Improved blood banking practices and the development and implementation of increasingly sensitive serological and nucleic acid amplification technology (NAT) assays for screening donors for HCV over the past few decades have helped minimize the residual risk from transfusion-transmitted HCV in the developed world. Furthermore, studies of transfusion-transmitted infections and of donors identified as infected by routine screening have provided significant insights into HCV transmission, epidemiology and pathogenesis. However, transfusion-transmission of HCV is still a significant route of infection in the developing world. Key preventive mechanisms to ensure safe blood include elimination of paid donors and development of national donor pools comprised of volunteer repeat blood donors, combined with implementation of standardized and maximally sensitive screening assays for HCV. There is also a need to develop up-to-date data on HCV disease burden on a global scale, in part derived from systematic screening of donors for HCV. We suggest the creation of blood donor databases and specimen repositories, both at national and international levels, to facilitate epidemiological surveillance and pathogenesis and treatment studies in the future.
The Retrovirus Epidemiology Donor Study (REDS), conducted from 1989–2001, and the Retrovirus Epidemiology Donor Study-II (REDS-II), conducted from 2004–2012, were National Heart Lung and Blood Institute (NHLBI) funded multicenter programs focused on improving blood safety and availability in the United States. REDS-II also included international study sites in Brazil and China. The three major research domains of REDS/REDS-II have been infectious disease risk evaluation, blood donation availability, and blood donor characterization. Both programs have made significant contributions to transfusion medicine research methodology by the use of mathematical modeling, large-scale donor surveys, innovative methods of repository sample storage, and establishing an infrastructure that responded to potential emerging blood safety threats such as XMRV. Blood safety studies have included protocols evaluating epidemiologic and/or laboratory aspects of HIV, HTLV I/II, HCV, HBV, WNV, CMV, HHV-8, B19V, malaria, CJD, influenza, and T. cruzi infections. Other analyses have characterized: blood donor demographics, motivations to donate, factors influencing donor return, behavioral risk factors, donors’ perception of the blood donation screening process, and aspects of donor deferral. In REDS-II, two large-scale blood donor protocols examined iron deficiency in donors and the prevalence of leukocyte antibodies. This review describes the major study results from over 150 peer-reviewed articles published by these two REDS programs. In 2011, a new seven year program, the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III), was launched. REDS-III expands beyond donor-based research to include studies of blood transfusion recipients in the hospital setting, and adds a third country, South Africa, to the international program.
blood safety; transfusion-transmitted infections; blood availability; blood donors
Prior to the identification of hepatitis C virus (HCV), transfusion-transmission was common. Viral transmission in subjects with a known date of infection allows the study of the immune responses to acute HCV infection. We analysed 39 soluble immune factors in serum samples from subjects with transfusion-transmitted HCV. Dynamic expression kinetics of interferon gamma-induced protein 10 (IP-10), tumour necrosis factor-alpha and interleukin (IL)-10 were observed during acute HCV infection. Serum IP-10 was the only analyte that was significantly elevated in HCV resolvers compared with uninfected controls. In individuals who progressed to chronic HCV elevated levels of IP-10 and IL-10 coincided with first significant alanine aminotransferase elevation and remained elevated during the first year of acute HCV infection. In addition to monitoring lack of reduction in viral load, serum levels of IP-10 and IL-10 expression during acute HCV infection may be useful biomarkers to predict the progress to chronic HCV.
