TT病毒与肝炎关系的临床流行病学研究

目的 对闽南地区各种肝炎患者、健康体检者、义力献血员和肝癌患者共４８０例从临床流行病学角度探讨ＴＴ病毒（ＴＴＶ）的致生及其与各种肝炎的关系。方法 采用巢式ＰＣＲＩｇＧ,用ＥＰＩ ＩＮＦＯ６．０软件进行统计分析。结果 ４８０名研究对象中ＴＴＶＤＮＡ的总检出率为２３．９６％。各种胆炎患者的ＴＴＶ总阳性率为２３．９４％,肝癌患者的ＴＴＶ阳性率为２０．６９％,而健康者的ＴＴＶ阳性率为２４．８４％,义务献血     

中国人丙型肝炎病毒基因组3′端非编码区的研究

目的分析中国丙型肝炎病人ＨＣＶ基因组３′端非编码区（３′ＮＣＲ）,以促进对ＨＣＶ基因组复制机制的研究。方法采用两种方法,从上海地区感染ＨＣＶ的病人血清中,扩增获得ＨＣＶ基因组３′端非编码区：一是用套式ＰＣＲ直接扩增,二是先分别获得ＨＣＶ３′ＮＣＲ的前半部分和后半部分,再将两片段进行融合ＰＣＲ。ＰＣＲ产物进行测序后作同源性分析。在此基础上,建立了针对３′端非编码区的ＲＴＰＣＲ方法,并与基于５′端非编码区的ＲＴＰＣＲ方法检测ＨＣＶＲＮＡ的特异性和灵敏度比较。结果序列分析表明,中国丙型肝炎病人ＨＣＶ基因组３′非编码区由４部分组成：高度变异区、Ｐｏｌｙ（Ｕ）区、Ｐｏｌｙ（Ｕ／Ｃ）区和９８碱基区。同源性分析显示,９８碱基区在不同分离株间高度保守并与国外报道株一致,而Ｐｏｌｙ（ＵＵＣ）区存在较大差异。３′端非编码区和５′非编码区ＲＴＰＣＲ检测血清ＨＣＶＲＮＡ有较高符合率（９５％）。结论ＨＣＶ基因组３′端非编码区的３′末端（９８碱基）,在不同分离株间的高度保守性提示,该区在ＨＣＶ基因复制中起重要作用。基于３′非编码区的ＲＴＰＣＲ方法,将有助于ＨＣＶ感染的诊断。     

南京市部分幼儿TT病毒DNA检测及基因序列分析

目的 了解幼儿人群中TT病毒的流行率及基因判别。方法 设计、合成引物,采用半套式聚合酶链反应（hemi-nested PCR)方法检测幼儿血清标本并进行序列分析。结果 在110份幼儿血清中,TTV DNA总检出率为12．73％。在107名ALT正常,抗HAV－IgM、HBsAg、抗HCV阴性的幼儿血清中,TTV DNA检出率为11．2％（12／107）;从1名ALT升高幼儿血清中检出TTV DNA,从2名HBsSg阳性幼儿血清中检出TTV DNA阳性血清1份。对2株TTV DNA阳性株序列分析结果显示,它们与日本分离株N22、TA278（G1a)、TX011（G1b)、TS003(G2a)、NA004（G2b)和中国株CHN1相应位置核苷酸序列的同源性分别为83．3％／86．0％、84．2％／87．8％、93．7％／98．6％、67．6％／67．1％、64．9％／64．4％、83．8％／88．3％,经系统发育分析它们属于G1b型。结论 幼儿人群中存在TTV感染,TTV流行率为12．73％。TTV感染可能存在血源传播途径外的其他传播途径,并存在健康携带状态。     

The prevalence of TT virus (TTV) infection and its relationship to hepatitis in children

