Steven H Kleinman

University of British Columbia - Vancouver, Vancouver, British Columbia, Canada

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Publications (46)410.49 Total impact

  • Article: Comparative analysis of triplex nucleic acid test assays in United States blood donors.
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    ABSTRACT: BACKGROUND: This study assessed the clinical sensitivity of three fully automated, human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) triplex nucleic acid test (NAT) assays by individual donation (ID-NAT) and at operational minipool (MP-NAT) sizes used worldwide. STUDY DESIGN AND METHODS: MPX, Ultrio, and Ultrio Plus were used to test 2222 pedigreed, marker-positive samples with varying viral loads, each from a unique US blood donor. NAT-positive, seronegative yield samples (16 HBV, 156 HCV, and 23 HIV) were tested in replicates of three; undiluted; and in 1:6, 1:8, and 1:16 dilutions (MP6, MP8, and MP16), simulating various MP sizes. Seropositive samples (1276 HBV, 488 HCV, and 263 HIV) were tested by ID-NAT in singlet. RESULTS: MPX-MP6 and Ultrio Plus-MP16 had equivalent HCV sensitivity. Although Ultrio Plus-MP16 for HIV trended toward lesser sensitivity, this was not corroborated in a large substudy of low-viral-load samples in which Ultrio Plus-MP8/MP16 showed 100% reactivity. MPX-ID and Ultrio Plus-ID HBV clinical sensitivity were identical, but MPX-MP6 was significantly more sensitive than Ultrio Plus-MP16; the differential yield projected to one HBV NAT yield per 4.72 million US donations. Ultrio Plus HBV sensitivity did not increase at MP8 versus MP16. Ultrio Plus versus Ultrio sensitivity was significantly increased in HBV-infected donors with early acute, late acute or chronic, and occult infections. No difference in sensitivity was noted for any virus for MPX-MP6 versus Ultrio Plus-ID. CONCLUSIONS: Our data support US donation screening with MPX-MP6 or Ultrio Plus-MP16 since the HBV DNA detection of Ultrio Plus was significantly enhanced (vs. Ultrio) without compromising HIV or HCV RNA detection.
    Transfusion 04/2013; · 3.22 Impact Factor
  • Article: Emerging infectious agents and the nation's blood supply: responding to potential threats in the 21st century.
    Transfusion 06/2012; · 3.22 Impact Factor
  • Article: Genetic diversity of recently acquired and prevalent HIV, hepatitis B virus, and hepatitis C virus infections in US blood donors.
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    ABSTRACT: Genetic variations of human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) can affect diagnostic assays and therapeutic interventions. Recent changes in prevalence of subtypes/genotypes and drug/immune-escape variants were characterized by comparing recently infected vs more remotely infected blood donors. Infected donors were identified among approximately 34 million US blood donations, 2006-2009; incident infections were defined as having no or low antiviral antibody titers. Viral genomes were partially sequenced. Of 321 HIV strains (50% incident), 2.5% were non-B HIV subtypes. Protease and reverse transcriptase (RT) inhibitor resistance mutations were found in 2% and 11% of infected donors, respectively. Subtypes in 278 HCV strains (31% incident) yielded 1a>1b>3a>2b>2a>4a>6d, 6e: higher frequencies of 3a in incident cases vs higher frequencies of 1b in prevalent cases were found (P = .04). Twenty subgenotypes among 193 HBV strains (26% incident) yielded higher frequencies of A2 in incident cases and higher frequencies of A1, B2, and B4 in prevalent cases (P = .007). No HBV drug resistance mutations were detected. Six percent of incident vs 26% of prevalent HBV contained antibody neutralization escape mutations (P = .01). Viral genetic variant distribution in blood donors was similar to that seen in high-risk US populations. Blood-borne viruses detected through large-scale routine screening of blood donors can complement molecular surveillance studies of highly exposed populations.
    The Journal of Infectious Diseases 03/2012; 205(6):875-85. · 6.41 Impact Factor
  • Article: The difference between fingerstick and venous hemoglobin and hematocrit varies by sex and iron stores.
