Occult hepatitis C virus infection: a new form of hepatitis C

Evaluation of hepatitis C viral RNA persistence in HIV-infected patients with long-term sustained virological response by droplet digital PCR

Several studies have reported the persistence of HCV RNA in liver and/or peripheral blood mononuclear cells (PBMCs) in spite of undetectable viremia in patients who have achieved sustained virological response (SVR). This event, defined as occult HCV infection, remains controversial and low titers of persistent virus may be underestimated because it has not yet been analyzed by a highly sensitive test such as droplet digital PCR (ddPCR). This method provides an alternate ultra-sensitive detection technique for very low numbers of copies of viral RNA or DNA. The aim of this study was to evaluate the persistence of HCV in HIV-coinfected patients with long-term SVR using ddPCR. For each patient, the presence of HCV RNA in serum and PBMCs at baseline was determined by nested RT-ddPCR. Patients with HCV RNA in PBMCs at baseline were followed until the end of the study. One hundred and twenty-three patients were analyzed for persistence of HCV RNA in serum and PBMCs. Persistence of HCV was not found in serum in any patient. HCV RNA was detected in PBMCs in one patient (0.81%; 95% CI: 0.04–3.94) and resolved spontaneously during follow-up. Persistence of HCV RNA in PBMCs is not a common event in HIV/HCV co-infected patients with long-term SVR evaluated by RT-ddPCR.

Occult Hepatitis C Virus Infection: A Review

Occult hepatitis C virus (HCV) infection (OCI), first described in 2004, is defined as the presence of HCV RNA in hepatocytes or peripheral blood mononuclear cells without detectable HCV RNA in the serum. Here, we aimed to review the epidemiology, diagnostic methods, clinical implications and potential management recommendations currently described in the literature, as well as the future directions for investigation of this entity. PubMed and Cochrane databases were searched with combination of the following keywords: "occult", "hepatitis C virus", and "occult HCV infection". There are data to support OCI as a potential culprit in cryptogenic liver disease. There are also consistent data demonstrating the existence of OCI in specific populations, such as dialysis, human immunodeficiency virus-infected and hepatitis B virus-infected patients, and also in the general population. While the gold standard for diagnosis is liver biopsy, examination of peripheral blood mononuclear cells may be a reliable, safer alternative method of diagnosis. Occult HCV infection is likely associated with liver fibrosis and progression of liver disease. Additional studies are required to determine the infectivity of OCI patients, as well as clarify the natural course and specific clinical implications of OCI. Lastly, studies are needed to determine whether treatment of OCI leads to decreased morbidity and/or mortality.

Prevalence of occult hepatitis C virus among hemodialysis patients in Tanta university hospitals: a single-center study

Occult hepatitis C virus infection (OCI) is a newly defined type of infection by the chronic hepatitis virus (HCV) distinguished by the existence of HCV RNA in liver tissue and/or peripheral blood mononuclear cells (PBMCs) in patients whose plasma are devoid of both positive serology and RNA. Patients on maintenance hemodialysis evince a higher HCV prevalence than the general population due to high nosocomial transmission by the dialysis units. We investigated the prevalence of occult HCV infection in patients attending our university hemodialysis centers for maintenance hemodialysis. Sixty-two CHD patients negative for serum HCV tests were enrolled in the study. PMNCs were tested by real-time PCR for the presence of HCV RNA. For the 62 patients, the average duration since starting dialysis was 32.7 months and the mean (SD) alanine transaminase and aspartate transaminase were 25.74 ± 9.75 and 28.81 ± 11.32 IU/l, respectively. Out of the 62 CHD patients negative for serum anti-HCV and HCV RNA patients, only three (4.84%) were shown to have HCV RNA in their PBMCs implying the diagnosis of OCI; their viral load range was 1.24-4.15 IU/ml. All three OCI-proven patients gave no history of hepatic disease. In this study, we found that patients considered to be free of HCV can have HCV replicating in their PBMCs. This awareness points to the possibility of HCV being transmitted from apparently uninfected persons. A positive HCV RNA detection in PBMCs is dependable in determining OCI among high-risk subjects particularly when a liver biopsy is not an option. HCV transmission can occur through hemodialysis units signaling incorrect application of infection control measures in our Egyptian dialysis units. Additional studies on hemodialysis patients are necessary to realize the true magnitude of OCI among this patient group and to highlight the importance of incorporating HCV viral assays in PBMCs into the diagnostic algorithm.

Occult hepatitis C virus infection among Egyptian hemodialysis patients

Occult hepatitis C virus (HCV) infection (OCI) was reported in an apparently disease-free state in the absence of liver disease, anti-HCV and HCV-RNA in the serum. The existing data examining the clinical significance of OCI and its potential as a source of HCV infection among hemodialysis patients are very limited. We examined the presence of OCI among patients on maintenance hemodialysis at Minia Governorate, Egypt; an HCV endemic country. A total of 81 subjects with negative markers for HCV were enrolled. HCV-RNA was tested in PBMCs by real-time PCR. For the 81 subjects, the average dialysis duration was 32.7 ± 21.7 months and the average ALT level (±SD) was 26 ± 12 U/L while that of AST was 29 ± 16 U/L. Out of the 81 subjects, three (3.7%) were HCV-RNA positive in PBMCs in the absence of serum anti-HCV and HCV-RNA indicating OCI. The viral load of the OCI subjects ranged from 172 to 4150 IU/ml. History of liver disease was positive in one of the three positive patients. These results highlight the potential risk of HCV transmission from patients within hemodialysis units in Egypt. J. Med. Virol. 88:1388-1393, 2016. © 2016 Wiley Periodicals, Inc.

Prevalence of occult hepatitis C virus infection in the Iranian patients with human immunodeficiency virus infection

Occult hepatitis C virus (HCV) infection is a new form of chronic HCV infection described by the presence of the genomic HCV-RNA in liver biopsy and/or peripheral blood mononuclear cell (PBMC) samples, and undetectable levels or absence of HCV-RNA and in the absence or presence of anti HCV antibodies in the plasma specimens. The aim of the present study was to evaluate the occurrence of occult HCV infection (OCI) among Iranian subjects infected with human immunodeficiency virus (HIV) using RT-nested PCR. From March 2014 until April 2015, 109 Iranian patients with established HIV infection were enrolled in this cross-sectional study. After extraction of viral RNA from the plasma and PBMC samples, HCV-RNA status was examined by RT-nested PCR using primers from the 5'-NTR. HCV genotyping was conducted using RFLP analysis. For the confirmation of HCV genotyping by RFLP method, the PCR products were sequenced. Of the 109 patients, 50 were positive for antibodies against HCV. The HCV-RNA was detected in PBMC specimens in 6 (10.2%) out of the total 59 patients negative for anti-HCV Abs and undetectable plasma HCV-RNA and also from 4 (8.0%) out of the total 50 patients positive for anti-HCV Abs and undetectable plasma HCV-RNA. HCV genotyping analysis showed that 6 (60.0%) patients were infected with HCV subtype 3a, 3 (30.0%) were infected with HCV subtype 1a and 1 (10.0%) patient was infected with HCV subtype 1b. This study revealed the incidence of OCI (9.2%) in HIV-infected Iranian patients. Hence, designing prospective studies focusing on the detection of OCI in these patients would provide more information. J. Med. Virol. 88:1960-1966, 2016. © 2016 Wiley Periodicals, Inc.

