Genetic variation in IL28B and spontaneous clearance of hepatitis C virus.

Hepatitis C virus (HCV) infection is the most common blood-borne infection in the United States, with estimates of 4 million HCV-infected individuals in the United States and 170 million worldwide. Most (70-80%) HCV infections persist and about 30% of individuals with persistent infection develop chronic liver disease, including cirrhosis and hepatocellular carcinoma. Epidemiological, viral and host factors have been associated with the differences in HCV clearance or persistence, and studies have demonstrated that a strong host immune response against HCV favours viral clearance. Thus, variation in genes involved in the immune response may contribute to the ability to clear the virus. In a recent genome-wide association study, a single nucleotide polymorphism (rs12979860) 3 kilobases upstream of the IL28B gene, which encodes the type III interferon IFN-3, was shown to associate strongly with more than a twofold difference in response to HCV drug treatment. To determine the potential effect of rs12979860 variation on outcome to HCV infection in a natural history setting, we genotyped this variant in HCV cohorts comprised of individuals who spontaneously cleared the virus (n = 388) or had persistent infection (n = 620). We show that the C/C genotype strongly enhances resolution of HCV infection among individuals of both European and African ancestry. To our knowledge, this is the strongest and most significant genetic effect associated with natural clearance of HCV, and these results implicate a primary role for IL28B in resolution of HCV infection.

Characteristics of antibody responses in West Nile virus-seropositive blood donors.

West Nile virus (WNV) is now endemic in the United States. Protection against infection is thought to be conferred in part by humoral immunity. An understanding of the durability and specificity of the humoral response is not well established. We studied the magnitude and specificity of antibody responses in 370 WNV-seropositive blood donors. We also recalled 18 donors who were infected in 2005 to compare their antibody responses at 6 months following infection versus at 5 years postinfection. There were no significant differences in IgG antibody levels based on age, sex, or recent infection (as evidenced by IgM positivity). Specific antibody responses by viral plaque reduction neutralization testing (PRNT) were seen in 51/54 subjects evaluated. All donors who were seropositive in 2005 remained seropositive at 5 years and maintained neutralizing antibodies. IgG levels at 5 years postinfection showed fairly minimal decreases compared with the paired levels at 6 months postinfection (mean of paired differences,-0.54 signal-to-cutoff ratio (S/CO) units [95% confidence interval {CI}, -0.86 to -0.21 S/CO units]) and only minimal decreases in PRNT titers. WNV induces a significant antibody response that remains present even 5 years after infection.

West Nile virus nucleic acid persistence in whole blood months after clearance in plasma: implication for transfusion and transplantation safety.

BACKGROUND: Previous reports of West Nile virus (WNV) RNA persistence in blood compartments have raised concerns around the remaining risk of WNV transfusion transmission. This study characterized the dynamics of WNV viremia in blood compartments in a longitudinal cohort of 54 WNV-infected blood donors. STUDY DESIGN AND METHODS: Blood samples were collected throughout the year after WNV RNA-positive blood donation (index) and characterized for WNV immunoglobulin (Ig)M and IgG antibodies and for WNV RNA by real-time reverse transcription-polymerase chain reaction. WNV viral loads were compared in plasma and whole blood samples and correlated with blood groups and clinical outcomes. RESULTS: WNV RNA persisted in the red blood cell (RBC) compartment up to 3 months postindex in 42% of the donors. Donors with the highest WNV RNA levels in plasma at index maintained the highest WNV RNA levels in whole blood over the 3 months postindex. Blood group A donors maintained higher postindex WNV viral load in whole blood than blood group O individuals (p = 0.027). Despite a trend for WNV RNA to persist longer in whole blood from symptomatic subjects, no significant association was found between WNV RNA levels in whole blood and disease outcome. CONCLUSION: This study confirmed that WNV RNA persists in the RBC fraction in whole blood and further suggested that the level of persistence in whole blood may be a reflection of initial viral burden in plasma. The association with blood groups suggests that WNV adherence to RBCs may be mediated by molecules overrepresented at the surface of blood group A RBCs.

Genome-wide association study of spontaneous resolution of hepatitis C virus infection: data from multiple cohorts.