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    ABSTRACT: Fingerstick blood samples are used to estimate donor venous hemoglobin (Hb). Fingerstick Hb or hematocrit (Hct) was determined routinely for 2425 selected donors at six blood centers, along with venous Hb. Using sex and measures of iron status including absent iron stores (AIS; ferritin < 12 ng/mL), linear regression models were developed to predict venous Hb from fingerstick. Across all subjects, fingerstick Hb was higher than venous Hb in the higher part of the clinical range, but lower in the lower part of the range. The relationship varied by sex and iron status. Across centers, a female donor had on average a venous Hb result 0.5 to 0.8 g/dL lower than a male donor with the same fingerstick Hb and iron status. Similarly, a donor with AIS had on average a venous Hb result 0.3 to 1.1 g/dL lower than an iron-replete donor with the same fingerstick value and sex. An iron-replete male donor with a fingerstick result at the cutoff (Hb 12.5 g/dL) had an acceptable expected venous Hb (12.8 to 13.8 g/dL). A female donor with AIS with a fingerstick result at the cutoff had an expected venous Hb below 12.5 g/dL (11.7 to 12.4 g/dL). Of females with AIS, 40.2% donated blood when their venous Hb was less than 12.5 g/dL. Fingerstick is considered a useful estimator of venous Hb. However, in some donor groups, particularly female donors with AIS, fingerstick overestimates venous Hb at the donation cutoff. This significant limitation should be considered in setting donor fingerstick Hb or Hct requirements.
    Transfusion 10/2011; 52(5):1031-40. · 3.22 Impact Factor
  • Article: Surveillance of transfusion-transmissible infections comparison of systems in five developed countries.
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    ABSTRACT: Most industrialized countries maintain surveillance programs for monitoring transmissible infection in blood donations, revising approaches to methodology and risk assessment as new threats emerge. A comparison of programs in the United States, Canada, France, the UK, and Australia indicates that they have similar function, although the structure of blood programs vary as does the extent and nature of formal ties with public health. The emergence of HIV in the late 1970s and early 1980s was key in recognizing that surveillance systems specific to blood transfusion were essential. Hence, most industrialized countries monitor transfusion-transmissible infections in donors and evaluate the impact of new testing and of predonation screening strategies. Emerging infections since HIV have had different transmission pathways and challenged blood programs to draw upon resources for a rapid and effective response, with recognition that the original focus on sexual/drug-related risk of HIV and hepatitis was inadequate. The focus of surveillance programs on new and emerging pathogens fulfills a key role in risk assessment and policy formulation. The precise nature of such activities varies by country because of the structure of the blood programs and surveillance systems, the strategic focus of the blood programs, and the epidemiology of disease in each country.
    Transfusion medicine reviews 09/2011; 26(1):38-57. · 3.61 Impact Factor
  • Article: Sensitivity comparison of two Food and Drug Administration-licensed, triplex nucleic acid test automated assays for hepatitis B virus DNA detection and associated projections of United States yield.
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    ABSTRACT: There have been no comparisons of the relative sensitivity of the two Food and Drug Administration-licensed multiplex (MPX) nucleic acid test (NAT) systems (Procleix Ultrio [Gen-Probe], TIGRIS platform [Novartis]; and cobas TaqScreen MPX [Roche Molecular Systems], cobas s 201 platform [Roche Instrument Center]) for detecting hepatitis B virus (HBV)-infected donors in minipool sizes (MP) used in the United States. Routine blood samples from Thailand were obtained from plasma units from 129 hepatitis B surface antigen (HBsAg)-negative, HBV NAT-yield donations. Blinded US testing included antibody to hepatitis B core antigen (anti-HBc), NAT using both manufacturers' systems (undiluted-individual donation [ID], in singlet and diluted 1:6 and 1:16 in triplicate), quantitative antibody to hepatitis B surface antigen, HBV DNA viral loads, and HBV genotyping. HBV yields in the United States were estimated using the incidence/window period (WP) model and compared to the calculated assay sensitivities. Eighty samples were classified as occult HBV (anti-HBc reactive) and 49 as WP (anti-HBc nonreactive). For US pool sizes, MPX detected significantly more samples than Ultrio (MPX MP6 vs. Ultrio MP16; p < 0.0001 for occult and WP). Ultrio MP16 results were not statistically different from Ultrio MP6 (p = 0.68 for occult; p = 0.42 for WP). There was no difference between platforms for MP sizes used in most of the world (MPX MP6 vs. Ultrio ID; p = 0.70 for occult and p = 0.34 for WP). Viral loads were higher in WP samples. Modeled yield estimates were consistent with measured assay sensitivity on the Thai donor samples. As used in the United States, MPX MP6 is more sensitive than Ultrio MP16, but the impact of this difference is mitigated by low numbers of HBV WP infections.