Occult HCV Infection: The Current State of Knowledge

CONTEXT

Occult HCV infection (OCI) is defined as the presence of HCV-RNA in hepatocytes and the absence of HCV in the serum according to usual tests. We aimed to define OCI and provide information about the currently available diagnostic methods. Then we focus on specific groups that are at high risk of OCI and finally investigate immune responses to OCI and the available treatment approaches.

EVIDENCE ACQUISITION

PubMed, Scopus and Google Scholar were comprehensively searched with combination of following keywords: "occult", "hepatitis C virus" and "occult HCV infection". The definition of OCI, diagnostic methods, specific groups that are at high risk and available treatment approaches were extract from literature. An analysis of available articles on OCI also was done based on Scopus search results.

RESULTS

OCI has been reported in several high-risk groups, especially in hemodialysis patients and subjects with cryptogenic liver disease. Furthermore, some studies have proposed a specific immune response for OCI in comparison with chronic hepatitis C (CHC).

CONCLUSIONS

With a clinical history of approximately 11 years, occult HCV infection can be considered an occult type of CHC. Evidences suggest that considering OCI in these high-risk groups seems to be necessary. We suggest that alternative diagnostic tests should be applied and that there is a need for the participation of all countries to determine the epidemiology of this type of HCV infection. Additionally, evaluating OCI in blood transfusion centers and in patients who receive large amounts of blood and clotting factors, such as patients with hemophilia, should be performed in future projects.

Interactions between Hepatitis C Virus and the Human Apolipoprotein H Acute Phase Protein: A Tool for a Sensitive Detection of the Virus

The Hepatitis C virus (HCV) infection exhibits a high global prevalence frequently associated with hepatocellular carcinoma, taking years to develop. Despite the standardization of highly sensitive HCV quantitative RT-PCR (qRT-PCR) detection methods, false-negative diagnoses may be generated with current methods, mainly due to the presence of PCR inhibitors and/or low viral loads in the patient’s sample. These false-negative diagnoses impact both public health systems, in developing countries, and an in lesser extent, in developed countries, including both the risk of virus transmission during organ transplantation and/or blood transfusion and the quality of the antiviral treatment monitoring. To adopt an appropriate therapeutic strategy to improve the patient’s prognosis, it is urgent to increase the HCV detection sensitivity. Based upon previous studies on HBV, we worked on the capacity of the scavenger acute phase protein, Apolipoprotein H (ApoH) to interact with HCV. Using different approaches, including immunoassays, antibody-inhibition, oxidation, ultracentrifugation, electron microscopy and RT-PCR analyses, we demonstrated specific interactions between HCV particles and ApoH. Moreover, when using a two-step HCV detection process, including capture of HCV by ApoH-coated nanomagnetic beads and a home-made real-time HCV-RT-PCR, we confirmed the presence of HCV for all samples from a clinical collection of HCV-seropositive patients exhibiting an RT-PCR COBAS® TaqMan® HCV Test, v2.0 (COBAS)-positive result. In contrast, for HCV-seropositive patients with either low HCV-load as determined with COBAS or exhibiting HCV-negative COBAS results, the addition of the two-step ApoH-HCV-capture and HCV-detection process was able to increase the sensitivity of HCV detection or more interestingly, detect in a genotype sequence-independent manner, a high-proportion (44%) of HCV/RNA-positive among the COBAS HCV-negative patients. Thus, the immune interaction between ApoH and HCV could be used as a sample preparation tool to enrich and/or cleanse HCV patient’s samples to enhance the detection sensitivity of HCV and therefore significantly reduce the numbers of false-negative HCV diagnosis results.

Virus-Specific Cellular Response in Hepatitis C Virus Infection

Studies performed on chimpanzees and humans have revealed that strong, multispecific and sustained CD4(+) and CD8(+) T cell immune responses is a major determinant of hepatitis C virus (HCV) clearance. However, spontaneous elimination of the virus occurs in minority of infected individuals and cellular response directed against HCV antigens is not persistent in individuals with chronic infection. This review presents characteristics of the HCV-specific T cell response in patients with different clinical course of infection, including acute and chronic infection, persons who spontaneously eliminated HCV and non-infected subjects exposed to HCV. Detection of HCV-specific response, especially in non-infected subjects exposed to HCV, may be indicative of HCV prevalence in population and rate of spontaneous viral clearance. Understanding the mechanisms and role of HCV-specific cellular immune response would contribute to better understanding of HCV epidemiology, immunopathogenesis and may help to design an effective vaccine.

Viremia levels in hepatitis C infection among Egyptian blood donors and implications for transmission risk with different screening scenarios

BACKGROUND

Knowledge about the viral load (VL) distributions in different stages of hepatitis C virus (HCV) infection is essential to compare the efficacy of serologic screening and nucleic acid testing (NAT) in preventing transfusion transmission risk. We studied HCV-RNA levels in Egyptian blood donors in the preseroconversion window period (WP) and in later anti-HCV-positive stages of infection.

STUDY DESIGN AND METHODS

Subsets of individual-donation (ID)-NAT and anti-HCV-yield samples from a screening study among 119,756 donors were tested for VL by quantitative polymerase chain reaction (qPCR). Low viremia levels below the quantification limit of qPCR were determined by probit analysis using the proportion of reactive results on replicate NATs. Poisson distribution statistics were used to estimate transmission risk in different stages of HCV infection based on 50% minimum infectious doses (MID50 ) of 3.2 (1-10) and 316 (100-1000) virions in the absence and presence of anti-HCV, respectively.

