Evaluation of enzyme immunoassay for hepatitis B virus DNA based on anti-double-stranded DNA

Prevalence of occult hepatitis B in a population from the Brazilian Amazon region

In the present study, we evaluated the prevalence of occult hepatitis B (OBI) in a population from the Brazilian Amazon region, identify circulating genotypes, and mutations in the S gene. One hundred eighty-one patients with negative serology for HBsAg and anti-HBs and positive serology for anti-HBc participated in the study. Detection of viral DNA, genotyping by sequencing, and analysis of nucleotide sequences to detect possible mutations were performed. HBV DNA was detected in 14.36% of the patients. Genotyping revealed genotype A in 88.46% of HBV DNA-positive subjects, with subgenotype A1 being the most prevalent (78.26%) followed by subgenotype A2 (21.74%). Genotype F was detected in 11.54% (all of them subgenotype F2). Amino acid substitutions were observed in the amplified S gene in individuals with OBI compared to HBsAg-positive individuals (evident infection). In conclusion, the results show a high prevalence of OBI in the population studied, with a pattern of genotypes A and F that circulate in the Brazilian Amazon region. Amino acid substitutions were detected in part of the S gene in patients with OBI. Further studies on the molecular epidemiology of HBV in this region are important to identify patients considered healthy but who are potential transmitters of the disease.

Sandwich-type immunosensors and immunoassays exploiting nanostructure labels: A review

Methods based on sandwich-type immunosensors and immunoassays have been developed for detection of multivalent antigens/analytes with more than one eptiope due to the use of two matched antibodies. High-affinity antibodies and appropriate labels are usually employed for the amplification of detectable signal. Recent research has looked to develop innovative and powerful novel nanoparticle labels, controlling and tailoring their properties in a very predictable manner to meet the requirements of specific applications. This articles reviews recent advances, exploiting nanoparticle labels, in the sandwich-type immunosensors and immunoassays. Routine approaches involve noble metal nanoparticles, carbon nanomaterials, semiconductor nanoparticles, metal oxide nanostructures, and hybrid nanostructures. The enormous signal enhancement associated with the use of nanoparticle labels and with the formation of nanoparticle-antibody-antigen assemblies provides the basis for sensitive detection of disease-related proteins or biomolecules. Techniques commonly rely on the use of biofunctionalized nanoparticles, inorganic-biological hybrid nanoparticles, and signal tag-doped nanoparticles. Rather than being exhaustive, this review focuses on selected examples to illustrate novel concepts and promising applications. Approaches described include the biofunctionalized nanoparticles, inorganic-biological hybrid nanoparticles, and signal tage-doped nanoparticles. Further, promising application in electrochemical, mass-sensitive, optical and multianalyte detection are discussed in detail.

Silent non-alcoholic fatty liver disease-a clinical-histological study

BACKGROUND/AIMS

We studied the prevalence of non-alcoholic fatty liver disease and non-alcoholic-steatohepatitis in patients with metabolic-syndrome but normal liver enzymes. The histological findings of patients with normal liver enzymes and non-alcoholic-steatohepatitis were compared with those of a control-group with persistently abnormal liver enzymes.

METHODS

Patients presenting with normal liver enzymes were enrolled in the study and underwent liver biopsy. Prevalence of non-alcoholic-steatohepatitis and risk factors for fibrosis and cirrhosis were evaluated. Data from a control-group with non-alcoholic-steatohepatitis and abnormal liver enzymes were used to compare the histological findings.

RESULTS

Fifty-eight of the 80 patients enrolled had varying degrees of non-alcoholic steatohepatitis, of these 26 had fibrosis and 8 silent cirrhosis. The association of metabolic-syndrome, female-sex, a long-history of obesity and body mass index>45 were considered to be independent risk-factors for fibrosis. Comparing the histological findings of cases and controls we found a similar severity of steatosis and fibrosis, with a greater prevalence of ballooning degeneration and glycogenated-nuclei rather than lobular-inflammation.

CONCLUSIONS

In the subjects selected according to our criteria, liver enzyme levels could not be used as surrogate markers of non-alcoholic-steatohepatitis. Histological hallmarks of patients with metabolic-syndrome, normal liver enzymes and non-alcoholic-steatohepatitis consist to a lesser degree of lobular-inflammation and a more severe ballooning and glycogenated-nuclei.

Direct diagnosis of human respiratory coronaviruses 229E and OC43 by the polymerase chain reaction

An RT-PCR-hybridization was developed that amplified genetic material from the M protein gene of HCoV-229E and HCoV-OC43. The analytic sensitivity of these original primers were compared with primers defined in the N gene and described previously. The results show that 0.05 TCID50 of HCoV-229E and 0.01 TCID50 of HCoV-OC43 can be detected by this molecular method using the original method. Detection of HCoV-229E and HCoV-OC43 in clinical specimens is possible using this method: 348 respiratory specimens (202 sputum and 146 nasal aspirates) were tested with this RT-PCR-hybridization and 12 human coronavirus are detected (3%). The method could provide a useful tool for demonstrating the role of human coronavirus in infections of the respiratory tract.

Liver fibrosis in overweight patients

BACKGROUND & AIMS

A common clinical issue is whether overweight patients with abnormal liver function test results should undergo liver biopsy. Although serious liver injury can occur, its prevalence and risk factors are not well known.

METHODS

Ninety-three consecutive patients with abnormal liver function tests (but without overt liver disease), body mass index (BMI) > 25 kg/m(2), and no alcoholic, viral, autoimmune, drug-induced, or genetic liver disease were retrospectively studied. Clinical, biological, and histological variables were tested for association with septal fibrosis or cirrhosis.

