Development of cost-effective real-time PCR test: to detect a wide range of HBV DNA concentrations in the western Amazon region of Brazil

Development of a Multiplex PCR Test System for the Determination of a Transgene Based on the pBC1 Plasmid and Its Derivatives for the Expression of Recombinant Proteins in Mus musculus Milk

A multiplex PCR test system for identification of the regulatory sequences of genetic constructs for transformation (promotor, insulator, and terminator) in the Mus musculus genome and for transgenic animal selection by genotyping with horizontal agarose gel electrophoresis detection was developed. The proposed system was validated by genotyping mouse strains producing human lactoferrin, heat shock protein HSP 70, firefly luciferase, and lysozyme, which were obtained by microinjections of linearized DNA into murine zygote pronucleus with random transgene integration into the genome using the pBC1 plasmid for expression of the gene of interest in milk of transformed animals (milk expression vector kit).

Usefulness of in-house real time PCR for HBV DNA quantification in serum and oral fluid samples

For quantification of hepatitis B virus DNA (HBV DNA), commercial assays are used with serum or plasma samples, but oral fluid samples could be an alternative for HBV diagnosis due to ease of collection. This study aims to develop in-house real time PCR using synthetic curve for HBV DNA quantification for serum and oral fluid samples. Samples were collected from 103 individuals (55 HBsAg reactive and HBV DNA reactive by commercial assay and 48 without HBV markers) and submitted to two in-house real time PCR assays for HBV pre-S/S region with different standard curves: qPCR plasmidial and qPCR synthetic. A total of 27 serum samples were HBV DNA positive by qPCR plasmidial and 40 with qPCR synthetic (72% and 85% of concordance, respectively). Quantitative PCR synthetic presented efficiency of 99% and sensitivity of 2log10 copies/mL. Among oral fluid samples, five and ten were detected using qPCR plasmidial and synthetic, respectively. This study demonstrated that qPCR synthetic using serum samples could be used as alternative for HBV DNA quantification due to its sensitivity. In addition, it was possible to quantify HBV DNA in oral fluid samples suggesting the potential of this specimen for molecular diagnosis of HBV.

An in-house real-time polymerase chain reaction: standardisation and comparison with the Cobas Amplicor HBV monitor and Cobas AmpliPrep/Cobas TaqMan HBV tests for the quantification of hepatitis B virus DNA

This study aimed to standardise an in-house real-time polymerase chain reaction (rtPCR) to allow quantification of hepatitis B virus (HBV) DNA in serum or plasma samples, and to compare this method with two commercial assays, the Cobas Amplicor HBV monitor and the Cobas AmpliPrep/Cobas TaqMan HBV test. Samples from 397 patients from the state of São Paulo were analysed by all three methods. Fifty-two samples were from patients who were human immunodeficiency virus and hepatitis C virus positive, but HBV negative. Genotypes were characterised, and the viral load was measure in each sample. The in-house rtPCR showed an excellent success rate compared with commercial tests; inter-assay and intra-assay coefficients correlated with commercial tests (r = 0.96 and r = 0.913, p < 0.001) and the in-house test showed no genotype-dependent differences in detection and quantification rates. The in-house assay tested in this study could be used for screening and quantifying HBV DNA in order to monitor patients during therapy.

High Functional Stability of a Low-cost HBV DNA qPCR Primer Pair and Plasmid Standard

Aim

We studied the functional stability of a primer pair and the standard curve based on a plasmid carrying full-length HBV genome, from a novel low-cost real-time quantitative polymerase chain reaction (qPCR) assay. The assay was developed at the Center for Genetic Engineering and Biotechnology (CIGB) in Havana, to quantify the serum hepatitis B virus (HBV) DNA from chronic HBV-infected (CHB) patients.

Materials and methods

In-house generated oligonucleotides and plasmids were incubated at 37°C during 1 month and compared with the same materials incubated at –20, 4, and 25°C during the same time in qPCR experiments.

Results

This work shows that the oligonucleotide pair and the plasmid for the quantitative standard curve are functionally stable in severe temperature conditions during 1 month. Polymerase chain reaction amplification with both materials after its incubation 30 days at 37°C produced similar cycle threshold (CT) values and similar degree of sample quantifications compared with the same materials preserved using the conventional storage conditions at –20°C.

Conclusion

These results are indicative of the robustness of this low-cost qPCR system for HBV DNA quantification. These results also support that this qPCR assay can be used as a low-cost technology in clinical studies to monitor the viral load changes of serum HBV DNA of CHB patients, which could be used by poor people of third world countries, where there are frequent blackouts and temperature changes that can hinder the primer and plasmid stability.