TT virus (TTV) is a newly discovered virus from a patient with post-transfusion hepatitis. We investigated the frequency and pathogenesis of TTV infection in children. A semi-nested PCR assay was used to amplify TTV-DNA in serum samples from 254 ambulatory children without liver disease, 20 with hepatitis of unknown etiology, and 18 transfusion recipients or hemophiliacs. In positive samples, TTV-DNA was quantified by real-time quantitative PCR using a fluorescent probe. We detected TTV-DNA in 20% of children with hepatitis of unknown etiology, which was not statistically different from the 23% prevalence in ambulatory children. In transfusion recipients or hemophiliacs, the frequency was higher (50%) than that in ambulatory children (P = 0.01). Among ambulatory children, TTV-DNA was frequently detected in children with acute gastroenteritis (36%). TTV-DNA was detected in 10% of the infants under 6 months old, and 20% of the children from 7 to 12  months old. The prevalence was constant after the age of 1 year; however, the copy number of TTV-DNA was significantly higher in children under 1 year of age (mean: 10^5.4 versus 10^3.8 copies/ml, P= 0.008). Finally, TTV-DNA was quantified serially in three children with chronic hepatitis who were positive for TTV-DNA. The presence or amount of TTV-DNA was unrelated to the serum alanine aminotransferase level. These results indicate that TTV infection is common in children. The larger quantity of TTV-DNA in infants and the high prevalence of TTV in children of all ages suggest that TTV may be transmitted in early childhood. Its relationship to hepatitis is doubtful in children. Received: 8 April 1999     

Low prevalence of TT virus in the cerebrospinal fluid of viremic patients with central nervous system disorders

TT virus (TTV) is a widespread infectious agent of humans identified in 1998. In infected individuals, TTV induces persistent viremia but its life cycle and pathogenic potential are still poorly understood. In the present study, the presence of TTV DNA in 32 consecutive paired serum and cerebrospinal fluid (CSF) samples from patients with neurological (mainly multiple sclerosis) disorders was investigated by means of a sensitive quantitative real-time PCR assay. Of the 24 patients who were found to carry TTV DNA in serum, 3 also had detectable TTV DNA in their CSF. Two TTV positive CSF samples had markers indicative of blood contamination or a disrupted blood-brain barrier and contained considerably lower TTV loads as compared with the corresponding serum samples, thus suggesting that the virus they contained was of plasma origin. These findings indicated that in general TTV does not permeate effectively an intact blood-brain barrier. Furthermore, the CNS does not represent a common site of TTV replication and persistence. However, at least one exception was observed: the third TTV positive CSF sample (obtained from a patient with subacute dementia of unknown origin) showed no markers suggestive of disrupted blood-brain barrier or blood contamination and had a TTV DNA concentration similar to that found in the patient's serum. In addition, the TTV isolates detected in the two body fluids were distinct genetically. The detection of TTV DNA in CSF is of considerable interest but the clinical significance remains unknown.     

Histopathologic impact of TT virus infection on the liver of type C chronic hepatitis and liver cirrhosis in Japan

The present investigation compared the histological findings in the liver of chronic hepatitis C patients who were or were not co-infected with TT virus (TTV) to determine the histological and clinical characteristics of TTV infection. One hundred eighty patients with chronic hepatitis or liver cirrhosis type C were included in this study. Serum samples were tested for the presence of TTV DNA by a nested polymerase chain reaction. The liver biopsy specimen of each patient was examined, and scores were assigned to indicate the severity of each of the following features: inflammatory cell infiltration in the periportal, parenchymal, and portal areas; fibrous stage; lymphoid reaction in the portal area; portal sclerotic change; perivenular fibrosis; pericellular fibrosis; damage of bile duct; and irregular regeneration of hepatocytes. Sixty-four (34.4%) of the 180 patients were positive for TTV DNA. The histological features of the liver and the blood biochemical parameters of the TTV DNA-positive and TTV DNA-negative patients, did not differ significantly except for the score of irregular regeneration (IR) of hepatocytes. Among those in the F4 stage of fibrosis, the score of IR of the TTV DNA-positive patients was significantly higher than that of the TTV DNA-negative patients. In conclusion, chronic TTV infection does not modify the biochemical features of chronic hepatitis type C patients. TTV may be a risk factor, however, for the development of hepatocellular carcinoma in patients with type C liver disease in the F4 stage.     

