High prevalence and phylogenetic analysis of TT-virus infection in Mongolia

Prevalence and genotype distribution of hepatitis C virus in Mongolia: Systematic review and meta-analysis

OBJECTIVE

To characterize hepatitis C virus (HCV) infection epidemiology in Mongolia.

METHOD

Publications on HCV antibody (Ab) and RNA prevalence, and/or genotypes/subtypes were systematically reviewed and reported following PRISMA guidelines. Random-effects meta-analyses and age adjustments were conducted to estimate the prevalence of Mongolians exposed to HCV (pooled HCV-Ab prevalence) by time period, sex, and at-risk populations; and to estimate the prevalence of chronically-infected HCV individuals.

RESULTS

The national pooled HCV-Ab prevalence was 12.3% in 2000-2009 and 11.2% in 2013. Sex-specific pooled prevalence appeared higher among females than males (14.0% versus 6.8%). Age-specific pooled prevalence significantly increased from 3.7% among children (aged 0-10 years) to 34.1% among people aged ≥50 years (p < 0.001). Among the adult general population (low-risk population), the national age-adjusted prevalence was 8.1%. Age-adjusted chronic infection prevalence in adults was 6.0%. Among healthcare workers, pooled prevalence was 18.0%. Among patients with liver diseases, pooled prevalence was 53.7%. Among individuals engaging in risky sexual behaviors, pooled prevalence was 11.1%. The identified circulating genotypes/subtypes were 1b (58.0%), 2a (21.7%), and 1a (20.2%).

CONCLUSION

The national HCV prevalence in Mongolia appeared to be among the highest worldwide. Higher prevalence in the clinical setting indicated potential ongoing HCV iatrogenic and occupational transmission. Additionally, HCV transmission in community settings should be investigated.

Phylogenetic analysis of torque teno virus in hepatitis C virus infected patients in shiraz

BACKGROUND

Torque teno virus (TTV) was the first human Circoviridae detected in a Japanese patient with unknown hepatitis in 1997. Subsequently, several studies performed to evaluate different aspects of Torque teno virus pathogenesis.

OBJECTIVES

The present study aimed to determine dominant genotype of Torque teno virus in chronic hepatitis disease using 5΄-UTR sequence among patients infected by hepatitis C virus in Shiraz - Iran.

PATIENTS AND METHODS

The study conducted in 240 patients with chronic hepatitis C from Prof. Alborzi Clinical Microbiology Research Center. The presence of Torque teno virus DNA and its genotype in plasma was assessed by nested polymerase chain reaction using two primer sets for 5΄-UTR and N22 regions. Phylogenetic analysis was performed based on 5΄-UTR region.

RESULTS

DNA of Torque teno virus was detected in 220 out of 240 (92 %) patients with chronic hepatitis C by the use of 5΄-UTR primer based PCR method and in 12 out of 240 (5%) by the use of N22 primer. Based on phylogenetic analysis it was shown that the Dominant genotype in this study was 11. Genotypes 1, 3, 17, and 22 were also detected. Some sequences could not be classified to a specific genotype.

CONCLUSIONS

The prevalence of Torque teno virus DNA in patients with chronic hepatitis C disease by the use of 5΄-UTR primer appeared to be higher compared to that revealed by N22 primer. We observed five genotypes among hepatitis C chronic patients in our study.

High frequency of hepatocellular carcinoma in Mongolia; association with mono-, or co-infection with hepatitis C, B, and delta viruses