UNLABELLED: Chinese translation BACKGROUND: Hepatitis C virus (HCV) infections occur worldwide and either spontaneously resolve or persist and markedly increase the person's lifetime risk for cirrhosis and hepatocellular carcinoma. Although HCV persistence occurs more often in persons of African ancestry and persons with genetic variants near interleukin-28B (IL-28B), the genetic basis is not well-understood. OBJECTIVE: To evaluate the host genetic basis for spontaneous resolution of HCV infection. DESIGN: 2-stage, genome-wide association study. SETTING: 13 international multicenter study sites. PATIENTS: 919 persons with serum HCV antibodies but no HCV RNA (spontaneous resolution) and 1482 persons with serum HCV antibodies and HCV RNA (persistence). MEASUREMENTS: Frequencies of 792 721 single nucleotide polymorphisms (SNPs). RESULTS: Differences in allele frequencies between persons with spontaneous resolution and persistence were identified on chromosomes 19q13.13 and 6p21.32. On chromosome 19, allele frequency differences localized near IL-28B and included rs12979860 (overall per-allele OR, 0.45; P = 2.17 × 10-30) and 10 additional SNPs spanning 55 000 base pairs. On chromosome 6, allele frequency differences localized near genes for HLA class II and included rs4273729 (overall per-allele OR, 0.59; P = 1.71 × 10-16) near DQB1*03:01 and an additional 116 SNPs spanning 1 090 000 base pairs. The associations in chromosomes 19 and 6 were independent and additive and explain an estimated 14.9% (95% CI, 8.5% to 22.6%) and 15.8% (CI, 4.4% to 31.0%) of the variation in HCV resolution in persons of European and African ancestry, respectively. Replication of the chromosome 6 SNP, rs4272729, in an additional 745 persons confirmed the findings (P = 0.015). LIMITATION: Epigenetic effects were not studied. CONCLUSION: IL-28B and HLA class II are independently associated with spontaneous resolution of HCV infection, and SNPs marking IL-28B and DQB1*03:01 may explain approximately 15% of spontaneous resolution of HCV infection.

Genetic diversity of recently acquired and prevalent HIV, hepatitis B virus, and hepatitis C virus infections in US blood donors.

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.

Iron deficiency in blood donors: the REDS-II Donor Iron Status Evaluation (RISE) study.

BACKGROUND: Blood donors are at risk of iron deficiency. We evaluated the effects of blood donation intensity on iron and hemoglobin (Hb) in a prospective study. STUDY DESIGN AND METHODS: Four cohorts of frequent and first-time or reactivated (FT/RA) blood donors (no donation in 2 years), female and male, totaling 2425, were characterized and followed as they donated blood frequently. At enrollment and the final visit, ferritin, soluble transferrin receptor (sTfR), and Hb were determined. Models to predict iron deficiency and Hb deferral were developed. Iron depletion was defined at two levels: iron deficiency erythropoiesis (IDE) [log(sTfR/ferritin) ≥ 2.07] and absent iron stores (AIS; ferritin < 12 ng/mL). RESULTS: Among returning female FT and RA donors, 20 and 51% had AIS and IDE at their final visit, respectively; corresponding proportions for males were 8 and 20%. Among female frequent donors who returned, 27 and 62% had AIS and IDE, respectively, while corresponding proportions for males were 18 and 47%. Predictors of IDE and/or AIS included a higher frequency of blood donation in the past 2 years, a shorter interdonation interval, and being female and young; conversely, taking iron supplements reduced the risk of iron depletion. Predictors of Hb deferral included female sex, black race, and a shorter interdonation interval. CONCLUSIONS: There is a high prevalence of iron depletion in frequent blood donors. Increasing the interdonation interval would reduce the prevalence of iron depletion and Hb deferral. Alternatively, replacement with iron supplements may allow frequent donation without the adverse outcome of iron depletion.

Distinct roles of trauma and transfusion in induction of immune modulation after injury.

BACKGROUND: Trauma and transfusion can both alter immunity, and while transfusions are common among traumatically injured patients, few studies have examined their combined effects on immunity. STUDY DESIGN AND METHODS: We tracked the plasma levels of 41 immunomodulatory proteins in 56 trauma patients from time of injury up to 1 year later. In addition, a murine model was developed to distinguish between the effects of transfusion and underlying injury and blood loss. RESULTS: Thirty-one of the proteins had a significant change over time after traumatic injury, with a mixed early response that was predominantly anti-inflammatory followed by a later increase in proteins involved in wound healing and homeostasis. Results from the murine model revealed similar cytokine responses to humans. In mice, trauma and hemorrhage caused early perturbations in a number of the pro- and anti-inflammatory mediators measured, and transfusion blunted early elevations in interleukin (IL)-6, IL-10, matrix metalloproteinase-9, and interferon-γ. Transfusion caused or exacerbated changes in monocyte chemotactic protein-1, IL-1α, IL-5, IL-15, and soluble E-selectin. Finally, trauma and hemorrhage alone increased CXCL1 and IL-13. CONCLUSIONS: This work provides a detailed characterization of the major shift in the immunologic environment in response to trauma and transfusion and clarifies which immune mediators are affected by trauma and hemorrhage and which by transfusion.

