Evaluation of the protective ability of plasma from Japanese individuals against mosquito-borne viral infections

Background

Most of the Japanese population is seropositive for anti-Japanese encephalitis virus (JEV) antibodies because of previous JEV vaccination or natural infection. Because the virological characteristics of JEV are similar to those of West Nile virus (WNV) and dengue virus (DENV), we hypothesized that anti-JEV antibodies can cross-react with WNV and DENV antigens, leading to protection against infection by these viruses.

Methods

Using isolated intravenous immunoglobulin (IVIG) from plasma collected in Japan, neutralizing activities against WNV and DENV and antibody-dependent enhancement (ADE) of these viral infections were evaluated using an in vitro assay to determine the potency of immunity against these viruses.

Results

The prepared IVIG showed considerable neutralizing activity of 2.57 log10 reduction factor against WNV infection but showed little effect against DENV infection. A strong correlation was observed between the neutralizing activity of individual plasma samples against JEV and WNV (ρ=0.768). Moreover, IVIG showed no significant ADE of WNV infection.

Conclusions

Based on these results, we presume that the Japanese population is generally protected from WNV infection. Furthermore, IVIG prepared from plasma donations from Japanese individuals is expected to be an effective therapeutic agent based on its neutralizing activity against JEV and WNV.

The HIV care cascade: Japanese perspectives

Japan has been known as a low HIV-prevalence country with a concentrated epidemic among high-risk groups. However, it has not been determined whether Japan meets the 90-90-90 goals set by the Joint United Nations Programme on HIV/AIDS (UNAIDS)/World Health Organization (WHO). Moreover, to date, the HIV care cascade has not been examined. We estimated the total number of diagnosed people living with HIV/AIDS (PLWHA) (n = 22,840) based on legal reports to the Ministry of Health, Labour and Welfare by subtracting the number of foreigners who left Japan (n = 2,273) and deaths (n = 2,321) from the cumulative diagnosis report (n = 27,434). The number of total undiagnosed PLWHA was estimated by age and sex specific HIV-positive rates observed among first-time blood donors between 2011–2015 in Japan. Our estimates show that 14.4% (n = 3,830) of all PLWHA (n = 26,670) were undiagnosed in Japan at the end of 2015. The number of patients retained in care (n = 20,615: 77.3% of PLWHA), the percentage of those on antiretroviral therapy (n = 18,921: 70.9% of PLWHA) and those with suppressed viral loads (<200 copies/mL; n = 18,756: 70.3% of PLWHA) were obtained through a questionnaire survey conducted in the AIDS Core Hospitals throughout the country. According to these estimates, Japan failed to achieve the first two of the three UNAIDS/WHO targets (22,840/26,670 = 85.6% of HIV-positive cases were diagnosed; 18,921/22,840 = 82.8% of those diagnosed were treated; 18,756/18,921 = 99.1% of those treated experienced viral suppression). Although the antiretroviral treatment uptake and success after retention in medical care appears to be excellent in Japan, there are unmet needs, mainly at the surveillance level before patients are retained in care. The promotion of HIV testing and treatment programs among the key affected populations (especially men who have sex with men) may contribute to further decreasing the HIV epidemic and achieving the UNAIDS/WHO targets in Japan.

Analysis of HTLV-1 proviral load (PVL) and antibody detected with various kinds of tests in Japanese blood donors to understand the relationship between PVL and antibody level and to gain insights toward better antibody testing