In patients with chronic hepatitis C, the hepatitis C virus (HCV) RNA level is an important predictor of treatment response. To explore the relationship of HCV RNA with viral and demographic factors, as well as IL28B genotype, we examined viral levels in an ethnically diverse group of injection drug users (IDUs). Between 1998 and 2000, the Urban Health Study (UHS) recruited IDUs from street settings in San Francisco Bay area neighborhoods. Participants who were positive by HCV EIA were tested for HCV viremia by a bDNA assay. HCV genotype was determined by sequencing the HCV NS5B region. For a subset of participants, IL28B rs12979860 genotype was determined by Taqman. Among 1701 participants with HCV viremia, median age was 46 years and median duration of injection drug use was 26 years; 56.0% were African American and 34.0% were of European ancestry (non-Hispanic). HIV-1 prevalence was 13.9%. The overall median HCV RNA level was 6.45 log10 copies/ml. In unadjusted analyses, higher levels were found with older age, male gender, African American ancestry, HBV infection, HIV-1 infection and IL28B rs12979860-CC genotype; compared to participants infected with HCV genotype 1, HCV RNA was lower in participants with genotype 3 or genotype 4. In an adjusted analysis, age, gender, racial ancestry, HIV-1 infection, HCV genotype and IL28B rs12979860 genotype were all independently associated with HCV RNA. Conclusion: The level of HCV viremia is influenced by a large number of demographic, viral and human genetic factors.
epidemiology; genetics; HCV; IL28B; viremia
Bi-directional trafficking of cells between the mother and the fetus is routine in pregnancy and a component of maternal-fetal tolerance. Changes in fetal-to-maternal cellular trafficking have been reported in prenatal complications, but maternal-to-fetal trafficking has never been studied in the context of fetal intervention. We hypothesized that patients undergoing open fetal surgery would have altered maternal-fetal cellular trafficking.
Cellular trafficking was analyzed in patients with myelomeningocele (MMC) who underwent open fetal surgical repair (n=5), MMC patients who had routine postnatal repair (n=6), and normal term patients (n=9). As a control for the fetal operation, trafficking was also analyzed in patients who were delivered by an ex utero intrapartum treatment (EXIT) procedure (n=6). Microchimerism in maternal and cord blood was determined using quantitative real-time PCR for non-shared alleles.
Maternal-to-fetal trafficking was significantly increased in patients who underwent open fetal surgery for MMC compared to normal controls, postnatal MMC repair, and EXIT patients. There were no differences in fetal-to-maternal cell trafficking between groups.
Patients undergoing open fetal surgery for MMC have elevated levels of maternal microchimerism. These results suggest altered trafficking and/or increased proliferation of maternal cells in fetal blood and may have important implications for preterm labor.
Fetal surgery; myelomeningocele; spina bifida; maternal-fetal cellular trafficking; microchimerism; preterm labor; EXIT
Recent-infection testing assays/algorithms (RITAs) have been developed to exploit the titer and avidity of HIV antibody evolution following seroconversion for incidence estimation. The Vitros Anti-HIV 1+2 assay (Ortho-Clinical Diagnostics) was approved by the FDA to detect HIV-1 and HIV-2 infections. We developed a less-sensitive (LS) and an avidity-modified version of this assay to detect recent HIV infection. Seroconversion panels (80 subjects, 416 samples) were tested to calculate the mean duration of recent infection (MDR) for these assays. A panel from known long-term (2+ years) HIV-infected subjects on highly active antiretroviral therapy (HAART) (n = 134) and subjects with low CD4 counts (AIDS patients [n = 140]) was used to measure the false-recent rate (FRR) of the assays. Using a signal-to-cutoff ratio of 20 and the LS-Vitros assay gave a RITA MDR of 215 days (95% confidence interval [95% CI], ±65 days) and using an avidity index (AI) of 0.6 gave an MDR of 170 days (±44 days), while a combination of the two assays yielded a MDR of 146 days (±38.6) and an FRR of 8%. Misclassifying subjects with known long-term infection as recently infected occurred in 14% of AIDS patients and 29% (95% CI, 22, 38) of HAART subjects and 3% (95% CI, 0.8, 7.2) and 42% (95% CI, 33, 51), respectively, for the LS- and avidity-modified Vitros assays, with a misclassification rate of 15% (95% CI, 11, 20) overall using a dual-assay algorithm. Both modified Vitros assays can be used to estimate the length of time since seroconversion and in calculations for HIV incidence. Like other RITAs, they are subject to high FRR in subjects on HAART or with AIDS.
