HIV test needs just a spot of blood
An HIV test using dried blood samples is fast, inexpensive, and could aid the testing and treatment of HIV-positive babies in the first year of life, scientists say.
The technique extracts and amplifies the virus's genetic material from a tiny amount of blood blotted onto filter paper.
Researchers say that HIV-positive babies are more likely to survive if treated in the first year of life (see Treat HIV babies early, urge researchers).
But diagnosis with conventional antibody tests cannot be done until babies are 18 months old — when antibodies transferred from the mother have been eliminated — while commercial tests to detect virus genetic material are relatively expensive, require large quantities of blood and need special conditions for storage and transport of samples.
The filter paper test, reported in PLoS ONE this month (5 June), requires only small blood samples on filter paper which can be conveniently collected and transported — even posted — to laboratories in a zip lock bag.
The researchers, led by Mohan Somasundaran at the US-based University of Massachusetts Medical School, tested the method on 56 patients, including 19 infants born to HIV-positive mothers at Heal Hospital, Goma, in the Democratic Republic of Congo.
They found it to be accurate as well as twice as fast and 40-fold cheaper than commercial viral tests. It was also just as accurate after samples were stored at 37 degrees Celsius for seven days.
Somasundaran told SciDev.Net that the test could also be used to assess how well antiretroviral therapy is working by detecting the levels of virus in the blood.
Dry blood samples are less likely to degrade than their liquid counterparts — especially useful in rural areas where there are no laboratories, Quarraisha Abdool Karim, director of the Centre for Aids Research in South Africa, at the University of KwaZulu-Natal told SciDev.Net.
"We only wait for six weeks before infants can be tested with this method — therapy can be provided and they can be monitored earlier," says Karim.
The technique of sampling is easy. It allows clinics to have tested results every month while storing the samples in good condition," says Vindu Eulalievyolo, a researcher based at Heal Hospital.
PLoS ONE doi 10.1371/journal.pone.0005819 (2009)