RESULTS

Septal fibrosis was present in 28 patients (30%) including cirrhosis in 10 (11%). Age >/= 50 years (odds ratio [OR], 14.1), BMI >/= 28 kg/m(2) (OR, 5.7), triglycerides >/= 1.7 mmol/L (OR, 5), and alanine aminotransferase (ALT) >/= 2N (OR, 4.6) were independently associated with septal fibrosis. Among histological features, septal fibrosis was strongly associated with necroinflammatory activity (OR, 44). A score combining age, BMI, triglycerides, and ALT had 100% negative predictive value for septal fibrosis when scoring 0 or 1 (100% sensitivity for a specificity of 47%).

CONCLUSIONS

Septal fibrosis occurs frequently in overweight patients with abnormal liver function tests. A clinicobiological score combining BMI, age, ALT, and triglycerides could improve selection of patients for liver biopsy.

Prevalence, patterns, and course of past hepatitis B virus infection in intravenous drug users with HIV-1 infection

OBJECTIVE

Hepatitis B virus (HBV) and human immunodeficiency virus (HIV) share common routes of transmission. Therefore, markers of either active or past HBV infection are present in many HIV-infected patients, particularly in intravenous drug users (IDUs). The aim of this study was to analyze the serological pattern of past HBV infection (presence or absence of anti-HBs) and the course of past HBV infection (changes in anti-HBs status, and HBV reactivation) in two cohorts of IDUs with and without HIV infection.

METHODS

HBV serum markers were studied in 388 HIV-positive and 197 HIV-negative IDUs. Among them, 263 HIV-positive and 50 HIV-negative patients with past HBV infection (serum HBsAg negative and anti-HBc positive, with or without anti-HBs) were followed-up for a median of 21 and 13 months, respectively, to detect changes in anti-HBs status and HBV reactivation.

RESULTS

The prevalence of HBV infection (either active or past) was higher in HIV-positive than in HIV-negative cases (90% vs 62%, p < 0.001), even when stratified by years of drug use. Most cases (92% of HIV-positive and 89% of HIV-negative) had markers of past infection. Among those patients with past HBV infection, 60% of HIV-positive and 72% of HIV-negative presented serum anti-HBs (p = 0.03). The incidence of anti-HBs loss was 1.8 cases/100 person-year in HIV-positive, and 1.8 cases/100 person-year in HIV-negative patients (RR 1.0, 95% CI 0.1-94, p = NS). Incidence of anti-HBs development was 17.6 cases/100 person-year in HIV-positive and 25.6 cases/100 person-year in HIV-negative IDUs (RR, 1.5, 95% CI, 0.6-3.5, p = NS). Only one HIV-positive patient with markers of past HBV infection developed an active infection (0.2 events/100 person-year).

CONCLUSIONS

HBV infection (either active or past) is particularly frequent in HIV-positive IDUs. Most cases have markers of past infection. Isolated detection of anti-HBc (absence of anti-HBs) is more common in HIV-positive than in HIV-negative IDUs. Despite their progressive immunosuppression, both anti-HBs loss and HBV reactivation are rare in HIV-infected IDUs.

Quantitative detection of hepatitis B virus by transcription-mediated amplification and hybridization protection assay

We have developed a sensitive and quantitative assay using transcription-mediated amplification and hybridization protection assay for the detection of hepatitis B virus (HBV) DNA in serum. The transcription-mediated amplification was carried out in a single tube. The hybridization protection assay was carried out in a microtiter plate with two probes with different specific activities to obtain a broad detection range. As a result, the assay had a detection range of 5 x 10(3) to 5 x 10(8) genome equivalents (GE)/ml and good quantitative accuracy on a logarithmic scale. A moderately sized manual assay run can be completed within 5 h. Measurements of the amounts of HBV DNA in clinical samples by the assay showed the amounts under various disease conditions to be widely distributed (more than 5 logs, from approximately 5 x 10(3) to 5 x 10(8) GE/ml). It was also shown that the amount of HBV DNA in one chronic hepatitis patient varied widely, with a range of more than 5 logs during long-term monitoring. Our assay has the potential to be used to monitor and determine the prognosis of HBV patients and carriers, especially during interferon treatment.

Quantitative assay of PCR-amplified hepatitis B virus DNA using a peroxidase-labelled DNA probe and enhanced chemiluminescence

We have developed a sensitive and quantitative assay for hepatitis B virus (HBV) DNA in serum or plasma in which PCR and then microtiter hybridization analysis are used. Assay of HBV DNA in serum or plasma is important for demonstrating viral replication, indicating and monitoring antiviral therapy, determining the infectivities of virus carriers, and ensuring the safety of blood products. Under optimum conditions PCR can amplify one HBV DNA molecule to 10(8) copies, but detection of this amount of DNA still requires hybridization with labelled probes or a nested PCR. We labelled one strand of the PCR product with a biotinylated primer. The double-stranded amplicon was incubated in streptavidin-coated microplate wells. The nonlabelled strand was removed after denaturation of the double-stranded DNA with alkali, and the bound strand was hybridized with a peroxidase-coupled single-stranded probe. The amount of bound peroxidase was measured in a luminometer. Four picograms of amplicon was detectable in this system, whereas conventional ethidium bromide staining requires a 1,000 times higher amplicon concentration. The performance of the new assay was compared with those of nested PCR and a PCR system that uses a digoxigenin label, hybridization to a solid-phase adsorbed probe, and colorimetric detection. The chemiluminescence assay was found to be almost as sensitive as nested PCR and approximately five times more sensitive than the colorimetric test.