According to the 2007–2008 National Health and Nutrition Examination Survey, the prevalence of obesity in the US population was 33·8 %; 34·3 % and 38·2 %, respectively, in middle-aged men and women. We asked whether available blood donor data could be used for obesity surveillance.
Cross-sectional study of BMI and obesity, defined as BMI ≥ 30·0 kg/m2. Adjusted odds ratios (aOR) were calculated with logistic regression.
A network of six US blood centres.
Existing data on self-reported height and weight from blood donors, excluding persons deferred for very low body weight.
Among 1 042 817 donors between January 2007 and December 2008, the prevalence of obesity was 25·1 %; 25·7 % in men and 24·4 % in women. Obesity was associated with middle age (age 50–59 years v. <20 years: aOR =1·92 for men and 1·81 for women), black (aOR =1·57 for men and 2·35 for women) and Hispanic (aOR =1·47 for men and 1·49 for women) race/ethnicity compared with white race/ethnicity, and inversely associated with higher educational attainment (college degree v. high school or lower: aOR =0·56 for men and 0·48 for women) and double red cell donation and platelet donation.
Obesity is common among US blood donors, although of modestly lower prevalence than in the general population, and is associated with recognized demographic factors. Blood donors with higher BMI are specifically recruited for certain blood collection procedures. Blood centres can play a public health role in obesity surveillance and interventions.
BMI; Obesity; Blood donors; Prevalence; United States; Continental population groups; Age; Educational status
Transfusion-associated microchimerism (TA-MC), the persistence of significant levels of donor leukocytes in blood recipients for prolonged periods, has been demonstrated following non-leukoreduced and leukoreduced transfusion to patients with severe traumatic injury. Development of TA-MC has not been rigorously studied in settings that do not involve massive trauma where the blood is leukoreduced and irradiated.
STUDY DESIGN AND METHODS
A cohort of 409 prospectively followed medical and surgical adult and pediatric female recipients of leukoreduced and mostly irradiated allogeneic red blood cell and platelet transfusions were evaluated to determine development of TA-MC. Four and eight-week post-transfusion samples were analyzed using quantitative real-time polymerase chain reaction (RT-PCR) for Y-chromosome sequences in leukocyte DNA, the marker for microchimeric cells in female blood recipients. Repeat testing was performed on Y-chromosome positive samples to confirm microchimerism (MC), and subsequent post-transfusion samples were tested to investigate persistence of MC.
On initial testing, forty of 207 (19%) adult and forty-four of 202 (22%) pediatric female blood recipients demonstrated low level MC. On repeat testing of these and additional specimens, twelve (3%) recipients demonstrated low level transient MC, but none had persistent TA-MC similar to that seen in transfused trauma patients.
Persistence of MC was not demonstrated in adult and pediatric recipients of leukoreduced and mostly irradiated blood components. The risk of TA-MC appears to be dependent on the clinical setting and is rare other than in patients sustaining severe traumatic injury.
microchimerism; transfusion; irradiation; pediatric; blood recipients
Brazilian blood centers ask candidate blood donors about the number of sexual partners in the last 12 months. Candidates who report a number over the limit are deferred. We studied the implications of this practice on blood safety.
STUDY DESIGN AND METHODS
We analyzed demographic characteristics, number of heterosexual partners, and disease marker rates among 689,868 donations from three Brazilian Centers between July 2007 and December 2009. Donors were grouped based on maximum number of partners allowed in the last 12 months for each center. Chi-square and logistic regression analysis were conducted to examine associations between demographic characteristics, number of sex partners, and individual and overall positive markers rates for HIV, HTLV-1/2, HBV, HCV, and syphilis.
