Solid-phase enzyme-immunoassay for detection of hepatitis B surface antigen

Solid-phase recombinase polymerase amplification using an extremely low concentration of a solution primer for sensitive electrochemical detection of hepatitis B viral DNA

Recombinase polymerase amplification (RPA) is considered one of the best amplification methods for realizing a miniaturized diagnostic instrument; however, it is notably challenging to obtain low detection limits in solid-phase RPA. To overcome these difficulties, we combined solid-phase RPA with electrochemical detection and used a new concentration combination of three primers (surface-bound forward primer, solution reverse primer, and an extremely low concentration of solution forward primer). When solid-phase RPA was performed on an indium tin oxide (ITO) electrode modified with a surface-bound forward primer in a solution containing a biotin-terminated solution reverse primer, an extremely low concentration of a solution forward primer, and a template DNA or genomic DNA for a target gene of hepatitis B virus (HBV), amplification occurred mainly in solution until all the solution forward primers were consumed. Subsequently, DNA amplicons produced in solution participated in solid-phase amplification involving surface-bound forward primer and solution reverse primer. Afterward, neutravidin-conjugated DT-diaphorase (DT-D) was attached to a biotin-terminated DNA amplicon on the ITO electrode. Finally, chronocoulometric charges were measured using electrochemical-enzymatic redox cycling involving the ITO electrode, 1,4-naphthoquinone, DT-D, and reduced β-nicotinamide adenine dinucleotide. The detection limit for HBV was measured using microfabricated electrodes and was found to be approximately 0.1 fM. This proposed method demonstrated better amplification efficiency for HBV genomic DNA than solid-phase RPA without using additional solution primer and asymmetric solid-phase RPA.

Enzymatic oligomerization and polymerization of arylamines: state of the art and perspectives

The literature concerning the oxidative oligomerization and polymerization of various arylamines, e.g., aniline, substituted anilines, aminonaphthalene and its derivatives, catalyzed by oxidoreductases, such as laccases and peroxidases, in aqueous, organic, and mixed aqueous organic monophasic or biphasic media, is reviewed. An overview of template-free as well as template-assisted enzymatic syntheses of oligomers and polymers of arylamines is given. Special attention is paid to mechanistic aspects of these biocatalytic processes. Because of the nontoxicity of oxidoreductases and their high catalytic efficiency, as well as high selectivity of enzymatic oligomerizations/polymerizations under mild conditions-using mainly water as a solvent and often resulting in minimal byproduct formation-enzymatic oligomerizations and polymerizations of arylamines are environmentally friendly and significantly contribute to a "green" chemistry of conducting and redox-active oligomers and polymers. Current and potential future applications of enzymatic polymerization processes and enzymatically synthesized oligo/polyarylamines are discussed.

Novel paradigm for immunotherapy of breast cancer by engaging prophylactic immunity against hepatitis B

BACKGROUND

Immunotherapy of patients suffering from the human epidermal growth factor receptor 2 overexpressing (HER-2(+)) breast cancers with the anti-HER-2 antibodies results in increase of the patients' overall survival. However, no prophylactic vaccine is available against HER-2(+) breast cancers. Although, prophylactic vaccine for human hepatitis B virus (HBV) is very effective.

SPECIFIC AIM

The specific aim of this work was to design, synthesize, and test bio-molecules which would engage prophylactic immunity against hepatitis B virus towards killing breast cancers cells.

METHODS AND RESULTS

By biomolecular engineering, we have created a novel family of biomolecules: antibody (anti-HER-2) × vaccine (HBsAg) engineered constructs (AVEC: anti-HER-2 × HBsAg). These biomolecules were utilized for redirecting, accelerating, and amplifying of the vaccination-induced, prophylactic immunity originally targeted against HBV as therapeutic immunity, newly targeted against HER-2(+) breast cancers. Treatment of the HER-2(+) breast cancer cells with AVEC: anti-HER-2 × HBsAg in blood of the patients, vaccinated with HBsAg, rapidly increased efficacy of killing of HER-2(+) breast cancer cells over that attained with the naked anti-HER-2 antibodies.

CONCLUSION

Novel antibody-vaccine engineered constructs (AVEC) facilitate redirecting, accelerating, and amplifying of prophylactic, HBV vaccination-induced immunity as immunotherapy (RAAVIIT) of HER-2(+) breast cancer. We currently streamline this novel therapeutic paradigm into clinical trials of breast and other cancers.

Aptamer-based competitive binding assay for one-step quantitation of hepatitis B surface antigen

An aptamer-based competitive binding assay for one-step (i.e. no requirement of pre-treatment) quantitation of target molecules of interest has been developed. This method has been successfully employed for the fast and sensitive detection of the surface antigen of the hepatitis B virus (HBsAg). The key features of our method include its low intrinsic background noise, low costs, high resolution, and high sensitivity, enabling the detection of as low as 1.25 mIU mL(-1), approximately 40-fold better than that of the most widely used Abbott Architect assay for HBsAg detection, without the tedious extraction and/or washing procedures. Moreover, this assay has better recovery and accuracy than that of conventional competitive binding assay or others for HBsAg quantitation.

