Presence of hepatitis B and C viral genomes in US blood donors as detected by polymerase chain reaction amplification

Are current screening protocols for chronic hepatitis B virus infection adequate?

Chronic hepatitis B virus (HBV) infection screening usually includes only HBV surface antigen (HBsAg) testing; HBV core and surface antibody (anti-HBc, anti-HBs) assays, indicating resolved infection and immunity, are not routinely performed. Yet, serum HBV DNA is measurable in approximately 10% of HBsAg-negative/anti-HBc-positive cases, representing occult HBV infection (OBI). Patient blood samples from 2 Veterans Affairs medical center look-back investigations were screened for HBV infection using HBsAg enzyme immunoassays. Supplementary testing included anti-HBc and anti-HBs enzyme immunoassays. For anti-HBc-positive samples, HBV DNA testing was performed. Background OBI prevalence was further estimated at these 2 facilities based on HBV serology testing results from 1999-2012. Finally, a literature review was performed to determine OBI prevalence in the published literature. Of 1887 HBsAg-negative cohort patients, 98 (5.2%) were anti-HBc positive/anti-HBs negative; and 175 (9.3%), anti-HBc positive/anti-HBs positive. Six of 273 were HBV DNA positive, representing 0.3% of the total tested and 2.2% who were anti-HBc positive/anti-HBs negative or anti-HBc positive/anti-HBs positive. Among 32,229 general population veterans at these 2 sites who had any HBV testing, 4/108 (3.7%) were HBV DNA positive, none of whom were part of the cohort. In 129 publications with HBsAg-negative patients, 1817/1,209,426 (0.15%) had OBI. However, excluding blood bank studies with greater than 1000 patients, the OBI rate increased to 1800/17,893 (10%). OBI is not rare and has implications for transmission and disease detection. HBsAg testing alone is insufficient for detecting all chronic HBV infections. These findings may impact blood donation, patient HBV screening, follow-up protocols for patients assumed to have cleared the infection, and initiation of immunosuppression in patients with distant or undetected HBV.

Natural History of Hepatitis C

Hepatitis C infection is a common cause of cirrhosis and indication for liver transplantation in the United States. The incidence of chronic hepatitis C has been declining, but rates of cirrhosis and hepatocellular carcinoma are projected to increase. The outcome of chronic hepatitis C is variable. It is estimated that 20% to 25% will develop cirrhosis over a 25-year to 30-year period. The rate of disease progression is influenced by many host, viral, and environmental factors. Few can be modified.

A strategical re-thinking on National Blood Donor Pool: Anti-HBc positivity related re-entry mechanisms

BACKGROUND AND OBJECTIVES

Screening of blood donations for antibodies against hepatitis B core antigen (anti-HBc) is used to prevent transfusion transmitted hepatitis B virus (HBV) infection. In this study, we studied the magnitude of blood donor gain by using a re-entry mechanism in our Blood Bank of Gulhane Military Academy of Medicine.

MATERIALS AND METHODS

Between January and May 2013, 5148 voluntary blood donors were screened by ELISA method for HBsAg, anti-HBc total and other screening markers, prospectively. Samples with repeated reactivity for the presence of anti-HBc were further tested with four supplemental assays.

RESULTS

We detected 515 (10%) anti-HBc positive and 4612 (90%) anti-HBc negative cases in 5127 HBsAg negative serum samples. A total of 461 (89.5%) blood units were reactive for at least one additional serologic parameter and 54 were (10.5%) negative. Isolated anti-HBc positivity rate was 1.3% (69/5127). In the isolated anti-HBc positive samples, 54 were also anti-HBe and HBeAg negative. HBV DNA was not detected in any of the samples.

CONCLUSION

Applying the EDQM criteria would decrease our blood donor loss from 10% to 5.4%. As alternative re-entry mechanisms have already been presented in the literature, institution of a new policy is needed to enhance the limited blood donor pool in our system.

The detection of occult HBV infection in patients with HBsAg negative pattern by real-time PCR method

AIM

Diagnostic problems may be encountered in Hepatitis B virus (HBV) infections by serological tests and HBV DNA can be detectable in plasma and liver tissue while the HBsAg test is negative. This situation can be defined as occult or isolated Anti-HBc infections. Occult HBV infections may be divided into two categories by using hepatitis markers. One of them being that all hepatitis markers are negative and the other situation is having Anti-HBc +/- and Anti-HBs+patterns. These situations can be seen in isolated Anti-HBc cases.

