Association of preexisting drug-resistance mutations and treatment failure in hepatitis B patients

Hepatitis B virus clinical and virologic characteristics in an HIV perinatal transmission study in sub-Saharan Africa

OBJECTIVES

To describe the clinical and virologic characteristics of HIV-HBV coinfection, including the predictors of high maternal HBV viral load in pregnant women with HIV in sub-Saharan Africa (SSA).

METHODS

HPTN 046 was a HIV perinatal transmission clinical trial evaluating infant nevirapine vs. placebo. Women-infant pairs ( n  = 2016) were enrolled in SSA from 2007 to 2010; 1579 (78%) received antiretrovirals (ARV). Maternal delivery samples were retrospectively tested for hepatitis B surface antigen (HBsAg), and if positive, were tested for hepatitis B e antigen (HBeAg) and HBV viral load (VL). High HBV VL was defined as ≥10 6  IU/ml.

RESULTS

Overall, 4.4% (88/2016) had HBV co-infection, with geographic variability ranging from 2.4% to 8.7% ( P  < 0.0001); 25% (22/88) were HBeAg positive with prevalence in countries ranging from 10.5% to 39%. Fifty-two percentage (40/77) of those with HBV received ARV, the majority (97%) received 3TC as the only HBV active agent. HBeAg positivity was associated with high maternal HBV VL, odds ratio (OR) 37.0, 95% confidence interval (CI) 5.4-252.4. Of those with high HBV VL, 40% (4/10) were receiving HBV active drugs (HBV-ARV). HBV drug resistance occurred in 7.5% (3/40) receiving HBV-ARV.

CONCLUSIONS

In SSA, HBV co-infection is common in pregnant women with HIV. HBsAg and HBeAg prevalence vary widely by country in this clinical trial cohort. HBeAg is a surrogate for high HBV viral load. HBV drug resistance occurred in 7.5% receiving HBV-ARV with lamivudine as the only HBV active agent. These findings reinforce the importance of HBsAg screening and early treatment with two active agents for HBV.

Host Restrictive Factors Are the Emerging Storm Troopers Against Enterovirus: A Mini-Review

Enterovirus infection continues to be a global health problem. The lack of specific drugs and broad-spectrum vaccines means an urgent need to develop effective strategies against enteroviruses. Host restrictive factors are a class of intrinsic host antiviral factors that have been broadly defined and investigated during HIV infections and have great significance for drug development and treatment design. In recent years, the essential role of host restrictive factors in regulating enteroviral infections has been gradually recognized and investigated. An increasing number of studies have shown that host-restrictive factors regulate multiple steps in the life cycle of enteroviruses. This mini-review discusses the restrictive factors against enteroviruses, their antiviral mechanism, and the arms race between them and enteroviruses. We also summarise the pathways that enteroviruses use to impair host antiviral signals. This mini-review characterizes the essential role of host restriction factors in enterovirus infections, which provides ideas and potential targets for antiviral drug design by regulating host restrictive factors. It also reveals potential future research on the interplay between host restrictive factors and enteroviruses.

Antimicrobial Resistance and Antimicrobial Nanomaterials

Back in the mid-nineties, the discovery of antimicrobials denoted a profound and remarkable achievement in medicine which was capable of saving lives. However, recently, antimicrobial resistance became a major global issue facing modern medicine and significantly increased among bacteria, fungi, and viruses which results in reduced efficacy of many clinically important and lifesaving antimicrobials. The growing rise of antimicrobial resistance inflicts a remarkable economic and social burden on the health care system globally. The replacement of conventional antimicrobials by new technology to counteract and lessen antimicrobial resistance is currently ongoing. Nanotechnology is an advanced approach to overcome challenges of such resisted conventional drug delivery systems mainly based on the development and fabrication of nanoparticulate structures. Numerous forms of nanoparticulate systems have been discovered and tried as prospective drug delivery systems, comprising organic and inorganic nanoparticles.