Plasmon-Enhanced Enzymatic Reactions: A Study of Nanoparticle-Enzyme Distance- and Nanoparticle Loading-Dependent Enzymatic Activity

A detailed investigation of the dependence of the efficiency of plasmon-enhanced enzymatic reactions on the distance between silver island films (SIFs) and horse radish peroxidase (HRP) enzyme and on the loading of SIFs on glass surfaces is presented. Three different extent of loading of SIFs on glass slides were used: 1) low, 2) medium and 3) high, which was characterized by using optical absorption spectroscopy and scanning electron microscopy. Streptavidin-linked HRP enzyme was deposited onto SIFs and glass slides by using three different strategies: strategy 1: biotin-avidin protein assay (distance between SIFs and HRP = 4-8 nm), strategy 2: self assembled monolayers (SAMs) (1-5 nm), strategy 3: polymer layer (1-5 nm). The efficiency of enzymatic conversion of O-phenylenediamine dihydrochloride (OPD) to a colored product by HRP on SIFs and glass surfaces was assessed by optical absorption spectroscopy. The distance between SIFs and HRP and the extent of loading of SIFs on the glass surfaces were shown to have significant effect on the efficiency of plasmon-enhanced enzymatic reactions. In this regard, up to an %250 increase in enzymatic conversion of OPD was observed from SIFs with high loading using strategy 1. In addition, we have studied the potential of repeated use of SIFs in plasmon-enhanced enzymatic reactions.

Quantification of HBsAg: Basic virology for clinical practice

Hepatitis B surface antigen (HBsAg) is produced and secreted through a complex mechanism that is still not fully understood. In clinical fields, HBsAg has long served as a qualitative diagnostic marker for hepatitis B virus infection. Notably, advances have been made in the development of quantitative HBsAg assays, which have allowed viral replication monitoring, and there is an opportunity to make maximal use of quantitative HBsAg to elucidate its role in clinical fields. Yet, it needs to be underscored that a further understanding of HBsAg, not only from clinical point of view but also from a virologic point of view, would enable us to deepen our insights, so that we could more widely expand and apply its utility. It is also important to be familiar with HBsAg variants and their clinical consequences in terms of immune escape mutants, issues resulting from overlap with corresponding mutation in the P gene, and detection problems for the HBsAg variants. In this article, we review current concepts and issues on the quantification of HBsAg titers with respect to their biologic nature, method principles, and clinically relevant topics.

Expression of apoptotic markers BCL-2 and Bax in chronic hepatitis C virus patients

OBJECTIVES

Hepatitis C viral infection(HCV) influence the susceptibility to apoptosis. This could lead to insufficient antiviral immune response and persistent viral infection.

DESIGN AND METHODS

Group 1: chronic HCV patients with liver cirrhosis and ascites. Group 2: chronic HCV patients without liver cirrhosis and group 3: healthy subjects as control group. Bcl-2 and Bax expression were evaluated by flowcytometry.

RESULTS

HCV patients (with cirrhosis and ascites) had a statistically significantly low Bcl-2 expression, a significantly high Bax expression and a significantly decreased Bcl-2/Bax ratio compared with controls. While, the results are inverted in the other HCV group. Both groups of HCV, Bcl-2/Bax ratio showed a significant positive correlation with Bcl-2 and a significantly negative correlation with Bax.

CONCLUSIONS

Chronic HCV exhibit a deregulation of apoptosis with the disease progression. This provides an insight into the pathogenesis of chronic HCV infection, and may contribute to the therapy.

Isolation of autochthonous non-white rot fungi with potential for enzymatic upgrading of Venezuelan extra-heavy crude oil

The increasing world demand for fuels makes it necessary to exploit the largest reserve of extra-heavy crude oil (EHCO) of the Orinoco Oil Belt from Venezuela. We propose the use of extracellular oxidative enzymes, in particular, lignin-degrading enzyme systems (LDS) of fungi, for enzymatic improvement of EHCO. Autochthonous non-white rot fungal strains able to use EHCO, and several polycyclic aromatic hydrocarbons (PAHs) as sole carbon source and energy, were isolated from EHCO-polluted soils and identified as belonging to the genera Fusarium, Penicillium , Trichoderma , Aspergillus , Neosartorya, Pseudallescheria, Cladosporium, Pestalotiopsis , Phoma and Paecillomyces. Phenotypic and biochemical assays revealed the ability of these filamentous fungi to synthesize extracellular oxidative enzymes, and suggested a relationship between the LDS and EHCO bioconversion. This work reports, for the first time, the use of o-phenylenediamine dihydrochloride (OPD) as substrate to measure extracellular ligninolytic peroxidases (ELP) in culture broths of filamentous fungi (Fusarium solani HP-1), and constitutes the first formal study of the fungal community associated with the EHCO of the Orinoco Oil Belt.

Role of Rab5 in insulin receptor-mediated endocytosis and signaling

Activated insulin receptors recruit various intracellular proteins leading to signal generation and endocytic trafficking. Although activated receptors are rapidly internalized into the endocytic compartment and subsequently degraded in lysosomes, the linkage between insulin receptor signaling and endocytosis is not well understood. This study utilizes both overexpression and depletion of Rab5 proteins to show that they play a critical role in both insulin-stimulated fluid phase and receptor-mediated endocytosis. Specifically, Rab5:WT and Rab5:Q79L (a GTP-hydrolysis defective mutant) enhance both types of endocytosis in response to insulin, while Rab5:S34N (a GTP-binding defective mutant) has the opposite effect. Morphological analysis indicates that both Rab5 and insulin receptor are found on early endosomes, but not at the plasma membrane. In addition, expression of Rab5:WT and Rab5:Q79L enhance both Erk1/2 and Akt activation without affecting JN- and p38-kinase activities, while the expression of Rab5:S34N blocks both Erk1/2 and Akt activation. Consistent with these observations, DNA synthesis is also altered by the expression of Rab5:S34N. Taken together, these results demonstrate that Rab5 is required for insulin receptor membrane trafficking and signaling.