RESULTS

Rates of total HCV infections and WP-NAT-yield donations in two Egyptian blood centers varied between 2.6% to 4.5% and 1:3100 to 1:9500, respectively. VLs ranged from 82 to 3 × 10(7) copies/mL in WP and from fewer than 1600 to 1.6 × 10(6) copies/mL in anti-HCV-positive carrier donations. Only two (1.1%) of 175 donors with probable resolved infection had detectable RNA on replicate testing (estimated VLs of 0.5 and 1.8 copies/mL). This translates to an estimated transmission risk of 0.028% if ID-NAT-nonreactive, anti-HCV-positive donations would be used for RBC transfusions.

CONCLUSION

Almost 99% of anti-HCV-reactive donations without detectable HCV-RNA on initial ID-NAT screening had eradicated the virus from the circulation, while 1% had extremely low VLs and are likely not infectious. The incremental safety offered by serologic testing of ID-NAT-screened blood seems minimal.

Detection of occult hepatitis C virus among healthy spouses of patients with HCV infection

The criterion standard for the diagnosis of occult hepatitis C virus (HCV) infection is detection of HCV-RNA in liver cells. However, because of the invasive nature of liver biopsy, other methods have been studied. The present study aimed to identify subjects with occult HCV-4 infection among healthy sexual partners of patients with chronic HCV-4 infection by detecting HCV-RNA in peripheral blood mononuclear cells (PBMCs) using real-time polymerase chain reaction (PCR). Fifty healthy Egyptian spouses of patients with chronic HCV-4 infection were included in this study. Real-time PCR was used to detect HCV-RNA in PBMCs in all the study subjects. The prevalence of occult HCV-4 infection was 4%, and a statistically significant higher prevalence was found among patients with a history of sexually transmitted infection. The results of the present study indicate the importance of intra-spousal transmission of HCV-4 infection, especially in subjects with a history of sexually transmitted infection.

Active co-infection with HBV and/or HCV in South African HIV positive patients due for cancer therapy

Human immunodeficiency virus (HIV), Hepatitis B virus (HBV) and Hepatitis C virus (HCV) share routes of transmission. There is limited data on the incidence of active co-infection with HBV and/or HCV in cancer patients infected with HIV in Africa. This was a prospective study based on 34 patients with varied cancer diagnosis, infected with HIV and awaiting cancer therapy in South Africa. HIV viral load, CD4+ cell counts, Alanine-aminotransferase and aspartate aminotransferase levels were tested. Exposure to HBV and HCV was assessed serologically using commercial kits. Active HBV and/or HCV co-infection was detected using viral specific nested PCR assays. HCV 5'-UTR PCR products were sequenced to confirm active HCV infection. Active viral infection was detected in 64.7% of patients for HBV, 38.2% for HCV, and 29.4% for both HBV and HCV. Occult HBV infection was observed in 63.6% of the patients, while seronegative HCV infection was found in 30.8% of patients. In addition, CD4+ cell count < 350 cells/µl was not a risk factor for increased active HBV, HCV or both HBV and HCV co-infections. A total of 72.7%, 18.2% and 9.1% of the HCV sequences were assigned genotype 5, 1 and 4 respectively.The study revealed for the first time a high active HBV and/or HCV co-infection rate in cancer patients infected with HIV. The findings call for HBV and HCV testing in such patients, and where feasible, appropriate antiviral treatment be indicated, as chemotherapy or radiotherapy has been associated with reactivation of viral hepatitis and termination of cancer therapy.

Review: Occult hepatitis C virus infection: still remains a controversy

Occult hepatitis C virus (HCV) infection is characterized by the presence of HCV RNA in the liver cells or peripheral blood mononuclear cells of the patients whose serum samples test negative for HCV RNA, with or without presence of HCV antibodies. The present study reviews the existing literature on the persistence of occult hepatitis C virus infection, with description of the clinical characteristics and methods for identification of occult hepatitis C. Occult hepatitis C virus infection was detected in patients with abnormal results of liver function tests of unknown origin, with HCV antibodies and HCV RNA negativity in serum, and also in patients with spontaneous or treatment-induced recovery from hepatitis C. The viral replication in the liver cells and/or peripheral blood mononuclear cells was present in all clinical presentations of occult hepatitis C. The peripheral blood mononuclear cells represent an extra-hepatic site of HCV replication. The reason why HCV RNA was not detectable in the serum of patients with occult hepatitis C, could be the low number of circulating viral particles not detectable by the diagnostic tests with low sensitivity. It is uncertain whether occult hepatitis C is a different clinical entity or just a form of chronic hepatitis C virus infection. Data accumulated over the last decade demonstrated that an effective approach to the diagnosis of HCV infection would be the implementation of more sensitive HCV RNA diagnostic assays, and also, examination of the presence of viral particles in the cells of the immune system.

Hepatitis B and hepatitis C viral infections in patients with chronic lymphocytic leukemia

BACKGROUND

Whether chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infections contribute to the pathogenesis and⁄or course of chronic lymphocytic leukemia is unclear.

OBJECTIVE

To document the prevalences of HBV and HCV infections in chronic lymphocytic leukemia patients, and to determine whether infected patients experience more aggressive disease than those without infection.

METHODS

Patient sera were screened for antibodies to HBV core antigen and HCV (anti-HCV) using ELISA; both sera and peripheral blood lymphocytes were further tested (regardless of antibody results) for HBV-DNA and HCV-RNA using real-time polymerase chain reaction. Prognostic markers for chronic lymphocytic leukemia included Rai stage, IgVH mutational status, β2-microglobulin levels, Zap-70 and CD38 status.

RESULTS

Fourteen of 222 (6.3%) chronic lymphocytic leukemia patients and two of 72 (2.8%) healthy controls tested positive for previous or ongoing HBV infection (OR 2.4 [95% CI 0.5 to 7.7]; P=0.25) while four of 222 (1.8%) chronic lymphocytic leukemia patients and one of 72 (1.4%) controls tested positive for HCV markers (OR 1.3 [95% CI 0.2 to 6.4]; P=0.81). The levels and distribution of the various indicators of aggressive chronic lymphocytic leukemia disease were similar among HBV- and HCV-infected and uninfected patients. Survival times were also similar. Occult HBV and HCV infection (HBV-DNA or HCV-RNA positive in the absence of diagnostic serological markers) were uncommon in chronic lymphocytic leukemia patients (0.5% and 1.8%, respectively).

CONCLUSIONS

The results of the present study do not support the hypothesis that HBV or HCV infections play an important role in the pathogenesis or course of chronic lymphocytic leukemia.