大理白族健康成人TT3、TT4、TSH正常值调查

放射免疫分析（RIA）血清总T3（TT3）、总T4（TT4）、促甲状腺激素（TSH）是判断甲状腺功能及垂体对甲状腺功能调节的灵敏而相对可靠的指标。自采用RIA以来均用厂家提供的参考正常值。为较准确而客观使用该指标,对白族健康成人进行TT3、TT4、TSH测定,确定了本地区正常值。     

Comparative and mutational analyses of promoter regions of rinderpest virus

Comparative and mutational analysis of promoter regions of rinderpest virus was conducted. Minigenomic RNAs harboring the genomic and antigenomic promoter of the lapinized virulent strain (Lv) or an attenuated vaccine strain (RBOK) were constructed, and the expression of the reporter gene was examined. The activities of the antigenomic promoters of these strains were similar, whereas the activity of the genomic promoter (GP) of the RBOK strain was significantly higher than that of the Lv strain, regardless of cell type and the source of the N, P and L proteins. Increased replication (and/or encapsidation) activities were observed in the minigenomes that contained RBOK GP. Mutational analysis revealed that the nucleotides specific to the RBOK strain are responsible for the strong GP activity of the strain. It was also demonstrated that other virulent strains of RPV (Kabete O, Saudi/81 and Kuwait 82/1) have weaker GPs than that of the RBOK strain.     

Specific mutations in the enhancer II/core promoter/precore regions of hepatitis B virus subgenotype C2 in Korean patients with hepatocellular carcinoma

Recently, hepatitis B virus (HBV) genotypes and mutations have been reported to be related to hepatocellular carcinoma (HCC). This cross‐sectional case–control study examined the relationship between HCC and mutations in the enhancer II/core promoter and precore regions of HBV by comparing 135 Korean HCC patients infected with HBV genotype C2 (HBV/C2; HCC group) with 135 age‐, sex‐, and hepatitis B e antigen (HBeAg) status‐matched patients without HCC (non‐ HCC group). Age and sex were also matched between HBeAg‐positive and ‐negative patients. The prevalence of T1653, A1689, V1753, T1762/A1764, T1846, A1850, C1858, and A1896 mutations was evaluated in this population. The prevalence of the T1653 mutation in the box α region, the A1689 mutation in between the box α and β regions, and the T1762/A1764 mutations in the basal core promoter region was significantly higher in the HCC group compared to the non‐HCC group (8.9% vs. 2.2%, P = 0.017; 19.3% vs. 4.4%, P < 0.001; and 60.7% vs. 22.2%; P < 0.001). Among HBeAg‐negative patients, the frequency of the T1653 mutation was higher in the HCC group. Regardless of HBeAg status, the prevalence of the A1689, and T1762/A1764 mutations was higher in the HCC group than in the non‐HCC group. However, no association was observed between mutations in the precore region and HCC. Upon multivariate analysis, the presence of the T1653, A1689, and T1762/A1764 mutations was an independent predictive factor for HCC. The addition of the T1653 or A1689 mutation to T1762/A1764 increased the risk of HCC. In conclusion, the T1653, A1689, and/or T1762/A1764 mutations were associated with the development of HCC in Korean patients infected with HBV/C2. J. Med. Virol. 81:1002–1008, 2009. © 2009 Wiley‐Liss, Inc.     