Rin1 regulates insulin receptor signal transduction pathways

Rin1 is a multifunctional protein containing several domains, including Ras binding and Rab5 GEF domains. The role of Rin1 in insulin receptor internalization and signaling was examined by expressing Rin1 and deletion mutants in cells utilizing a retrovirus system. Here, we show that insulin-receptor-mediated endocystosis and fluid phase insulin-stimulated endocytosis are enhanced in cells expressing the Rin1:wild type and the Rin1:C deletion mutant, which contain both the Rab5-GEF and GTP-bound Ras binding domains. However, the Rin1:N deletion mutant, which contains both the SH2 and proline-rich domains, blocked insulin-stimulated receptor-mediated and insulin-stimulated fluid phase endocytosis. In addition, the expression of Rin1:delta (429-490), a natural occurring splice variant, also blocked both receptor-mediated and fluid phase endocystosis. Furthermore, association of the Rin1 SH2 domain with the insulin receptor was dependent on tyrosine phosphorylation of the insulin receptor. Morphological analysis indicates that Rin1 co-localizes with insulin receptor both at the cell surface and in endosomes upon insulin stimulation. Interestingly, the expression of Rin1:wild type and both deletion mutants blocks the activation of Erk1/2 and Akt1 kinase activities without affecting either JN or p38 kinase activities. DNA synthesis and Elk-1 activation are also altered by the expression of Rin1:wild type and the Rin1:C deletion mutant. In contrast, the expression of Rin1:delta stimulates both Erk1/2 and Akt1 activation, DNA synthesis and Elk-1 activation. These results demonstrate that Rin1 plays an important role in both insulin receptor membrane trafficking and signaling.

Liquid chromatographic/mass spectrometric investigation on the reaction products in the peroxidase-catalyzed oxidation of o-phenylenediamine by hydrogen peroxide

Mass spectrometric evidence was obtained to confirm that the main reaction product of the horseradish peroxidase (POD)-catalyzed oxidation of o-phenylenediamine (OPD) by hydrogen peroxide is 2,3-diaminophenazine. Although this reaction is one of the most widespread detection schemes in enzyme-linked immunosorbent assays (ELISAs), the literature data on the identity of the reaction product(s) have been strongly contradictory throughout the last few decades. Liquid chromatography with UV/Vis and mass spectrometric detection as well as exact mass measurements after LC fraction collection have led to the unambiguous identification of 2,3-diaminophenazine as main reaction product. 2,2'-Diaminoazobenzene, which is frequently described in other publications to be the major reaction product, was not detected at all.

Viral diagnosis by antigen detection techniques

BACKGROUND

Diagnosis of viral infections can be obtained in the early stages of a disease by detection of viral antigens directly in the clinical specimen. This has become an important tool for rapid virus diagnosis.

METHODS

Antigens produced during virus infections can be detected either in cells collected from the site of infection by immunohistological investigation or in secretions and blood by solid phase immunoassays (IA). Viruses causing acute respiratory infections can be diagnosed in cells from the respiratory tract, viruses causing vesicular eruptions in epithelial cells from skin scrapings, rabies virus in nerve cells of the brain or epithelial cells from skin and cornea and cytomegalovirus (CMV) matrix antigen, pp65, can be detected in peripheral blood leukocytes (PBL) by immunofluorescence (IF) or immunoperoxidase techniques. The quality of specimens can be easily checked during the reading of results. Some IAs for antigen detection, such as detection of HBsAg and HIV p24 antigen in blood are standardized and sensitive. Others give less sensitive results because of the variation of quality of the clinical specimen. The latex agglutination tests are mainly used for rapid detection of virus or viral antigens in faeces: rota-and adenoviruses; the method may not be very sensitive but yields a result within a few minutes. Assays detecting viral nucleic acids are more sensitive than antigen detection tests because of a tremendous amplification of gene segments obtained by the polymerase chain reaction (PCR). So far such assays are time consuming and expensive and are mainly used in specific clinical situations.

RESULTS

After introduction of specific monoclonal antibodies (Mabs), the antigen detection techniques are increasingly used. the need for quality control, trained staff, and standardized reagents and methods for specimen collection and preparation is now being appreciated. IF for viral respiratory viruses is used for diagnosis and epidemiological studies all over the world. Likewise, IF is still the method most often used for rabies diagnosis. For CMV, the pp65 matrix antigen is shown to be a sensitive marker closely correlated with clinical symptoms. Its detection by the IF technique has proven to be superior to other techniques for prediction of CMV pneumonia in bone marrow transplant patients. IAs are currently used in fully automated systems for large scale diagnosis based on antigen detection in serum specimens. Increase of antibody specificity on the solid phase by use of Mabs directed against the most abundant viral antigen in the clinical specimen shortens the reaction time; this has been employed in most of the constantly appearing new rapid diagnosis kits based on the immunoassay principle.

CONCLUSION

Although, in virology, more sensitive results are obtained by the gene detection method, PCR, directly in clinical samples, viral antigen detection tests are, after the introduction of Mabs for diagnostic purposes, increasingly used because of their low demand on laboratory equipment, their rapid and early result and relatively low cost. Antigen detection is successfully used directly in clinical specimens for rapid diagnosis of many viral infections as well as for identification of tissue culture isolated viruses. With Mab-based IAs the reaction time is shortened and new rapid, almost 'instant test' kits are appearing on the market.