Necessity for reassessment of patients with serogroup 2 hepatitis C virus (HCV) and undetectable serum HCV RNA

We encountered a patient positive for anti-hepatitis C virus (HCV) whose serum HCV RNA was undetectable with the Roche AmpliPrep/Cobas TaqMan HCV assay (CAP/CTM) version 1 but showed a high viral load with the Abbott RealTime HCV assay (ART). Discrepancies in the detectability of serum HCV RNA were investigated among 891 consecutive patients who were positive for anti-HCV. Specific nucleotide variations causing the undetectability of HCV RNA were determined and confirmed by synthesizing RNA coding those variations. Serum samples with the discrepancies were also reassessed by CAP/CTM version 2. Among the 891 anti-HCV-positive patients, 4 patients had serum HCV RNA levels that were undetectable by CAP/CTM version 1 despite having levels of >5 log IU/ml that were detected by ART. All four patients had HCV genotype 2a and high titers of anti-HCV. Sequencing of the HCV 5' noncoding regions revealed 2 common variations, A at nucleotide (nt) 145 and T at nt 151. Synthesized RNAs of the HCV 5' noncoding region with standard (NCR145G151C) and variant nucleotides at nt 145 and nt 151 were quantified with CAP/CTM. RNAs of NCR145G151C and NCR145G151T were quantifiable with CAP/CTM version 1, while those of NCR145A151T and NCR145A151C went undetected. The substitution from G to A at nt 145 specifically conferred this undetectability, while this undetectability was reverted in synthesized HCV RNA with correction of this variation. Reassessment of these samples by CAP/CTM version 2 resulted in similar levels of HCV RNA being detected by ART. We conclude that HCV patients with undetectable HCV RNA by CAP/CTM version 1 should be reassessed for viral quantification.

Seronegative hepatitis C virus infection

Hepatitis C virus (HCV) is a major cause of liver disease worldwide. The routine diagnostics identifying HCV infection include testing for specific anti-HCV antibodies by enzyme-linked immnunosorbent assay and viral genetic material in serum or plasma. However, a small proportion of patients persistently infected with HCV, in whom anti-HCV are undetectable, constitute a serious diagnostic and possibly epidemiologic problem, as they could facilitate pathogen spread in the population. This type of infection is termed seronegative or serosilent. Seronegative HCV infection is currently of great interest to both scientists and physicians. The review presents epidemiological data concerning the prevalence of seronegative HCV infection in HIV/HCV co-infected individuals, hemodialysis patients, and blood and organ donors. The possible mechanisms behind this atypical course of infection are discussed. Furthermore, the differences between seronegative and occult infections and prolonged seroconversion are explained.

Hepatitis C virus infection in nephrology patients

CONTEXT

Hepatitis C virus (HCV) infection leads to chronic liver disease, but also to extra-hepatic manifestations.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar, Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched.

RESULTS

Herein, we provide an overview of renal diseases related to HCV and their therapies, as well as the treatment options available for HCV (+)/RNA (+) dialysis patients. We will not mention, however, HCV infection-related complications in the post-kidney transplantation setting.

CONCLUSIONS

Extra-hepatic manifestations of HCV infection include mixed cryoglobulinemia, lymphoproliferative disorders, and renal disease. HCV infection has been reported in association with distinct histological patterns of glomerulonephritis in native kidneys.

Hepatitis C virus and kidney disease

Hepatitis C virus (HCV) is the most frequently observed viral infection in patients with kidney disease. HCV can cause glomerular disease, which can lead to end-stage renal disease that requires dialysis and/or kidney transplantation. It is recommended to test HCV patients once a year for proteinuria, microscopic hematuria and estimated glomerular filtration rate. Membranoproliferative glomerulonephritis is the most common glomerular disease induced by HCV. Over the past few decades, the prevalence of HCV infection has decreased among dialysis and kidney transplant patients. However, survival is significantly lower in HCV-positive than in HCV-negative dialysis patients whereas survival is significantly better in HCV-positive kidney transplant patients compared with HCV-positive dialysis patients. Thus, dialysis patients without a sustained virological response after anti-HCV therapy should be proposed for kidney transplantation. Recurrence or de novo occurrence of glomerular disease is responsible for the lower kidney allograft survival in HCV-positive compared with HCV-negative kidney transplant patients. Dialysis and kidney transplantation do not appear to negatively affect progression of liver fibrosis in the majority of patients. The available data also suggest that occult HCV infection does not exist in dialysis and kidney transplant patients.

Durability of a sustained virological response, late clinical sequelae, and long-term changes in aspartate aminotransferase to the platelet ratio index after successful treatment with peginterferon/ribavirin for chronic hepatitis C: a prospective study

OBJECTIVES

Previous studies, mostly retrospective using conventional interferon, have suggested a favorable prognosis for patients with chronic hepatitis C and a sustained virological response (SVR). However, long-term outcome, including changes in the degree of hepatic fibrosis, of SVR patients in the era of pegylated interferon (PegIFN) remains underdefined. We prospectively evaluated the long-term virological, clinical, and biochemical outcomes, including aspartate aminotransferase-to-platelet ratio index (APRI), in chronic hepatitis C patients with an SVR.

PATIENTS AND METHODS

We included 145 consecutive, treatment-naive chronic hepatitis C patients (mean age 47.3±9.1 years; 87 men; 42.1% genotype 1; 36.6% genotype 2/3) who achieved an SVR after combination therapy with PegIFN-α/ribavirin.

RESULTS

The mean follow-up time was 68.8±35 months. The overall incidence of hepatocellular carcinoma (HCC) and liver-related death was 1.4 and 0.7%, respectively. Among nine (7.6%) patients with pretreatment cirrhosis, two (22.2%) developed HCC and one of them (11.1%) died. No patient had conclusive evidence of late virological relapse. All patients retained normal liver biochemistry, except for five of 145 (3.5%), who had persistently elevated transaminase levels, all of whom were diagnosed with new liver disease. APRI values improved significantly with treatment (0.95±1.09 vs. 0.66±0.64, P<0.001) and continued to improve after a mean of 61.4±45.5 months from an SVR in patients (n=54; 37.2%) with significant (Metavir ≥F2) pretreatment fibrosis (1.13±0.66 vs. 0.67±0.45, P<0.001).

CONCLUSION

The long-term outcome, including APRI, of chronic hepatitis C patients treated successfully with PegIFN/ribavirin and followed for a mean of 5.7 years is favorable. However, a high risk of progression to HCC and liver-related death remains for patients with pretreatment cirrhosis, in our setting, as high as 22.2 and 11.1%, respectively.