METHOD

In this study, we aimed to detect the ratio of occult HBV infections by investigating HBV DNA in four different groups. These groups are: (1) 20 isolated Anti-HBc positive individuals, (2) 23 individuals naturally immune to HBV infection, (3) 20 individuals with seronegative hepatitis markers and high ALT levels, and (4) 23 vaccinated individuals against HBV. In order to detect HBV DNA the real-time PCR kit (QIAGEN, Artus HBV RG PCR Kit, Germany) with high analytical sensitivity (≤3.8IU/ml) was used.

RESULTS

The reliability of the molecular methods was assessed by increasing the quantitation standards of internal, external and also positive controls. No HBV DNA was detected in any of the 86 individuals consisting of four study groups.

CONCLUSION

In conclusion, we did not detect occult HBV infection in our four study groups by using a high sensitivity real-time (RT) PCR method, while occult HBV infections with various frequencies were detected in other large, serial international studies in which highly sensitive analytical molecular methods were used. Although we also used a high standard molecular kit to detect occult HBV infections, we suggest that the reason for the absence of detection of occult HBV infections may be due to the small number of cases included in this study. However, it was assumed that the use of a nucleic acid amplification technology (NAT) with high analytical sensitivity in blood banks to prevent HBV transmission by blood transfusion is controversial due to both costs and diagnostic efficacy and for this reason we suggest that it will be useful to perform large serial studies regarding occult HBV infections in the future.

Molecular detection of autosomal-dominant feline polycystic kidney disease by multiplex amplification refractory mutation system polymerase chain reaction

Feline autosomal-dominant polycystic kidney disease (ADPKD), with its characteristic growth of fluid-filled cysts of different sizes, is the most prevalent inherited genetic disease of cats. The point mutation (C-->A transversion) in exon 29 of the PKD1 gene is known to contribute to ADPKD development and can thus serve as a target for the molecular genetic diagnosis of ADPKD. To this end, a simple amplification refractory mutation system (ARMS) polymerase chain reaction (PCR) was designed with 3 primers: 2 forward primers specifically targeting either the mutant or normal allele, and 1 universal reverse primer for amplification of both alleles. The new method was tested on the DNA from 35 feline blood samples, which included 15 mutant cats and 20 wild type cats. As verified by direct DNA sequencing, both sensitivity and specificity of this tri-primer ARMS PCR were 100%. As the multiplex ARMS PCR test can be performed in a single PCR reaction without other post-PCR procedures, it is a simple and accurate method for molecular studies of feline ADPKD.

Multiplex Amplification Refractory Mutation System Polymerase Chain Reaction (ARMS-PCR) for diagnosis of natural infection with canine distemper virus

BACKGROUND

Canine distemper virus (CDV) is present worldwide and produces a lethal systemic infection of wild and domestic Canidae. Pre-existing antibodies acquired from vaccination or previous CDV infection might interfere the interpretation of a serologic diagnosis method. In addition, due to the high similarity of nucleic acid sequences between wild-type CDV and the new vaccine strain, current PCR derived methods cannot be applied for the definite confirmation of CD infection. Hence, it is worthy of developing a simple and rapid nucleotide-based assay for differentiation of wild-type CDV which is a cause of disease from attenuated CDVs after vaccination. High frequency variations have been found in the region spanning from the 3'-untranslated region (UTR) of the matrix (M) gene to the fusion (F) gene (designated M-F UTR) in a few CDV strains. To establish a differential diagnosis assay, an amplification refractory mutation analysis was established based on the highly variable region on M-F UTR and F regions.

RESULTS

Sequences of frequent polymorphisms were found scattered throughout the M-F UTR region; the identity of nucleic acid between local strains and vaccine strains ranged from 82.5% to 93.8%. A track of AAA residue located 35 nucleotides downstream from F gene start codon highly conserved in three vaccine strains were replaced with TGC in the local strains; that severed as target sequences for deign of discrimination primers. The method established in the present study successfully differentiated seven Taiwanese CDV field isolates, all belonging to the Asia-1 lineage, from vaccine strains.

CONCLUSIONS

The method described herein would be useful for several clinical applications, such as confirmation of nature CDV infection, evaluation of vaccination status and verification of the circulating viral genotypes.

