Dynamics Of Hepatitis Research Articles

Harnessing CD8+ T cell dynamics in hepatitis B virus‐associated liver diseases: Insights, therapies and future directions

AbstractHepatitis B virus (HBV) infection playsa significant role in the etiology and progression of liver‐relatedpathologies, encompassing chronic hepatitis, fibrosis, cirrhosis, and eventual hepatocellularcarcinoma (HCC). Notably, HBV infection stands as the primary etiologicalfactor driving the development of HCC. Given the significant contribution ofHBV infection to liver diseases, a comprehensive understanding of immunedynamics in the liver microenvironment, spanning chronic HBV infection,fibrosis, cirrhosis, and HCC, is essential. In this review, we focused on thefunctional alterations of CD8+ T cells within the pathogenic livermicroenvironment from HBV infection to HCC. We thoroughly reviewed the roles ofhypoxia, acidic pH, metabolic reprogramming, amino acid deficiency, inhibitory checkpointmolecules, immunosuppressive cytokines, and the gut‐liver communication in shapingthe dysfunction of CD8+ T cells in the liver microenvironment. Thesefactors significantly impact the clinical prognosis. Furthermore, we comprehensivelyreviewed CD8+ T cell‐based therapy strategies for liver diseases,encompassing HBV infection, fibrosis, cirrhosis, and HCC. Strategies includeimmune checkpoint blockades, metabolic T‐cell targeting therapy, therapeuticT‐cell vaccination, and adoptive transfer of genetically engineered CD8+ T cells, along with the combined usage of programmed cell death protein‐1/programmeddeath ligand‐1 (PD‐1/PD‐L1) inhibitors with mitochondria‐targeted antioxidants.Given that targeting CD8+ T cells at various stages of hepatitis Bvirus‐induced hepatocellular carcinoma (HBV + HCC) shows promise, we reviewedthe ongoing need for research to elucidate the complex interplay between CD8+ T cells and the liver microenvironment in the progression of HBV infection toHCC. We also discussed personalized treatment regimens, combining therapeuticstrategies and harnessing gut microbiota modulation, which holds potential forenhanced clinical benefits. In conclusion, this review delves into the immunedynamics of CD8+ T cells, microenvironment changes, and therapeuticstrategies within the liver during chronic HBV infection, HCC progression, andrelated liver diseases.

Analyzing energetics and dynamics of hepatitis C virus polymerase interactions with marine bacterial compounds: a computational study

Analyzing energetics and dynamics of hepatitis C virus polymerase interactions with marine bacterial compounds: a computational study

Efficient formation and maintenance of humoral and CD4 T-cell immunity targeting the viral capsid in acute-resolving hepatitis E infection

CD4 T cells shape the neutralizing antibody (nAb) response and facilitate viral clearance in various infections. Knowledge of their phenotype, specificity and dynamics in hepatitis E virus (HEV) infection is limited. HEV is enterically transmitted as a naked virus (nHEV) but acquires a host-derived quasi-envelope (eHEV) when budding from cells. While nHEV is composed of the open reading frame (ORF)-2-derived capsid, eHEV particles also contain ORF3-derived proteins. We aimed to longitudinally characterize the HEV-specific CD4 T cells targeting ORF1, 2 and 3 and antibodies against nHEV or eHEV in immunocompetent individuals with acute and resolved HEV infection. HEV-specific CD4 T cells were analyzed by intracellular cytokine staining after stimulation with in silico-predicted ORF1- and ORF2-derived epitopes and overlapping peptides spanning the ORF3 region. Exvivo multiparametric characterization of capsid-specific CD4 T cells was performed using customized MHC class II tetramers. Total and neutralizing antibodies targeting nHEV or eHEV particles were determined. HEV-specific CD4 T-cell frequencies and antibody titers are highest in individuals with acute infection and decline in a time-dependent process with an antigen hierarchy. HEV-specific CD4 T cells strongly target the ORF2-derived capsid and ORF3-specific CD4 T cells are hardly detectable. NAbs targeting nHEV are found in high titers while eHEV particles are less efficiently neutralized. Capsid-specific CD4 T cells undergo memory formation and stepwise contraction, accompanied by dynamic phenotypical and transcriptional changes over time. The viral capsid is the main target of HEV-specific CD4 T cells and antibodies in acute-resolving infection, correlating with efficient neutralization of nHEV. Capsid-specific immunity rapidly emerges followed by a stepwise contraction several years after infection. The interplay of CD4 T cells and neutralizing antibody responses is critical in the host defense against viral infections, yet little is known about their characteristics in hepatitis E virus (HEV) infection. We conducted a longitudinal study of immunocompetent individuals with acute and resolved HEV infection to understand the characteristics of HEV-specific CD4 T cells and neutralizing antibodies targeting different viral proteins and particles. We found that HEV-specific CD4 T cells mainly target capsid-derived epitopes. This correlates with efficient neutralization of naked virions while quasi-enveloped particles are less susceptible to neutralization. As individuals with pre-existing liver disease and immunocompromised individuals are at risk for fulminant or chronic courses of HEV infection, these individuals might benefit from the development of vaccination strategies which require a detailed knowledge of the composition and longevity of HEV-specific CD4 T-cell and antibody immunity.

