodies – don't account for the differences in antibodies produced across a population, which can hamper their sensitivity.
"The polyclonal diversity of the population of infected people can mean that their antibodies bind [to the capture peptide] with better or less affinity," Heath said.
Using the PCC technology, which employs click chemistry combined with pairs of random peptide libraries – one containing acetylene functionalities and the other containing azide groups – to create affinity reagents to given proteins, Heath's team plans to generate a small series of capture agents that will account for the diversity of anti-HIV antibodies across the population, hopefully making for a more sensitive test.
The stability of the PCCs could also offer an advantage, Heath suggested, noting that there have been reports of conventional HIV tests going bad in the field.
"We typically store [PCCs] as powders on shelves under ambient conditions, and they have worked fine," he said. He added that this stability could prove useful in point-of-care devices for other diseases, as well – malaria, in particular.
"As we've gotten involved in the Gates Foundation, we've begun identifying other places where this technology could have a near-term impact, and one in particular is malaria," he said. Current malaria assays are very effective at detecting the disease, Heath said, "but they fail so often [in the field] because of the nature of the reagents used, that everyone [being tested] just gets treated for malaria whether the test comes back positive or not."
Heath's team has thus far developed three PCCs for anti-HIV antibodies that it is currently optimizing – a process he said would take several months. He said he doesn't anticipate any problems incorporating the final agents into a point-of-care device, noting that "we've developed a pretty good number of [PCCs] and haven't had any issues putting them into whatever platforms we've wanted."
How any test that emerges might proceed through the regulatory process remains unclear, Heath said.
"I don't think that [Integrated Diagnostics] as a company has the resources," he said. "One could easily imagine [a cost of] $50 million or something to get [regulatory] approval. So that's a struggle we'll have to figure out working with the Gates Foundation. But they're fully aware of this problem."
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