First-time, younger and more educated donors were associated with a higher number of recent sexual partners, as was male gender in São Paulo and Recife (p <0.001). Serologic markers for HIV, syphilis and overall were associated with multiple partners in São Paulo and Recife (p<0.001), but not in Belo Horizonte (p= 0.05, 0.94, 0.75, respectively). In logistic regression analysis, number of recent sexual partners were associated with positive serologic markers (AOR=1.2–1.5) especially HIV (AOR=1.0–4.4).
Number of recent heterosexual partners was associated with HIV positivity and overall rates of serological markers of sexually transmitted infections. The association was not consistent across centers, making it difficult to define the best cut-off value. These findings suggest the use of recent heterosexual contacts as a potentially important deferral criterion to improve blood safety in Brazil.
(See the editorial commentary by Katz, on pages 867–9 and see the article by Stramer et al, on pages 886–94.)
Background. 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.
Methods. 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.
Results. 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).
Conclusions. 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.
(See the article by Delwart et al, on pages 875–85, and see the editorial commentary by Katz, on pages 867–9.)
Background. There have been anecdotal reports of influenza viremia since the 1960s. We present an assessment of the prevalence of seasonal and 2009 H1N1 influenza viremia (via RNA testing) in blood donor populations using multiple sensitive detection assays.
Methods. Several influenza RNA amplification assays, including transcription-mediated amplification (TMA) and 2 reverse-transcription polymerase chain reaction (RT-PCR) assays, were evaluated and used to test donor samples. Retrospective samples from 478 subjects drawn at sites with high influenza activity were tested. Prospective samples were collected from 1004 blood donors who called their donation center within 3 days of donation complaining of influenza-like illness (ILI). The plasma collected on the day of donation for these subjects was tested.
Results. Of the repository samples, 2 of 478 plasma samples were initially reactive but not repeat reactive by influenza TMA. Of blood donors reporting ILI symptoms postdonation, 1 of 1004 samples was TMA initially reactive but not repeat reactive; all samples were nonreactive by RT-PCR testing.
Conclusions. Targeting blood donor populations most likely to have influenza infection, we failed to detect influenza RNA in 1482 donor samples, with most tested by 3 different RNA assays. Seasonal influenza does not appear to pose a significant contamination threat to the blood supply.
Because the receptor for Parvovirus B19 (B19V) is on erythrocytes, we investigated B19V distribution in blood by in-vitro spiking experiments and evaluated viral compartmentalization and persistence in natural infection.
Two whole blood protocols (ultracentrifugation and a rapid RBC lysis/removal protocol) were evaluated using quantitative real-time PCR. Whole blood (WB) was spiked with known concentrations of B19V and recovery in various blood fractions was determined. The rapid RBC lysis/removal protocol was then used to compare B19V concentrations in 104 paired whole blood 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, ~one-third of viral DNA was recovered in plasma and two-thirds was loosely bound to erythrocytes. In the IgM positive stage of infection in blood donors when plasma B19V DNA concentrations were > 100 IU/mL, median DNA concentrations were ~30-fold higher in WB than in plasma. In contrast, when IgM was absent and when the B19V DNA concentration was lower, the median whole blood to plasma ratio was ~1. Analysis of longitudinal samples demonstrated persistent detection of B19V in WB but declining ratios of WB/plasma B19V with declining plasma VL levels and loss of IgM-reactivity.
The WB/plasma B19V DNA ratio varies by stage of infection. Further study is required to determine if this is related to the presence of circulating DNA-positive erythrocytes derived from B19V infected erythroblasts, B19V-specific IgM mediated binding of virus to cells, or other factors.
Transfusion related acute lung injury (TRALI) has been associated with both HLA and HNA antibodies. HNA antibody frequency, specificity, and demographic associations have not been well defined in the blood donor population.