Treatment of HBV/HCV coinfection

IMPORTANCE OF THE FIELD

Hepatitis B (HBV) and hepatitis C (HCV) virus infections are among the most common causes of advanced chronic liver disease worldwide. HBV/HCV coinfection is not uncommon with an estimated 7 - 20 million individuals affected worldwide. Patients with HBV/HCV coinfection have an increased risk for cirrhosis, hepatocellular carcinoma (HCC) and even death.

AREAS COVERED IN THIS REVIEW

The pathophysiology of HBV/HCV coinfection is complex, as different patterns of virological dominance may occur, which can even fluctuate over time. Recently, combination of pegylated interferon (PEG-IFN) plus ribavirin has been explored in HBV/HCV coinfected patients who are positive for HCV-RNA. HBV polymerase inhibitors may be indicated if HBV-DNA concentrations are above 2000 IU/ml. In this review, we summarize the epidemiology, viral interaction, its clinical features and the available treatment options.

WHAT THE READER WILL GAIN

Insights into viral interaction of HBV/HCV coinfection and treatment individualization strategies are provided in the review.

TAKE HOME MESSAGE

Detailed serological and virological evaluations are required for HBV/HCV coinfected patients before initiation of antiviral therapy. At present, PEG-IFN-alpha plus ribavirin should be the treatment of choice in patients with dominant HCV replication. However, HBV rebound may occur after elimination of HCV, and thus close monitoring for both viruses is recommended even for patients with initially suppressed HBV-DNA.

Amplification refractory mutation system PCR assays for the detection of variola and Orthopoxvirus

PCR assays that can identify the presence of variola virus (VARV) sequences in an unknown DNA sample were developed using principles established for the amplification refractory mutation system (ARMS). The assay’s specificity utilised unique single nucleotide polymorphisms (SNP) identified among Orthopoxvirus (OPV) orthologs of the vaccinia virus Copenhagen strain A13L and A36R genes. When a variola virus specific primer was used with a consensus primer in an ARMS assay with different Orthopoxvirus genomes, a PCR product was only amplified from variola virus DNA. Incorporating a second consensus primer into the assay produced a multiplex PCR that provided Orthopoxvirus generic and variola-specific products with variola virus DNA. We tested two single nucleotide polymorphisms with a panel of 43 variola virus strains, collected over 40 years from countries across the world, and have shown that they provide reliable markers for variola virus identification. The variola virus specific primers did not produce amplicons with either assay format when tested with 50 other Orthopoxvirus DNA samples. Our analysis shows that these two polymorphisms were conserved in variola virus genomes and provide a reliable signature of Orthopoxvirus species identification.

Low doses of hepadnavirus induce infection of the lymphatic system that does not engage the liver

Woodchuck hepatitis virus (WHV), which is closely related to human hepatitis B virus and is considered to be principally hepatotropic, invades the host's lymphatic system and persists in lymphoid cells independently of whether the infection is symptomatic and serologically evident or concealed. In this study, we show, with the woodchuck model of hepatitis B, that hepadnavirus can establish an infection that engages the lymphatic system, but not the liver, and persists in the absence of virus serological markers, including antiviral antibodies. This primary occult infection is caused by wild-type virus invading the host at a quantity usually not greater than 10(3) virions. It is characterized by trace virus replication progressing in lymphatic organs and peripheral lymphoid cells that, with time, may also spread to the liver. The infection is transmissible to virus-naive hosts as an asymptomatic, indefinitely long, occult carriage of small amounts of biologically competent virus. In contrast to residual silent WHV persistence, which normally endures after the resolution of viral hepatitis and involves the liver, primary occult infection restricted to the lymphatic system does not protect against reinfection with a large, liver-pathogenic WHV dose; however, the occult infection is associated with a swift recovery from hepatitis caused by the superinfection. Our study documents that the lymphatic system is the primary target of WHV infection when small quantities of virions invade a susceptible host.

A novel DNA virus (SEN) among patients on maintenance hemodialysis: prevalence and clinical importance

BACKGROUND

A recently discovered DNA virus (SEN) has been assumed to be responsible for posttransfusion hepatitis in humans. Phylogenetic analysis of SEN virus has revealed the existence of 8 different strains. Two of them (SEN virus strain H (SENV-H) and SENV-D) have been described as possible candidate viruses for inducing posttransfusion hepatitis. Until now, it is unclear whether patients on maintenance hemodialysis are on increased risk for acquiring SEN virus.

