Prediction of conformational changes by single mutation in the hepatitis B virus surface antigen (HBsAg) identified in HBsAg-negative blood donors

<p>Abstract</p> <p>Background</p> <p>Selection of hepatitis B virus (HBV) by host immunity has been suggested to give rise to variants with amino acid substitutions at or around the <it>'a' </it>determinant of the surface antigen (HBsAg), the main target of antibody neutralization and diagnostic assays. However, there have never been successful attempts to provide evidence for this hypothesis, partly because the 3 D structure of HBsAg molecules has not been determined. Tertiary structure prediction of HBsAg solely from its primary amino acid sequence may reveal the molecular energetic of the mutated proteins. We carried out this preliminary study to analyze the predicted HBsAg conformation changes of HBV variants isolated from Indonesian blood donors undetectable by HBsAg assays and its significance, compared to other previously-reported variants that were associated with diagnostic failure.</p> <p>Results</p> <p>Three HBV variants (T123A, M133L and T143M) and a wild type sequence were analyzed together with frequently emerged variants T123N, M133I, M133T, M133V, and T143L. Based on the Jameson-Wolf algorithm for calculating antigenic index, the first two amino acid substitutions resulted in slight changes in the antigenicity of the <it>'a' </it>determinant, while all four of the comparative variants showed relatively more significant changes. In the pattern T143M, changes in antigenic index were more significant, both in its coverage and magnitude, even when compared to variant T143L. These data were also partially supported by the tertiary structure prediction, in which the pattern T143M showed larger shift in the HBsAg second loop structure compared to the others.</p> <p>Conclusions</p> <p>Single amino acid substitutions within or near the <it>'a' </it>determinant of HBsAg may alter antigenicity properties of variant HBsAg, which can be shown by both its antigenic index and predicted 3 D conformation. Findings in this study emphasize the significance of variant T143M, the prevalent isolate with highest degree of antigenicity changes found in Indonesian blood donors. This highlights the importance of evaluating the effects of protein structure alterations on the sensitivity of screening methods being used in detection of ongoing HBV infection, as well as the use of vaccines and immunoglobulin therapy in contributing to the selection of HBV variants.</p

Reverse-Transcriptase Characteristics of Hepatitis B Virus Polymerase Gene in Treatment-Naïve Asymptomatic Chronic Hepatitis B Individuals

Nucleos(t)ide analogues (NUCs) remain the main treatment for chronic hepatitis B (CHB). Long-term use of NUCs significantly reduces disease progression; however, it might lead to resistance-associated mutations. We studied characteristics of polymerase gene related to NUCs resistance in na&iuml;ve hepatitis B surface antigen (HBsAg)-positive individuals. The research was done at Laboratory of Hepatitis, Eijkman Institute, Jakarta Thirty eight samples were obtained and submitted for HBV DNA detection. Identification of mutations was performed by PCR-sequencing, and analyzed to obtain NUCs resistance motifs. Genotype and subtype were determined based on HBsAg sequence. Mutation of rtQ238H/N was found in 37 (97.4%) samples. Of those, 23 (62.2%) showed rtQ238H mutation, 10 (27.0%) had rtQ238N mutation, and four (10.8%) with double mutations of rtA194T and rtQ238H. Genotype B was found in 26 (68.4%), C in 11 (28.9%), and D in one (2.6%) samples. Statistically, the mutation variant of rtQ238H was associated with genotype B (p&lt;0.001), while rtQ238N with C (p&lt;0.001). The ayw subtype was found in 25 (65.8%), adr in 11 (28.9%), and adw in two (5.3%) samples. No mutation associated with NUCs resistance was found in most samples. This emphasizes that NUCs are still a prospective treatment in na&iuml;ve CHB patients.&nbsp; Mutation of rtQ238H was a variant found to be significantly associated with HBV genotype B and rtQ238N with genotype C

Chronic hepatitis B in pregnant women: is hepatitis B surface antigen quantification useful for viral load prediction?