Occult hepatitis C virus infection in Iranian patients with cryptogenic liver disease

The diagnosis of cryptogenic liver disease is made when after extensive evaluations, recognizable etiologies of chronic liver disease are excluded. In this study, the presence of hepatitis C virus (HCV) RNA was tested in peripheral blood mononuclear cells (PBMCs) taken from Iranian patients who although were found negative for plasma HCV RNA and anti-HCV antibodies, suffered from chronic liver disease of unknown etiology. From September 2007 to March 2010, 69 patients from Tehran with chronic liver disease of unknown etiology who were referred to our center were enrolled in the present study. PBMCs were isolated from 10 mL peripheral blood specimens. HCV-RNA status was tested in plasma and PBMCs samples by reverse-transcription polymerase chain reaction (RT-PCR). HCV-RNA was detected in HCV-positive PBMCs specimens by RT-PCR method. HCV genotypes were subsequently analyzed in HCV-positive samples using restriction fragment length polymorphism (RFLP) assay; then HCV genotypes were confirmed by sequencing of 5' non-coding fragments after cloning PCR products into pJET1.2/blunt cloning vector. HCV-RNA was detected in PBMCs specimens belonging to 7 (10%) out of 69 patients. Genotyping of the HCV-RNA isolated from PBMCs showed that 3 (43%) patients with occult HCV infection had genotype 1b, 2 (29%) had genotype 1a, and another 2 (29%) had genotype 3a. The results of this study suggest that patients with chronic liver disease of unknown etiology may have occult HCV infection in the absence of anti-HCV antibodies and plasma HCV-RNA. It has been suggested that in the absence of liver biopsy specimens, analysis of PBMC sample for HCV-RNA would be informative.

Prevalence and follow-up of occult HCV infection in an Italian population free of clinically detectable infectious liver disease

Background

Occult hepatitis C virus infection (OCI) is a recently described phenomenon characterized by undetectable levels of HCV-RNA in serum/plasma by current laboratory assays, with identifiable levels in peripheral blood mononuclear cells (PBMCs) and/or liver tissue by molecular tests with enhanced sensitivity. Previous results from our group showed an OCI prevalence of 3.3% in a population unselected for hepatic disease. The present study aimed to evaluate OCI prevalence in a larger cohort of infectious liver disease-free (ILDF) subjects. Clinical follow-up of OCI subjects was performed to investigate the natural history of the infection.

Methods and Findings

439 subjects referred to a Turin Blood Bank for phlebotomy therapy were recruited. They included 314 ILDF subjects, 40 HCV-positive subjects and 85 HBV-positive subjects, of whom 7 were active HBV carriers. Six subjects (4/314 ILDF subjects [1.27%] and 2/7 active HBV carriers [28%]) were positive for HCV-RNA in PBMCs, but negative for serological and virological markers of HCV, indicating OCI. HCV genotypes were determined in the PBMCs of 3/6 OCI subjects two had type 1b; the other had type 2a/2c. OCI subjects were followed up for at least 2 years. After 12 months only one OCI persisted, showing a low HCV viral load (3.73×10¹ UI/ml). By the end of follow-up all OCI subjects were negative for HCV. No seroconversion, alteration of liver enzyme levels, or reduction of liver synthesis occurred during follow-up.

Conclusions

This study demonstrated the existence of OCI in ILDF subjects, and suggested a high OCI prevalence among active HBV carriers. Follow-up suggested that OCI could be transient, with a trend toward the decrease of HCV viral load to levels undetectable by conventional methods after 12–18 months. Confirmation studies with a longer follow-up period are needed for identification of the OCI clearance or recurrence rates, and to characterize the viruses involved.

Hepatitis C virus (HCV) status in newborns born to HCV positive women performing intracytoplasmic sperm injection

BACKGROUND

A low risk of HCV vertical transmission has been reported especially in those born to women with viraemia. Intracytoplasmic sperm injection (ICSI) being an assisted reproduction technique includes procedures that may increase risk of transmission.

OBJECTIVE

To determine the rate of vertical transmission of HCV to newborns born to HCV positive mothers in ICSI cycles.

METHODS

In a cross-sectional observational study, serum samples have were collected within the first week after birth from newborns of two groups of ICSI cycles females. Group one: 30 women HCV antibody (Ab) positive/HCV RNA negative. Group two: 30 women HCV Ab positive/HCV RNA positive. Newborn sera were subjected to HCV antibody testing, and detection of HCV viral RNA by PCR.

RESULTS

None of the newborns born to PCR negative females undergoing ICSI cycles showed positive results neither for HCV antibody, or for HCV RNA. Only one out of the 30 newborns born to PCR positive females was positive for HCV antibody and HCV RNA.

CONCLUSION

HCV vertical transmission in ICSI cycles seemed to be of low incidence in PCR positive women, while in the case of HCV PCR negative/sero-positive women, it appeared to be completely absent. This observation could have an impact on the clinicians' counseling for HCV positive females seeking ICSI.

Occult hepatitis C virus elicits mitochondrial oxidative stress in lymphocytes and triggers PI3-kinase-mediated DNA damage response

Occult hepatitis C viral infection (OHCI) is a newly reported pathological entity associated with increased risk of developing hepatocellular carcinoma and lymphoproliferative disorders. Although hepatocytes are the primary sites of viral replication, hepatitis C virus is potentially lymphotropic, invading and propagating in cells of the immune system. Lymphocytes, the extrahepatic viral reservoirs, are differentially implicated in the occult and the active forms of the disease. This study aimed to elucidate the implications of mitochondrial oxidative stress on the immune pathophysiological mechanisms of OHCI. We herein report that OHCI induces mitochondrial oxidative stress, leading to DNA double-strand breaks and elicitation of a phosphoinositol 3-kinase-mediated cellular response in peripheral blood lymphocytes. Compared to controls, OHCI subjects showed higher accumulation of pATM, pATR, γH2AX, and p-p53, along with active recruitment of repair proteins (Mre11, Rad50, and Nbs1) and altered mitochondrial DNA content. Increased mitochondrial membrane depolarization and circulating nucleosome levels along with chromatid-type aberrations and decreased T-cell proliferative index observed in the OHCI group further indicated that this damage might lead to Bax-triggered mitochondria-mediated cellular apoptosis. Together our results provide the mechanistic underpinnings of mitochondrial dysfunction in OHCI, a previously unknown paradigm, for explaining the immune pathogenesis in a redox-dependent manner.