Adult T-cell leukemia/lymphoma (ATL) occurs in approximately 5% of individuals infected with human T-cell leukemia virus type 1 (HTLV-1). A high proviral load (PVL; more than four copies per 100 peripheral blood mononuclear cells (PBMCs) or 1.6 copies per 100 blood leukocytes) and being male are risk factors for ATL development. Whether anti-HTLV-1 antibody level is related to such risk is unknown. Here, PVL and antibody levels were examined using real-time PCR and other tests in 600 HTLV-1 positive screened Japanese blood donors to understand the relationship between PVL and antibody level in asymptomatic carriers and to gain insights toward better antibody testing for HTLV-1 infection. The 430 donors in whom proviral DNA was detected were considered as true positives for HTLV-1 infection. Among donors aged 40 years or older, more males than females had a PVL corresponding to more than 1.6% infected leukocytes, and an antibody titer below the median (P = 0.0018). In antibody tests using an HTLV-1 positive cell line or Env antigens there was a large discrepancy in antibody titer among 13 provirus-positive samples, probably suggesting that antibody-based screening tests should incorporate multiple HTLV-1 antigens, such as Gag and Env antigens.

Unique clinical courses of transfusion-transmitted hepatitis E in patients with immunosuppression

BACKGROUND

The high prevalence of specific immunoglobulin G for hepatitis E virus (HEV) in Japanese people raises the possibility of a high incidence of HEV-viremic blood donors and therefore frequent transfusion-transmitted HEV (TT-HEV).

STUDY DESIGN AND METHODS

TT-HEV cases established in Japan through hemovigilance and those published in the literature were collected. Infectivity of HEV-contaminated blood components and disease severity in relation to immunosuppression were investigated.

RESULTS

Twenty established TT-HEV cases were recorded over the past 17 years. A lookback study verified that five of 10 patients transfused with known HEV-contaminated blood components acquired HEV infection. The minimal infectious dose of HEV through transfusion was 3.6 × 10⁴ IU. Nine of the 19 TT-HEV cases analyzed had hematologic diseases. Only two cases showed the maximal alanine aminotransferase level of more than 1000 U/L. Two patients with hematologic malignancy and two liver transplant recipients had chronic liver injury of moderate severity.

CONCLUSION

The infectivity of HEV-contaminated components was 50%. Immunosuppression likely causes the moderate illness of TT-HEV, but it may lead to the establishment of chronic sequelae. Transfusion recipients, a population that is variably immunosuppressed, are more vulnerable to chronic liver injury as a result of TT-HEV than the general population is as a result of food-borne infection.

Genetic Analysis of HIV-1 in Japan: a Comprehensive Analysis of Donated Blood

In Japan, the number of human immunodeficiency virus (HIV)-1 infections remains relatively low; nevertheless, the annual incidence of HIV-1 infection has not decreased. New infections remain a great concern, and an improved understanding of epidemiological trends is critical for public health. The env C2V3 and pol sequences of HIV-1 RNA from 240 early (1996-2001) and 223 more recent (2010-2012) blood donations were used to compare the distribution of virus subtypes and to generate phylogenetic trees. Subtype B was clearly predominant in both early and more recent donations (both were 88.3%), and CRF01_AE was the second most common subtype. Phylogenetic analysis revealed a peculiar epidemiological transition. Compared to early subtype B isolates from 2 major endemic areas (Tokyo and Osaka), the more recent subtype B isolates formed fewer tight clusters in phylogenetic trees (from 8 to 2 clusters in Tokyo and 5 to zero clusters in Osaka). Furthermore, mixing of HIV-1 infections between these 2 endemic areas appear to increase. Analysis of phylogenetic trees suggested that local outbreaks have become smaller in Japan; however, intermixing of viral types between these 2 areas was more evident in the more recent samples.

Reduction of bacteria and human immunodeficiency virus Type 1 infectivity of platelet suspension in plasma using xenon flash-pulse light in a bench-scale trial

BACKGROUND

Current pathogen reduction systems for platelet concentrates (PCs) require addition of chemical compounds and/or reduction of plasma content in PCs. We have investigated a new method using xenon (Xe) flash-pulse light without additional compounds or plasma replacement.

STUDY DESIGN AND METHODS

An aliquot of apheresis platelets (PLTs) in plasma inoculated with bacteria or human immunodeficiency virus Type 1 (HIV-1) was irradiated with Xe flash-pulse light (Xe flash phototreatment). Bacterial growth was monitored up to 6 days of storage, whereas HIV-1 infectivity was assayed just after treatment. Pairs of Xe flash-phototreated and untreated PCs were examined for PLT lesion during the storage period.