SummaryBackgroundNew cases of hepatitis B virus (HBV) infection continue to occur worldwide. Most of these are due to mother-to-child transmission (MTCT), with maternal viraemia as the most important contributing factor. The hepatitis B surface antigen (HBsAg) level, which correlates positively with viral load, has been used for treatment monitoring in chronic hepatitis B. This study evaluated the usefulness of quantitative HBsAg for viral load prediction in HBsAg-positive pregnant women.MethodsA total of 943 pregnant women in Makassar, Indonesia, were screened for HBsAg. Sixty-four women were HBsAg-positive and investigated. HBsAg level and hepatitis B e antigen (HBeAg)/hepatitis B e antibody (anti-HBe) status were determined serologically. Viral load was measured by real-time PCR. HBV DNA was sequenced and analysed for identification of genotype and basal core promoter (BCP)/precore (PC) mutations.ResultsOf 64 subjects, 12 (18.8%) were HBeAg-positive and 52 (81.3%) were HBeAg-negative. HBsAg and HBV DNA levels were significantly higher in the HBeAg-positive group (p<0.001). HBsAg and HBV DNA levels were positively correlated in the HBeAg-positive group (r = 0.659; p=0.02), but not in the HBeAg-negative group (r=0.194; p=0.168). Low HBsAg levels (<3.0 log10 IU/ml) corresponded with HBV DNA levels<6.0 log10 IU/ml (r=0.404; p=0.001), a recognized threshold for MTCT. Genotype C was more prevalent than genotype B, but not associated with HBsAg level, viral load, or HBeAg status. Two-thirds of HBeAg-negative subjects with high HBV DNA levels harboured BCP (A1762T/G1764A) and/or PC (G1896A) variants.ConclusionsHBsAg levels provide a good viral load predictor in HBeAg-positive but not HBeAg-negative pregnant women. The HBeAg-negative group had a frequent occurrence of BCP/PC variants, which may have contributed to the lack of correlation observed. Samples with a low HBsAg level, which is associated with a low risk of MTCT, do not require HBV DNA measurement

Genetic and antigenic characterization of influenza A/H5N1 viruses isolated from patients in Indonesia, 2008–2015

Since the initial detection in 2003, Indonesia has reported 200 human cases of highly pathogenic avian influenza H5N1 (HPAI H5N1), associated with an exceptionally high case fatality rate (84%) compared to other geographical regions affected by other genetic clades of the virus. However, there is limited information on the genetic diversity of HPAI H5N1 viruses, especially those isolated from humans in Indonesia. In this study, the genetic and antigenic characteristics of 35 HPAI H5N1 viruses isolated from humans were analyzed. Full genome sequences were analyzed for the presence of substitutions in the receptor binding site, and p

Global prevalence and genotype distribution of hepatitis C virus infection in 2015 : A modelling study

Publisher Copyright: © 2017 Elsevier LtdBackground The 69th World Health Assembly approved the Global Health Sector Strategy to eliminate hepatitis C virus (HCV) infection by 2030, which can become a reality with the recent launch of direct acting antiviral therapies. Reliable disease burden estimates are required for national strategies. This analysis estimates the global prevalence of viraemic HCV at the end of 2015, an update of—and expansion on—the 2014 analysis, which reported 80 million (95% CI 64–103) viraemic infections in 2013. Methods We developed country-level disease burden models following a systematic review of HCV prevalence (number of studies, n=6754) and genotype (n=11 342) studies published after 2013. A Delphi process was used to gain country expert consensus and validate inputs. Published estimates alone were used for countries where expert panel meetings could not be scheduled. Global prevalence was estimated using regional averages for countries without data. Findings Models were built for 100 countries, 59 of which were approved by country experts, with the remaining 41 estimated using published data alone. The remaining countries had insufficient data to create a model. The global prevalence of viraemic HCV is estimated to be 1·0% (95% uncertainty interval 0·8–1·1) in 2015, corresponding to 71·1 million (62·5–79·4) viraemic infections. Genotypes 1 and 3 were the most common cause of infections (44% and 25%, respectively). Interpretation The global estimate of viraemic infections is lower than previous estimates, largely due to more recent (lower) prevalence estimates in Africa. Additionally, increased mortality due to liver-related causes and an ageing population may have contributed to a reduction in infections. Funding John C Martin Foundation.publishersversionPeer reviewe

current prevalence of hepatitis B infection among parturient women in Jakarta, Indonesia

Aim: to determine the current prevalence of hepatitis B infection among parturient women in Jakarta, Indonesia. Methods: a cross-sectional study was conducted in women giving birth between May and July 2009, recruited by consecutive sampling technique in 2 hospitals and 13 public health centers in Jakarta. Mothers with history of chronic liver disease were excluded. Data were collected by questionnaires including obstetric history, hepatitis B immunization history, and the presence of jaundice; maternal venous blood samples were taken before parturition for HBsAg determination that was performed by ELISA. Results: of 1,009 parturient women screened for hepatitis B infection, 22 were found positive, giving an overall hepatitis B prevalence of 2.2%, previous 5.2% in 1985. None of the subjects had any symptoms of HBV infection. The highest HBsAg prevalence was found in the East Jakarta study site, with predominance in mothers aged <20 years and those with multi-parities. Conclusion: present prevalence of HBsAg among Indonesian parturient women in Jakarta was 2.2% and markedly reduced compared with prevalence in 1985