    Transfusion 09/2011; 51(9):2012-22. · 3.22 Impact Factor
  • Article: The Leukocyte Antibody Prevalence Study-II (LAPS-II): a retrospective cohort study of transfusion-related acute lung injury in recipients of high-plasma-volume human leukocyte antigen antibody-positive or -negative components.
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    ABSTRACT: We used a multicenter retrospective cohort study design to evaluate whether human leukocyte antigen (HLA) antibody donor screening would reduce the risk of transfusion-related acute lung injury (TRALI) or possible TRALI. In the Leukocyte Antibody Prevalence Study-II (LAPS-II), we evaluated pulmonary outcomes in recipients of 2596 plasma-rich blood components (transfusable plasma and plateletpheresis) sent to participating hospitals; half of the components were collected from anti-HLA-positive donors (study arm) and half from anti-HLA-negative donors (control arm) matched by sex, parity, and blood center. A staged medical record review process was used. Final recipient diagnosis was based on case review by a blinded expert panel of pulmonary or critical care physicians. TRALI incidence was 0.59% (seven cases) in study arm recipients versus 0.16% (two cases) in control arm recipients for an odds ratio (OR) of 3.6 (95% confidence interval [CI], 0.7-17.4; p = 0.10). For possible TRALI cases (nine study arm, eight control arm), the OR was 1.2 (95% CI, 0.4-3.0; p = 0.81), and for TRALI and possible TRALI aggregated together, it was 1.7 (95% CI, 0.7-3.7; p = 0.24). Transfusion-associated circulatory overload incidence was identical in the two arms (1.17 and 1.22%, respectively; OR, 1.0; p = 1.0). TRALI incidence in recipients of anti-HLA-positive components was relatively low for a lookback study (1 in 170) and was higher than in the control arm, but did not reach significance. Based on this trend, the data are consistent with the likelihood that TRALI risk is decreased by selecting high-volume plasma components for transfusion from donors at low risk of having HLA antibodies.
    Transfusion 03/2011; 51(10):2078-91. · 3.22 Impact Factor
  • Article: Distribution of parvovirus B19 DNA in blood compartments and persistence of virus in blood donors.
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    ABSTRACT: Because the receptor for parvovirus B19 (B19V) is on red blood cells (RBCs), we investigated B19V distribution in blood by in vitro spiking experiments and evaluated viral compartmentalization and persistence in natural infection. Two whole blood (WB) protocols (ultracentrifugation and a rapid RBC lysis and removal protocol) were evaluated using quantitative real-time polymerase chain reaction. WB was spiked with known concentrations of B19V and recovery in various blood fractions was determined. The rapid RBC lysis and removal protocol was then used to compare B19V concentrations in 104 paired WB and plasma samples collected longitudinally from 43 B19V-infected donors with frozen specimens in the REDS Allogeneic Donor and Recipient Repository (RADAR). In B19V spiking experiments, approximately one-third of viral DNA was recovered in plasma and two-thirds was loosely bound to RBCs. In the immunoglobulin (Ig)M-positive stage of infection in blood donors when plasma B19V DNA concentrations were greater than 100 IU/mL, median DNA concentrations were approximately 30-fold higher in WB than in plasma. In contrast, when IgM was absent and when the B19V DNA concentration was lower, the median WB-to-plasma ratio was approximately 1. Analysis of longitudinal samples demonstrated persistent detection of B19V in WB but declining ratios of WB to plasma B19V with declining plasma viral load levels and loss of IgM reactivity. The WB-to-plasma B19V DNA ratio varies by stage of infection, with 30-fold higher concentrations of B19V DNA in WB relative to plasma during the IgM-positive stage of infection followed by comparable levels during persistent infection when only IgG is present. Further study is required to determine if this is related to the presence of circulating DNA-positive RBCs derived from B19V-infected erythroblasts, B19V-specific IgM-mediated binding of virus to cells, or other factors.