RESULTS

Under the current conditions, a low titer (1.8 colony-forming units [CFUs]/mL) of Staphylococcus aureus did not proliferate during the 6-day storage period, but grew in some cases at high-titer (24.0 CFUs/mL) inoculation. HIV-1 infectivity was reduced by 1.8 log. PLT recovery of the treated PCs was lower than untreated ones. An increase of mean PLT volume and glucose consumption, together with a decrease of hypotonic shock response and pH, were enhanced by the treatment. CD62P- and PAC-1-positive PLTs increased after the treatment, indicating the induction of PLT activation. Among biologic response modifiers, soluble CD40 ligand was significantly increased in the treated PCs on Day 6.

CONCLUSIONS

Xe flash phototreatment could prevent bacterial proliferation and reduce HIV-1 infectivity in 100% plasma PCs without any additional compounds, but enhanced PLT storage lesions. Further improvement is required to increase the potency of pathogen inactivation with reducing PLT damage.

Sequence analysis of two variable cytomegalovirus genes for distinction between transfusion- and breast milk-transmitted infections in a very-low-birthweight infant

BACKGROUND

Cytomegalovirus (CMV) infections in very-low-birthweight infants can lead to serious clinical consequences. When CMV-related symptoms occur after transfusion, CMV transmission is often attributed to the transfusion products rather than to breast milk. However, it is sometimes difficult to distinguish between transfusion-transmitted and breast milk-transmitted CMV infections.

PATIENT AND METHODS

A patient was born at 27 gestational weeks with a weight of 689 g. He was transfused with leukoreduced red blood cells (LR-RBCs), which were later found to be CMV seropositive and CMV DNA positive. He was also fed with CMV DNA-positive breast milk. Thereafter, he developed CMV disease with thrombocytopenia and jaundice. To determine the route of transmission, we analyzed the sequences of two variable CMV genes, UL139 and UL146, by direct sequence analysis. We also performed deep sequence analysis to determine whether there were polyclonal CMV strains in the LR-RBCs transfused.

RESULTS

CMV DNA sequence-matching rates for the LR-RBCs and the patient's blood were 64.6% for the UL139 gene and 68.6% for the UL146 gene. In contrast, the sequences of these genes in the patient's blood were 100% matched with those in the breast milk. Furthermore, by deep sequence analysis, the CMV strain found in the patient's blood was not detected in the LR-RBCs transfused.

CONCLUSION

The results indicate that the pathogenic CMV strain was transmitted through breast milk, which is consistent with the claims that transfusion-transmitted CMV infection due to leukoreduced blood products is uncommon.

Real-time measurement of platelet shape change by light scattering under riboflavin and ultraviolet light treatment

BACKGROUND

The adoption of pathogen reduction technologies (PRTs) is considered for the implementation of safer platelet (PLT) transfusion. However, the effects of PRT treatment including irradiation with ultraviolet (UV) light on PLT shape have not yet been fully clarified.

STUDY DESIGN AND METHODS

Leukoreduced PLT concentrates (PCs) were treated with riboflavin and UV light (Mirasol PRT, TerumoBCT). PLT shape and adenosine diphosphate (ADP)-induced shape change were evaluated by a light scattering method where the amplitude of the scattered signal intensity was measured as the indicator of the proportion of discoid PLTs. Using a modified fluorometer, the real-time effects of different wavelengths of UV light on PLT shape were examined over the range of 300 to 360 nm at the same dose.

RESULTS

The proportion of discoid PLTs in the Mirasol PRT-treated PCs decreased immediately after treatment. The difference in the proportion between PRT-treated and untreated PLTs became larger with storage. Although this modification correlated significantly with the pH decrease and P-selectin expression, the Mirasol PRT-treated PLTs retained sufficient ability to undergo an ADP-induced shape change. In the study using the modified fluorometer, the proportion of discoid PLTs significantly decreased with the wavelength (< 320 nm) of irradiated UV light.