Induction of CXCR3- and CCR5-associated chemokines during acute hepatitis C virus infection.

BACKGROUND & AIMS: Characterization of inflammatory mediators, such as chemokines, during acute hepatitis C virus (HCV) infection might shed some light on viral clearance mechanisms. METHODS: 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 10 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 overall changes. Residuals were analyzed to characterize short-term fluctuations. RESULTS: CXCL9-11 induction began 38-53days and peaked 72-83days after virus acquisition. Increases in ALT levels followed a similar pattern. Substantial negative auto-correlations of chemokine levels at 1 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. CONCLUSIONS: 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.

A linked donor-recipient study to evaluate parvovirus B19 transmission by blood component transfusion.

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.

Distribution of parvovirus B19 DNA in blood compartments and persistence of virus in blood donors.

BACKGROUND: 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. STUDY DESIGN AND METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

Large-scale candidate gene analysis of spontaneous clearance of hepatitis C virus.

Human genetic variation is a determinant of recovery from acute hepatitis C virus (HCV) infection; however, to date, single-nucleotide polymorphisms (SNPs) in only a limited number of genes have been studied with respect to HCV clearance. We determined whether SNPs in 112 selected immune response genes are important for HCV clearance, by genotyping 1536 SNPs in a cohort of 343 persons with natural HCV clearance and 547 persons with HCV persistence. PLINK (version 1.05) and Haploview (version 4.1) software packages were used to perform association, permutation, and haplotype analyses stratified by African American and European American race. Of the 1536 SNPs tested, 1426 (92.8%) were successfully genotyped. In African Americans, we identified 18 SNPs located in 11 gene regions that were associated with HCV infection outcome (empirical P value, < .01). In European Americans, there were 20 SNPs located in 8 gene regions associated with HCV infection outcome. Four of the gene regions studied (TNFSF18, TANK, HAVCR1, and IL18BP) contained SNPs for which the empirical P value was <.01 in both of the race groups. In this large-scale analysis of 1426 genotyped SNPs in 112 candidate genes, we identified 4 gene regions that are likely candidates for a role in HCV clearance or persistence in both African Americans and European Americans.

Host genetic basis for hepatitis C virus clearance: a role for blood collection centers.

PURPOSE OF REVIEW: Host genetic factors influencing hepatitis C virus (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 last 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 FINDINGS: Recent groundbreaking genome-wide association study 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. SUMMARY: 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.

A case-control study of factors associated with resolution of hepatitis C viremia in former blood donors (CME).

BACKGROUND: Nucleic acid testing (NAT) is performed on blood collected in the United States allowing for the classification of hepatitis C virus (HCV) antibody-positive donors into resolved and chronic hepatitis C infections. We report a case-control study of factors associated with HCV resolution. STUDY DESIGN AND METHODS: Blood donors with resolved (HCV antibody positive, RNA negative defined as "cases") or chronic (HCV antibody positive, RNA positive defined as "controls") based on their index donation HCV test results were enrolled. Participants completed a risk factor, symptoms, and treatment questionnaire followed by HCV antibody, HCV RNA, and liver biochemical testing. RESULTS: We enrolled 100 cases and 202 controls. In a multivariate logistic regression model, significant independent effects for spontaneous viral clearance were observed for African American (inverse; odds ratio [OR], 0.11; 95% confidence interval [CI], 0.01-0.87), autologous blood donation (OR, 4.70; 95% CI, 2.02-10.94), alcohol intake (OR, 2.39; 95% CI, 1.13-5.03), and transfusion before May 1990 (inverse; OR, 0.36; 95% CI, 0.14-0.91). Cases admitting injection drug use had shorter time since first injection than did controls. Forty-nine index RNA positive controls received antiviral therapy and 25 (51%) were RNA negative at enrollment; surprisingly several RNA-negative cases received liver biopsies and/or antiviral treatment. CONCLUSIONS: We document the role donor screening plays in the identification, subsequent medical evaluation, and treatment among individuals who presumably did not know that they were at risk for HCV infection. Additionally, we confirmed race/ethnicity as a determinant of clearance and suggest infectious dose and route of infection may play a role in clearance.