Fibrinogen Alès: a homozygous case of dysfibrinogenemia (γ-Asp330 →Val) characterized by a defective fibrin polymerization site “a”

Congenital homozygous dysfibrinogenemia was diagnosed in a man with a history of 2 thrombotic strokes before age 30. His hemostatic profile was characterized by a dramatically prolonged plasma thrombin clotting time, and no clotting was observed with reptilase. Complete clotting of the abnormal fibrinogen occurred after a prolonged incubation of plasma with thrombin. The release of fibrinopeptides A and B by thrombin and of fibrinopeptide A by reptilase were both normal. Thrombin-induced fibrin polymerization was impaired, and no polymerization occurred with reptilase. The polymerization defect was characterized by a defective site “a,” resulting in an absence of interaction between sites A and a, indicated by the lack of fragment D1 (or fibrinogen) binding to normal fibrin monomers depleted in fibrinopeptide A only (Des-AA fm). By SDS-PAGE, the defect was detected on the γ-chain and in its fragment D1. The molecular defect determined by analysis of genomic DNA showed a single base change (A→T) in exon VIII of the γ-chain. The resulting change in the amino acid structure is γ 330 aspartic acid (GAT) → valine (GTT). It is concluded that the residue γ-Asp330 is essential for the normal functioning of the polymerization site a on the fibrinogen γ-chain.

Fibrinogen Alès: a homozygous case of dysfibrinogenemia (γ-Asp330 →Val) characterized by a defective fibrin polymerization site “a”

Congenital homozygous dysfibrinogenemia was diagnosed in a man with a history of 2 thrombotic strokes before age 30. His hemostatic profile was characterized by a dramatically prolonged plasma thrombin clotting time, and no clotting was observed with reptilase. Complete clotting of the abnormal fibrinogen occurred after a prolonged incubation of plasma with thrombin. The release of fibrinopeptides A and B by thrombin and of fibrinopeptide A by reptilase were both normal. Thrombin-induced fibrin polymerization was impaired, and no polymerization occurred with reptilase. The polymerization defect was characterized by a defective site “a,” resulting in an absence of interaction between sites A and a, indicated by the lack of fragment D1 (or fibrinogen) binding to normal fibrin monomers depleted in fibrinopeptide A only (Des-AA fm). By SDS-PAGE, the defect was detected on the γ-chain and in its fragment D1. The molecular defect determined by analysis of genomic DNA showed a single base change (A→T) in exon VIII of the γ-chain. The resulting change in the amino acid structure is γ 330 aspartic acid (GAT) → valine (GTT). It is concluded that the residue γ-Asp330 is essential for the normal functioning of the polymerization site a on the fibrinogen γ-chain.

Thrombotic dysfibrinogenemia. Fibrinogen "Caracas V" relation between very tight fibrin network and defective clot degradability

Fibrinogen Caracas V is a thrombotic dysfibrinogenemia with an Aalpha 532 Ser-->Cys mutation characterized by a tight fibrin network formed of thin fibers responsible for a less porous clot than a normal one. In the present work, fibrinogen Caracas V is further characterized in order to understand the relationship between the structural defect and thrombophilia. This thrombotic disorder has been attributed to a tight fibrin network responsible for a decreased permeation of flow through the clot, leading to defective thrombus lysis due to a diminished availability of fibrinolytic enzymes to the inner fibrin surface. Correction of clot structure anomaly, by addition of dextran 40 to fibrinogen before clotting, induces an improvement in fibrin degradation that was attributed to an increase in porosity. The pulmonary embolism observed in this family has been related to an hyper rigidity of the clot, an anomaly that is also corrected by dextran. Furthermore, this abnormal fibrinogen binds more albumin than does normal fibrinogen, a phenomenon attributed to the mutation of serine in Aalpha-532 by cysteine. Therefore, this fibrinogen shows a striking similarity to the fibrinogen Dusart, allowing us to confirm that the alphaC-terminal part of fibrinogen plays an important role in fibrin structure, and to conclude that the anomaly of fibrin network observed in fibrinogen Caracas V is responsible for a deficient thrombus lysis.

Rab7 regulates transport from early to late endocytic compartments in Xenopus oocytes

Rab7 has been shown to localize to late endosomes and to mediate transport from early to late endosome/lysosome in mammalian cells and in yeast. We developed a novel assay to quantify transport from early to late endosomes using the Xenopus oocyte. Oocytes were pulsed with avidin after which the oocytes were incubated to allow avidin transport to a late compartment. The oocytes were then allowed to internalize biotin-horseradish peroxidase (HRP). The oocytes were then injected with test proteins and incubated further to allow transport of biotin-HRP from early endosomes to late endosomal/lysosomal compartments. Transport was quantified by assessing the formation of HRP-biotin-avidin complexes. Injection of Rab7:wild-type (WT) and Rab7:Q67L, a GTPase defective mutant, stimulated transport. Rab5:WT had no effect. Rab7:WT-stimulated transport was inhibited by nocodazole, suggesting a role for intact microtubules. Wortmannin, a phosphatidylinositol 3-kinase inhibitor, blocked Rab7:WT-stimulated transport, but Rab7:Q67L-stimulated transport was unaffected by the drug. Rab7:Q67L is constitutively activated and may not require phosphatidylinositol 3-kinase activity for activation. Rab7-stimulated transport requires N-ethylmaleimide-sensitive factor (NSF) activity as transport was blocked by N-ethylmaleimide and ATPase defective NSF mutants. Our results indicate that sequentially acting endocytic Rab GTPases utilize similar factors although their modes of action may be different.