How to cite this article

Aguiar J, García G, León Y, Canales E, Silva JA, Gell O, Estrada R, Morán I, Muzio V, Guillén G, Pentón E, Aguilar JC. High Functional Stability of a Low-cost HBV DNA qPCR Primer Pair and Plasmid Standard. Euroasian J Hepato-Gastroenterol 2016;6(1):19-24.

Treatment of hepatitis delta virus genotype 3 infection with peg-interferon and entecavir

OBJECTIVES

Hepatitis delta virus (HDV) is recognized as the most pathogenic and infectious among the hepatotropic viruses. Studies on the treatment of HDV have predominantly included European patients and carriers of genotype 1 (HDV-1) in their clinical protocols. For the Amazon region, data show that infected individuals have mainly Native American ancestry and that >90% of HDV carriers have the genotype 3 (HDV-3). Thus combined therapy clinical protocols do not adequately address the treatment of these patients.

METHODS

A prospective, non-randomized study was conducted in which 22 patients received 180μg of pegylated interferon alpha 2a (PEG-IFN) plus entecavir at a dose of 0.5mg for 48 weeks, with a subsequent 24-week follow-up. Throughout treatment, the patients were monitored for biochemical responses and the kinetics of hepatitis B virus (HBV) and HDV viral loads.

RESULTS

Of the 22 patients treated, 15 presented normal alanine aminotransferase values at the end of treatment (p=0.002). At week 24 of treatment, 86.4% of the patients did not present detectable HDV-RNA; at week 48, the rate of negative patients increased to >95% and remained the same after 6 months. With regard to HBV, only two patients (9%) still presented detectable HBV genetic material at the end of treatment, suggesting the effectiveness of combined therapy in combating the two viruses.

CONCLUSIONS

These findings support the use of this effective therapeutic protocol for HDV-3 in patients of non-European ethnicity and suggest a possible 'easy to treat' variant when compared to HDV-1.

Usefulness of in-house PCR methods for hepatitis B virus DNA detection

The aim of the present study was to evaluate the performance of three in-house PCR techniques for HBV DNA detection and compare it with commercial quantitative methods to evaluate the usefulness of in-house methods for HBV diagnosis. Three panels of HBsAg reactive sera samples were evaluated: (i) 50 samples were examined using three methods for in-house qualitative PCR and the Cobas Amplicor HBV Monitor Assay; (ii) 87 samples were assayed using in-house semi-nested PCR and the Cobas TaqMan HBV test; (iii) 11 serial samples obtained from 2 HBV-infected individuals were assayed using the Cobas Amplicor HBV test and semi-nested PCR. In panel I, HBV DNA was detected in 44 samples using the Cobas Amplicor HBV test, 42 samples using semi-nested PCR (90% concordance with Cobas Amplicor), 22 samples using PCR for the core gene (63.6% concordance) and 29 samples using single-round PCR for the pre-S/S gene (75% concordance). In panel II, HBV DNA was quantified in 78 of the 87 HBsAg reactive samples using Cobas TaqMan but 52 samples using semi-nested PCR (67.8% concordance). HBV DNA was detected in serial samples until the 17th and 26th week after first donation using in-house semi-nested PCR and the Cobas Amplicor HBV test, respectively. In-house semi-nested PCR presented adequate concordance with commercial methods as an alternative method for HBV molecular diagnosis in low-resource settings.

A novel method to produce armored double-stranded DNA by encapsulation of MS2 viral capsids

With the rapid development of molecular diagnostic techniques, there is a growing need for quality controls and standards with favorable properties to monitor the entire detection process. In this study, we describe a novel method to produce armored hepatitis B virus (HBV) and human papillomavirus (HPV) DNA for use in nucleic acid tests, which was confirmed to be stable, homogeneous, noninfectious, nuclease resistant, and safe for shipping. We demonstrated that MS2 bacteriophage could successfully package double-stranded DNA of 1.3-, 3-, 3.5-, and 6.5-kb length into viral capsids with high reassembly efficiency. This is the first application of RNA bacteriophage MS2 as a platform to encapsulate double-stranded DNA, forming virus-like particles (VLPs) which were indistinguishable from native MS2 capsids in size and morphology. Moreover, by analyzing the interaction mechanism of pac site and the MS2 coat protein (CP), we found that in addition to the recognized initiation signal TR-RNA, TR-DNA can also trigger spontaneous reassembly of CP dimers, providing a more convenient and feasible method of assembly. In conclusion, this straightforward and reliable manufacturing approach makes armored DNA an ideal control and standard for use in clinical laboratory tests and diagnostics, possessing prospects for broad application, especially providing a new platform for the production of quality controls for DNA viruses.

