NUCLEIC ACID AMPLIFICATION TESTING DETECTS HIV TRANSMISSION RISK IN SEROLOGICALLY- TESTED BLOOD DONOR UNITS. |Presented by Miss Shemau Muniru| Authors: Dadzie I., Muniru S., Adu P, Cudjoe O| |Department of Medical Laboratory Science, School of Allied Health Sciences, University of Cape Coast, Cape Coast, Ghana|

OUTLINE Background Current Menace Aim & Objectives Why NAT? Methods Results Conclusion References

BACKGROUND The number of infectious disease markers for which blood is screened has continued to increase over the years. Before 1984, there were only 2 diseases for which blood was tested—HBV and VDRL. By the late 1990s, blood had to be tested for nine different infectious disease markers- HIV, HBV, HCV, VDRL and others (Organization, 2010) Donor interviewing techniques combined with sensitive testing methods have drastically reduced the risks for acquiring such infections. However, the possibility of transfusion-transmitted disease still remains a constant threat for all blood banks and transfusion facilities.

BACKGROUND There are four sources of this remaining risk: pre-seroconversion (window phase) donations, viral variants, atypical seroconversion, and laboratory testing error (Schreiber, Busch, Kleinman, & Korelitz, 1996). The main objective of HIV testing in donors is to eliminate the risk of HIV transmission through blood transfusion. The clinically significant time interval between infection and detection of antibodies (window period) is vital Effort should be made to reduce the risk of transfusing donor blood within this period. This period is characterized by a sero negative result from an antibody based test, detectable antigenemia (p24) and viremia (as measured by RNA).

CURRENT MENACE Rapid/simple single-use assays (rapid tests) detects antibodies produced against the HIV virus after a period of 12 weeks (3 months) and Line immunoassay reduces the widow period to 5weeks thus people who have contracted the virus before these periods of detection would test negative Donations during the window period related thus constitute the predominant risk for each of the major viral agents and for example, in HIV and hepatitis B virus (HBV), at least 90 percent of the risk is attributable to donations of window-period units (Busch, Stramer, & Kleinman, 1997)

AIM & OBJECTIVES OF THE STUDY To find if there is a significant number of blood-banked samples labelled as “safe for transfusion” that test positive for HIV-1 using NAT and evaluating the effectiveness of adding NAT to the algorithm of tests done during screening for blood donation in prevalent areas in the country. 1. 2. 3. Obtain donor blood samples and conduct screening for HBV, HCV, HIV-1 & 2 and Syphilis with the licensed kits Conduct qualitative HIV-1 NAT on all samples that pass the donor screening tests Determine discrepancy between rapid test and NAT for determining the true status of samples labelled as safe for transfusion- to determine if NAT demonstrates improvement in the detection of acute HIV in high risk blood donors of known status

WHY NAT? Although NAT reduces the window period of infection, in countries with a low incidence of infection, the incremental gain is minimal as the number of donors in the window period at the point of donation is generally very low. However, in countries with a high incidence of infection there are likely to be significant numbers of window period donations that can be identified by NAT (Syria Laperche, 2008; Vermeulen et al., 2009) which also includes regions with high prevalence in Ghana.

METHODOLOGY Type: hospital-based cross-sectional diagnostic study Site: Koforidua Regional Hospital Sample Size: 100 plasma EDTA anticoagulated donor samples that had passed the preliminary donor screening tests (HBV, HCV, Syphilis, and HIV-1 & 2 using ) NAT Method: analyzed using the COBAS® AmpliPrep/COBAS® TaqMan® HIV-1 Qual Test for the detection of HIV-1 RNA and proviral DNA. Authorization: by the Institutional Review Board (UCC), NACP, and authorities of the Koforidua Regional Hospital.

RESULTS Of the 100 donor samples that tested sero-negative for HIV-1 and 2 using the antibody screening kit, 4% were reactive by NAT for HIV-1 (n=100) Test Method REACTIVE NON-REACTIVE NAT 4 (4%) 96 (96 %) ANTIBODY SCREENING KIT Nil 100 (100%)

CONCLUSION Study demonstrated there is a significant number of falsely diagnosed HIV cases related to transfusion services . This finding has necessitated the need for inclusion of NAT in donor blood screening, especially in areas prevalent for HIV-1 in Ghana, considering the risk involved in using the licensed antibody test provided by the health authorities. In cases where NAT screening may not be feasible, newer tests that have greater sensitivity compared to the FDA-licensed 3rd generation EIA which only detects HIV antibodies can be adopted.

REFERENCES Organization, World Health. (2010). Screening donated blood for transfusion-transmissible infections: recommendations: World Health Organization. Schreiber, George B, Busch, Michael P, Kleinman, Steven H, & Korelitz, James J. (1996). The risk of transfusion-transmitted viral infections. New England journal of medicine, 334(26), 1685-1690. Busch, MP, Stramer, SL, & Kleinman, SH. (1997). Evolving applications of nucleic acid amplification assays for prevention of virus transmission by blood components and derivatives. Applications of Molecular Biology to Blood Transfusion Medicine. AABB. Bethesda, MD, 123-176. Vermeulen, Marion, Lelie, Nico, Sykes, Wendy, Crookes, Robert, Swanevelder, Johanna, Gaggia, Lilian, . . . Reddy, Ravi. (2009). Impact of individual‐donation nucleic acid testing on risk of human immunodeficiency virus, hepatitis B virus, and hepatitis C virus transmission by blood transfusion in South Africa. Transfusion, 49(6), 1115-1125. Laperche, Syria. (2008). Antigen‐antibody combination assays for blood donor screening: weighing the advantages and costs. Transfusion, 48(4), 576-579.

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