CONCLUSION

Mirasol PRT treatment of PCs decreases the proportion of discoid PLTs, which seemed to be caused by the irradiation with UV light of short wavelengths (< 320 nm), not that of long wavelengths (≥ 320 nm) in the Mirasol PRT system. Modification of UV light wavelength may improve the quality of PRT-treated PCs.

Autoantibody Profiles in Collagen Disease Patients with Interstitial Lung Disease (ILD): Antibodies to Major Histocompatibility Complex Class I-Related Chain A (MICA) as Markers of ILD

Interstitial lung disease (ILD) is frequently associated with collagen disease. It is then designated as collagen vascular disease-associated ILD (CVD-ILD), and influences patients' prognosis. The prognosis of acute-onset diffuse ILD (AoDILD) occurring in patients with collagen disease is quite poor. Here, we report our investigation of auto-antibody (Ab) profiles to determine whether they may be useful in diagnosing CVD-ILD or AoDILD in collagen disease. Auto-Ab profiles were analyzed using the Lambda Array Beads Multi-Analyte System, granulocyte immunofluorescence test, Proto-Array Human Protein Microarray, AlphaScreen assay, and glutathione S-transferase capture enzyme-linked immunosorbent assay in 34 patients with rheumatoid arthritis (RA) with or without CVD-ILD and in 15 patients with collagen disease with AoDILD. The average anti-major histocompatibility complex class I-related chain A (MICA) Ab levels were higher in RA patients with CVD-ILD than in those without (P = 0.0013). The ratio of the average anti-MICA Ab level to the average anti-human leukocyte antigen class I Ab level (ie, MICA/Class I) was significantly higher in RA patients with CVD-ILD compared with those without (P = 4.47 × 10(-5)). To the best of our knowledge, this is the first report of auto-Ab profiles in CVD-ILD. The MICA/Class I ratio could be a better marker for diagnosing CVD-ILD than KL-6 (Krebs von den lungen-6).

Efficacy of the Mirasol pathogen reduction technology system against severe fever with thrombocytopenia syndrome virus (SFTSV)

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tickborne virus in the Bunyaviridae family. This virus has recently been found in China, Japan and Korea. The risk of transfusion-transmitted SFTSV infection (TTI-SFTSV) is a concern because person-to-person transmission resulting from contact with SFTSV-contaminated blood has been reported. Therefore, we investigated the efficacy of the Mirasol pathogen reduction technology (PRT) system for inactivating SFTSV in vitro. The Mirasol PRT system achieved a > 4.11 log10 reduction value (LRV) for SFTSV. In conclusion, we showed that the Mirasol PRT system could potentially be used to reduce the risk of TTI-SFTSV.

Estimation of the infectious viral load required for transfusion-transmitted human T-lymphotropic virus type 1 infection (TT-HTLV-1) and of the effectiveness of leukocyte reduction in preventing TT-HTLV-1

BACKGROUND AND OBJECTIVES

The risk of transfusion-transmitted human T-lymphotropic virus type 1 infection (TT-HTLV-1) after prestorage leucocyte reduction (LR) remains unknown, as the proviral load in the blood component that would cause TT-HTLV-1 is undetermined. On the basis of the distribution of HTLV-1 proviral load among HTLV-1-sero-positive blood donors, we attempted to estimate the proviral load for transfusion-related infectivity. We also discuss the effectiveness of LR in preventing TT-HTLV-1.

MATERIALS AND METHODS

The HTLV-1 proviral load in 300 HTLV-1-sero-positive blood donors was determined by real-time polymerase chain reaction analysis. The proviral load required for transfusion-related infectivity was estimated using historical TT-HTLV-1 frequency data from a retrospective study on patients who had received blood from HTLV-1-sero-positive blood donors and the distribution pattern of HTLV-1 proviral load among blood donors.