Sequential actions of Rab5 and Rab7 regulate endocytosis in the Xenopus oocyte

To explore the role of GTPases in endocytosis, we developed an assay using Xenopus oocytes injected with recombinant proteins to follow the uptake of the fluid phase marker HRP. HRP uptake was inhibited in cells injected with GTPgammaS or incubated with aluminum fluoride, suggesting a general role for GTPases in endocytosis. Injection of Rab5 into oocytes, as well as Rab5:Q79L, a mutant with decreased GTPase activity, increased HRP uptake. Injection of Rab5:S34N, the dominant-negative mutant, inhibited HRP uptake. Injection of N-ethylmaleimide-sensitive factor (NSF) stimulated HRP uptake, and ATPase-defective NSF mutants inhibited HRP uptake when coinjected with Rab5:Q79L, confirming a requirement for NSF in endocytosis. Surprisingly, injection of Rab7:WT stimulated both uptake and degradation/activation of HRP. The latter appears to be due to enhanced transport to a late endosomal/prelysosomal degradative compartment that is monensin sensitive. Enhancement of uptake by Rab7 appears to function via an Rab5-sensitive pathway in oocytes since the stimulatory effect of Rab7 was blocked by coinjection of Rab5:S34N. Stimulation of uptake by Rab5 was blocked by Rab5:S34N but not by Rab7:T22N. Our results suggest that Rab7, while functioning downstream of Rab5, may be rate limiting for endocytosis in oocytes.

Detection of prostatic-inhibin-like peptide in the cytoplasm of LNCaP cells, a human prostatic adenocarcinoma cell line

Prostatic inhibin peptide (PIP) is a 94-amino acid peptide involved in various cellular functions. The concentration of this peptide changes with prostatic pathophysiology suggesting a role in various disease conditions; present study was undertaken to investigate the presence of this peptide in two human prostatic cell lines: LNCaP and PC3 cells. The LNCaP cells showed an intense intracellular fluorescence pattern after staining with rabbit-anti-PIP antiserum and FITC conjugated goat antirabbit-IgG, while the PC3 cells did not exhibit any fluorescence. There was no alteration in the concentration of PIP in LNCaP cells with or without supplementation of steroids in culture medium. Immunoblot analysis indicates similarities between PIP from LNCaP cells and that from the human seminal plasma. Thus, present study demonstrates the presence of PIP in a human prostatic cell line, i.e., LNCaP cells. Its intracellular concentration is androgen independent, and has a close similarity with PIP isolated from the human seminal plasma.

Clinical significance of low or negative titer of antibody to hepatitis B core antigen during the course of chronic hepatitis B virus infection in adolescents

Antibody to hepatitis B core antigen (anti-HBc) was measured by radioimmunoassay in 127 asymptomatic hepatitis B surface antigen (HBsAg) carriers (ASC; mean age 19) who had normal serum alanine aminotransferase (ALT) levels and 16 patients with chronic hepatitis B (CH; 19). All 16 CH patients, who were positive for hepatitis B e antigen (HBeAg) and 5 ASC cases who were negative for both HBeAg and its antibody (anti-HBe), had high anti-HBc titers. Anti-HBc titers in 27 (56.3%) of the 48 HBeAg-positive ASC and 18 (24.3%) of the 74 anti-HBe-positive ASC were relatively low. Two of the ASC were HBeAg-positive/anti-HBc-negative. In a follow-up study of the 19 HBeAg-positive ASC with low or negative anti-HBc titers, 5 had abnormal serum ALT levels and increased anti-HBc titers. In contrast, in the other 14 of these subjects, serum ALT levels remained normal and the low anti-HBc titers remained unchanged and/or decreased. The serological profile of HBsAg-positive/low or negative anti-HBc titer and increased anti-HBc titer with abnormal serum ALT levels are not necessarily exceptional in HBeAg-positive adolescent ASC. It is suggested that anti-HBc is associated with the liver damage that occurs before adolescence in chronic hepatitis B virus infection.

Evaluation of enzyme immunoassay (EIA) as a screening method for hepatitis B markers in an open population

Commercially available kits for detection of hepatitis B surface antigen (HBsAg) and hepatitis B surface antibody (anti-HBs) by enzyme immunoassay (EIA) were evaluated in American Samoa during a public health programme to eliminate the transmission of hepatitis B. The first 19,184 serum specimens obtained, representing 68% of the total cooperating population, were initially tested for anti-HBs, and those without detectable antibody were tested for HBsAg. All the antigen-positive serum samples, and a selection of the antigen- and antibody-negative specimens were tested by radioimmunoassay (RIA) for detection of both markers. Compared with the standard tests, the EIA kits for anti-HBs and HBsAg performed well; sensitivity and specificity were 90.3 and 96.0%, respectively, for antibody, and 97.8 and 97.9% respectively for antigen. Substantial disagreement between the EIA and RIA tests for HBsAg was found only for specimens considered weakly reactive by EIA. Few differences were found between three EIA method options for follow-up HBsAg testing of weakly reactive serum specimens; each option contributed about equally to improved test specificity for these 'borderline' specimens. Based on their demonstrated equivalence to the standard RIA tests, we conclude that the EIA kits for anti-HBs and HBsAg detection are suitable for use in hepatitis B control programmes in open populations.

Salt-soluble collagen and elastin in the human aorta and pulmonary artery

Collagen and elastin, the major structural components of blood vessels, have a very low turnover. In disease, this rate may be increased and an elevation of the tissue concentration of the soluble degradation fragments might be anticipated. In this preliminary study the concentration of extractable collagen and elastin in the aorta and pulmonary artery of eight human subjects postmortem was determined. The proportion of pulmonary artery collagen and elastin that was soluble was generally either equal to or greater than that in the abdominal aorta. The fraction of collagen that was salt extractable was larger than the soluble elastin fraction.