A subset of 1171 donors (388 non-transfused males, 390 HLA antibody negative females with three or more pregnancies, and 393 HLA antibody positive females with three or more pregnancies) from a larger leukocyte antibody prevalence study (LAPS) was tested for IgG and IgM HNA antibody using a granulocyte immunofluorescence flow cytometry assay. Additional testing on selected samples included monoclonal antibody immobilization of granulocyte antigen – flow cytometry and granulocyte genotyping.
Eight samples were HNA antibody positive (prevalence 0.7% [95% CI, 0.3 - 1.3%]). Three HNA antibodies (one IgG and two IgM) were found in non-transfused males (prevalence 0.8% [95% CI, 0.2 - 2.2%]); all were pan-reactive or non-specific. One HLA antibody negative previously pregnant female had an IgG HNA antibody with HNA-1a specificity (prevalence 0.3% [95% CI, 0.01-1.4%]). Four HLA antibody positive previously pregnant females demonstrated HNA antibodies, three IgG and one IgM (prevalence 1% [95% CI, 0.3 - 2.6%]). Two of these were HNA-1a specific, one HNA-4a specific, and one non-specific.
HNA antibodies occur with low frequency in the donor population and are present in both male and female donors. Despite the implementation of TRALI reduction strategies, HNA antibodies are still present in donor blood products. Though our data do not create a case for urgent implementation of donor HNA antibody testing, future new developments for high throughput HNA antibody screening, including for HNA-3a, may warrant reconsideration.
Frequent blood donors become iron deficient. HFE mutations are present in over 30% of donors. A 24-month study of 888 first time/reactivated donors and 1537 frequent donors measured haemoglobin and iron status to assess how HFE mutations impact the development of iron deficiency erythropoiesis. Donors with two HFE mutations had increased baseline haemoglobin and iron stores as did those with one mutation, albeit to a lesser extent. Over multiple donations haemoglobin and iron status of donors with HFE mutations paralleled those lacking mutations. The prevalence of HFE mutations was not increased in higher intensity donors. Thus, in general, HFE mutations do not temper donation-induced changes in haemoglobin and iron status. However, in Black donors there was an increase of H63D carriers at baseline, from 3.7% in first time/reactivated donors to 15.8% in frequent donors, suggesting that the relative effects of HFE mutations on iron absorption may vary between racial/ethnic groups. In secondary analyses, venous haemoglobin decreased more slowly in donors with ferritin ≥ 12 μg/l; and haemoglobin recovery time was shorter in donors with reticulocyte haemoglobin (CHr) ≥ 32.6 pg, indicating that these biochemical measures are better indicators of a donor’s response to phlebotomy than their HFE mutation status.
HFE; blood donor; iron deficiency; haemoglobin; ferritin
Perinatal HIV transmission could occur via microtransfused maternal blood during delivery. If so, detecting maternal cells in umbilical cord blood should correlate with infection risk.
To develop sensitive assays for maternal DNA in infant's blood stored as dried blood spots (DBS) and examine the correlation between microtransfusion and perinatal HIV infection risk.
Blood-in-blood serial dilutions were prepared as DBS. Extracted DNA was amplified for unique minor-population sequences using 24 allele-specific polymerase-chain-reaction (AS-PCR) assays. Using newborns born to HIV+ mothers, paired mother-infant samples were similarly examined to identify unique maternal sequences targeted by AS-PCR of DNA extracted from cord blood DBS. Cord-blood PCR-negative infants were categorized as uninfected or perinatally infected by HIV PCR on samples collected 4–8 weeks after birth.
Sequences from added cells were detected at ≤1:1000 dilutions in 19 of 20 aliquots, and ≤1:10,000 dilutions in 7 of 20 aliquots; the median limit of detection (probit analysis) was 1 added genomic sequence in 9500 background sequences of amplifiable DNA. Maternal sequences were detected in cord-blood DBS of 50% of infected infants (N=18) and 44% of uninfected infants (N=43). Infection did not correlate with more frequent detection of maternal sequences.
