TT virus infections among blood donors in Iceland: prevalence, genotypes, and lack of relationship to serum ALT levels

BACKGROUND: The TT virus (TTV) is a newly identified blood-borne virus. Its association with disease is still unknown, and screening of blood donors has not been implemented. Several genotypes of the TTV have been identified. STUDY DESIGN AND METHODS: Three hundred seventy healthy blood donors were randomly selected and tested for TTV by the PCR method. Sequencing of a part of the genome was performed to identify various genotypes of the virus. ALT levels were determined in both infected and uninfected individuals. RESULTS: The TT virus (TTV), was detected in the sera of 23 (6.2%) of 370 healthy Icelandic blood donors; this prevalence is lower than that reported in Japan but higher than that in Scotland. The virus was found in all groups over the age of 19. Sequencing and phylogenetic analysis of 202 bp from open reading frame 1 demonstrated genotypes 1b and 2b 2c and genotype 4 isolates, with the latter bearing 89-percent nucleotide homology with other genotype 4 sequences deposited at GenBank. One sample showed a mixed genotype 1b/2c infection. Serum ALT levels were within normal limits in all infected individuals. CONCLUSION: The TTV carrier state does not cause significant liver injury.     

High prevalence of TT virus infection in French blood donors revealed by the use of three PCR systems

BACKGROUND: The purpose of this study was to determine the prevalence of TT virus (TTV) infection in voluntary blood donors in Southeastern France. STUDY DESIGN AND METHODS: The sera of 289 blood donors were tested for the presence of TTV DNA by two PCR systems detecting genes located in the 5' UTR (primer set A [Set A]) and the open reading frame (ORF2) (primer set B [Set B]) of the viral genome. A randomized sample of 40 blood donors was also tested by a nested-PCR system in the ORF1 by use of primer set C (Set C). Donors were questioned for possible risk factors for virus transmission. RESULTS: In the entire population studied, 30.8 percent of blood donors tested positive with both Sets A and B, and 70.6 percent with at least one set. In the sample tested with three sets of primers, 27.5 percent of blood donors were positive in testing with all PCR systems and 80 percent with at least one system. The specificity of TTV DNA amplification was confirmed by sequencing 10 PCR products obtained with each set of primers. Statistical analysis revealed that the prevalence of TTV reactivity increased with age. CONCLUSION: The high prevalence of TTV reactivity and the absence of a pathologic condition or risk factors obviously associated with the infection in blood donors suggest that there is no need for systematic detection of TTV infection before blood donation. Further studies are required to determine if TTV isolates can be responsible for a pathologic condition in humans after blood transfusion.     

Incidence and clinical presentation of posttransfusion TT virus infection in prospectively followed transfusion recipients: emphasis on its relevance to hepatitis

BACKGROUND: A novel transfusion-transmissible human DNA virus, TT virus (TTV), has been discovered recently. An attempt was made to determine the incidence and clinical outcome of TTV infection in recipients of blood transfusion. STUDY DESIGN AND METHODS: Serial serum samples collected as part of a prospective study of posttransfusion hepatitis were examined for TTV DNA by a nested PCR assay. RESULTS: Among 150 adults undergoing cardiac surgery, posttransfusion specimens from 59 individuals were positive for TTV DNA. Pretransfusion sera were found to be positive in 13 of these individuals. Therefore, 46 (33.6%) of the 137 previously uninfected patients developed new TTV viremia after transfusion. Among the 46 patients, 3 were coinfected with HCV, 5 were coinfected with HGV, and 38 were infected with TTV alone. No apparent symptoms or signs were noted in the 38 patients infected by TTV alone or the 5 infected with HGV plus TTV. The average peak serum ALT activity was 31 IU per L, with persistently normal levels in 34 of the 38 patients with TTV infection alone. In 8 other patients who subsequently developed well-documented non-A-G hepatitis, 3 were positive for TTV (3/8 vs. 46/137, p = 0.8). In 12 patients followed for more than 1 year, TTV viremia persisted in every case. CONCLUSION: In this population, TTV is transmitted by transfusion to approximately 30 percent of patients who undergo cardiac surgery. Most of the infections appear to become persistent. Despite the high prevalence rate, TTV does not appear to cause hepatitis on its own.     