Viral infection dynamics of HBV DNA-containing capsids with logistics growth and saturated rate

Knowing more about the dynamics of hepatitis B viral infection with DNA containing capsids, still under research. In this paper, we propose a new mathematical model dealing with the infection of hepatocytes with capsids logistics growth functions and saturated rate. We initiate the work with the description and the wellposedness of the formulation, then we study the stability of different equilibria to get a set of results which express that the system has tree equilibrium points. For the basic reproduction number is less then one (R 0 < 1) the diseasefree equilibrium is stable and when R 0 > 1 other conditions determinate the stability of the endemic equilibrium points. By numerical simulation, we verify numerically the theoretical founding.

Dynamics of Hepatitis B infection prevention practices among pregnant women attending antenatal care at Lubaga Hospital Kampala, Uganda using the constructs of information-motivation-behavioural skills model

BackgroundHepatitis B virus (HBV) infection is considered a significant global public health challenge with infectivity as well as estimated potential for transmission more than 50 to 100 times that of HIV. Over time, numerous empirical studies have shown that majority of HBV-related yearly global deaths are secondary to carcinoma of the liver. It is also known that HBV infected Women have the potential to transmit the infection vertically to their infants during pregnancy. This accounts for the WHO reported 3.16% prevalence among children less than 5 years of age in Uganda. This study assessed the predictors of HBV infection prevention practices among eligible consenting pregnant women using Lubaga health facility for antenatal care (ANC).MethodsA cross-sectional descriptive study employing quantitative data collection based on the constructs of IMB model was used to capture data on the study variables among 385 randomly selected eligible pregnant women attending antenatal care at Lubaga hospital between September 2020 and October 2020. Data derived from the quantitative instrument was analysed by data reduction and transformation to summaries of descriptive statistics using (SPSS version 26) and regression analysis was performed to establish characteristics of the association between the variables with significance level set as (p < 0.05). Chi-square goodness-of-fit test was employed for significant differences in the proportion of dichotomous responses.ResultsThe findings showed that more than half of the respondents (59%) were between the ages of 18 and 28 and majority of them (42.3%) had secondary education. Furthermore, an average but inadequate knowledge (overline{X }= 5.97 ± 6.61; B = 0.57; p < .001), positive perception (overline{X }= 17.10 ± 18.31; B = 0.97; p = .014) and good behavioural skills (overline{X }= 12.39 ± 13.37; B = 0.56; p < .001) for adopting prevention practices all statistically predicted the averagely acceptable level of prevention practices (overline{X }= 15.03 ± 16.20) among the study respondents as measured on rating scales of 12, 33, 21 and 30 respectively.Conclusion and recommendationThere were observed gaps in their knowledge about some basic features of the infection like transmission and risk factors as well as some misperceptions about vaccination despite the relatively average score level for both, which is likely to influence their prevention behaviours and predispose them to the risk of the infection if actions are not taken. Therefore, personalized health education is needed during antenatal visits and subsequent health campaign in order to inform better prevention practices among this vulnerable population group.

Different evolutionary dynamics of hepatitis B virus genotypes A and D, and hepatitis D virus genotypes 1 and 2 in an endemic area of Yakutia, Russia