This semi-quantitative assay reliably detected maternal DNA sequences in DBS at levels of less than 1:1000 cells. Maternal sequences were frequently detected but did not correlate infection risk with detection or level of maternal DNA in umbilical cord blood. Therefore we could not demonstrate that microtransfusions at parturition were responsible for perinatal HIV transmission.
The mechanisms of HIV transmission from mothers to infants are poorly understood. A possible mechanism of in utero transmission is transplacental transfer of HIV-infected maternal leukocytes into the fetal circulation during pregnancy.
To determine if the frequency of in utero HIV infection correlates with presence or levels of maternal cells (MC) in placenta-derived cord blood.
DNA was extracted from dried cord blood spots (DBS) from newborns born to HIV+ mothers and corresponding maternal DBS specimens. Paired mother-infant samples were probed to identify unique maternal sequences targeted by 24 allele-specific real-time PCR assays. Infant DBS-derived DNA was then probed in replicate analyses for non-inherited maternal allelic-sequences. Rates of detection and levels of maternal cells in DBS samples of HIV(+) and HIV(−) newborns were compared.
Of 114 mother-infant pairs with informative alleles, 38 newborns were HIV(+) and 76 HIV(−), based on detection of HIV DNA/RNA at birth. MC were detected in 23 of 38 HIV(+) newborns (60.5%) and in 47 of 76 HIV(−) newborns (61.8%). The mean and median concentrations of nucleated maternal cells in DBS for the HIV(+)/MC(+) newborns (N=23) were 0.33% and 0.27%, respectively, compared with 0.09% and 0.10% for the HIV(−)/MC(+) newborns (N=47) (Two-Sample T-test for means: p=0.78).
There was no significant difference in rates of detection or concentrations of MC in DBS between HIV(+) and HIV(−) newborns. Therefore, we could not demonstrate a correlation between MC in DBS, assumed to reflect levels of in utero maternal-fetal cell trafficking, and the risk of in utero HIV transmission.
HIV; maternal-fetal transmission; polymerase chain reaction; PCR; microchimerism; placenta
West Nile virus (WNV) is an emerging flavivirus capable of infecting the central nervous system (CNS) and mediating neuronal cell death and tissue destruction. The processes that promote inflammation and encephalitis within the CNS are important for control of WNV disease but, how inflammatory signaling pathways operate to control CNS infection is not defined. Here, we identify IL-1β signaling and the NLRP3 inflammasome as key host restriction factors involved in viral control and CNS disease associated with WNV infection. Individuals presenting with acute WNV infection displayed elevated levels of IL-1β in their plasma over the course of infection, suggesting a role for IL-1β in WNV immunity. Indeed, we found that in a mouse model of infection, WNV induced the acute production of IL-1β in vivo, and that animals lacking the IL-1 receptor or components involved in inflammasome signaling complex exhibited increased susceptibility to WNV pathogenesis. This outcome associated with increased accumulation of virus within the CNS but not peripheral tissues and was further associated with altered kinetics and magnitude of inflammation, reduced quality of the effector CD8+ T cell response and reduced anti-viral activity within the CNS. Importantly, we found that WNV infection triggers production of IL-1β from cortical neurons. Furthermore, we found that IL-1β signaling synergizes with type I IFN to suppress WNV replication in neurons, thus implicating antiviral activity of IL-1β within neurons and control of virus replication within the CNS. Our studies thus define the NLRP3 inflammasome pathway and IL-1β signaling as key features controlling WNV infection and immunity in the CNS, and reveal a novel role for IL-1β in antiviral action that restricts virus replication in neurons.
