HIV NAT testing

HIV Viral Components

The area of molecular diagnostics in transplantation is an emerging field.  Its impact on viral detection can be felt in a recent case where a patient contracted HIV after receiving a kidney transplant from a live donor.  In this case the donor was HIV tested using the Enzyme Immune Assay ~3 months (79 days) prior to transplant.  This assay was unable to detect a HIV exposure which occurred closer to the day of transplant.  After the incidence the CDC NAT (nucleic acid testing) tested the donor leukocytes collected 57 days pre-transplant and found they were negative for the presence of HIV genes (gp41, pol, p17), however these genes were amplified from donor leukocytes at day 11 pre-transplant.   In light of the first case in over two decades, the CDC has created new recommendations for HIV testing organ donors no more than seven days before transplantation.  These new guidelines should eliminate or dramatically reduce the risk for transplant-transmitted HIV infection

This situation emphasizes the strength of NAT testing as a diagnostic tool to shorten the gap between HIV infection and detection to 8-10 days compare to serological techniques (EIA/ELISA/Western Blot) which measure the development of HIV-specific antibodies after 3-8 weeks.  The ability of NAT testing to detect the presence of HIV genes in a relatively short period of time will increase support within the transplant community to immediately rescreen living donors with identified behavioral risk factors  prior to organ transplant.

Currently, the US Public Health Service guidelines only recommend serologic screening of HIV infection in potential living donors.  Revising these guidelines to include NAT testing and a standardized testing timeline before live donor transplant is essential. A 2009 study in AJT found that incorporation of NAT testing was able to significantly increase the utilization of certain (high risk donor) HRD organs by OPOs. (organ procurement organizations)  They also surveyed OPO clinical directors found 52% of centers always performed HIV NAT testing whereas 24% do not test donors for HIV.  It is possible these low numbers refect the cost-benefit analysis being performed for NAT testing where several disadvantages including loss of donor organs due to a false-positive NAT result need to be addressed.