OBJECTIVES

To investigate the prevalence of SENV-H among patients on maintenance hemodialysis and to examine whether special measures have to be taken to prevent nosocomial spreading of the virus.

STUDY DESIGN

Serum samples derived from 78 chronically hemodialysed patients were examined for SENV-H viremia by seminested polymerase chain reaction. A panel of 226 samples from healthy blood donors served as a control group.

RESULTS

The prevalence of SENV-H was determined to be 12.8% (n=10) among patients on maintenance hemodialysis. This is nearly the same prevalence as in healthy blood donors (16.8%; n=38). None of the solely SENV-H-viremic individuals had clinical or biochemical signs of liver disease. Enhanced severity of liver disease could not be observed in patients coinfected with hepatitis C virus and SENV-H.

CONCLUSION

We conclude that SENV-H viremia is widespread among hemodialysis patients. Since no viremic patient had clinical or biochemical signs of liver disease, in our setting the hepatitis-inducing capacity of SENV-H remains unclear. On the basis of our results, at present, we do not regard it as necessary to dialyse SENV-H-viremic patients on separate machines.

Occult hepatitis B virus infection and its clinical implications

Occult hepatitis B virus (HBV) infection is characterized by presence of HBV infection with undetectable hepatitis B surface antigen (HBsAg). Serum HBV level is usually less than 104 copies/mL in these patients. Diagnosis of occult HBV infection requires sensitive HBV-DNA PCR assay. Several possibilities have been hypothesized as the mechanisms of occult HBV infection. These include: (i) mutations of HBV-DNA sequence; (ii) integration of HBV-DNA into host's chromosomes; (iii) infection of peripheral blood mononuclear cells by HBV; (iv) formation of HBV-containing immune complex; (v) altered host immune response; and (vi) interference of HBV by other viruses. The precise prevalence of occult HBV infection remains to be defined. The clinical implications of occult HBV infection involve different clinical aspects. First of all, occult HBV infection harbours potential risk of HBV transmission through blood transfusion, haemodialysis, and organ transplantation. Second, it may serve as the cause of cryptogenic liver disease, contribute to acute exacerbation of chronic hepatitis B, or even fulminant hepatitis. Third, it is associated with development of hepatocellular carcinoma. Fourth, it may affect disease progression and treatment response of chronic hepatitis C. Most of the previous studies utilized retrospective observation without control groups, and lacked direct association of occult HBV infection with specific pathological changes and disease progression. Highly sensitive, quantitative, and functional molecular analyses of HBV, combined with a well-designed prospective clinical assessment will provide the best approach for the future study of occult HBV infection.

NAT for HBV and anti-HBc testing increase blood safety

BACKGROUND

Routine HBV PCR screening of blood donations to our institutes was introduced in January 1997 to complete the NAT screening program for transfusion-relevant viruses. Testing was successively extended to customer transfusion services with a total of 1,300,000 samples tested per year.

STUDY DESIGN AND METHODS

Minipools of 96 blood donation samples were formed by automatic pipettors. HBsAg-reactive samples were included. HBV particles were enriched from the minipools by centrifugation. Conventional and in-house TaqMan PCRs were successively applied for HBV amplification. Sensitivity reached 1000 genome equivalents per mL for each individual donation. Confirmatory single-sample and single-sample enrichment PCRs were established with sensitivities of 300 and 5 to 10 genome equivalents per mL, respectively.

RESULTS

After screening of 3.6 million donor samples, 6 HBV PCR-positive, HBsAg-negative donations were identified. Two samples were from infected donors who had not seroconverted and four were from chronic anti-HBc-positive low-level HBV carriers. Retesting by single-sample PCR of 432 samples confirmed positive for HBsAg identified 37 donations that were negative in minipool PCR. Donor-directed look-back procedures indicated that no infected donor who had not yet seroconverted was missed by minipool PCR. However, recipient-directed look-back procedures revealed two anti-HBc-positive recipients of HBsAg-negative minipool PCR-negative, anti-HBc-positive and single-sample PCR-positive blood components. After testing randomly selected 729 HBsAg-negative minipool PCR-negative, anti-HBc-positive donors by single-sample enrichment PCR, 7 were identified with < or = 10 HBV particles per mL of donor plasma.