RESULTS

HTLV-1 proviral loads ranged between < 0.01 and 25.0 copies per 100 leucocytes. Historical data showed TT-HTLV-1 frequency to be 80%. Assuming that 80% of the 300 sero-positive samples are infectious, it is estimated that the transfer of ≥ 9 × 10(4) cells containing the HTLV-1 provirus is required to establish TT-HTLV-1.

CONCLUSION

The residual number of HTLV-1-infected cells after LR is substantially lower than the viral load necessary for TT-HTLV-1. LR therefore appears to be effective in minimizing the incidence of TT-HTLV-1.

Novel swine model of transfusion-related acute lung injury

BACKGROUND

Transfusion-related acute lung injury (TRALI) is a life-threatening complication of blood transfusion. Antibodies against human leukocyte antigens in donors' plasma are the major causes of TRALI. Several animal models of TRALI have been developed, and the mechanism underlying TRALI development has been extensively investigated using rodent models. Although sheep models of nonimmune TRALI have been developed, large-animal models of antibody-mediated TRALI are not yet available.

STUDY DESIGN AND METHODS

To develop a swine model of TRALI, male Clawn strain miniature pigs were used. A monoclonal antibody (MoAb) against swine leukocyte antigens (SLAs) Class I (4G8, 0.3 or 1.0 mg/kg body weight [BW]) and a control antibody (1.0 mg/kg BW) were injected into the peripheral vein after priming with or without 1 μg/kg BW lipopolysaccharide (LPS; n = 3 each). Lung injury was assessed using PaO2 /FiO2 (P/F) ratio and by chest X-ray imaging. Histopathologic analysis was also conducted.

RESULTS

Lung injury could be induced by injecting 4G8 at an amount of 1.0 mg/kg BW, after LPS. The P/F ratio 90 minutes after the administration of 4G8 significantly decreased (p < 0.05). Bilateral infiltration was shown in chest X-ray imaging. Lung injury was confirmed by histopathologic analysis.

CONCLUSION

Lung injury in pigs was successfully induced by anti-SLA MoAb. Priming with LPS is a prerequisite for inducing lung injury and the amount of the antibody is a critical condition.

Establishment of culture systems for Genotypes 3 and 4 hepatitis E virus (HEV) obtained from human blood and application of HEV inactivation using a pathogen reduction technology system

BACKGROUND

It has been demonstrated that the hepatitis E virus (HEV) can be transmitted via blood transfusion, and the risk of HEV transmission via transfusion has become a major global concern. An HEV culture system for blood-derived HEV has been sought to obtain valuable knowledge of the virus and the risk of HEV infection through blood products.

STUDY DESIGN AND METHODS

We endeavored to establish an HEV culture system using RNA-positive blood specimens for Genotypes (G) 3 and 4 and applied this system to evaluate tissue culture infectious dose (TCID). We applied this method to investigate the potential of the Mirasol pathogen reduction technology (PRT) system (Terumo BCT) to inactivate live HEV in contaminated platelet samples (PLTs). PLTs were spiked with cultured HEV G3 or G4 and then treated with the Mirasol PRT system. PLTs were examined before and after the treatment for HEV load using TCID titration.

RESULTS

We successfully established two strains for HEV production: the JRC-HE3 strain for G3 and the UA1 strain for G4. The Mirasol PRT system expressed more than 3 log inactivation for JRC-HE3 and more than 2 log inactivation for UA1.

CONCLUSION

The Mirasol PRT system inactivated greater than 2 to 3 logs of live HEV in PLTs and can potentially be used to lower the possibility of blood-borne HEV transmission. The G3 and G4 HEV inocula identified in this study and the hepatoma cell culture system provide a new means to assess HEV infectious titer and to evaluate other pathogen reduction strategies.

Introduction of glycated albumin measurement for all blood donors and the prevalence of a high glycated albumin level in Japan

(J Diabetes Invest, doi: 10.1111/j.2040-1124.2012.00224.x, 2012) Aims/Introduction:  The Japanese Red Cross Society introduced measurement of glycated albumin (GA) for all blood donors as a glycemic control marker. The GA levels were examined by sex and age.