Screening the blood supply for West Nile virus RNA by nucleic acid amplification testing.

BACKGROUND: The use of nucleic acid amplification tests of "minipools" of 16 samples to screen blood donors for West Nile virus RNA began in July 2003. We report the yield and characteristics of positive donations and the incremental yield and safety of nucleic acid amplification tests of individual donations. METHODS: Reactive minipools were analyzed to identify the individual reactive donations. For the regions with the highest yield on minipool testing, retrospective nucleic acid amplification testing was performed on individual donations that were negative on minipool testing. Reactive donations were confirmed by alternative nucleic acid amplification tests and IgM and IgG tests, and donors were followed to document seroconversion. RESULTS: From July 1 through October 31, 2003, 677,603 donations were prospectively screened for West Nile virus by minipool testing, yielding 183 confirmed viremic donations (0.027 percent, or 1 in 3703 donations). Retrospective individual testing of 23,088 donations from high-prevalence regions that were negative on minipool testing yielded 30 additional units with a low level of viremia, with 14 additional viremic units detected by prospective testing of individual donations late in the 2003 transmission season. Of all the viremic units detected, 5 percent were detected only by individual testing and were negative for IgM antibody, 29 percent were detected by individual testing after IgM seroconversion, and 66 percent were detected by minipool testing. West Nile virus infection was confirmed in both recipients of IgM-negative units that were reactive on individual testing, whereas neither recipient of antibody-positive blood components that were reactive on individual testing was infected. In 2004, prospective testing of individual donations in regions that yielded donations that were reactive on minipool testing resulted in a 32 percent incremental yield of units with a low level of viremia that would have been missed by minipool testing. CONCLUSIONS: Although nucleic acid amplification testing of minipools of blood donations prevented hundreds of cases of West Nile virus infection in 2003, it failed to detect units with a low level of viremia, some of which were antibody-negative and infectious. These data support the use of targeted nucleic acid amplification testing of individual donations in high-prevalence regions, a strategy that was implemented successfully in 2004.

Testing strategy to identify cases of acute hepatitis C virus (HCV) infection and to project HCV incidence rates.

Surveillance for hepatitis C virus (HCV) is limited by the challenge of differentiating between acute and chronic infections. In this study, we evaluate a cross-sectional testing strategy that identifies individuals with acute HCV infection and we estimate HCV incidence. Anti-HCV-negative persons from four populations with various risks, i.e., blood donors, Veterans Administration (VA) patients, young injection drug users (IDU), and older IDU, were screened for HCV RNA by minipool or individual sample nucleic acid testing (NAT). The number of detected viremic seronegative infections was combined with the duration of the preseroconversion NAT-positive window period (derived from analysis of frequent serial samples from plasma donors followed from NAT detection to seroconversion) to estimate annual HCV incidence rates. Projected incidence rates were compared to observed incidence rates. Projected HCV incidence rates per 100 person-years were 0.0042 (95% confidence interval [95% CI], 0.0025 to 0.007) for blood donors, 0.86 (95% CI, 0.02 to 0.71) for VA patients, 39.8 (95% CI, 25.9 to 53.7) for young IDU, and 53.7 (95% CI, 23.4 to 108.8) for older IDU. Projected rates were most similar to observed incidence rates for young IDU (33.4; 95% CI, 28.0 to 39.9). This study demonstrates the value of applying a cross-sectional screening strategy to detect acute HCV infections and to estimate HCV incidence.

Persistence of antibodies to West Nile virus nonstructural protein 5.