Since its introduction into North America in 1999, West Nile virus (WNV) has emerged as a leading cause of viral encephalitic disease in the United States. While low level inflammation is important for clearance of WNV, high levels of inflammation are associated with increased disease. The goal of this study was to identify host signaling pathways that control the balance of inflammation and protective immunity to WNV. Using a mouse model of infection, we identified a central nervous system (CNS)-intrinsic requirement for the NLRP3 inflammasome and IL-1β signaling in limiting WNV associated disease within the CNS. First, IL-1β signaling was essential for regulating the magnitude and kinetics of inflammation within CNS. Secondly, the absence of IL-1β signaling disrupted the quality of the effector T lymphocyte response against the virus. Finally, these dysregulated immune responses were linked to a direct ability for IL-1β signaling to synergize with type I IFN signaling and limit virus replication within cortical neurons, key target cells of WNV infection within the CNS. Together this study identifies the NLRP3 inflammasome and IL-1β signaling as key restriction factors that act to regulate viral load and the quality of inflammatory responses within the CNS to impart protective immunity against WNV infection.
Purpose of review
Host genetic factors influencing HCV transmission outcomes are incompletely defined. However, vast differences observed in rates of spontaneous clearance between individuals infected with the same parental HCV strain strongly indicate a role for genetic determinants in the host immune response to HCV. This review discusses genetic association studies, particularly those published in the past year, that show gene linkages with spontaneous and treatment-induced HCV clearance. The valuable role that blood collection centers can play in increasing the sample size of HCV confirmed seropositive donors with resolved versus persistent infections for large-scale genetic association studies is highlighted.
Recent groundbreaking genome-wide association study (GWAS) and targeted single-nucleotide polymorphism (SNP) analysis from independent groups have demonstrated immune response gene polymorphisms, and particularly in the interleukin (IL)-28B gene, that are strongly linked to HCV clearance. The IL-28B gene encodes interferon lambda 3, an innate immune response cytokine. SNPs in the promoter region of IL-28B were first shown to be associated with HCV treatment-induced viral clearance and subsequently to be a key determinant of spontaneous HCV resolution in infected individuals. Samples from blood donors with resolved and chronic HCV infections have contributed to these findings.
These genetic studies have provided the strongest evidence so far of a host genetic determinant linked to HCV clearance. Such large-scale genetic association studies will promote better understanding of HCV disease pathogenesis and assist in effective prognosis of HCV in the future. Continued and preferably expanded participation of blood centers in this research is encouraged.
Hepatitis C virus; HCV; HCV host genetics; HCV clearance; role for blood centers
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 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 (SAB) data from blood donors in the REDS-II Leukocyte Antibody Prevalence Study (LAPS) 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 Ab 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 upon 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 platelets that is consistent with how much donation loss the blood center can tolerate.
TRALI; Transfusion-Related Acute Lung Injury; HLA antibodies; platelet transfusions
Transient HIV infections have been invoked to account for the cellular immune responses detected in highly virus-exposed individuals who have remained HIV seronegative. We tested for very low levels of HIV RNA in 524 seronegative plasma samples from 311 highly exposed women and men from 3 longitudinal HIV cohorts.
2073 transcription mediated amplification (TMA) HIV RNA tests were performed for an average of 3.95 TMA assays per plasma sample. Quadruplicate TMA assays, analyzing a total of 2 ml of plasma, provided an estimated sensitivity of 3.5 HIV RNA copies/ml.
Four samples from subjects who did not sero-convert within the following six months were positive for HIV RNA. For one sample, human polymorphism DNA analysis indicated a sample mix up. Borderline HIV RNA detection signals were detected for the other three positive samples and further replicate TMA testing yielded no positive results. Nested PCR assays (n=254) for HIV proviral DNA on PBMC from these 3 subjects were negative.
Transient viremia was not reproducibly detected in highly HIV exposed seronegative men and women. If transient infections do occur, plasma HIV RNA levels may remain below the detection limits of the sensitive assay used here, be of very short duration, or viral replication may be restricted to mucosal surfaces or their draining lymphoid tissues.
Background and Aims
Characterization of inflammatory mediators, such as chemokines, during acute hepatitis C virus (HCV) infection might shed some light on viral clearance mechanisms.