Prevalence of the newly described human circovirus, TTV, in United States blood donors

BACKGROUND: A novel nonenveloped single-stranded circular DNA virus (TTV) was recently identified. The prevalence of TTV in blood donors in the United States is, however, still unclear. STUDY DESIGN AND METHODS: Viral DNA was detected in US blood donors from five cities by using two sets of TTV primers: NG059/NG061/NG063 primers, which amplified the conserved region of strains 1 and 2, and T801/T935 primers, which amplified the 5' end region of the TTV sequence. A TTV antibody assay system was based on the detection of the truncated open reading frame (ORF)-1 (amino acids 1-411) from type 1b. The truncated ORF-1 was expressed as a fusion protein in Escherichia coli, and the fusion protein was used as the antigen in the antibody assay system. RESULTS: Viremia was detected in 21 (8. 4%) of 250 donors by use of NG059/NG061/NG063 primers and 104 (41. 6%) of 250 by use of T801/T935 primers. There was little correlation among the assays, which suggests the preferential detection of different strains with the different primers. TTV antibody was detected in 38 of 100 donors: 32 (84%) of 38 with concurrent TTV viremia and 6 (16%) of 38 without TTV viremia. TTV viremia and/or TTV antibody-positive samples were detected in 52 (52%) of 100 of US blood donors. CONCLUSION: Evidence of infection or exposure to TTV appears to be common among blood donors in United States.     

献血者中SEN病毒部分基因的克隆和序列分析

目的　了解我国献血者中是否存在SEN病毒 (SENV)感染 ,并分析SENV国内分离株的部分基因序列。方法　根据SENVORF1区保守序列设计引物 ,采用套式PCR方法 ,从献血者血浆标本中分离SENV基因片段 ,对分离的DNA片段进行基因重组和核苷酸序列分析。结果　从 32 9名献血者中分离出 6株SENV基因片段 ,其核苷酸推导氨基酸序列与SENVA～H基因型序列比较 ,同源性在 5 2 %～ 10 0 % ;系统进化树分析发现 ,分离的 6株SENV属SENV H基因型。结论　国内献血者中存在SENV H基因型感染 ,输血可能成为传播SENV途径之一。     

Multicenter evaluation of PCR methods for detecting CMV DNA in blood donors

BACKGROUND: CMV DNA screening may be a useful adjunct to serologic tests in distinguishing potentially infectious blood donations from those that are "CMV-safe." However, there is currently no consensus on the optimal assay method for accurate detection of CMV DNA in donors. STUDY DESIGN AND METHODS: A blinded multicenter evaluation of seven CMV PCR assays was performed by five laboratories by using coded sets of analytical controls and donor blood samples. RESULTS: Five assays displayed sufficient sensitivity for donor screening, as judged by consistent detection of a minimum of 25 CMV genome equivalents (geq) in analytical controls constructed to contain from 1 to 100 CMV geq in background DNA from 250,000 cells, while the other two assays displayed inadequate sensitivity. Three sensitive assays, two based on nested PCR directed at the UL93 and UL32 regions of the CMV genome and another test (Monitor Assay, Roche), did not detect CMV DNA in samples from any of 20 pedigreed CMV-seronegative, Western blot-negative (S-/WB-) donors. Two other assays based on nested PCR occasionally detected CMV DNA in S-WB- samples, and one sensitive nested PCR assay directed at UL123 detected CMV DNA in a large proportion (85%) of S-WB- samples. CONCLUSION: Seven CMV PCR assays currently used for research and/or diagnostic applications displayed marked variations in sensitivity, specificity, and reproducibility when applied to coded analytical and clinical control samples containing cellular DNA from the equivalent of 250,000 WBCs. These results will be useful in the selection of assays with performance characteristics appropriate to donor screening objectives. They may also help explain discrepant findings from previous studies that used PCR to determine CMV DNA prevalence in seronegative and seropositive blood donors.     

广东中山地区献血人群人类嗜T淋巴细胞病毒感染状况调查

目的了解中山地区人类嗜T淋巴细胞病毒(HTLV)在无偿献血人群中的感染情况。方法对2016年3-12月40 874份在中山地区无偿献血的血液标本,采用酶联免疫吸附试验方法(ELISA)进行HTLV抗体筛查,筛查呈反应性的标本进行双孔复查,复查仍阳性的标本使用免疫化学发光法(CLIA)检测,检测阳性的标本使用免疫蛋白印迹法(WB)进行确证,确证阳性的视为感染。结果中山地区40 874份无偿献血者中HTLV抗体ELISA检测阳性21例,ELISA检测阳性率为0.05%,免疫化学发光法检测阳性5例,WB确证阳性1例,感染率为0.002 4%。结论为了保证输血安全,降低输血感染HTLV,有必要对中山地区的初次献血者进行HTLV的筛查。     

Risk factor analysis of hepatitis C virus infection among Chinese blood donors in Hong Kong

Background: Hepatitis C virus (HCV) infection can result in serious hepatic complications and hence potentially significant burden to the society. Despite advances in technology, transfusion‐transmitted HCV infection still exists. To further minimise the risk, a review on the epidemiology of HCV infection among Chinese blood donors in Hong Kong was conducted. Methods: All donations associated with HCV infection confirmed by positive serologic diagnosis with or without molecular confirmation during the period from 2003 to 2010 were studied. Demographic data were retrieved and risk factors were identified. Results: HCV infection was more commonly seen in first time donors and donors with blood transfusion history before the availability of HCV testing, whereas its association with intravenous drug use was noted to be decreasing. Interestingly, half of the HCV positive donors in 2008–2010 were young donors aged below 21, which was also the group with the highest rate of no known source of infection. Conclusion: A subgroup of younger age donors was found to have no known risk factor. To develop better screening strategy, it is recommended that a more detailed analysis of this group of donors is required.     