CONCLUSION

Minipool PCR testing after virus enrichment was sensitive enough to identify HBsAg-negative donors who had seroconverterd and HBsAg-negative, anti-HBc-positive chronic HBV carriers. HBV NAT in conjunction with anti-HBc screening would reduce the residual risk of transfusion-transmitted HBV infection.

Hepatitis B virus infection in heart transplant recipients in a hepatitis B endemic area

BACKGROUND

Hepatitis B virus (HBV) infection is hyperendemic in Taiwan. It is almost impossible for us to reject organ donors or recipients with positive serum hepatitis B surface antigen (HBsAg). We report our experience with HBV infection in heart transplant recipients with particular attention to outcome of recipients who were HBsAg+ or who had received donor hearts from HBsAg+ donors.

METHODS

We performed a retrospective review of medical records.

RESULTS

In the study, we included 101 heart recipients with post-transplant survival of more than 6 months. According to pre-transplant HBV serology markers, we divided patients into 4 groups. Group 1 (n = 8) had been HBsAg+ at the time of heart transplantation. Of these, 6 patients had HBV reactivation in the post-transplant follow-up and needed lamivudine treatment. Complete response was achieved in all 6 patients; however, HBV recurrence occurred in 1 patient after 8 months of lamivudine treatment. The recurrence remained under partial control. Group 2 (n = 16) was HBV naïve at the time of heart transplantation. Of these, 2 received HBsAg+ donor hearts under perioperative hepatitis B immunoglobulin prophylaxis. HBV infection was successfully prevented in 1 patient, but the other contracted HBV hepatitis, which was successfully treated with lamivudine. In Group 2, 10 patients received donor hearts from anti-HBs+ donors, and none contracted HBV hepatitis after transplantation. Group 3 (n = 55) had protective anti-HBs antibody at the time of heart transplantation either from previous HBV vaccination (n = 10) or from natural HGB infection (n = 45). HBsAg+ donor hearts were transplanted into 2 patients with anti-HBs from previous HBV vaccination, and into 8 patients with anti-HBs form natural HBV infection. However, none of these 10 patients who received HBsAg+ donor hearts had HBV hepatitis after transplantation. Group 4 (n = 22) was HBs-, anti-HBs-, and anti-HBc+ at the time of heart transplantation. Of these, 7 patients received HBsAg+ donor hearts. Six patients experienced no HBV hepatitis after heart transplantation, and serum HBV DNA by polymerase chain reaction (PCR) at the time of heart transplantation was negative in all 6 patients. One patient had HBV hepatitis after transplantation, and serum HBV DNA by PCR at the time of heart transplantation also was positive.

CONCLUSION

HBV reactivation after the heart transplantation was common but usually well controlled with lamivudine treatment. Therefore, HBV carrier status should not contraindicate heart transplantation. HBsAg+ donor hearts were safely transplanted into anti-HBs+ recipients; therefore, HBsAg+ itself was not a contraindication to heart donation. Patients with HBsAg-, anti-HBs-, anti-HBc+, and negative HBV DNA in the serum by PCR could be protected from HBV infection from HBsAg+ donor hearts. However, patients with HBsAg-, anti-HBs-, anti-HBc+, and positive HBV DNA in the serum by PCR should be recognized as HBV carriers and closely followed for potential HBV flare-up after heart transplantation.

Genomic screening for blood-borne viruses in transfusion settings

The residual risk of post-transfusion human immunodeficiency virus (HIV) infection is low but slightly higher for hepatitis B virus (HBV) and hepatitis C virus (HCV), the main reason being viraemia during the window period preceding antibody or antigen detection by enzyme immunoassays. Immunosilent-infected individuals and carriers of distant viral variants also play an unquantifiable role. Multiple techniques, e.g. reverse transcription-polymerase chain reaction (RT-PCR), PCR, ligase-chain reaction, nucleic acid sequence-based amplification (NASBA) and transcription-mediated amplification (TMA) have been developed to amplify and detect viral genomes as single or multiplex assays. Equipment providing various degrees of automation has been adapted to these techniques. Applying nucleic acid amplification techniques (NAT) to blood screening, two main approaches have been advocated: plasma pool and single-donation testing. Pool testing presents the advantage of lower cost and readily available equipment although it is prone to false negative and positive reactions. The time required to identify infected donations is incompatible with blood component release, and may lead to product waste. Single-unit testing, although appealing, is not yet fully automated and potentially very costly unless a systematic multiplex approach is taken. Although technically feasible, NAT applied to the blood supply needs to be clinically evaluated and its cost efficiency assessed in the general public health context. However, pool NAT is currently implemented in continental Europe and the USA.