Seroepidemiology of HCV and HBV infection in northern China

The HCVAb positive rate in normal population in Beijing was 2.1% and HBsAg positive rate was 2.5%. There is an increasing tendency in the aged group. Plasmapheresis might have been the major cause of HCV transmission in blood donors in the Hebei area. There was a high prevalence of HCVAb and HBsAg in chronic liver diseases in the Beijing area and the HCVAb-positive rate significantly increased corresponding to disease progression.

Antibody to the hepatitis C virus in acute hepatitis and chronic liver diseases in Japan

In a 6-month follow-up study of acute hepatitis in Japan, 31 out of 41 (75.6%) cases of post-transfusion non-A and non-B hepatitis (NANB-PTH) and 14 out of 40 (35.0%) cases of sporadic non-A non-B hepatitis (NANB-SPO) were found to be positive for antibody to the hepatitis C virus (HCVAb). After 12 months of follow-up, 30 cases (81.1%) became chronic among 37 HCVAb positive acute NANB hepatitis cases. This figure shows a significantly higher rate of chronicity as compared with HCVAb negative acute NANB hepatitis. The prevalences of HCVAb in hepatitis B surface antigen (HBsAg) negative cases of chronic hepatitis and liver cirrhosis were 76.3% (200/262) and 66.7% (106/159), respectively, which were significantly different from the values of 5.1% (13/255) and 10.6% (13/123) observed in HBsAg positive cases. Of chronic liver disease cases positive for HCVAb, 45.8% (152/332) had a history of blood transfusion, in contrast to the value of 3.7% (13/352) observed in HBsAg positive cases of chronic liver disease that were negative for HCVAb.

Identification of structural differences between different forms of interleukin-2 (IL-2) using anti-(human recombinant) IL-2 monoclonal antibodies

We have generated a panel of murine monoclonal antibodies (mAbs) directed against recombinant human interleukin-2 (rh IL-2). All mAbs have similar affinities (Kaff approximately equal to 10(-8) M) and are of the IgG1 isotype. Specificity of the mAbs has been established using an ELISA method and immunoprecipitation of native human interleukin-2 (nh IL-2) present in supernatants from PHA-stimulated human mononuclear cells (PBMNC). Four of the nine mAbs inhibit the rh IL-2-dependent proliferation of a murine cytotoxic T-lymphocyte line (CTLL-2). The estimated ID50, in the presence of 0.75 IU rh IL-2/ml, ranges from 2.0 micrograms/ml to 30 micrograms/ml final concentrations of the antibodies. Using different forms of IL-2 we found that the mAbs give different patterns of inhibition of the IL-2-dependent proliferation. One mAb (AMCIB 27) is able to discriminate between rh and nh IL-2. Findings with another mAb (AMCIB 24) indicate that possible functional differences between human IL-2 and recombinant murine (rm) IL-2 are caused by differences in the active sites. The results of this investigation show that it is possible to obtain mAbs, after immunization with rh IL-2, that differ in their ability to inhibit the biological action of different forms of IL-2.

Changes of pre-S1 and pre-S2 antigens in sera of patients with hepatitis B virus infection

Polypeptides encoded by the pre-S1 and pre-S2 genes of hepatitis B virus (HBV) (pre-S1 antigen and pre-S2 antigen) were detected by enzyme-linked immunosorbent assay (ELISA) in 137 serum samples of patients with HBV infection. The HBV-DNA level closely correlated with the titer of pre-S antigens. However, HBV-DNA levels more closely correlated with the titer of the pre-S1 antigen [HBV-asymptomatic carrier (ASC): n = 40, r = 0.800, P less than 0.01; chronic hepatitis B (CH): n = 60, r = 0.730, P less than 0.01] than with the titer of the pre-S2 antigen [ASC: r = 0.675, P less than 0.01; CH: r = 0.575, P less than 0.01]. Thirty patients with CH, in whom hepatitis e antigen (HBeAg) was cleared after acute exacerbation (AE) [alanine aminotransferase (ALT) level greater than 200 IU/L] and the ALT level normalized, were followed for 12 months and classified into two groups: Group 1, those in whom HBeAg reappeared with an elevated ALT level within 12 months, and Group 2, those in whom HBeAg was persistently cleared from the serum and a normal ALT level continued. Of the 30 patients, 24 (80%) were classified into Group 1 and 6 (20%) were classified into Group 2. Changes in serum levels of HBV markers a month before and after AE were observed. The HBV-DNA level and DNA-P activity became negative after AE in both groups. The titer of pre-S1 antigen also decreased after AE, and no significant differences were observed between Group 1 and Group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection and determination of factor C--a regulatory protein--in Streptomyces strains by antiserum and monoclonal antibody

Rabbit antisera and monoclonal antibodies were raised against factor C, a regulatory protein of Streptomyces griseus. ELISA and immunoblotting techniques suitable to determine and characterize factor C antigen was detected in all the 23 Streptomyces strains and variants examined thus far and in one Bacillus subtilis too. Depending on the strain analysed it has a molecular mass of 34,000 or 70,000 in mycelial homogenates. Most of factor C was found excreted into the cultivation medium. The quantity of factor C antigen in different Streptomyces strains showed great variation. Amy+ strains were usually good producers of factor C while Amy- were not. This was consistent with our assumption that factor C was an inducer of reproductive phase in Streptomyces.