    Transfusion 02/2011; 51(9):1896-908. · 3.22 Impact Factor
  • Article: Establishing assay cutoffs for HLA antibody screening of apheresis donors.
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    ABSTRACT: Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related deaths. Donor HLA antibodies have been implicated in TRALI cases. Blood centers are implementing TRALI risk reduction strategies based on HLA antibody screening of some subpopulations of ever-pregnant apheresis platelet (PLT) donors. However, if screening assay cutoffs are too sensitive, donation loss may adversely impact blood availability. Pregnancy history and HLA antibody screening and single-antigen bead data from blood donors in the Retrovirus Epidemiology Donor Study-II Leukocyte Antibody Prevalence Study were evaluated for correlations between assay screening values, HLA antibody titer, and number of HLA antigen specificities. The probabilities of matching a cognate antigen in a recipient were calculated and examined in association with total number of specificities observed and screening values. The relative impact of imposing various screening assay cutoffs or pregnancy stratification was examined in relation to detection of HLA antibody-reactive donations and loss of donors and donations. We provide evidence that higher HLA antibody screening assay values are associated with maintaining higher screening signals upon dilution and an increased breadth of specificities compared with lower screening values; the latter correlated with an increased risk of a cognate antigen match in potential recipients. Depending on the TRALI risk reduction strategy used, the potential loss of donations ranged between 0.9 and 6.0%. This analysis should enable blood centers to decide upon a TRALI risk reduction strategy for apheresis PLTs that is consistent with how much donation loss the blood center can tolerate.
    Transfusion 02/2011; 51(10):2092-101. · 3.22 Impact Factor
  • Article: Agreement among HLA antibody detection assays is higher in ever-pregnant donors and improved using a consensus cutoff.
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    ABSTRACT: HLA antibodies might contribute to the pathogenesis of transfusion-related acute lung injury (TRALI). HLA antibody detection methods include ELISA, flow cytometry, and multiplex bead-based assays, as well as the older lymphocytotoxicity assay, and it is not obvious how to compare results across platforms. Five hundred twenty-five serum samples were selected from 7841 donors in the Leukocyte Antibody Prevalence Study (LAPS) repository based on risk for the development of HLA antibodies, using the number of pregnancies as the risk factor. Subjects included 81 males and females with 0 (n = 187), 1 (n = 67), or 2+ pregnancies (n = 190). Replicate frozen serum aliquots were sent blinded to four different HLA antibody assay manufacturers for detection using five different assays. The flow cytometry and multiplex bead based-assays typically resulted in a larger proportion of HLA antibody positive samples compared with ELISA based assays. Latent variable analysis was used to derive a new set of consensus cutoffs, which yielded similar sensitivities across test platforms and increased concordance amongst assays. Assay agreement was higher in ever pregnant females than in males and never-pregnant females. Different assays resulted in varied positivity rates when the manufacturer's suggested cutoffs were used, demonstrating that care needs to be taken when comparing clinical outcomes data generated using different HLA antibody assays and testing platforms. The method used here, involving latent variable analysis, presents one possible approach to calculating comparable cutoffs that result in broad agreement across assays with respect to positivity designation.
    Transfusion 11/2010; 51(5):1105-16. · 3.22 Impact Factor
  • Article: Prevalence of HLA antibodies in remotely transfused or alloexposed volunteer blood donors.
