The impact on blood donor screening for human immunodeficiency virus, hepatitis C virus, and hepatitis B virus using plasma from frozen-thawed plasma preparation tubes.

BACKGROUND: Blood services are required to maintain repositories of frozen samples for confirmation of results and/or retrospective testing. The Australian Red Cross Blood Service archives donor samples in plasma preparation tubes (PPTs). This study aims to evaluate the effect of freeze-thawing and extended frozen storage on the ability to detect human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) using blood donation screening assays in samples stored in PPTs. STUDY DESIGN AND METHODS: Whole blood was spiked with HIV-, HCV-, or HBV-reactive plasma at high and low viral loads and stored in PPTs or as plasma aliquots. All samples were frozen and stored at not more than -30°C. At 0, 3, 6, 12, 18, and 36 months, samples were tested for HIV and HCV antibodies, HBV surface antigen, and viral nucleic acid. Additional samples were thawed and refrozen either once or twice before testing to simulate up to three freeze-thaw cycles. RESULTS: All PPT and plasma aliquots retained appropriate viral reactivity, including those with multiple freeze-thaw cycles, on both nucleic acid testing and serology platforms. CONCLUSION: Frozen storage of biologicals in PPTs, as opposed to plasma aliquots, does not affect the ability to detect HIV, HCV, and HBV using viral nucleic acid or serology donation screening systems for up to 36 months. Freezing and thawing PPT samples did not impact the ability to detect these viruses. Our study demonstrates that PPTs appear to be an appropriate receptacle for frozen plasma sample archiving for up to 3 years.

Detection of emergent strains of West Nile virus with a blood screening assay.

BACKGROUND: West Nile virus (WNV) is a threat to transfusion safety. WNV Kunjin strain (WNVKUN ) is endemic across parts of Australia; however, human infection is believed to be infrequent and is often associated with relatively minor symptoms. A virulent strain, closely related to WNVKUN (termed WNVNSW2011 ) was recently identified as the etiologic agent of encephalitis in Australian horses. The aim of this project was to investigate whether a commercially available WNV blood screening assay can detect different strains of WNVKUN , including the virulent WNVNSW2011 , in human blood donor samples. STUDY DESIGN AND METHODS: Plasma samples were spiked with four different strains of WNVKUN , as well as a prototype WNV strain, at high, medium, and low viral loads. Spiking was confirmed with real-time reverse transcription-polymerase chain reaction (RT-PCR), before testing with the Procleix WNV transcription-mediated amplification (TMA) blood screening assay (Grifols). RESULTS: All WNV strains used were detectable by RT-PCR after being spiked into plasma. Additionally, all viral spiked samples were reactive by WNV TMA. CONCLUSION: We experimentally demonstrate that a commercially available WNV blood screening assay can detect different strains of WNVKUN . Given that WNV can be transfusion transmissible, it is essential to confirm that emergent strains are detectable by existing blood screening methods.

Trends in transfusion-transmissible infections among Australian blood donors from 2005 to 2010.

BACKGROUND: Routine monitoring of trends in transfusion-transmissible infections (TTIs) is essential to maintaining and improving transfusion safety. Although periodic studies have been published there is no comprehensive trend analysis for TTIs in Australian donors. This study determined recent trends in TTIs for which testing is conducted in Australia and described key attributes of infected blood donors. STUDY DESIGN AND METHODS: This is a retrospective analysis using data on donation testing for TTIs (2005-2010) from the national blood service donor database and data on postdonation interviews with TTI-positive donors (2008-2010) from a risk factor database incorporating responses to standardized interview questions. The study measured the prevalence and incidence of TTIs in Australia and assessed their time trends. Multivariate analysis of time trends was conducted using Poisson regression models. RESULTS: Overall, the prevalence and incidence of TTIs in 2005 to 2010 remained low and steady. The prevalence of hepatitis C virus decreased (rate ratio [RR], 0.93; 95% confidence interval [CI], 0.89-0.97) and the prevalence of active syphilis increased (RR, 1.51; 95% CI, 1.15-1.99) significantly during the study period. Prevalence of TTIs among Australian blood donors was substantially lower than that in the general population and no unique risk factors were identified in test-positive blood donors when compared with the general population. CONCLUSION: Both the prevalence and the incidence of TTIs in Australian blood donors remained low, with a steady or declining trend for most infections except active syphilis. The lower prevalence of TTIs in blood donors compared with the general population reflects the effectiveness of donor education and donor selection measures in Australia.

Assessing the accuracy of three viral risk models in predicting the outcome of implementing HIV and HCV NAT donor screening in Australia and the implications for future HBV NAT.

BACKGROUND: Risk modeling is now the most practical method of estimating the residual risk of viral transmission in developed countries. One method of assessing the accuracy of a risk model is to measure the observed against the predicted outcome after implementing a new screening method. The primary objective of this paper is to assess the accuracy of three published models in predicting the impact of implementing HIV and HCV NAT in Australia. STUDY DESIGN AND METHODS: Viral screening data on Australian donors for 2000 and 2001 were retrospectively analyzed. The data were applied to the three models to estimate the risk of transmission and predicted NAT yield for HIV, HCV, and HBV. RESULTS: The median risk estimates for the three models were 1 in 3,415,000 for HIV NAT, 1 in 911,000 for HCV NAT, and 1 in 483,000 for HBsAg. The predicted NAT yield for the three models ranged from 0.17 to 0.30 per million donations for HIV, 1.20 to 5.55 for HCV, and 0.47 to 1.01 for HBV. The observed NAT yield was not significantly different from the expected yield with any of the three models for either HIV or HCV. CONCLUSIONS: First, the residual risk in Australian donors is small in comparison with other transfusion complications and comparable to or lower than the risk in US and European nonremunerated donors. Second, mathematical risk modeling has sufficient precision to be used as a predictive tool for risk-benefit assessments of novel screening procedures. Finally, in relation to the case for implementing HBV NAT and/or anti-HBc in Australia, we conclude that at present, there is inadequate information about our donor population to perform an evidence-based risk-benefit analysis.