Monoclonal antibody studies of the antigenic determinants of human plasma retinol-binding protein

A battery of monoclonal antibodies (MoAbs) against human retinol-binding protein (RBP) was produced to obtain useful probes for the study of the antigenic determinants of RBP. The 12 antibodies all reacted with human RBP by immunoblotting. Based on antibody cross-competition radioimmunoassays, four distinct and different groups of antibodies were identified: group I, 1A4 and 2F4; group II, 1G10, 5C5, 6F4, and 7G3; group III, 5H6, 6C7, 10G5, and 14E3; and group IV, 5H9 and 13A1. Information about the epitopes of RBP recognized by these MoAbs was obtained by testing the reactivity of each antibody with human, rabbit, and rat RBPs by immunoblotting. Group I and group IV antibodies reacted to a similar extent with human, rabbit, and rat RBPs. Group II antibodies reacted strongly with human and rabbit RBPs, but reacted very weakly with rat RBP. Group III antibodies reacted strongly with human RBP, but did not react with rabbit or rat RBP. Thus, the epitopes for group I and group IV antibodies appear to be regions of the RBP molecule that are conserved across the three species, whereas group III antibodies recognized only human RBP. In a preliminary study, the reactivity of each antibody with purified cyanogen bromide fragments of RBP was tested by slot immunoblotting. None of the MoAbs reacted with any of the cyanogen bromide fragments. This study shows that MoAbs specific for at least four different regions of the RBP molecule can be produced; hence, RBP contains at least four major antigenic domains.

Changes in serum levels of hepatitis B virus markers after interferon treatment

The effect of interferon (IFN) treatment on serum levels of pre-S antigens [pre-S(1) antigen, pre-S(2) antigen, polymerized human serum albumin receptor (pAR)] which are coded by the pre-S region of hepatitis B virus DNA (HBV-DNA), and HBV-markers was analyzed in 23 patients with chronic hepatitis B. One year after IFN treatment, 4 patients (Group C) became HBeAg negative. Six patients (Group B) transiently became HBeAg-negative, but reverted to HBeAg positive. Thirteen patients (Group A) remained HBeAg positive. All of the patients remained HBsAg-positive. Initiation of IFN treatment was rapidly followed by reduction or loss of DNA-P in the serum whether the patients became HBeAg negative or remained positive, and whether serum transaminase (S-GPT) levels became normal or not after IFN treatment. Group C patients, in whom pre-S antigens decreased rapidly during IFN treatment and disappeared before S-GPT levels normalized, became HBeAg negative one year after IFN treatment. Anti-pAR was detected in three out of these 4 patients. In contrast, Group A and Group B patients, in whom pre-S antigens decreased slowly during IFN treatment and did not disappear in spite of those patients being transiently negative for HBeAg and DNA-P, remained HBeAg positive with elevated S-GPT levels one year after IFN treatment. Anti-pAR was almost undetectable. These results suggest that testing for pre-S antigens is more useful for determining the prognosis of patients with chronic hepatitis B treated with IFN than testing for HBsAg, HBeAg and DNA-P.

Production and characterization of monoclonal antibodies to human myeloperoxidase

Monoclonal antibodies (mAbs) against human myeloperoxidase (MPO) have been derived for immunopurifying MPO and immunophenotyping acute leukemias. Eight antibodies were obtained from a fusion of the P3 plasmacytoma cell line with splenic lymphocytes from mice immunized with purified human MPO. Hybridoma supernatant culture fluids were screened for antibody to MPO by an enzyme-linked immunosorbent assay. The specificity of the mAbs was characterized by immunoblotting, immunoprecipitation, and reactivity against various hematopoietic cells, cell lines, and leukemic blast cells. The eight mAbs generated were of the IgG1 isotype. One of these mAbs was successfully used to develop a one-step immunoaffinity chromatographic purification procedure for MPO. Immunoblotting and immunoprecipitation experiments suggested that the eight mAbs were reactive with at least three antigenic determinants on the MPO molecule. Immunofluorescent studies showed that these mAbs reacted specifically with cells of granulocytic-monocytic lineage and were negative with lymphoid cells. Our results suggest that these mAbs should be useful reagents for immunophenotyping hematopoietic cells.

Rapid determination of Trypanosoma cruzi urinary antigens in human chronic Chagas disease by agglutination test

Detection of Trypanosoma cruzi in man becomes particularly difficult during the chronic stage of Chagas disease because of the low parasitemia. We were able to develop a simple and straightforward method for determining the concentration of T. cruzi antigens in urine using nitrocellulose micellar suspension (Nitrocell-Mr, Polychaco Argentina) and for their subsequent detection through a "latex" type agglutination test. The latex used was an esferocell nitrocellulose suspension (Esferocell-Mr, Polychaco). Specific antigens for T. cruzi were detected in 54 of 58 urine samples from chronic chagasic patients. The antigens characterized by affinity chromatography and SDS-PAGE were glycoproteins with apparent molecular weights (and pIs) of 100 kDa (pI 5 to 5.5), 80 kDa (pI 6.0), and 50 kDa (pI 6.5 to 7.0). This method is practical and fulfills the requirement of large-scale epidemiological studies. It is also helpful in cases of conflictive serology.

Rapid and accurate viral diagnosis

In recent years, there has been increased recognition of the importance of viral infections. In addition, new antiviral agents have become available. These factors have led to a marked increase in utilization of viral diagnostic services. In this review, both conventional and rapid methods for viral diagnosis are presented, with emphasis on recent advances. The antiviral agents currently available and the major drugs under investigation are also briefly discussed. It is hoped that this review will serve as a useful adjunct for the management of patients with virus infections.