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    ABSTRACT: HLA antibody testing of previously transfused or pregnant donors may help reduce the risk of transfusion-related acute lung injury (TRALI). However, the prevalence of HLA antibodies in transfused donors has not been well characterized. Transfusion and pregnancy history was obtained from consenting donors. HLA Class I and II antibody testing was performed by multiantigen bead Luminex platform. Cutoff values for Class I and II antibodies used normalized background ratios of 10.8 and 6.9, respectively. Linear probability models were used to evaluate potential associations between HLA alloimmunization and donor characteristics. A total of 7920 donors (2086 males and 5834 females) were tested. HLA antibody prevalence did not significantly differ between 895 transfused (1.7%) and 1138 nontransfused males (1.0%; odds ratio [OR], 1.75; 95% confidence interval [CI], 0.80-3.82]. Prevalence in 45 transfused nulliparous females (4.4%; 95% CI, 0.1%-11.8%) was not different from the 1.6% prevalence in 1732 nontransfused nulliparous females (OR, 2.94; 95% CI, 0.68-12.74). Transfused parous females had higher prevalence than nontransfused counterparts (p = 0.004; OR, 1.39; 95% CI, 1.07-1.80). In a linear probability model, the estimated additive risk of transfusion-induced alloimmunization was only 0.8% (95% CI, -0.2% to 1.8%; p = 0.10). Donor transfusion history showed that 58% of transfusions occurred more than 10 years previously. Transfused volunteer blood donors do not appear to have a significantly higher prevalence of HLA antibodies than their nontransfused counterparts. Thus, in an effort to reduce TRALI risk, ascertaining past history of transfusion and testing these donors for HLA antibodies is not necessary.
    Transfusion 06/2010; 50(6):1328-34. · 3.22 Impact Factor
  • Article: Identification of specificities of antibodies against human leukocyte antigens in blood donors.
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    ABSTRACT: Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related mortality. Blood centers are implementing TRALI risk reduction strategies based on screening apheresis donors for antibodies to human leukocyte antigens (HLA). HLA antibody screening was performed on 7920 blood donors from the Leukocyte Antibody Prevalence Study (LAPS) using Luminex-based normalized background (NBG) cutoff ratios of 10.8 (Class I) and 6.9 (Class II). Single antigen bead (SAB) assay cutoffs of 2500 median fluorescence intensity units (Class I) and 1500 (Class II) were established based on results of two subpopulations of LAPS donors. Antibody frequencies against HLA A, B, C, DR, DQ, and DP antigens were determined for screen-reactive donors with prior pregnancies. SAB reactivity for samples above our multiantigen bead NBG cutoffs was 78% for Class I and 79% for Class II. The SAB-positive rate increased among women with zero to four or more pregnancies (0.3%-15.6% Class I and 0.4%-18% Class II; p < 0.00001). The highest frequency antibodies were DR11 and B15 (4.4% of women with prior pregnancies). The majority of Class I positives contained more than five specificities. For Class II, antibody-positive women segregated into two groups: a single specificity or more than five specificities. Identification of HLA antigen specificities supports pregnancy associations previously found with screening assays. The significance of particular HLA specificities for inducing TRALI is currently being evaluated in a large lookback study of recipients of high-plasma-volume components from this donor cohort.
    Transfusion 02/2010; 50(8):1749-60. · 3.22 Impact Factor
  • Article: Infectivity of human immunodeficiency virus-1, hepatitis C virus, and hepatitis B virus and risk of transmission by transfusion.
    Steven H Kleinman, Nico Lelie, Michael P Busch
    Transfusion 08/2009; 49(11):2454-89. · 3.22 Impact Factor
  • Article: A linked donor-recipient study to evaluate parvovirus B19 transmission by blood component transfusion.