MATERIALS AND METHODS

  GA was measured in 3.14 million blood donors who donated between April 2009 and March 2010. For the reference range for GA, values that were three times the reference range for glycated hemoglobin (Japan Diabetes Society value) were used. All donors were notified of their GA levels. For repeat donors, a comparison was made between the GA levels at the first and second donations to verify the GA change after notification.

RESULTS

  The mean GA was significantly lower in males than in females in donors aged <60 years. The mean GAs of both sexes increased with age and reached the same level of 14.8% in their 60s. The percentage of donors with prediabetes/diabetes (GA ≥16.5%) was 2.8% in males and 2.3% in females. In the normal high group (15.6% ≤ GA < 16.5%), the mean GA at the second donation was lower by 0.20% than at the first donation. In 42.4% of these donors, GA decreased to the normal range at the second donation.

CONCLUSIONS

  Overall, 2.7% of otherwise healthy Japanese blood donors had a high GA (GA ≥16.5%). Donor blood screening for GA represents an effective measure to identify people at risk of diabetes. The decrease in the GA level after GA notification might indicate the potential usefulness of this strategy to improve glycemic control among people with high GA.

JK null alleles identified from Japanese individuals with Jk(a−b−) phenotype

The Kidd blood group system consists of three common phenotypes: Jk(a+b−), Jk(a−b+) and Jk(a+b+), and one rare phenotype, Jk(a−b−). Jka/Jkb polymorphism is associated with c.838G>A (p.Asp280Asn) in exon 9 of the JK (SLC14A1) gene, and the corresponding alleles are named JK*01 and JK*02. The rare phenotype Jk(a−b−) was first found in a Filipina of Spanish and Chinese ancestry, and to date, several JK null alleles responsible for the Jk(a−b−) phenotype have been reported. We report seven novel JK null alleles, 4 with a JK*01 background and 3 with a JK*02 background, identified from Jk(a−b−) Japanese.

Cytomegalovirus (CMV) seroprevalence in Japanese blood donors and high detection frequency of CMV DNA in elderly donors

BACKGROUND

The current prevalence of cytomegalovirus (CMV) in Japan and the risk of CMV transfusion transmission are unknown in the era of seronegative leukoreduced blood components.

STUDY DESIGN AND METHODS

We measured CMV-specific immunoglobulin (Ig)M and IgG in 2400 samples of whole blood collected from 12 groups of blood donors categorized by sex and age at 10-year intervals from their teens to their 60s. We also tested for CMV DNA using polymerase chain reaction in the cellular fractions of all samples.

RESULTS

We found that 76.6% of blood donors were CMV seropositive. The seroprevalences among donors in their 20s and 30s were 58.3 and 73.3%, respectively. We detected CMV DNA in the cellular fraction of 4.3% of samples from donors in their 60s and in 1.0% of samples from donors younger than 60 years. None of the 562 seronegative samples was DNA positive. Furthermore, 14% of DNA-positive samples also contained DNA in the plasma fraction, and two of five such samples were derived from donors in their 60s. Leukoreduced plasma components derived from donations with CMV DNA in plasma samples also contained a relevant amount of CMV DNA.

CONCLUSION

The seroprevalence of CMV among Japanese blood donors of child-bearing age has not changed over the past 15 years. Latent CMV becomes reactivated more frequently among elderly donors than among younger donors. A proportion of them have free CMV DNA in their plasma fraction, which could not be diminished by leukoreduction. The risk of transfusion-transmitted CMV infection in blood with plasma CMV DNA should be determined.

Two novel null HLA-A alleles with identical exon 4 nonsense mutations: HLA-A*24:183N and A*02:356N

HLA-A*24:183N, A*02:356N, and A*02:15N share the same stop codon at the same position in exon 4.