Distribution of TT virus (TTV), TTV-like minivirus,and related viruses in humans and nonhuman primates

TT virus (TTV) and TTV-like minivirus (TLMV) are small DNA viruses with single-stranded, closed circular, antisense genomes infecting man. Despite their extreme sequence heterogeneity (>50%), a highly conserved region in the untranslated region (UTR) allows both viruses to be amplified by polymerase chain reaction (PCR). TTV/TLMV infection was detected in 88 of 100 human plasma samples; amplified sequences were differentiated into TTV and TLMV by analysis of melting profiles, showing that both viruses were similarly prevalent. PCR with UTR primers also detected frequent infection with TTV/TLMV-related viruses in a wide range of apes (chimpanzees, gorillas, orangutans, gibbons) and African monkey species (mangabeys, drills, mandrills). These findings support the hypothesis for the co-evolution of TTV-like viruses with their hosts over the period of primate speciation, potentially analogous to the evolution of primate herpesviruses.     

Zika virus: Molecular responses and tissue tropism in the mammalian host

Zika virus (ZIKV) outbreaks have raised alarm because of reports of congenital Zika virus syndrome in infants. The virus is also known to cause the debilitating Guillain–Barré syndrome in adults. As a result, extensive research has been carried out on the virus over the past few years. To study the molecular responses of viral infectivity in mammals, in vitro two‐dimensional and three‐dimensional cellular models have been employed. The in vivo models of mouse, pig, chicken, and nonhuman primates are primarily used to investigate the teratogenicity of the virus, to study effects of the virus on specific tissues, and to study the systemic effects of a proposed antiviral agent. The virus exhibits wide tissue tropism in the mammalian host. The major host tissues of viral persistence and propagation are neural tissue, ocular tissue, testicular tissue and placental tissue. An understanding of the function of viral components, viral replication cycle, and the molecular responses elicited in the host tissues is imperative for designing antiviral treatment strategies and for development of vaccines. This review provides an update on ZIKV research models and mammalian host responses with respect to ZIKV tissue infection.     

TT virus (TTV) genotyping in blood donors and multiple transfused patients in Brazil

TT virus (TTV) is widely distributed in the general population. The objective of the present study was to investigate the prevalence and distribution of TTV genotypes among blood donor candidates and multiple transfused patients in the Southeast region of the state of São Paulo, Brazil. TTV-DNA detection by amplification of a segment of the ORF-1 region, presented a prevalence of 11.9% in 270 serum samples from blood donors, of 46.2% in 18 samples from patients with coagulopathies, and of 31.8% in 15 samples from patients with hemoglobinopathies. When specific primers for the non-coding (UTR) region of the TTV genome were used the prevalences were 50.5%, 95.0%, and 82.0% for blood donors, patients with coagulopathies and patients with hemoglobinopathies, respectively. Positive samples from 49 individuals were sequenced and partial segments of 230 base pairs referring to the ORF-1 region of the TTV genome were used for the determination of their genotypes with the aid of phylogenetic analysis. The most frequent genotype was 1 (74.0%), followed by genotype 2 (26.0%). These data indicate a high prevalence of this virus in the populations of blood donors and transfused patients, providing further evidence for the role of transfusions as an efficient pathway in the transmission chain.     

TT virus: preferential distribution in CD19(+) peripheral blood mononuclear cells and lack of viral integration.

In order to determine whether peripheral blood mononuclear cells (PBMC) contain proviral DNA or double-stranded replicative forms of TT virus (TTV) and to define which cell subset harbors TTV, we analyzed 126 PBMC DNA samples by PCR, using the NG059/NG061/NG063 and the T801/T935 primer sets. TTV sequences were detected in nearly 20% (25/126) of PBMC DNA samples. Analysis of PBMC subsets revealed that TTV was preferentially distributed in CD19(+) cells. TTV DNA was also detected in CD3(+)/CD19(+) double-depleted cells but was undetectable in CD3(+) cells. After degradation of single-stranded DNA using mung bean nuclease (MBN), TTV could not be detected in previously TTV-positive PBMC DNA samples nor in DNA from CD19(+) cells, CD3(+)-depleted, and CD3(+)/CD19(+) double-depleted cells, indicating the lack of TTV DNA integration and the absence of viral double-stranded replicative intermediates in PBMC or PBMC subset cells. Our data indicate that PBMC and PBMC subsets are not the major sites of TTV replication.