The results presented in this report demonstrate that the sequential use of screening immunoassays before immunoblot testing can significantly reduce both the number of immunoblot tests and proportion of indeterminate results, without impacting sensitivity, thereby improving algorithm efficiency and simplifying donor management.

Our analysis suggests that a combination of indicators can be used to help clarify RIBA-3-indeterminate, RNA-negative results. Specifically, donors with high S/CO ratios on a screening immunoassay, RIBA-3 reactivity to c22p or c33c with band intensity of 2+ or greater, without a previous history of negative or BFR donations and with an identifiable risk factor, have a high probability of representing true anti-HCV rather than nonspecific reactivity.

BACKGROUND:Cytomegalovirus (CMV) antibody donor screening assays have predominantly included both immunoglobulin G (IgG) and immunoglobulin M (IgM) detection. However, since in the majority of cases both CMV IgG and IgM are detected concomitantly during early seroconversion, CMV assays based only on IgG are now widely applied for donor screening. STUDY DESIGN AND METHODS:The performance of an automated microparticle CMV IgG assay (Abbott AxSYM CMV IgG microparticle enzyme immunoassay [MEIA]) was compared with an established total antibody blood screening assay (Abbott CMV Total AB EIA). Sensitivity and specificity were assessed using 5050 random blood donors and 13 seroconversion panels. A risk analysis was undertaken to estimate the residual risk of transfusion-transmitted CMV (TT-CMV) from presumptive seronegative blood components. RESULTS: The EIA achieved marginally (but not significantly) better resolved sensitivity (100%) than the AxSYM IgG assay (99.93%). The AxSYM IgG resolved specificity (99.34%) was superior to the EIA (96.4%). This superiority was maintained (98.61%) when a modified cutoff was applied to the AxSYM IgG assay to achieve 100 percent resolved sensitivity. The seroconversion sensitivities of the EIA and the AxSYM IgG were equivalent, detecting the same bleed as positive in the majority of the seroconversion panels tested. The median TT-CMV residual risk estimate for the two assays was approximately 1 in 66,000 (range, 42,000-165,000). CONCLUSION: The AxSYM IgG MEIA is suitable for blood donor screening and was optimized by applying a modified cutoff of 9 AU per mL. The modeling predicts that implementing the AxSYM IgG assay would not negatively impact the already very low risk of TT-CMV associated with seronegative blood components in Australia.H uman cytomegalovirus (CMV) is a ubiquitous betaherpesvirus that generally causes asymptomatic infection in the 40 to 90 percent of individuals it infects.1 However, transfusiontransmitted CMV (TT-CMV) can cause serious morbidity and mortality in susceptible patients particularly when immunocompromised. At-risk patient populations include preterm CMV-seronegative neonates, seronegative recipients of autologous or allogeneic marrow or peripheral blood stem cell transplantation, solid organ transplant recipients, and CMV-seronegative AIDS patients. [2][3][4] The primary mechanism for TT-CMV is thought to be the infusion of latently infected mononuclear cells; however, reinfection or reactivation in seropositive recipients has also been reported. 5,6 The detection of CMV DNA in the plasma of some newly infected blood donors suggests the possibility that plasma viremia might also contribute to the incidence of TT-CMV. 7 The incidence of TT-CMV in susceptible patients, which was reported in the range of 10 to 40 percent in the 1970s and 1980s, has declined substantially to 1 to 4 percent as a result of CMV antibody screening and more recently leukodepletion of donated blood. 8,9 There has been substantial debate about the value of maintaining CMV antibo...