Residual risk of transfusion-transmitted hepatitis B virus (HBV) infection caused by blood components derived from donors with occult HBV infection in Japan

BACKGROUND

Nucleic acid amplification testing (NAT) for hepatitis B virus (HBV) during blood screening has helped to prevent transfusion-transmitted HBV infection (TT-HBV) in Japan. Nevertheless, 4 to 13 TT-HBV infections arise annually.

STUDY DESIGN AND METHODS

The Japanese Red Cross (JRC) analyzed repository samples of donated blood for TT-HBV that was suspected through hemovigilance. Blood donations implicated in TT-HBV infections were categorized as either window period (WP) or occult HBV infection (OBI) related. In addition, we analyzed blood from 4742 donors with low antibody to hepatitis B core antigen (anti-HBc) and antibody to hepatitis B surface antigen (anti-HBs) titers using individual-donation NAT (ID-NAT) to investigate the relationship between anti-HBc titer and proportion of viremic donors.

RESULTS

Introduction of a more sensitive NAT method for screening minipools of 20 donations increased the OBI detection rate from 3.9 to 15.2 per million, while also the confirmed OBI transmission rate increased from 0.67 to 1.49 per million. By contrast the WP transmission rate decreased from 0.92 to 0.46 per million. Testing repository samples of donations missed by minipools of 20 donations NAT showed that 75 and 85% of TT-HBV that arose from WP and OBI donations, respectively, would have been interdicted by ID-NAT. The ID-NAT trial revealed that 1.94% of donations with low anti-HBc and anti-HBs titers were viremic and that anti-HBc titers and the frequency of viremia did not correlate.

CONCLUSIONS

The JRC has elected to achieve maximal safety by discarding all units with low anti-HBc and anti-HBs titers that account for 1.3% of the total donations.

Current prevalence of HTLV-1 in Japan as determined by screening of blood donors

Human T-cell leukemia virus type-1 (HTLV-1), a major source of adult T-cell leukemia and related diseases, is endemic to southwestern Japan. Mother-to-infant transmission via breast milk is an important route of infection, and establishing programs to prevent such transmission requires exact figures on the HTLV-1 prevalence rate and the number of carriers. Therefore, the seroprevalence of HTLV-1 among 1,196,321 Japanese first-time blood donors from 2006 to 2007 was investigated. A total of 3,787 of such donors were confirmed to be positive for anti-HTLV-1 antibody. By applying a fitness curve to the age ranges outside the blood donor age range, the present number of HTLV-1 carriers covering ages from 0 to 99 years was estimated to be at least 1.08 million in Japan; this value was 10% lower than that reported in 1988. The adjusted overall prevalence rates were estimated to be 0.66% and 1.02% in men and women, respectively. The peak in carrier numbers was found among individuals in their 70s, which is a shift from the previous peak observed in the 1988 database among individuals in their 50s. Carriers were distributed not only in the endemic southwestern region of Japan, but throughout the country, particularly in the greater Tokyo metropolitan area. By applying population projections, it was calculated that the carrier number will decrease by half in the next two decades; however, the carrier population will age over that interval, meaning that the age of patients with adult T-cell leukemia will also be higher.

Prevalence of amino acid mutation in hepatitis C virus core region among Japanese volunteer blood donors

It is not known whether there is a trend of increasing or decreasing incidence of new hepatitis C virus (HCV) infections in Japan. From the treatment point of view, it is important to verify HCV genotypes and the prevalence of treatment-resistant clones of HCV. At the Japanese Red Cross blood centers, all blood samples obtained from blood donation have been screened using serological methods and the minipool nucleic acid amplification testing. One hundred and fourteen donors have been identified over the past 10 years to be HCV RNA-only positive without detectable anti-HCV and were considered to be in the acute phase of HCV infection. There was a trend of decreasing incidence of such new infections among the blood donors. HCV RNA-only-positive samples were examined further for genotyping and HCV RNA quantitation. Genotype 2 (2a plus 2b) was predominant (78.2%) among them followed by genotype 1b (21.2%). Direct sequencing was carried out to detect the possible treatment-resistant mutant clones 70Q and 91M, clones with amino acid substitutions at positions 70 and 91 of the HCV core protein, respectively. 70Q and 91M were found regularly in donors with genotype 1b, but not in those with other genotypes. No particular endemic areas for the mutant clones were identified. There was no significant difference in the mean viral titer between the 70Q mutant type and the non-70Q wild-type. Even in newly infected people, the mutant clone 70Q was detected frequently.