Relationship between Campylobacter pylori and gastritis in healthy humans after administration of placebo or indomethacin

Endoscopic and microscopic appearances of antral and fundic mucosa were correlated with the presence or absence of Campylobacter pylori--and with plasma immunoglobulin G antibodies to that organism--in 23 healthy volunteers, 12 of whom had received indomethacin and 11 of whom had received no medication. Antral C. pylori, found in 9 of 23 biopsy specimens (3 of 11 controls, 6 of 12 indomethacin-treated patients; not significantly different), correlated strongly with histologic evidence of active superficial antral gastritis (p less than 0.005), but not with the endoscopic appearance of the antrum. In contrast to the antrum, fundic C. pylori, found in 14 of 23 biopsy specimens (61%), were frequently associated with histologically and endoscopically normal fundic mucosa. Campylobacter pylori-associated active antral gastritis occurred only in subjects whose fundus harbored this organism. Plasma immunoglobulin G antibody titers to C. pylori were highest in subjects with Campylobacter-associated antral gastritis and lowest in subjects without gastric Campylobacter. These studies suggest that healthy humans may harbor C. pylori in their proximal stomach without apparent ill effects. In some of these individuals, the organism also involves the antrum and is associated with active gastritis.

Association between coagulation factors VII and X with triglyceride rich lipoproteins

The association between the concentration of different plasma lipoproteins and plasma factor VII (F VII) was analysed by isolating plasma very low density lipoprotein (VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL) lipoproteins and assessing their in vitro interaction with F VII by immunoenzyme assay using peroxidase labelled anti-factor VII immunoglobulins to determine whether F VII coagulant activity is prognostic for cardiovascular mortality. F VII bound to triglyceride rich lipoproteins, the fixation being stronger on chylomicrons and VLDL fractions than on LDL fractions. In our experiments HDL did not bind to F VII. The fixation of coagulation factor X (FX) tested by the same method is comparable with that of F VII. The nature of this fixation seemed to arise from hydrophobic interaction as calcium was not necessary and the use of Tween 20 inhibited the interaction. The binding of factors VII and X was increased when lipids were previously treated by phospholipase C and the interaction seemed to be completely dependent on the lipid part of the lipoproteins. Hyrophobic fixation is a possible mechanism of interaction of plasma lipoproteins and F VII and X, and it may be of importance in the covariance of triglyceride concentrations and the activity of vitamin K dependent coagulation factors.

A rapid microassay for detecting hepatitis B surface antigen by dot enzyme immunoassay

This study describes a dot enzyme immunoassay (Dot-EIA) for detecting hepatitis B surface antigen (HBsAg). The results demonstrated that the detection level of this assay for HBsAg was 1.5 ng/ml; no false-positive or -negative readings were observed. Also, this Dot-EIA had some advantages over standard EIA: (1) antiserum could be directly and immediately bound on nitrocellulose paper set into microfiltration apparatus, (2) the paper could be easily washed under reduced pressure using a water aspirator, (3) all assay steps could be performed at room temperature within 2 h, (4) the well-defined brown spots could be evaluated by both visual observation and densitometric reading. The Dot-EIA reported here may be useful for rapid diagnosis and screening of HBsAg in serum.

Monoclonal antibodies against human alpha-fetoprotein. Exploitation of an unusual calcium-dependent interaction with the antigen for analytical and preparative purposes

Seven murine hybridomas were established producing IgG1 monoclonal antibodies (mAbs) against three different epitopes of human alpha-fetoprotein (alpha FP). The interaction of two of these mAbs (AFP-01 and AFP-02) with the antigen was strongly inhibited by calcium-chelating agents. The mAb AFP-11 could be used for estimation of alpha FP by RIA in the concentration range of 5-100 ng/ml. Several combinations of the mAbs could be used in a two-site sandwich-ELISA for similar purposes. Immunoaffinity chromatography on a column of immobilized mAb AFP-01 permitted the purification of alpha FP.

Defective thrombolysis due to collagen incorporation in fibrin clots

The migration of fibroblasts into a clot may be responsible at least in part, for its organization, thus leading to a defective thrombolysis. We have shown that collagen incorporated in a fibrin clot induces a dramatic decrease in fibrinolysis. Despite the fact that plasminogen binds to collagen, tissue plasminogen activator induced plasminogen activation in the presence of fibrin is only slightly decreased by the presence of collagen. This rather suggests that collagen induces a modification in clot structure, by rendering fibrin less accessible to fibrinolytic enzyme.

Dynamic coronary fibrinolysis evaluation in patients with myocardial infarction and unstable angina by specific plasma fibrin degradation product determination

It has been shown that myocardial infarction (MI) is caused by thrombotic occlusion of a coronary artery. A thrombotic process is also involved in the flow obstruction associated with peripheral embolization in unstable angina (UA). In UA, a local fibrinolytic process should occur, but biological evidence has never been reported. Therefore, we measured sequential changes in plasma fibrin degradation products (FDP) in patients with stable and unstable angina pectoris without MI and compared the levels to those in patients with MI. FDP determination was carried out by ELISA using a D neo monoclonal antibody allowing low amounts of FDP to be reliably and precisely detected. Our results show an early increase in FDP in UA indicating a thrombolytic process. In patients who presented only one episode of chest pain, a prompt decrease of FDP was noted whereas in patients with recurrent chest pain, the levels of FDP remained high. On the contrary, during the first 3 days of uncomplicated MI, FDP levels were not significantly different from those of normal control suggesting an absence of clot dissolution. This study underlines the important function of fibrinolysis in the spontaneous evolution of acute coronary syndrome.