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    ABSTRACT: Parvovirus B19V infection can be a serious infection for hematology patients with underlying hemolysis or compromised erythropoiesis syndromes. Although case reports of B19V transmission by blood component transfusion (as contrasted to manufactured plasma derivatives) are rare, no studies have systematically determined a rate of transmission to recipients transfused with B19V DNA-positive components. We used a linked donor and recipient repository and a sensitive, quantitative B19V DNA polymerase chain reaction (PCR) assay to assess such transmission in B19V-susceptible (ie, anti-B19V immunoglobulin G [IgG] negative) recipients. We assessed 112 B19V DNA-positive components from 105 donors (of 12 529 tested donations) transfused into a population of surgical patients with a pretransfusion B19V IgG seroprevalence of 78%. We found no transmission to 24 susceptible recipients from transfusion of components with B19V DNA at concentrations less than 10(6) IU/mL (upper 95% confidence interval, 11.7%). We found an anamnestic IgG response in one pretransfusion seropositive recipient transfused with a component containing greater than 10(10) IU/mL B19V DNA. These findings show either that transmission from components with less than 10(6) IU/mL does not occur, or, if it does, it is an uncommon event. These data do not support the need to routinely screen blood donations with a sensitive B19V DNA nucleic acid assay.
    Blood 08/2009; 114(17):3677-83. · 9.90 Impact Factor
  • Article: West Nile virus testing experience in 2007: evaluation of different criteria for triggering individual-donation nucleic acid testing.
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    ABSTRACT: In 2007, clients served by Blood Systems Laboratories used variable approaches for triggering West Nile virus (WNV) RNA individual-donation (ID) nucleic acid testing (NAT). These included two minipool (MP) NAT-reactive donations and a greater than 1:1000 rate in a 7-day interval (primary trigger), criteria based on one MP-NAT-reactive donation when there was WNV activity in overlapping and/or adjacent geographic areas (neighbor trigger), or zero MP-NAT-reactive donation (self-trigger). The Procleix WNV assay was used in either a 16-sample MP or an ID format. NAT-repeat reactivity or anti-immunoglobulin M (IgM) positivity defined true positives (TPs). TPs that were negative on 1:16 dilution testing were considered ID-NAT yield cases. WNV NAT performed on 1,217,929 donations identified 162 TPs; 87 were detected by MP (rate of 0.008%) and 75 by ID (rate of 0.10%; p < 0.0001). There were 34 ID-NAT yield cases, including 4 IgM/immunoglobulin G (IgG)-negative and 9 IgM-positive/IgG-negative donations. Rates of yield cases by primary, neighbor, and self-triggering were 0.077, 0.052, and 0.004% (p = 0.0003). None of 11 ID-NAT yield cases detected by the neighbor trigger would have been detected if the primary trigger had been used. Primary triggering criteria identified 21 viremic donations that would have been missed by MP testing; however, 11 other low-level viremic donations required more stringent criteria (e.g., neighbor trigger) for detection. It is reasonable to adopt more stringent ID-NAT triggers, including elimination of the rate criterion and triggering on one NAT-reactive donation for regions adjacent to centers which have already triggered.
    Transfusion 04/2009; 49(6):1160-70. · 3.22 Impact Factor
  • Article: Long-term in vitro reactivity for human leukocyte antigen antibodies and comparison of detection using serum versus plasma.
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    ABSTRACT: Human leukocyte antigen (HLA) antibodies are a possible cause of transfusion-related acute lung injury (TRALI), and fluorescent bead assays are often used for antibody detection. Serum is the manufacturer's recommended sample, but plasma may be easier to obtain for studies of HLA antibody prevalence and TRALI case investigations. Specimens were obtained from 44 multiparous females positive for the presence of HLA antibodies by lymphocytotoxicity testing at least 13 years prior and from 1000 contemporary blood donors. Screening tests were performed using a multiplex bead-based assay. In addition to comparing results obtained with paired plasma and serum samples, the effects of storage at 4 degrees C for 1 week and of multiple freeze-thaw cycles were evaluated. Of 42 evaluable subjects with HLA antibodies documented more than 13 years earlier, only 1 showed loss of detectable antibodies, with 39 (93%) positive in the screening assay for HLA Class I and 24 (57%) positive in the screening assay for HLA Class II antibodies. In 968 evaluable contemporary donors, 291 screened positive for the presence of HLA Class I and 206 for HLA Class II antibodies using a low assay cutoff. Screening test concordance using paired plasma and serum samples was high, particularly for subjects with higher-level antibodies. Refrigeration of samples for 1 week did not significantly affect assay results, while repeated freeze-thaw cycles caused a decrement in signal level. Serum and plasma samples gave concordant results in the majority of cases, particularly for specimens with higher-level antibodies. High-level HLA antibodies were present in most individuals for more than 13 years.