Plasma levels of CXCR3 (CXCL9-11)- and CCR5 (CCL3-4)-associated chemokines, ALT and HCV RNA were measured in nine injection drug users (median 26 samples/patient) before and during ten acute (eight primary and two secondary) HCV infections. Using functional data analysis, we estimated smooth long-term trends in chemokine expression levels to obtain the magnitude and timing of over-all changes. Residuals were analyzed to characterize short-term fluctuations.
CXCL9-11 induction began 38–53 days and peaked 72–83 days after virus acquisition. Increases in ALT levels followed a similar pattern. Substantial negative autocorrelations of chemokine levels at one week lags suggested substantial week-to-week oscillations. Significant correlations were observed between CXCL10 and HCV RNA as well as ALT and CXCR3-associated chemokines measured in the preceding week, CCL3-4 expression levels did not change appreciably during acute HCV infection.
Elevation of CXCR3-associated chemokines late during acute HCV infection suggests a role for cellular immune responses in chemokine induction. Week-to-week oscillations of HCV RNA, chemokines, and ALT suggest frequent, repeated cycles of gain and loss of immune control during acute hepatitis C.
CXCL9; CXCL10; CXCL11; CCL3; CCL4; inflammation
Background. Identifying persons with recent human immunodeficiency virus (HIV) antibody seroconversion is useful for treatment, research, and prevention, but the sensitivity and specificity of tests for this purpose are uncertain.
Methods. We used longitudinal specimens panels from 155 persons identified prior to HIV seroconversion to assess antibody-based methods for classifying persons as within 30, 60, or 90 days of seroconversion, including 2 incidence assays, a less-sensitive (LS) enzyme immunoassay (EIA), and the BED assay.
Results. Sensitivity and specificity, respectively, for identifying persons within 30 days of seroconversion were: 34%–57% and 98%–100% for 2 standard EIAs (employing a signal-to-cutoff ≤4.0; ≥1.0 defines HIV positive), 84% and 73% for the LS-EIA (≤0.2 cutoff), 88% and 72% for the BED (≤0.2 cutoff), and 43%–58% and 98% (≤3 bands) for 2 Western blot (WB) assays. By area under the receiver operator curves, the best test for identifying persons within 30 days of seroconversion was the number of bands on the Bio-Rad WB (0.90); within 60 days, the LS-EIA and BED (both 0.85); and for persons within 90 days the BED (0.86).
Conclusions. Standard EIAs, Western blots, and HIV incidence assays provide useful information for identifying persons 30 to 90 days after seroconversion.
The first stages of HIV-1 infection are essential to establish the diversity of virus population within host. It has been suggested that adaptation to host cells and antibody evasion are the leading forces driving HIV evolution at the initial stages of AIDS infection. In order to gain more insights on adaptive HIV-1 evolution, the genetic diversity was evaluated during the infection time in individuals contaminated by the same viral source in an epidemic cluster. Multiple sequences of V3 loop region of the HIV-1 were serially sampled from four individuals: comprising a single blood donor, two blood recipients, and another sexually infected by one of the blood recipients. The diversity of the viral population within each host was analyzed independently in distinct time points during HIV-1 infection.
Phylogenetic analysis identified multiple HIV-1 variants transmitted through blood transfusion but the establishing of new infections was initiated by a limited number of viruses. Positive selection (dN/dS>1) was detected in the viruses within each host in all time points. In the intra-host viruses of the blood donor and of one blood recipient, X4 variants appeared respectively in 1993 and 1989. In both patients X4 variants never reached high frequencies during infection time. The recipient, who X4 variants appeared, developed AIDS but kept narrow and constant immune response against HIV-1 during the infection time.
Slowing rates of adaptive evolution and increasing diversity in HIV-1 are consequences of the CD4+ T cells depletion. The dynamic of R5 to X4 shift is not associated with the initial amplitude of humoral immune response or intensity of positive selection.