Antimicrobial Resistance and Antimicrobial Nanomaterials

Back in the mid-nineties, the discovery of antimicrobials denoted a profound and remarkable achievement in medicine which was capable of saving lives. However, recently, antimicrobial resistance became a major global issue facing modern medicine and significantly increased among bacteria, fungi, and viruses which results in reduced efficacy of many clinically important and lifesaving antimicrobials. The growing rise of antimicrobial resistance inflicts a remarkable economic and social burden on the health care system globally. The replacement of conventional antimicrobials by new technology to counteract and lessen antimicrobial resistance is currently ongoing. Nanotechnology is an advanced approach to overcome challenges of such resisted conventional drug delivery systems mainly based on the development and fabrication of nanoparticulate structures. Numerous forms of nanoparticulate systems have been discovered and tried as prospective drug delivery systems, comprising organic and inorganic nanoparticles.

Epidemiological aspects and molecular characterization of the hepatitis B virus among blood donors in Lubumbashi, Democratic Republic of Congo

OBJECTIVES

The strains of HBV circulating among blood donors in Lubumbashi, Democratic Republic of Congo (DRC), are not yet characterized. The purpose of this study was to determine seroprevalence, changes in biochemical parameters during HBV infection and molecular characterization of HBV in blood donors in Lubumbashi.

METHODS

The detection of HBsAg was carried out by rapid diagnostic test then confirmed by the Liaison XL® Quant HBsAg technique. PCR targeting the P gene was carried out on LightCycler® 96 and genotyping by the sequencing technique on ABI 3500.

RESULTS

The seroprevalence was 7.9%. The genotypes E (53.1%), A (41.8%), A3/E (3.8%), A1/E (1.3%) and some drug resistance mutations were identified. Disturbances of HDL-cholesterol, direct bilirubin, transaminases (ASAT and ALAT), PAL, GGT and albumin have been observed in HBsAg positive blood donors.

CONCLUSION

The results of our study indicated that Lubumbashi is in a region with high endemicity for HBV and report for the first time HBV of genotypes A, E, A1/E and A3/E. They highlight the need to implement strategies to improve transfusion safety in blood transfusion centers and hospital blood banks in Lubumbashi in order to reduce HBV infection in recipients. They could also contribute to the implementation of treatment strategies and the development of mapping of circulating HBV genotypes in the DRC.

Composition and Interactions of Hepatitis B Virus Quasispecies Defined the Virological Response During Telbivudine Therapy

Reverse transcriptase (RT) mutations contribute to hepatitis B virus resistance during antiviral therapy with nucleos(t)ide analogs. However, the composition of the RT quasispecies and their interactions during antiviral treatment have not yet been thoroughly defined. In this report, 10 patients from each of 3 different virological response groups, i.e., complete virological response, partial virological response and virological breakthrough, were selected from a multicenter trial of Telbivudine treatment. Variations in the drug resistance-related critical RT regions in 107 serial serum samples from the 30 patients were examined by ultra-deep sequencing. A total of 496,577 sequence reads were obtained, with an average sequencing coverage of 4,641X per sample. The phylogenies of the quasispecies revealed the independent origins of two critical quasispecies, i.e., the rtA181T and rtM204I mutants. Data analyses and theoretical modeling showed a cooperative-competitive interplay among the quasispecies. In particular, rtM204I mutants compete against other quasispecies, which eventually leads to virological breakthrough. However, in the absence of rtM204I mutants, synergistic growth of the drug-resistant rtA181T mutants with the wild-type quasispecies could drive the composition of the viral population into a state of partial virological response. Furthermore, we demonstrated that the frequency of drug-resistant mutations in the early phase of treatment is important for predicting the virological response to antiviral therapy.