BackgroundThe geographic distribution of the hepatitis B virus (HBV) and the hepatitis D virus (HDV) genotypes is uneven. We reconstructed the temporal evolution of HBV and HDV in Yakutia, one of the regions of Russia most affected by HBV and HDV, in an attempt to understand the possible mechanisms that led to unusual for Russia pattern of viral genotypes and to identify current distribution trends.MethodsHBV and HDV genotypes were determined in sera collected in 2018–2019 in Yakutia from randomly selected 140 patients with HBV monoinfection and 59 patients with HBV/HDV. Total 86 HBV and 88 HDV genomic sequences isolated in Yakutia between 1997 and 2019 were subjected to phylodynamic and philogeographic Bayesian analysis using BEAST v1.10.4 software package. Bayesian SkyGrid reconstruction and Birth–Death Skyline analysis were applied to estimate HBV and HDV population dynamics.ResultsCurrently, HBV-A and HDV-D genotypes are prevalent in Yakutia, in both monoinfected and HDV-coinfected patients. Bayesian analysis has shown that the high prevalence of HBV-A in Yakutia, which is not typical for Russia, initially emerged after the genotype was introduced from Eastern Europe in the fifteenth century (around 600 (95% HPD: 50–715) years ago). The acute hepatitis B epidemics in the 1990s in Yakutia were largely associated with this particular genotype, as indicated by temporal changes in HBV-A population dynamics. HBV-D had a longer history in Yakutia and demonstrated stable population dynamics, indicating ongoing viral circulation despite vaccination. No correlation between HBV and HDV genotypes was observed for coinfected patients in Yakutia (r = − 0.016069332). HDV-2b circulates in Russia in Yakutia only and resulted from a single wave of introduction from Central Asia 135 years ago (95% HPD: 60–350 years), while HDV-1 strains resulted from multiple introductions from Europe, the Middle East, Central Asia, and different parts of Russia starting 180 years ago (95% HPD: 150–210 years) and continuing to the present day. The population dynamics of HDV-1 and HDV-2 show no signs of decline despite 20 years of HBV vaccination. The Birth–Death Skyline analysis showed an increase in the viral population in recent years for both HDV genotypes, indicating ongoing HDV epidemics.ConclusionsTaken together, these data call for strict control of HBV vaccination quality and coverage, and implementation of HBV and HDV screening programs in Yakutia.

Study of Animal Mixing and the Dynamics of Hepatitis E Virus Infection on a Farrow-to-Finish Pig Farm.

Simple SummaryIn Europe, swine are a livestock reservoir for Hepatitis E virus genotype 3 (HEV-3). Consumption of food containing HEV-3 may lead to human infection, and severe illness in some cases. Heat treatment and good hygiene practice during food preparation reduces human infection risk, but further control could be achieved by controlling HEV infection in pigs on farm. However, the key sources and timing of HEV infection in pig herds is not well understood. This study aimed to address these knowledge gaps. Pig faeces were collected from a farrow-to-finish farm on multiple occasions spanning five months and were tested for presence of HEV nucleic acid. Prevalence was always higher in growers (85.8% overall) compared to older fattener pigs (26.0%), but was detected at all visits indicating long-term persistence on the farm. Prevalence of HEV in the farm environment was also high (64.7% of 67 samples), and this may lead to continual herd re-infection. Studying infection in a single cohort of pigs over time revealed an absence of active infection in farrowing sows and young piglets. Infection first appeared in the cohort at weaner age, but only in groups that had either been weaned earlier or experienced a high degree of mixing with other pigs.In Europe, swine are a livestock reservoir for Hepatitis E virus genotype 3 (HEV-3). Consumption of food containing HEV-3 can cause zoonotic human infection, though risk is reduced by heat treatment. Implementing controls that limit infection in slaughter pigs may further reduce foodborne transmission risk but knowledge of infection dynamics on commercial farms is limited. This study addressed this knowledge gap and in particular investigated the influence of group mixing. Faeces were collected from grower (n = 212) and fattener (n = 262) pigs on a farrow-to-finish farm on four occasions. HEV RNA was detected on all occasions, and prevalence was higher in growers (85.8%) than fatteners (26.0%; p < 0.001). HEV-positive samples were also collected from the wider farm environment (n = 67; 64.7% prevalence), indicating potential sources for HEV re-circulation within the herd. Timing of infection in a cohort was also investigated. HEV was absent from all piglet faeces (n = 98) and first detected at weaner stage (25.7% prevalence), but only in groups weaned earlier or comprising pigs from many different litters. Farrowing sow faeces (n = 75) were HEV-negative but antibodies were detected in blood from two sows. Results suggest that multiple factors influence HEV infection dynamics on pig farms, and potential foci for further study into practical control solutions are highlighted.