Mini review: current molecular methods for the detection and quantification of hepatitis B virus, hepatitis C virus, and human immunodeficiency virus type 1

The detection of acute human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) infection is vital for controlling the spread of HIV, HBV, and HCV to uninfected individuals. Considering that these viruses have high replication rates and are undetectable by serological markers, early detection upon transmission is crucial. Various nucleic acid assays have been developed for diagnostics and therapeutic monitoring of infections. In the past decade, rapid and sensitive molecular techniques such as PCR have revolutionized the detection of a variety of infectious viruses, including HIV, HCV, and HBV. Here, we describe two of the most commonly used licensed methods for the detection and quantification of HIV, HCV, and HBV: the cobas TaqScreen MPX (PCR) test and the Tigris System. We used transcription-mediated amplification to review and compare the development and efficiency of these technologies.

Clinical impact of occult hepatitis B virus infection in immunosuppressed patients

Occult hepatitis B infection (OBI), is characterized by low level hepatitis B virus (HBV) DNA in circulating blood and/or liver tissue. In clinical practice the presence of antibody to hepatitis B core antigen in hepatitis B surface antigen (HBsAg)-/anti-HBs-negative subjects is considered indicative of OBI. OBI is mostly observed in the window period of acute HBV infection in blood donors and in recipients of blood and blood products, in hepatitis C virus chronic carriers, in patients under pharmacological immunosuppression, and in those with immunodepression due to HIV infection or cancer. Reactivation of OBI mostly occurs in anti-HIV-positive subjects, in patients treated with immunosuppressive therapy in onco-hematological settings, in patients who undergo hematopoietic stem cell transplantation, in those treated with anti-CD20 or anti-CD52 monoclonal antibody, or anti-tumor necrosis factors antibody for rheumatological diseases, or chemotherapy for solid tumors. Under these conditions the mortality rate for hepatic failure or progression of the underlying disease due to discontinuation of specific treatment can reach 20%. For patients with OBI, prophylaxis with nucleot(s)ide analogues should be based on the HBV serological markers, the underlying diseases and the type of immunosuppressive treatment. Lamivudine prophylaxis is indicated in hemopoietic stem cell transplantation and in onco-hematological diseases when high dose corticosteroids and rituximab are used; monitoring may be indicated when rituximab-sparing schedules are used, but early treatment should be applied as soon as HBsAg becomes detectable. This review article presents an up-to-date evaluation of the current knowledge on OBI.

Clinical impact of occult hepatitis B virus infection in immunosuppressed patients

Occult hepatitis B infection (OBI), is characterized by low level hepatitis B virus (HBV) DNA in circulating blood and/or liver tissue. In clinical practice the presence of antibody to hepatitis B core antigen in hepatitis B surface antigen (HBsAg)-/anti-HBs-negative subjects is considered indicative of OBI. OBI is mostly observed in the window period of acute HBV infection in blood donors and in recipients of blood and blood products, in hepatitis C virus chronic carriers, in patients under pharmacological immunosuppression, and in those with immunodepression due to HIV infection or cancer. Reactivation of OBI mostly occurs in anti-HIV-positive subjects, in patients treated with immunosuppressive therapy in onco-hematological settings, in patients who undergo hematopoietic stem cell transplantation, in those treated with anti-CD20 or anti-CD52 monoclonal antibody, or anti-tumor necrosis factors antibody for rheumatological diseases, or chemotherapy for solid tumors. Under these conditions the mortality rate for hepatic failure or progression of the underlying disease due to discontinuation of specific treatment can reach 20%. For patients with OBI, prophylaxis with nucleot(s)ide analogues should be based on the HBV serological markers, the underlying diseases and the type of immunosuppressive treatment. Lamivudine prophylaxis is indicated in hemopoietic stem cell transplantation and in onco-hematological diseases when high dose corticosteroids and rituximab are used; monitoring may be indicated when rituximab-sparing schedules are used, but early treatment should be applied as soon as HBsAg becomes detectable. This review article presents an up-to-date evaluation of the current knowledge on OBI.

Tuberculosis: a six-month cure

Today the treatment of tuberculosis can be based on a course of chemotherapy that lasts only 6 months, giving patients the best change of cure and affording the health personnel an exceptional opportunity to improve both their patients' compliance with the treatment and the overall efficiency of their own activities.