Evidence that anti-HBc but not HBV DNA testing may prevent some HBV transmission by transfusion

Blood donor screening for antibody to hepatitis B core antigen (anti-HBc) implemented in some countries as a surrogate marker for non-A, non-B hepatitis has been superseded by anti-HCV screening. To assess the value of anti-HBc screening for the detection of hepatitis B surface antigen-negative blood donations that might contain infectious HBV, HBV genomic detection and recipient testing were used. Blood donations were screened and confirmed by multiple anti-HBc assays. Donations containing isolated anti-HBc and those with anti-hepatitis B surface antigen (anti-HBs) level < 0.1 IU/ml were tested for the presence of HBV DNA. Recipients of previous donations from the corresponding donors during the previous 5 years were traced and tested for markers of HBV infection. Of 103 869 donations screened, 586 (0.56%) were anti-HBc positive, two of which contained HBsAg, and 413 (0.4%) had protective (>/= 0.1 IU/ml) levels of anti-HBs. Anti-HBs < 0.1 IU/ml was found in 102 of these donations (0.1%) and isolated anti-HBc in 69 (0.07%). No donations with isolated anti-HBc were HBV DNA confirmed positive. Of 278 recipients of previous donations from 171 donors at risk of HBV carriage, 12 had markers of HBV infection. Six recipients had other identified risk factors. An association with blood transfusion was considered probable in two and possible in four recipients. None of the six corresponding donors had detectable HBV DNA 6-40 months after the implicated donation. The frequency of HBV transmission by chronic carriers negative for hepatitis B surface antigen was estimated in this study to be 1 in 52,000 donations (CI 0.3-7.8/100,000) from HBsAg-negative donors. Such HBV infectious donations may not be detected by DNA amplification.

Over a decade of experience with a yeast recombinant hepatitis B vaccine

Experience with the yeast recombinant hepatitis B vaccine Engerix-B now exceeds 10 years. We reviewed published studies on this vaccine. These show the vaccine to be safe, causing mostly only minor local symptoms and to be highly immunogenic both in monitored clinical trials and under field conditions. Engerix-B consistently elicits high geometric mean antibody titres and a high protective efficacy has been established in three groups at high-risk of hepatitis B infection, homosexual men, institutionalised mentally handicapped subjects and neonates of chronic carrier mothers. The profile of the recombinant hepatitis B vaccine in certain high-risk groups and immuno compromised people is discussed. Finally we present updated post marketing surveillance data based on 496 million distributed doses of vaccine.

Highly sensitive hepatitis B surface antigen detection by measuring stable nitroxide radical formation with ESR spectroscopy

In areas where hepatitis B virus (HBV) is prevalent, HBV carriers negative for hepatitis B surface antigen (HbsAg) by enzyme-linked immunosorbent assay (ELISA) have been reported. Moreover, even after screening donor blood for HbsAg and hepatitis B core antibody (HBcAb), post-transfusion hepatitis B continues to occur, though with a decreasing frequency. Therefore, screening tests far more sensitive for detecting HBsAg than those currently available are needed. We developed a highly sensitive method for HBsAg detection. It is based on the recognition of peroxidase activity through measuring the formation of stable nitroxide radical with electron spin resonance (ESR) spectroscopy in the presence of hydrogen peroxide, p-acetamidophenol (p-AP), and 4-hydrazonomethyl-1-hydroxy-2,2,5,5,-tetramethyl-3-imidazoline-3-o xide (HHTIO). A cut-off value was established by testing of 186 healthy adults and 50 HBsAg-positive individuals. The signal to noise (S/N) ratio of less than 1.488 obtained by ESR spectroscopy was considered to be negative and more than 2.181, positive. The p-AP/HHTIO method was found to be 10 times more sensitive than the standard ELISA and reproducibility was excellent. Additional investigations were made on the HBsAg levels in the serum from 26 healthy subjects, in whom cut-off index levels on ELISA were negative but relatively high (range: 0.6 to 1.0); and on 15 patients with non B non C hepatitis. Three of 26 cases and 3 of 15 with non B non C hepatitis were judged to be HBsAg positive. Of these, 5 were found to be positive for HBV DNA by polymerase chain reaction (PCR). It was shown in this study that the p-AP/HHTIO method is practical and useful in screening HBV carriers because of the sensitivity in HBsAg detection, which is comparable to PCR analysis.