Occult HCV or delayed viral clearance from lymphocytes of Chronic HCV genotype 3 patients after interferon therapy

Background

A recently discovered occult HCV entity reported by various investigators seems to be highly controversial. Especially, the clinical significance of these findings remains uncertain. For optimal outcome of antiviral therapy, investigation of occult HCV needs a broad-based probe in order to investigate the results of viral therapy and its host/viral interaction. The current study was aimed at determining the prevalence of occult HCV in peripheral blood lymphocytes of predominantly genotype 3 HCV-infected patients after completion of antiviral therapy and to investigate long term outcomes in the presence or absence of PBMC positivity.

Method

A total of 151 chronic, antiHCV and serum RNA-positive patients were enrolled in the study. Patients with a complete virological response at the end of treatment were screened for the presence of viral RNA in their PBMCs and were followed for up to one year for the presence of serum and PBMC viral genomic RNA.

Results

Out of 151 patients, 104 (70%) responded to the prescribed interferon treatment and showed viral-clearance from serum. These were screened for the presence of genomic RNA in their PBMCs. Sixteen samples were PBMC-positive for viral RNA at the end of treatment (EOT). All these patients had also cleared the virus from peripheral blood cells after the 6-12 month follow-up study.

Conclusion

True occult hepatitis C virus does not exist in our cohort. Residual viremia at the EOT stage merely reflects a difference in viral kinetics in various compartments that remains a target of immune response even after the end of antiviral therapy and is eventually cleared out at the sustained viral response (SVR).

Sustained virologic response to antiviral therapy for chronic hepatitis C virus infection: a cure and so much more

Sustained virologic response (SVR) is defined as aviremia 24 weeks after completion of antiviral therapy for chronic hepatitis C virus (HCV) infection. In analyses of SVR durability, the incidence of late relapse is extremely low (<1%). Histologic regression of both necroinflammation and fibrosis has been demonstrated in paired liver biopsy samples in SVR-achieving patients. More noteworthy is the sustained responder's favorable prognosis even with baseline cirrhosis; despite mostly retrospective analyses, relative to nonresponders or to those untreated, patients with SVR have significantly fewer liver-related complications, less hepatocellular carcinoma, and fewer liver-related deaths. Although HCV is associated with insulin resistance, successful eradication of HCV appears to reduce the risk of impaired fasting glucose and diabetes development. In summary, chronic HCV infection is curable with SVR attainment, and with cure comes improved liver histology and more favorable clinical outcomes, in comparison with patients who do not achieve the same therapeutic milestone.

Spontaneous loss of hepatitis C virus RNA from serum is associated with genotype 1 and younger age at exposure

A variety of factors have been associated with spontaneous loss of hepatitis C virus (HCV)-RNA from serum, including infecting HCV type, although results are conflicting. This study aimed to investigate further whether infecting HCV type was linked to spontaneous loss of HCV-RNA. Serum samples from 321 untreated HCV antibody positive patients presenting at the Hepatology clinic at Addenbrooke's Hospital, Cambridge between 2004 and 2007 were tested. These individuals were classified either as HCV antibody and HCV-RNA positive (viremic, n = 219) or HCV antibody positive and repeatedly HCV-RNA negative (non-viremic, n = 102). Infecting HCV type was identified by genotyping (viremic) or serotyping (non-viremic). Binomial regression analysis investigated the independent effect of HCV type on spontaneous loss of HCV-RNA from serum by comparing the two groups. Ninety-one percent of patients were found to be either genotype 1 or genotype 3. The prevalence of type 1 infection was greater among non-viremic (64.5%) than viremic individuals (45%). After controlling for the effects of potential confounding factors, multivariable analyses showed that individuals with type 1 infections were more likely to be non-viremic than genotype 3 infections (RR = 2.07; 95% CI: 1.25, 3.43; P = 0.005). Individuals infected at an older age were also less likely to become HCV-RNA negative spontaneously (RR = 0.42 comparing those infected at ≥20 years of age against those infected at <20 years of age, 95% CI: 0.25, 0.72; P = 0.002). In conclusion, the results suggest that HCV genotype 1 infections are more likely than genotype 3 infections to become spontaneously non-viremic, as are infections acquired at younger age.

Long-term outcome of chronic hepatitis C patients with sustained virological response to peginterferon plus ribavirin

AIM: To assess the clinical, biochemical and virological long-term outcome in chronic hepatitis C (CHC) patients with a sustained virological response (SVR) after peginterferon (PEG-IFN) plus ribavirin combination therapy.

METHODS: One hundred and fifty three patients with a SVR after treatment with PEG-IFN plus ribavirin were included in a 5-year follow-up study in a single Spanish center, based on standard clinical practice. Clinical anamnesis, biochemical analysis, hepatitis C virus RNA and alpha-fetoprotein measurement, ultrasonography and transient elastography were performed annually.

RESULTS: The mean follow-up period of the 153 patients was 76 ± 13 mo after they obtained a SVR. Five patients (3.26%) presented with cirrhosis before treatment and 116 (75.8%) had genotype 1. No patient showed evidence of hepatic decompensation. One patient (0.65%) developed a hepatocellular carcinoma at month 30 after achieving SVR. There were no virological relapses during this follow-up period. Persistently elevated alanine aminotransferase was found in only one patient (0.65%). At the end of the 5-year follow-up, the mean value of transient elastography was 7 ± 4.3 kPa (F1). There were no deaths and no other tumors.

CONCLUSION: The long-term outcome of 153 CHC patients with SVR to PEG-IFN plus ribavirin was good. No evidence of a virological relapse was seen. One patient (0.65%) developed a hepatocellular carcinoma.

Occult hepatitis C virus infection and associated predictive factors: the Pakistan experience

The aim of the present study was to determine the presence of HCV RNA in the liver biopsies of patients with abnormal liver tests but without detectable serum HCV RNA and anti-HCV antibodies in sera. Liver biopsies and whole blood of total 31 patients who were negative for anti-HCV antibodies with elevated liver function tests were received at Division of Molecular Diagnostics, University of the Punjab Pakistan from January 2002 to June 2009 for the detection of HCV RNA. HCV RNA status of the subjects was tested by reverse-transcription PCR and quantified using SmartCycler II real-time PCR. HCV genotyping was carried out in HCV RNA positive samples using molecular genotyping method. HCV RNA was found in liver-biopsy specimens from 23 (74.2%) of the total 31 patients negative for anti-HCV antibodies and undetectable serum HCV RNA. HCV RNA of both negative and positive polarity was found in the livers of 8 (25.8%) patients. Genotyping analysis showed that 65% patients were infected with HCV 3a, 17% with 3b, 13% with 1a and 4% patients were found with untypable genotype. In a multivariate logistic regression model, patients having previous history surgeries, male sex and age above 30 years were significantly associated with the presence of occult HCV infection (p<0.05). In conclusion, patients with elevated liver enzymes and negative HCV antibodies and negative serum RNA may have occult HCV infection and its chance increases with previous history of surgeries, in male sex and above 30 years of age.