Absence of human T-lymphotropic virus type I tax sequences in a population of normal blood donors in the Baltimore, MD/Washington, DC, area: results from a multicenter study

BACKGROUND: It was reported recently that sequences corresponding to the human T-lymphotropic virus type I (HTLV-I) tax gene were detected in peripheral blood mononuclear cells from 8 to 11 percent of healthy blood donors without detectable antibodies to HTLV-I. A multicenter blind study was conducted to determine if these results could be independently confirmed. STUDY DESIGN AND METHODS: Specimens were collected from 100 anti-HTLV-I-negative healthy blood donors and from 11 anti-HTLV-I- or anti-HTLV-II-positive individuals. All samples were coded and distributed to each of four independent testing laboratories for polymerase chain reaction analysis to detect sequences of the HTLV-I or HTLV-II tax gene, using detailed procedures specified by the laboratory reporting the original observation. Each laboratory also tested a dilution panel of a plasmid containing HTLV-I tax to determine the analytical sensitivity of the procedure. RESULTS: The analytical sensitivity of the screening methods permitted detection of as few as 1 to 10 copies of the tax gene. However, HTLV-I tax sequences could not be detected in any of the anti-HTLV-I-negative blood donors at more than one test site. CONCLUSION: HTLV-I tax sequences appear not to be present in this population of 100 blood donors negative for anti-HTLV-I.     

Molecular detection and sequence analysis of hepatitis E virus in patients with viral hepatitis from North India

Viral hepatitis is a major cause of mortality and morbidity in developing countries. Hepatitis E virus (HEV) is responsible for both sporadic and epidemic outbreaks of viral hepatitis in India. Here a total of 843 samples were collected: 685 from patients with acute viral hepatitis (AVH), 70 from patients with fulminant hepatic failure (FHF), 53 from patients with chronic liver disease (CLD), 11 from patients with antituberculosis therapy (ATT)–induced jaundice, and 24 from pregnant women. When tested for anti-HEV IgM, 58.3% of the pregnant women, 41.4% of the patients with FHF, 38.6% of the patients with AVH, 9.4% of the patients with CLD, and 18.2% of the patients with ATT-induced jaundice tested positive. We found that 34% and 16% of the acute hepatitis patients and fulminant hepatitis patients, respectively, showed no reactivity to the existing viral hepatitis markers and were thus grouped as non A to E. Among the HEV IgM–positive cases, males outnumbered females (62.8% versus 37.1%). HEV RNA was found in 35% of fulminant and 9.4% of acute hepatitis patients. From phylogenetic analysis, we observed that all the isolates were clustered within genotype 1. Critical analysis placed the acute isolates along with strains under subtype Ia, while the fulminant isolates clustered along with the FHF strain (X98292) under subtype Ic. The segregation of HEV isolates from AVH and FHF patients into different subtypes raises interesting questions on the molecular basis of HEV disease severity.     

鼻咽癌患者外周血淋巴细胞中EB病毒DNA载量与临床分期的关系研究

目的检测鼻咽癌患者外周血淋巴细胞中EB病毒DNA载量．并分析其与鼻咽癌临床分期的关系。方法选取2012年1月至2013年1月我院肿瘤科收治住院的87例鼻咽癌患者．采用实时荧光定量PCR法检测外周血淋巴细胞EB病毒DNA含量;统计学分析其与患者临床分期的关系。结果鼻咽癌患者外周血淋巴细胞中EB病毒DNA检出率为82．76％（72／87）,EB病毒DNA拷贝数的中位数为7．58×106拷贝数／ml,I、Ⅱ、Ⅲ和Ⅳ期患者每毫升DNA拷贝数分别为f4．25±1．141x10^3、（4．56±0．68）×10^4、（7．88±1．65）×10^5和（8．09±1．65）x106;EB病毒DNA载量随着疾病临床分期的增加呈现逐步升高的趋势。且差异显著（P〈0．05）。结论鼻咽癌患者外周血淋巴细胞中EB病毒DNA载量与患者临床分期相关．提示EB病毒DNA载量与鼻咽癌病情进展关系密切．在临床上可作为鼻咽癌患者病情监测及判断疗效的一种有效手段。