Duck hepatitis B virus inactivation and 8-methoxypsoralen photoadduct formation in human platelet concentrates

Photochemical inactivation (PCI) of virus and bacteria in platelet concentrates (PC) has been demonstrated using 8-methoxypsoralen (8-MOP) and long-wavelength UV light (UVA). To study inactivation of blood-borne virus, we have employed duck hepatitis B virus (DHBV), a model for human hepatitis B virus. A specific hepatocyte culture infectivity assay, with PCR detection, could measure 5-6 log10 virus kill. The DHBV inactivation in PC was dependent on UVA dose, was enhanced when plasma was reduced from 100% to 20% and was limited by 8-MOP solubility in the reduced-plasma medium. Optimum conditions for PCI were 100 micrograms/mL 8-MOP in 20% plasma and 80% synthetic platelet storage medium. A radiolabeling assay for 8-MOP photoadducts in hepatocytes seeded into PC confirmed that DHBV inactivation reflected DNA modification and indicated that adduct formation was insensitive to minor variations in conditions. Kinetic modeling indicated that optimum adduct formation was a compromise between 8-MOP dark binding and optical transmittance and that plasma proteins competed for 8-MOP binding. The PCI results in various media correlated with corresponding DNA modification densities and were compared to statistical models incorporating DHBV characteristics and predictions of 8-MOP crosslink formation between DNA strands. Behavior was consistent with one or a small number of lethal modifications per DNA strand, including monoadducts, but probably not crosslinks alone. A minor subpopulation of DHBV was found to be somewhat more difficult to inactivate, consistent with three-fold lower modification, due possibly to single-stranded DNA character or host repair of photoadducts.

Frequent chronic hepatitis B virus infection in HIV-infected patients positive for antibody to hepatitis B core antigen only. Swiss HIV Cohort Study

Persons with immune deficiency may present with atypical results in serological tests for hepatitis B virus (HBV). Frozen serum specimens that were sequentially obtained over time from a cohort of 57 HIV-infected patients, all of whom tested positive only for antibody to hepatitis B core antigen (anti-HBcAg), were therefore retested for HBV markers, including HBV DNA. The results were assessed for their time course and correlated with clinical data and alanine aminotransferase (ALT) values. Forty-eight patients were male; intravenous drug users constituted the principal risk group (n = 30), followed by homosexual men (n = 22). Thirty-three persons tested positive for antibody to hepatitis C virus (anti-HCV). During a median of 31 months from the first to the last serum, anti-HBcAg remained the sole marker of HBV infection in 98.2% of the patients. Polymerase chain reaction (PCR) to detect DNA for HBV core and HBV surface gene was positive in 126 (62.4%) and 121 (59.9%) of all 202 serum samples, respectively. Over time, HBV DNA was detected at least once in 51 (89.5%) patients. In contrast, decomplexed hepatitis B surface antigen (HBsAg) was detected at least once in 14 (24.6%) patients. Among patients positive for HBV DNA and negative for anti-HCV, eight (36.4%) of 22 had chronic hepatitis (ALT elevation > or = 6 months) that was attributable only to persisting HBV infection. Similarly, 12 (41.4%) of 29 patients positive for both HBV DNA and anti-HCV had chronic viral hepatitis, but their ALT values were significantly higher. In HIV-infected patients, anti-HBcAg as the sole serological HBV marker detected must be considered indicative of chronic HBV infection and is in part associated with chronic hepatitis and ALT elevation.

Use of renal allografts from donors positive for hepatitis B core antibody confers minimal risk for subsequent development of clinical hepatitis B virus disease

BACKGROUND

The risk associated with transplantation of renal allografts from hepatitis B virus core antibody-positive (HBcAb(+)), hepatitis B virus surface antigen-negative (HBsAg(-)) donors is not well defined.