BACKGROUND: Because IgM antibody against West Nile virus (WNV) pre-membrane/envelope (preM/E) recombinant protein may persist for more than 1 year, an assay distinguishing recent from past WNV infection would be useful. Published findings for a single patient suggest that the presence of antibody against WNV nonstructural protein 5 (NS5) indicates recent infection. OBJECTIVES: To compare the persistence of WNV NS5 antibodies and preM/E IgM using plasma samples from blood donors who were viremic at the time of donation. STUDY DESIGN: Follow-up plasma samples from 35 viremic donors were tested for WNV NS5 antibodies using a microsphere immunoassay, and compared to WNV preM/E IgM antibodies determined on the same samples using an enzyme-linked immunosorbent assay (ELISA). RESULTS: At 90+/-14 days of follow-up, 20/26 donors (77%) were positive for NS5 antibodies; 6/25 (24%) were positive at 180+/-27 days, and 3/23 (13%) were positive at 365+/-55 days. The comparable values for preM/E IgM antibodies were 77%, 32% and 17%, respectively. CONCLUSION: Persistence of WNV NS5 antibody in plasma is similar to that of preM/E IgM antibody. WNV NS5 antibody cannot be used to distinguish recent from past WNV infection.

Flavivirus serology by Western blot analysis.

The spread of West Nile virus (WNV) across the United States into areas with endemic flavivirus activity has complicated serologic surveillance of seasonal virus activity and diagnosis of infected individuals. Here we describe preliminary results from a comparison of serologic assays for flaviviruses: the reference plaque reduction neutralization test (PRNT), enzyme immunoassay (EIA), and a Western blot (WB) in which crude viral lysates were electrophoresed and blotted onto nitrocellulose. Human and chicken sera were tested and compared by each method against WNV and St. Louis encephalitis virus (SLEV). Antibody binding to three viral proteins determined WB interpretation: non-structural protein 1 (NS1), envelope (E), and pre-membrane (prM). WB results for a group of serially collected human plasma samples from WNV seroconverting blood donors were also correlated with transcription mediated amplification (TMA) and polymerase chain reaction (RT-PCR) results. Reactivity with NS1 appeared to be the most useful differentiating marker of WNV and SLEV infection in humans and chickens. Envelope protein was highly cross-reactive and, as indicated by additional results from dengue virus (DENV)-positive human sera, is perhaps useful serologically as a flavivirus group antigen.

Fine-mapping of genetic loci driving spontaneous clearance of hepatitis C virus infection.

Approximately three quarters of acute hepatitis C (HCV) infections evolve to a chronic state, while one quarter are spontaneously cleared. Genetic predispositions strongly contribute to the development of chronicity. We have conducted a genome-wide association study to identify genomic variants underlying HCV spontaneous clearance using ImmunoChip in European and African ancestries. We confirmed two previously reported significant associations, in the IL28B/IFNL4 and the major histocompatibility complex (MHC) regions, with spontaneous clearance in the European population. We further fine-mapped the association in the MHC to a region of about 50 kilo base pairs, down from 1 mega base pairs in the previous study. Additional analyses suggested that the association in MHC is stronger in samples from North America than those from Europe.

Comparison of Hepatitis C Virus RNA and antibody detection in dried blood spots and plasma specimens.

BACKGROUND: Current diagnostic tests for Hepatitis C Virus (HCV) involve phlebotomy and serologic testing for HCV antibodies (anti-HCV) and RNA, which are not always feasible. Dried blood spots (DBS) present a minimally invasive sampling method and are suitable for sample collection, storage and testing. OBJECTIVES: To assess the utility of DBS in HCV detection, we evaluated the sensitivity and specificity of DBS for anti-HCV and HCV RNA detection compared to plasma specimens. STUDY DESIGN: This cross-sectional validation study was conducted in the context of an existing prospective study of HCV in young injection drug users. Blood samples were collected by venipuncture into serum separator tubes (SST) and via finger stick onto Whatman 903(®) protein-saver cards. Plasma samples and eluates from the DBS were tested for anti-HCV using either a third generation enzyme-linked or chemiluminescent immunoassay (IA), and HCV RNA using discriminatory HCV transcription-mediated amplification assay (dHCV TMA). DBS results were compared to their corresponding plasma sample results. RESULTS: 148 participants were tested for anti-HCV and 132 participants were tested for HCV RNA. For anti-HCV, the sensitivity of DBS was 70%, specificity was 100%, positive predictive value (PPV) was 100%, negative predictive value (NPV) was 76% and Kappa was 0.69. For HCV RNA, the sensitivity of DBS was 90%, specificity was 100%, PPV was 100%, NPV was 94% and Kappa was 0.92. CONCLUSIONS: DBS are sensitive and very specific in detecting anti-HCV and HCV RNA, demonstrate good correlation with plasma results, and have potential to facilitate diagnosis of HCV infection.