    Transfusion 11/2008; 49(2):243-51. · 3.22 Impact Factor
  • Article: Virus and antibody dynamics in acute west nile virus infection.
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    ABSTRACT: The dynamics of the early stages of West Nile virus (WNV) infection can be assessed by follow-up studies of viremic blood donors. A total of 245 donors with WNV viremia were followed up weekly for 4 weeks and then monthly for up to 6 additional months or until seroconversion. Plasma samples were tested for WNV RNA by transcription-mediated amplification (TMA) and for WNV-specific IgM and IgG antibodies. RNA persistence was investigated by 6 replicate TMA tests; samples that were viremic for >40 days were tested for WNV-neutralizing activity. Follow up of 35 additional viremic donors for up to 404 days was conducted to evaluate persistence of WNV-specific antibody. The median time from RNA detection to IgM seroconversion was 3.9 days; to IgG seroconversion, 7.7 days; to RNA negativity by single-replicate TMA, 13.2 days; and to RNA negativity by 6-replicate TMA, 6.1 additional days after results of single-replicate TMA are negative. For 4 donors in whom RNA persisted for >40 days after the index donation, all samples obtained after this threshold were also positive for WNV IgG and neutralizing activity. The mean times to IgM and IgA negativity were 156 and 220 days, respectively. IgM and IgG develop rapidly after viremia and before RNA levels become undetectable, which occurred a mean of 13.2 days after the index donation among donors in this study. WNV RNA detection by replicate TMA rarely persists for >40 days after the index donation and is accompanied by WNV-specific neutralizing antibody, consistent with an absence of WNV transmission via transfusion of seropositive blood components.
    The Journal of Infectious Diseases 10/2008; 198(7):984-93. · 6.41 Impact Factor
  • Article: Prevalence and quantitation of parvovirus B19 DNA levels in blood donors with a sensitive polymerase chain reaction screening assay.
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    ABSTRACT: Blood donor parvovirus B19 DNA prevalence with sensitive nucleic acid test assays has recently been demonstrated to be higher than that found with assays designed to detect high viral titers in the plasma manufacturing sector. Stored plasma aliquots from 5020 donations collected between 2000 and 2003 at seven US blood centers were tested. Testing was performed with a real-time B19 DNA polymerase chain reaction (PCR; TaqMan, Applied Biosystems) assay with a 50 percent limit of detection (LOD) of 1.6 IU per mL (95% confidence interval [CI], 1.2-2.1 IU/mL) and a 95 percent LOD of 16.5 IU per mL (95% CI, 10.6-33.9 IU/mL). Confirmation and quantitation of B19 DNA was accomplished by retesting of two additional subaliquots. Confirmed-positive specimens were tested for the presence of anti-B19 immunoglobulin M (IgM) and IgG with FDA-licensed assays. B19 DNA prevalence was 0.88 percent (95% CI, 0.64%-1.2%). Among the 23 donations with B19 DNA titers of at least 20 IU per mL, the median DNA concentration was 105 IU per mL with an interquartile range of 42 to 481 IU per mL; the highest value was 1869 IU per mL. All B19 DNA-positive donations were positive for the presence of IgG and 10 (23%) were also positive for the presence of IgM; IgM seropositivity was associated with increasing DNA levels (p = 0.0013). Low-level B19 DNA was detected in nearly 1 percent of donations. The 23 percent of DNA-positive donations with both IgM and IgG B19 antibody most likely represent acute resolving infection, whereas those with IgG but no IgM are most consistent with a more chronic and possibly persistent phase of B19 infection.