METHODS

Over 4 years, we performed 45 kidney transplants from IgG HBcAb(+), IgM HBcAb(-), HBsAg(-) donors into recipients with a history of prior hepatitis B virus (HBV) infection or reported vaccination. We examined HBV-related outcomes in these 45 patients, in comparison with 45 recipients of allografts from HBcAb(-) donors (matched for transplant type, date, and pretransplant HBV antibodies). We sought evidence for HBV transmission by testing posttransplant sera for the presence of HBcAb, hepatitis B virus surface antibody, and HBsAg. Additionally, we analyzed alanine aminotransferase profiles and allograft survival rates for all patients.

RESULTS

No patient receiving an allograft from an HBcAb(+) donor developed clinical HBV infection. No patient receiving an allograft from an HBcAb(+) donor had HBsAg detected through retrospective testing of stored sera or through prospective routine clinical evaluation and care. However, among the HBcAb(+) kidney recipients, 27% developed new HBcAb and/or hepatitis B virus surface antibody after transplant; in contrast, only 4% of control patients developed new antibody responses (relative risk=4.94; confidence interval 1.07-22.83). Among the recipients of HBcAb(+) organs, 18% developed elevated transaminases after transplant, in comparison with 36% of the controls. No association was found between "seroconverter" status and elevated alanine aminotransferase profiles in either group.

CONCLUSIONS

Transplantation of renal allografts from HBcAb(+), HBsAg(-) donors was not associated with clinically detectable HBV disease or antigenemia. However, recipients had a significantly increased risk of HBV seroconversion, consistent with exposure to HBV antigen. These results suggest that HBcAb(+) kidneys can be safely used if transplanted into appropriate recipients, but highlight the need for effective HBV vaccination and vaccine-response monitoring in potential recipients.

Feasibility and usefulness of an efficient anti-HBc screening programme in blood donors

Post-transfusion hepatitis B remains a risk for recipients of hepatitis B surface antigen (HBsAg) screened blood. Anti-hepatitis B core antibody (anti-HBc) screening may help reduce this risk. To evaluate its usefulness, 9,238 East Anglian blood donors were screened for anti-HBc. Those with isolated anti-HBc were identified with two confirmatory anti-HBc and anti-HB surface antibody (anti-HBs) assays. The prevalence of anti-HBc reactions in screening and confirmatory assays was 1.29% and 0.35%, respectively. The level of reactivity was significantly higher when two anti-HBc assays gave concordant results or, being concordant, were anti-HBs positive. All isolated anti-HBc-positive units (0.04%) were negative for additional HBV markers including DNA tested with nested polymerase chain reaction (PCR). A 0.31% prevalence of past HBV infection was found in this population, all carrying both anti-HBc and anti-HBs antibody, most above the protective level (0.1 IU/ml). The proposed screening schemes would limit the number of deferred donors and discarded units and keep the testing time within the remit of routine blood banking practices for an additional cost of approximately 1 pound per unit. However, no evidence was found in this donor population to suggest that anti-HBc screening would significantly reduce the incidence of post-transfusion hepatitis B.

Development of a two-site immuno-PCR assay for hepatitis B surface antigen

Hepatitis B virus (HBV) gene transcription may occur at very low levels resulting in HBsAg concentrations in serum and liver below the limit of detection by currently available immunoassays. An assay has been developed that combines the specificity of two high affinity anti-HBs monoclonal antibodies (MAb) directed against distinct and separate determinants in the 'a' domain of HBsAg with the highly sensitive polymerase chain reaction (PCR) detection method. Following capture of HBsAg present in serum samples, the second anti-HBs MAb, which is biotinylated, is added. Binding of the second antibody allows the subsequent specific binding of streptavidin and a biotinylated linear DNA molecule derived from a bluetongue virus (BTV) gene. Presence of this DNA is then detected by PCR using BTV-specific primers. The PCR product is quantified by a liquid-phase oligonucleotide enzymatic assay, which further increases the sensitivity of the technique. The use of a two-site MAb capture and PCR detection system for HBsAg was shown to greatly enhance the specificity and sensitivity of the assay and detect as little as 0.5 pg of HBsAg in serum samples. It is suggested that the principles of this technique could be applied to measure other low level viral antigens in serum and biological samples.