To investigate the association between viral infection pattern and hepatocellular carcinoma (HCC), 292 chronic hepatitis patients, including 108 with developed HCC were screened using serological and molecular genetics methods. Viral etiology was established in 267 (91.4%), anti-HCV detected in 198 (67.8%), and HBsAg in 124 (42.5%) including 93 (74.4%) cases with HDV co-infection. HCV mono-infection predominated in both, "non-HCC" and "HCC" groups (54% and 39%, respectively) with higher frequency in the first group (P = 0.011), whereas HBV in co-infection with HDV was more frequent in HCC group (14% vs 25%, P = 0.017). Patients with HCV mono-infection were older than those with co-infection (P<0.02), had higher frequency of HCV-viraemia (82% vs 7%, P < 0.0001), and yet had significantly lower prevalence of HCC (29.6% vs. 49.1%, P = 0.003). Alpha-fetoprotein (AFP) and protein induced by vitamin K antagonist-II (PIVKA-II) were specifically elevated in 71% of HCC patients. In conclusion, although HCV monoinfection pattern predominates in Mongolia, co-infection with HBV and HDV had stronger association with HCC development at younger age. Liver tumor markers; AFP and PIVKA-II are useful tools for complex HCC-screening and clinical follow-up for chronic hepatitis patients in Mongolia.

Transcriptional regulation of TT virus: promoter and enhancer regions in the 1.2-kb noncoding region

Since the discovery of TT virus (TTV) in 1997, its mechanism of transcriptional control has remained unsolved. Molecular analysis points at the 1.2-kb noncoding region (NCR) as being responsible for transcriptional control. The 5' terminus of TTV mRNA was located at nt 114 using the primer extension method (nt 114 will be referred to as position +1). This employed the PE1 primer, designed to start approximately 100 nt downstream of the predicted initiation site. Overall promoter and enhancer activity of the NCR was analyzed using dual luciferase assays in K562, Jurkat, U937, A549, HepG2, Huh7, and HeLaS3 cells. Of those tested, K562 showed the highest relative luciferase activity of 31.1, and activity in HepG2 (14.6) was significantly higher than that in Huh7 (2.8). Fragments of <250 nt length, spanning the NCR, were inserted into a luciferase vector possessing an SV40 promoter. Fragments F5(-542/-311) and F6(-310/-197) showed promoter-enhancing activities of >6.0 by insertion not only in the sense orientation, but also both in the antisense orientation and downstream of the luciferase gene. The 5' deletion of NCR from -1201 to -370 resulted in no significant decrease in the level of luciferase activity. A gradual decrease in the activity of the 5'-deletion mutants from position -370 through -155 was consistent with the loss of enhancer binding sites detected during fragment analysis. A further deletion at position -76 completely abolished luciferase expression, indicating that region -154/-76 contains the critical regulatory element for functioning of the TTV promoter.

TT virus infection does not affect the clinical profiles of patients with hepatitis B and C in Yanbian City, China

China is an area of high endemicity for viral hepatitis, and the molecular epidemiological investigation of TT virus (TTV) infection is of interest. In the present study, we investigated the epidemiology, clinical significance and molecular characteristics of TTV infection in patients with chronic hepatitis B and C in Yanbian City, China. Serum samples obtained from 74 patients with hepatitis B and hepatitis C who visited Yanbian Hospital, located in northeast China, were analyzed in this study. The study group included 22 cases of chronic hepatitis B (B-CH), 17 cases of liver cirrhosis B (B-LC), 7 cases of hepatocellular carcinoma (B-HCC), 16 cases of chronic hepatitis C (C-CH), 11 cases of liver cirrhosis C (C-LC) and 1 case of hepatocellular carcinoma (C-HCC). Detection of TTV DNA was performed as described by Nishizawa et al. The second-round PCR products from 7 subjects were sequenced, followed by investigation of nucleotide homology and phylogenetic analysis. TTV DNA was present in 18.2, 5.9, 28.6, 6.3, 9.1 and 0% of the patients with B-CH, B-LC, B-HCC, C-CH, C-LC and C-HCC, respectively. The highest prevalence of TTV infection was seen in the groups aged 40-50 and over 60 years. There was no significant correlation between the presence of TTV DNA and the clinical parameters in patients with hepatitis B and C. The various isolates showed 97.9-100% with isolates reported previously from Japan and 98.4-100% with isolates reported previously from China. Nucleotide sequence analysis revealed that the Yanbian isolates could be classified in the same group as the Japan and China isolates. We concluded that chronic coinfection with TTV did not affect the serological features of chronic hepatitis B and C in China, as found in Tokyo, Japan.