Real-time quantitative assay for routine testing of HCV RNA in formalin-fixed, paraffin-embedded liver samples

The assessment of hepatitis C virus (HCV) RNA in liver tissues is clinically relevant in cases where histology, liver function tests, and HCV serology are not sufficient for a definitive diagnosis of HCV-related hepatitis. We analyzed 215 formalin-fixed, paraffin-embedded liver needle biopsies from patients infected with HCV genotypes 1b and 2. HCV RNA extracted from paraffin sections were quantified by means of a TaqMan real-time reverse transcription-polymerase chain reaction method. The quantification of HCV RNA in liver tissue was correlated with the amount of HCV detected by immunohistochemistry (IHC) on paired frozen biopsies, the HCV RNA load in the serum, and the main serum tests of liver function and cholestasis. HCV RNA was detected by real-time reverse transcription-polymerase chain reaction in 169 liver biopsies (78.6%) with a mean value of 13.59+/-37.25 IU/ng. Tissue HCV RNA levels strongly correlated with the IHC results (P<0.001, Spearman test), HCV serum load (P<0.001), aspartate aminotransferase (P=0.001), gamma-glutamyl transpeptidase (P=0.012), and aspartate aminotransferase/alanine aminotransferase ratio (P=0.029). HCV RNA was amplified in up to 7-year-old archival tissue samples. Real-time HCV RNA quantification on archival liver tissue may be clinically relevant in case of "occult" HCV infection or for the diagnosis of patients with known HCV infection and hepatic dysfunction but seronegative for HCV RNA. The assessment of the levels of HCV RNA in the liver might also be important for monitoring the effectiveness of antiviral therapy and the progression of disease in patients with chronic HCV hepatitis.

Study of nitric oxide in patients with chronic hepatitis C genotype 4: relationship to viremia and response to antiviral therapy

Hepatitis C virus (HCV) infection is a global medical problem. The role of Nitric oxide (NO) in chronic viral hepatitis is still unknown. It may play a prominent role as an antiviral agent that reduces its replication or as a mediator that causes accumulation of oxidative DNA damage and oncogenesis. The present study was carried out to study effect of combined peginterferon and ribavirin therapy for hepatitis C on NO in both responders and in non responder patients. The study included seventy three patients with positive serological markers for HCV. They were classified according to presence or absence of HCV viremia and the response to therapy. In addition sixteen control subjects were included. NO levels were determined as the stable end product nitrate and nitrite. Serum nitrite and nitrate concentrations in the patients with viral hepatitis were significantly higher than normal subjects and patients with serological evidence of hepatitis C infection in absence of viral load. The levels of nitrite >or= 31 microM, nitrate >or= 15 microM and NO(2)/NO(3) ratio < 1.5 microM were associated with increased risk of resistance to therapy. The multivariate logistic regression analysis showed that NO(2)/NO(3) ratio at levels < 1.5 microM was associated with HCV eradication independently. This study provides new insight into the pathogenesis of hepatitis C and highlights the effect of combined peginterferon and ribavirin on nitrite and nitrate as markers of endogenous NO system. There is a limitation level of NO that if it is increased above it may lead to non response to antiviral therapy. Therefore, it may be an important factor for chronic hepatitis C, which suggests an additional therapeutic pathway of anti-oxidants in combination with the standard regimen for further study.

Occult HCV infection: an unexpected finding in a population unselected for hepatic disease

Background

Occult Hepatitis C virus (HCV) infection is a new pathological entity characterized by presence of liver disease and absence or very low levels of detectable HCV-RNA in serum. Abnormal values of liver enzymes and presence of replicative HCV-RNA in peripheral blood mononuclear cells are also observed. Aim of the study was to evaluate occult HCV occurrence in a population unselected for hepatic disease.

Methodology/Principal Findings

We chose from previous epidemiological studies three series of subjects (n = 276, age range 40–65 years) unselected for hepatic disease. These subjects were tested for the presence of HCV antibodies and HCV-RNA in plasma and in the peripheral blood mononuclear cells (PBMCs) by using commercial systems. All subjects tested negative for HCV antibodies and plasma HCV-RNA and showed normal levels of liver enzymes; 9/276 patients (3.3%) were positive for HCV-RNA in PBMCs, identifying a subset of subjects with potential occult HCV infection. We could determine the HCV type for 8 of the 9 patients finding type 1a (3 patients), type 1b (2 patients), and type 2a (3 patients).

Conclusions

The results of this study show evidence that occult HCV infection may occur in a population unselected for hepatic disease. A potential risk of HCV infection spread by subjects harbouring occult HCV infection should be considered. Design of prospective studies focusing on the frequency of infection in the general population and on the clinical evolution of occult HCV infection will be needed to verify this unexpected finding.

Histological changes in HCV antibody-positive, HCV RNA-negative subjects suggest persistent virus infection

It is unclear whether hepatitis C virus (HCV) has been eradicated or persists at a low level in HCV antibody-positive HCV RNA-negative individuals. The natural history and liver histology are not well characterized. One hundred seventy-two HCV antibody-positive, serum HCV RNA-negative patients underwent diagnostic liver biopsy between 1992 and 2000 and were followed a median 7 years (range, 5-12). Patients with any possible cause of liver injury other than HCV were excluded. A single histopathologist scored sections using Ishak criteria. Characterization of the inflammatory infiltrate in selected cases used a novel semiquantitative technique and compared with HCV RNA-positive patients and healthy controls. One hundred two patients were excluded because of a risk factor for liver injury other than HCV. Seventy patients met the study criteria; four (5.7%) became HCV RNA-positive during follow-up. Sixty-six cases remained HCV RNA-negative; five (7.5%) had a normal liver biopsy; 54 (82%) had fibrosis (stage 2 or 3 in 16 (24%)). Nonviremic cases revealed expanded portal tracts (P < 0.05), with fewer CD4+ (P < 0.05) and more CD8+ cells (P < 0.05) than healthy controls, but were indistinguishable from HCV RNA-positive cases for these parameters. Lobular CD4 staining, absent in healthy controls, was noted in both HCV RNA-negative and -positive cases and was more marked in the latter (P < 0.05) with a sinusoidal lining cell distribution.