Significant background rates of HBV and HCV infections in patients and risks of blood transfusion from donors with low anti-HBc titres or high anti-HBc titres with high anti-HBs titres in Japan: a prospective, individual NAT study of transfusion-transmitted HBV, HCV and HIV infections

BACKGROUND

The Japanese Red Cross (JRC) conducted a prospective study to evaluate the frequency of transfusion-transmitted HBV, HCV and HIV infections to assess the risk of transfusion of blood components routinely supplied to hospitals.

STUDY DESIGN AND METHODS

Post-transfusion specimens from patients at eight medical institutes were examined for evidence of infection with HBV (2139 cases), HCV (2091) and HIV (2040) using individual nucleic acid amplification testing (NAT). If these specimens were reactive, pre-transfusion specimens were also examined for the virus concerned by individual NAT. In the event that the pre-transfusion specimen was non-reactive, then all repository specimens from implicated donors were tested for the viruses by individual donation NAT. In addition, a further study was carried out to evaluate the risk of transfusion of components from donors with low anti-HBc titres or high anti-HBc with high anti-HBs titres.

RESULTS

Transfusion-transmitted HCV and HIV infections were not observed. One case of post-transfusion HBV infection was identified (rate, 0·0004675; 95% CI for the risk of transmission, 1 in 451-41,841). The background rates of HBV, HCV and HIV infections in patients prior to transfusion were 3·4% (72/2139), 7·2% (150/2091) and 0% (0/2040), respectively. Sixty-four anti-HBc- and/or anti-HBs-reactive blood components were transfused to 52 patients non-reactive for anti-HBc or anti-HBs before and after transfusion (rate, 0; 95% CI for the risk of transmission, <1 in 22).

CONCLUSION

This study demonstrated that the current criteria employed by JRC have a low risk, but the background rates of HBV and HCV infections in Japanese patients are significant.

Novel DNA sequence isolated from blood donors with high transaminase levels

AIM

  In Japan, the etiology of 10-20% of cases of acute hepatitis remains unclarified. This study was conducted to verify the agent causing non-A-E hepatitis.

METHODS

  Serum samples from 500 blood donors with elevated alanine aminotransferase (ALT) levels were screened by polymerase chain reaction using primers constructed from conserved areas of RNA virus helicase. The sequence obtained was investigated for viral properties.

RESULTS

  Four blood samples were found to contain a novel DNA sequence of 9496 bp, which was designated KIs-V. KIs-V was sensitive to the restriction enzyme SalI and BstXI. Rolling-circle amplification produced an excessive amount of KIs-V DNA. In sucrose density gradient ultracentrifugation, KIs-V banded at a 1.158-g/cm(3) density. Detergent treatment increased the density of KIs-V. There was no KIs-V DNA amplification from human leukocyte DNA. Serial filtration suggested that KIs-V was included in a 30-50-nm size particle. In silico analysis revealed that KIs-V contained 13 potential genes, none of which showed homology to any viral proteins reported. One gene showed similarity to a DNA polymerase domain. Strong signals for transcription initiation and a CpG island were identified. The nucleotide composition of KIs-V showed a characteristic feature of circular DNA genomes that contain a replication origin and a terminus. In a preliminary study, KIs-V was frequently identified among hepatitis E virus antibody positive individuals with elevated ALT levels.

CONCLUSION

  A new sequence KIs-V was isolated from blood donors with elevated ALT levels. It was suggested that KIs-V is a double-stranded circular DNA genome derived from a novel category of enveloped viruses.