    Transfusion 11/2007; 47(10):1756-64. · 3.22 Impact Factor
  • Article: Current incidence and estimated residual risk of transfusion-transmitted infections in donations made to Canadian Blood Services.
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    ABSTRACT: New testing methods such as nucleic acid amplification testing (NAT) and chemiluminescent serologic assays have been introduced, more precise estimates for infectious window periods are available, and a new method for estimating the residual risk (RR) of transfusion-transmitted infections (TTIs) has been developed. Thus, available RR estimates for Canada need to be updated. Incidence rates for known TTI markers were determined for all allogeneic whole-blood donations made to Canadian Blood Services between 2001 and 2005; they were derived from NAT conversions or seroconversions of repeat donors with at least two donations in a 3-year period. RR estimates for human immunodeficiency virus (HIV)-1 and hepatitis C virus (HCV) derived from the classical incidence/window-period model were compared to those obtained by the new method that estimates incidence from NAT-positive, antibody-negative donations (NAT-yield cases) from all donors divided by person-years. With the classical method, the RR of HIV (1 per 7.8 million donations) and HCV (1 per 2.3 million) were low; HBV RR was higher (1 per 153,000). HCV RR was significantly lower when estimated with the new method (1 per 13 million). Eleven HCV NAT-yield cases were predicted by applying the classical method to our seroconversion data but only 2 were observed (p = 0.011). Observed HIV-1 NAT-yield cases (n = 1) matched those predicted (n = 0.7). New tests have reduced an already low risk of TTI in Canada. HCV RR estimates by two different methods differed but both were low.
    Transfusion 03/2007; 47(2):316-25. · 3.22 Impact Factor
  • Article: Two-year experience with aerobic culturing of apheresis and whole blood-derived platelets.
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    ABSTRACT: Throughout its system of regional centers, Blood Systems implemented culture based bacterial testing with a standardized protocol for both apheresis and whole blood-derived platelets (PLTs). After a 24-hour hold, 4 mL of PLT product was inoculated into an aerobic bottle (BacT/ALERT, bioMérieux). Cultures were incubated for 24 hours before routine product release to prevent distribution of infected products while minimizing consignee notification, product retrievals, and hospital PLT inventory problems. Initial-positives were further tested (and bacteria identified) by performing cultures from the original component and subcultures from the BacT/ALERT bottle. Results were categorized according to AABB recommended definitions with minor modifications. The rate of true-positive detections from culturing 122,971 apheresis PLTs was 0.017 percent (95% confidence interval [CI], 0.011%-0.026%). All true-positive microorganisms were Gram-positive with a predominance of coagulase-negative Staphylococcus and Bacillus species. Twenty of the 21 true-positive samples (95%) were detected by 24 hours but only 14 (68%) were detected by 18 hours. The false-positive rate due to contamination was 0.1 percent with the majority of isolates being skin or environmental organisms. Results did not differ significantly for whole blood-derived versus apheresis PLTs. These data corroborate the fact that the rate of detection of truly contaminated PLT apheresis products in the United States is approximately 1 in 5000 (0.02%); this is lower than the 0.03 to 0.05 percent rates that were generally quoted in the literature before the implementation of prospective bacterial culturing programs.
    Transfusion 11/2006; 46(10):1787-94. · 3.22 Impact Factor

Institutions

  • 2009–2013
    • University of British Columbia - Vancouver
      Vancouver, British Columbia, Canada
  • 2005–2012
    • Blood Systems Research Institute
      San Francisco, CA, USA
  • 2011
    • Société canadienne du sang
      Ottawa, Ontario, Canada
  • 2004–2011
    • Red Cross
      Washington, D. C., DC, USA
    • Abbott Laboratories
      • Abbott Laboratories
      North Chicago, IL, USA
  • 2005–2008
    • University of California, San Francisco
      San Francisco, CA, USA
  • 2002–2003
    • Westat
      Rockville, MD, USA