CONCLUSION

Nonviremic HCV antibody-positive patients have a liver biopsy that is usually abnormal. Fibrosis was present in most with similar inflammatory infiltrate to viremic cases. The presence of a CD8+ rich inflammatory infiltrate suggests an ongoing immune response in the liver, supporting the view that HCV may persist in the liver in the majority of HCV RNA-negative cases.

Hepatocellular carcinoma in long-term sustained virological responders following antiviral combination therapy for chronic hepatitis C

Antiviral treatment results in a sustained virologic response (SVR) in 50-75% of patients with chronic hepatitis C. Long-term follow up studies have observed ongoing SVR in the overwhelming majority of them. Thus chronic hepatitis C is considered 'cured' if an SVR is achieved. Consequently, it is expected that in sustained virologic responders long-term complications of hepatatic C virus (HCV) related chronic liver disease including hepatocellular carcinoma are eliminated or have a decreased incidence. We report on five patients (three from Austria, two from USA) who developed hepatocellular carcinoma during follow up (3-6 years) after achieving SVR. During follow up and at diagnosis all were HCV-RNA neg. None of the patients had other liver diseases. One patient presented with bilateral adrenal metastasis, the remaining four with large hepatic tumours. Three patients were noncirrhotic at the start of treatment at the time of tumour diagnosis. Successful antiviral treatment in HCV patients does not prevent development of hepatocellular carcinoma even in non-cirrhotic livers. Long-term follow up of patients with SVR is mandatory and should include surveillance for hepatocellular carcinoma.

Evidence for protection against chronic hepatitis C virus infection in chimpanzees by immunization with replicating recombinant vaccinia virus

Given the failures of nonreplicating vaccines against chronic hepatitis C virus (HCV) infection, we hypothesized that a replicating viral vector may provide protective immunity. Four chimpanzees were immunized transdermally twice with recombinant vaccinia viruses (rVV) expressing HCV genes. After challenge with 24 50% chimpanzee infective doses of homologous HCV, the two control animals that had received only the parental VV developed chronic HCV infection. All four immunized animals resolved HCV infection. The difference in the rate of chronicity between the immunized and the control animals was close to statistical significance (P = 0.067). Immunized animals developed vigorous gamma interferon enzyme-linked immunospot responses and moderate proliferative responses. To investigate cross-genotype protection, the immunized recovered chimpanzees were challenged with a pool of six major HCV genotypes. During the acute phase after the multigenotype challenge, all animals had high-titer viremia in which genotype 4 dominated (87%), followed by genotype 5 (13%). However, after fluctuating low-level viremia, the viremia finally turned negative or persisted at very low levels. This study suggests the potential efficacy of replicating recombinant vaccinia virus-based immunization against chronic HCV infection.

Desperately seeking hepatitis C virus

Spanish investigators described recently the so-called occult hepatitis C virus (HCV) infection, emphasizing the detection of genomic and antigenomic HCV RNA strands in liver and peripheral blood mononuclear cells. Therefore, the persistence of viral replication in occult HCV infection should be considered as a putative source of infection among family members and patients undergoing invasive procedures, transfusion or transplantation. Additionally, the most worrisome finding is that an occult HCV infection may persist in patients with sustained virological response.

Occult persistence and lymphotropism of hepatitis C virus infection

Recent discovery of occult hepatitis C virus (HCV) infection persisting after spontaneous or antiviral therapy-induced resolution of hepatitis C was made possible by the introduction of nucleic acid amplification assays capable of detecting HCV RNA at sensitivities superseding those offered by clinical tests. Although individuals with this seemingly silent HCV infection are usually anti-HCV antibody reactive and have normal liver function tests, occult HCV infection has also been reported in anti-HCV-negative individuals with persistently elevated liver enzymes of unknown etiology. Studies have shown that HCV RNA can persist for years in serum, lymphomononuclear cells and liver in the absence of clinical symptoms, although histological evidence of a mild inflammatory liver injury can be occasionally encountered. Furthermore, while HCV RNA can be detected in circulating lymphoid cells in approximately 30% of cases, a short-term culture under stimulatory conditions augments HCV replication in these cells allowing detection of virus in otherwise HCV-negative cases. HCV infects different immune cell subsets, including CD4⁺ and CD8⁺ T lymphocytes, B cells and monocytes. Studies employing clonal sequencing and single-stranded conformational polymorphism analyses have revealed unique HCV variants residing in immune cells, further strengthening the notion of HCV lymphotropism. Overall, the data accumulated suggest that occult HCV infection is a common consequence of resolution of symptomatic hepatitis C and that examination of the cells of the immune system is an effective approach to diagnosis of HCV infection and its long-term persistence. Further work is required to fully realize pathogenic and epidemiological consequences of occult HCV persistence.

Occult hepatitis C virus infection revisited with ultrasensitive real-time PCR assay

Occult hepatitis C infection is regarded as a new entity that should be considered when diagnosing patients with a liver disease of unknown origin. Using an ultrasensitive real-time PCR assay, we demonstrated that occult hepatitis C virus (HCV) infection cannot be found in peripheral blood mononuclear cells of patients with cryptogenic liver diseases, HCV--associated systemic vasculitis, or connective tissue diseases. The significance of such occult infection must be elucidated.

Verses, viruses, and the vulnerability of the blood supply in industrialized countries

In the last 30 years, tremendous progress in identifying transfusion-transmitted viruses such as HBV, HCV, and HIV in industrialized countries has been achieved. Currently, the residual risk of transmitting these viruses through transfusion is very low especially after the introduction of "minipool" nucleic acid-amplification tests. Despite these major technical advances, there remains a legitimate concern as to the transmission of other blood-borne infectious agents through blood transfusion. Among these agents are HBV mutants, occult HBV, and HCV infections, malaria, Chagas, West Nile, dengue, and vesiviruses, bacterial infections such as Yersinia enterocolitica, and tick borne diseases such as human monocytic ehrlichiosis, human granulocytic ehrlichiosis, Rocky Mountain spotted fever, and Lyme and prion diseases such as Creutzfeldt and variant Creutzfeldt. Most of these agents are very rarely transmitted by transfusion in industrialized countries. However, an awareness of their possible transmission is essential for the control of spread of these diseases among the public by human-to-human transmission via blood transfusion. This review summarizes the current status of prevalence and diagnosis of these emerging diseases and also updates our knowledge on recently discovered non-pathogenic blood-borne viruses such as GB virus C and Torque Tenoviruses.