HIV Diagnosis

  Assay for HIV

Rapid Lateral Flow Assay for HIV p24 Antigen for the Screening of HIV in Pediatric Samples
The current rapid test used in resource limited settings for screening infants detects antibodies to HIV that are present in the child’s blood (e.g. Determine®). As HIV and antibodies to HIV can be transmitted from mother to child in the womb, during the birthing process or as a result of breast feeding, the current tests for antibodies do not yield unequivocal results for children less than 2 years old. The goal of this project is to develop a simple to use, rapid test that detects p24 Antigen. HIV p24 antigen is found on the virus itself and if detected in blood is considered unequivocal evidence that a child is HIV positive. Utilizing similar technology as the rapid antibody tests, we have developed a sample pre-treatment process and an ultra-sensitive detection system that, when incorporated into a test strip, has a limit of detection of approximately 1 pg/ml of p24 antigen. This is a significant improvement in analytical sensitivity compared to automated immunochemistry analysers that can detect down to 18 pg/ml. We have also evaluated the test with panels of characterized adult blood samples that have known amounts of HIV and antibodies to HIV. These experiments have suggested that our rapid test can detect HIV positive samples having as little as 17,500 HIV copies/milliliter. While this is not the most sensitive test for HIV (nucleotide assays are the most sensitive) it is a significant improvement over existing diagnostic tests and should be sufficient to detect HIV in children. At the present time we have focused our research on examining frozen pediatric samples as a means of further characterizing our rapid test.

  PCR Results in 30 Minutes or Less

Development of a Point-of-Care Infant Diagnostic: PCR Results in 30 Minutes or Less
Diagnostic tests that detect the presence of antibodies in a patient’s blood against HIV-1 are simple, inexpensive and widely used in point of care settings in resource limited settings. These conventional antibody tests cannot be used to diagnose HIV-1 infection in infants, however, because the mother’s antibodies transmitted to the infant in the womb and through breast milk persist until the infant is 18 months to 2 years of age. Because of high mortality rates of infants from HIV-1, an early diagnosis is critical. We are developing a rapid, low cost, point-of-care (POC) diagnostic test for HIV proviral DNA. The assay consists of a whole blood sample applied to a collection device containing pre-punched filter paper discs followed by a cell separation protocol to collect white blood cells from blood. The filter paper discs containing the cells are introduced into cartridges pre-filled with reagents specific to HIV-1 proviral DNA and assayed by quantitative PCR (qPCR) in a robust low cost thermocycler. CIGHT is developing technologies for all three components (collection device, assay specific reagents, and low cost thermocycler) to generate an integrated and portable system. Recent work has focused on testing the cell isolation procedure with frozen pediatric samples to determine the sensitivity and specificity of our assay. Future work will include optimization of assay conditions to meet the goal of time to test result being less than 30 minutes. Also, the design process for the collection device and reaction vessel (i.e., cartridge) has been initiated to integrate sample collection and PCR reaction assembly.

Case Studies
Balancing Access with Accuracy for Infant HIV Diagnostics in Tanzania