A new viral load test developed by the University of Maryland’s Institute of Human Virology could be employed in the remotest settings in Africa that can be reached by car, expanding access to viral load testing from central hospitals down to primary health care level.
The testing method, reported in the July edition of the American Journal of Clinical Pathology, has still to be validated in clinical studies in the field, but has already passed the first hurdle by proving that it can detect HIV earlier than the currently used viral load test, RNA PCR, and that it can detect HIV at lower levels than RNA PCR using less blood (see accompanying article).
Dr Niel Constantine told aidsmap.com that the test kit can be powered by a car battery. It is based on a testing platform developed by the Norwegian company BioNor for antibody testing.
“What do you do in a country where the electricity supply is erratic, and the average temperature is above 37 degrees C, above the threshold for immunological reactions? A car battery will also power a light, allowing the tests to be done at night when it is cooler.”
Dr Constantine said that smaller lawnmower batteries might also provide sufficient power and that solar powered batteries would probably prove more expensive than car batteries.
The test method will not measure virus levels with the same precision as the Real Time Immuno PCR method outlined in the American Journal of Clinical Pathology.
“We plan to develop it to a threshold of 30,000 to 40,000 copies/ml since that’s the point at which people who are not on treatment generally need to consider treatment, and people who are on treatment need to change [before disease progression occurs],” said Dr Constantine
The test will rely on recognition of a colour change, as with an ELISA test, but may also employ a portable reader that measures the degree of change in colour intensity against a standardised colour scale. This might help to plot changes in viral load over time, Dr Constantine suggested, although the test is still in an early phase of development.
It is likely that the test could be used with minimal training and that operators will be able to carry out around 50 tests each day.
Development is supported by a $200,000 grant from a Doris Duke Foundation award programme designed to improve HIV clinical care in resource-limited settings.