Extensive recombination due to heteroduplexes generates large amounts of artificial gene fragments during PCR

Artificial recombinants can be generated during PCR when more than two genetically distinct templates coexist in a single PCR reaction. These recombinant amplicons can lead to the false interpretation of genetic diversity and incorrect identification of biological phenotypes that do not exist in vivo. We investigated how recombination between 2 or 35 genetically distinct HIV-1 genomes was affected by different PCR conditions using the parallel allele-specific sequencing (PASS) assay and the next generation sequencing method. In a standard PCR condition, about 40% of amplicons in a PCR reaction were recombinants. The high recombination frequency could be significantly reduced if the number of amplicons in a PCR reaction was below a threshold of 10¹³–10¹⁴ using low thermal cycles, fewer input templates, and longer extension time. Heteroduplexes (each DNA strand from a distinct template) were present at a large proportion in the PCR products when more thermal cycles, more templates, and shorter extension time were used. Importantly, the majority of recombinants were identified in heteroduplexes, indicating that the recombinants were mainly generated through heteroduplexes. Since prematurely terminated extension fragments can form heteroduplexes by annealing to different templates during PCR amplification, recombination has a better chance to occur with samples containing different genomes when the number of amplicons accumulate over the threshold. New technologies are warranted to accurately characterize complex quasispecies gene populations.

Nucleoside/nucleotide analog inhibitors of hepatitis B virus polymerase: mechanism of action and resistance

Hepatitis B virus (HBV) polymerase and human immunodeficiency virus (HIV) reverse transcriptase are structurally related. However, the HBV enzyme has a protein priming activity absent in the HIV enzyme. Approved nucleoside/nucleotide inhibitors of the HBV polymerase include lamivudine, adefovir, telbivudine, entecavir and tenofovir. Although most of them target DNA elongation, guanosine and adenosine analogs (e.g. entecavir and tenofovir, respectively) also impair protein priming. Major mutational patterns conferring nucleoside/nucleotide analog resistance include the combinations rtL180M/rtM204(I/V) (for lamivudine, entecavir, telbivudine and clevudine) and rtA181V/rtN236T (for adefovir and tenofovir). However, development of drug resistance is very slow for entecavir and tenofovir. Novel nucleoside/nucleotide analogs in advanced clinical trials include phosphonates similar to adefovir or tenofovir, and new tenofovir derivatives with improved pharmacological properties.

Detection of lamivudine-resistant variants and mutations related to reduced antigenicity of HBsAg in individuals from the cities of Santos and São Paulo, Brazil

Background

Continuous long-term treatment is recommended to reduce the hepatitis B virus (HBV) viral load. However, as a consequence, resistance mutations can emerge and be transmitted to other individuals. The polymerase (POL) gene overlaps the surface (S) gene. Thus, during treatment, mutations in the POL gene may lead to changes in hepatitis B surface antigen (HBsAg). The purpose of this study was to evaluate the frequency of lamivudine and vaccine escape mutations in HBsAg-positive blood donors from the city of Santos and in untreated HBV mono-infected patients from the city of São Paulo, Brazil.

Methods

HBV DNA was extracted from 80 serum samples, of which 61 were from volunteer blood donors and 19 were from untreated HBV patients. A fragment of the POL/S genes containing 593 base pairs was amplified using nested PCR. Thirty four were PCR-positive and sequencing was performed using an ABI Prism 3130 Genetic Analyzer. Alignments and mutation mapping were performed using BioEdit software.

Results

HBV DNA from 21 blood donors and 13 untreated patient samples were characterized using nucleotide sequencing PCR products from the POL/S genes. We were able to detect one sample with the resistance mutation to lamivudine rtM204V + rtL180M (2.94%), which was found in a volunteer blood donor that has never used antiviral drugs. The other samples showed only compensatory mutations, such as rtL80F (5.88%), rtL80V (2.94%), rtL82V + rtV207L (2.94%), rtT128P (5.88%), rtT128N/S (2.94%) and rtS219A (5.88%). We found modifications in the S gene in 14 of the 34 samples (41.16%). The mutations detected were as follows: sM133L + sI195T (2.94%), sI195M (2.94%), sP120T (2.94%), sY100S/F (2.94%), sY100C (17.64%), sI/T126P + sQ129P (2.94%), sM198I + sF183C (2.94%) and sS210R (5.88%).

Conclusions

Our results suggest the transmission of lamivudine-resistant forms. Thus, the evaluation of HBV-infected subjects for lamivudine resistance would improve treatment regime. Moreover, the mutations in the S gene may impair HBsAg antigenicity and contribute to HBsAg failure detection and vaccine escape.