Infection with hepatitis A and TT viruses and socioeconomic status in Rio de Janeiro, Brazil

The prevalence of antibodies directed against the enterically transmitted hepatitis A virus (HAV) was measured in 2 groups of people living in Rio de Janeiro, Brazil. Of 1,056 health care workers (HCWs), 778 (73.7%) were anti-HAV positive. A high prevalence of anti-HAV antibodies (85.7%) was also found among 274 voluntary blood donors (BDs). TT virus (TTV) is a DNA virus that has been found in the sera of patients with post-transfusion hepatitis of unknown etiology. Occurrence of virus shedding suggests that the fecal-oral route may be an important mode of TTV transmission, particularly in the developing world. The presence of TTV DNA was analyzed by PCR in the sera of 191 HCWs and 151 BDs. TTV was detected in 65.4% of HCWs and 79.5% of BDs. In both groups, a family income of < US$400 per month and a level of education of < 11 y of schooling were found to be risk factors for HAV infection. Furthermore, a low family income was associated with TTV viremia in the HCW group. However, the presence of TTV DNA was associated with neither low level of education nor anti-HAV positivity.

Molecular properties, biology, and clinical implications of TT virus, a recently identified widespread infectious agent of humans

TT virus (TTV) was first described in 1997 by representational difference analysis of sera from non-A to non-G posttransfusion hepatitis patients and hence intensively investigated as a possible addition to the list of hepatitis-inducing viruses. The TTV genome is a covalently closed single-stranded DNA of approximately 3.8 kb with a number of characteristics typical of animal circoviruses, especially the chicken anemia virus. TTV is genetically highly heterogeneous, which has led investigators to group isolates into numerous genotypes and subtypes and has limited the sensitivity of many PCR assays used for virus detection. The most remarkable feature of TTV is the extraordinarily high prevalence of chronic viremia in apparently healthy people, up to nearly 100% in some countries. The original hypothesis that it might be an important cause of cryptogenic hepatitis has not been borne out, although the possibility that it may produce liver damage under specific circumstances has not been excluded. The virus has not yet been etiologically linked to any other human disease. Thus, TTV should be considered an orphan virus.

Which agents threaten blood safety in the future?

The safety of the blood supply is critical to many parts of modern medicine. In a time when prescriber's and the public's expectations are increasing, it is essential that transfusion services globally ensure the safety of the blood supply. There are, however, many threats to this safety, one being the appearance of new infectious agents. Such agents may be truly 'novel', or may be existing agents, known but not routinely screened for, posing a new or increased threat. However, before an agent is considered to be a true threat to blood safety it must be well characterized, and evidence must be presented that (i) transfusion transmission is a significant route of spread, and (ii) the agent causes significant clinical disease. If either of these criteria are not met, the question has to be asked as to whether the agent is truly a threat to blood safety.

Lack of association between TTV viral load and aminotransferase levels in patients with hepatitis C or non-B-C

TT virus (TTV) is a newly identified un-enveloped single-stranded DNA virus. Although TTV was initially thought to be a new hepatitis virus, it is still unclear whether it causes hepatitis. To clarify the natural history and pathogenesis of TTV infection, serial serum samples from patients with chronic hepatitis were analysed. TTV DNA was quantified by real-time detection polymerase chain reaction assay (RTD-PCR), which was adapted for TTV. Five patients with chronic hepatitis, 4 with hepatitis C and 1 with non-B-C, were studied. The study period ranged from 9 to 50 months. In 3 patients there were frequent increases in TTV DNA titres, but no concomitant elevation of the aminotransferase (ALT) levels. In 2 patients who were treated with interferon, the changes in TTV titres were not synchronized with those of the ALT levels. Thus, in cases of chronic hepatitis, no correlation was observed between the serum TTV DNA titres and the ALT levels.