Internal quality control for HIV testing of blood donors - Dried tube specimen as a cost-effective alternative.

Background: An important aspect of ensuring blood safety is the performance of mandatory serological testing for transfusion transmissible infections. The practice of internal quality control (IQC) in blood banks in India is nonuniform, especially the use of third-party materials. Cited reasons are cost, lack of access to control materials, and need for deep-freezers for storage, if prepared in-house.

Objective: Validation of dried tube specimen (DTS) from HIV-positive plasma as a low-cost, stable material for use as IQC material in blood banks.

Methods: Fresh-frozen plasma (FFP) prepared from four HIV-positive blood-donors were pooled. Equal numbers of seronegative FFPs were pooled. Twenty microlitre aliquots of plasma were made in micro-centrifuge tubes and air-dried overnight at room-temperature. These were stored in 2-8°C refrigerators and tested once weekly for 6 months on multiple platforms with different detection principles: Rapid tests, second-generation enzyme-linked immunosorbent assay (ELISA), fourth-generation ELISA, and fourth-generation Chemiluminescence immunoassay. The protocol was sustained over the next 6 months with decreased testing frequency to study the extended stability of DTS.

Results: A total of 139 positive-DTS and 139 negative-DTS were tested with 100% samples showing consistent results on all platforms over 1 year. There was mild deterioration in reaction strengths, which did not interfere in result interpretations.

Conclusion: Plasma in form of DTS maintained stability when stored at 2-8°C for 1 year. This provides evidence that DTS can be a modality for the production of cost-effective, stable, in-house control material for resource-restricted countries.