PREVALENCE OF HEPATITIS A VIRUS, HEPATITIS B VIRUS, AND HEPATITIS C VIRUS, AMONG PATIENTS WITH HEPATIC JAUNDICE IN SANA’A CITY, YEMEN: A HOSPITAL BASED STUDY

Background: Hepatic jaundice results from abnormal metabolism of bilirubin in the liver. The main hepatic jaundice causes are severe damage to hepatocytes due to autoimmune diseases, infectious diseases, drugs/ medication induced, or, less commonly, hereditary genetic diseases.&#x0D; Aim: The aim of this study is to determine the prevalence of hepatitis B Virus (HBV), hepatitis A virus (HAV), and hepatitis C virus (HCV), in patients with hepatic jaundice as causes of acute viral hepatitis (AVH) in Sana'a city, Yemen.&#x0D; Subjects and Methods: Data of patients with hepatic jaundice tested for hepatitis B surface antigen, total anti-HCV antibody, and anti-HAV immunoglobulin M (IgM) by enzyme-linked immunosorbent assay were collected from Class I Viral Diagnostic Laboratories in Sana'a for 3 years. Then the statistical analysis of the data was used where the descriptive analysis was calculated: frequency and percentage, as well as the association of infection with sex and age group by means of detection odds ratio, 95% CI and X2 more than 3.9 and P&lt;0.05 were considered statistically significant.&#x0D; Results: The study included 644 males (43.8%) and 826 females (56.2%), while most patients were less than 21 years old. The rate of Hepatitis viruses positive was 27.6% positive. Hepatitis A virus infection was the most common virus diagnosed accounting for 259 cases (17.6% of the total), while HBV was less common with 104 (7.1%) and HCV only 42 cases (2.9%). The highest incidence of hepatitis B was in 11-20 years patients (18.2%), with an associated OR 9.3 (p &lt; 0.0001). The highest incidence of hepatitis C was in 31-40 years patients (7.3%), with an associated OR 3.3 (p&lt;0.0001).&#x0D; Conclusion: Alarmingly changing the epidemiology and dynamics of hepatitis A-C viruses in Yemen, a detailed study is required to understand the definite disease problem caused by these viruses. It is noticeable in this study the high prevalence of hepatitis A virus and hepatitis B virus in the Yemeni population with hepatic jaundice. Also, to our knowledge, this study is the first to report epidemiological transformation of hepatitis A virus in Sana'a, Yemen.&#x0D; &#x0D; Peer Review History: &#x0D; Received: 13 November 2021; Revised: 11 December; Accepted: 30 December, Available online: 15 January 2022&#x0D; Academic Editor: Dr. Nuray Arı, Ankara University, Turkiye, ari@ankara.edu.tr&#x0D; UJPR follows the most transparent and toughest ‘Advanced OPEN peer review’ system. The identity of the authors and, reviewers will be known to each other. This transparent process will help to eradicate any possible malicious/purposeful interference by any person (publishing staff, reviewer, editor, author, etc) during peer review. As a result of this unique system, all reviewers will get their due recognition and respect, once their names are published in the papers. We expect that, by publishing peer review reports with published papers, will be helpful to many authors for drafting their article according to the specifications. Auhors will remove any error of their article and they will improve their article(s) according to the previous reports displayed with published article(s). The main purpose of it is ‘to improve the quality of a candidate manuscript’. Our reviewers check the ‘strength and weakness of a manuscript honestly’. There will increase in the perfection, and transparency. &#x0D; Received file: Reviewer's Comments:&#x0D; Average Peer review marks at initial stage: 5.5/10&#x0D; Average Peer review marks at publication stage: 7.0/10&#x0D; Reviewers:&#x0D; Dr. Gulam Mohammed Husain,, National Research Institute of Unani Medicine for Skin Disorders, Hyderabad, India, gmhusain@gmail.com&#x0D; Dr. Salfarina Ramli, Department of Pharmacology and Pharmaceutical Chemistry, Faculty of Pharmacy, Universiti Teknologi MARA, 42300 Puncak Alam, Selangor, Malaysia. salfarina2892@uitm.edu.my &#x0D; Similar Articles:&#x0D; PREVALENCE OF DIFFERENT HEPATITIS B VIRUS GENOTYPES AND RISK FACTORS ASSOCIATED AMONG SELECTED YEMENI PATIENTS WITH CHRONIC HEPATITIS B INFECTION &#x0D; SERO-EPIDEMIOLOGICAL STUDY OF HEPATITIS B, C, HIV AND TREPONEMA PALLIDUM AMONG BLOOD DONORS IN HODEIDA CITY- YEMEN &#x0D; EXPLOSION OF HEPATITIS B AND C VIRUSES AMONG HEMODIALYSIS PATIENTS AS A RESULT OF HEMODIALYSIS CRISIS IN YEMEN

The impact of testing and treatment on the dynamics of Hepatitis B virus

Despite the intervention of WHO on vaccination for reducing the spread of Hepatitis B Virus (HBV), there are records of the high prevalence of HBV in some regions. In this paper, a mathematical model was formulated to analyze the acquisition and transmission process of the virus with the view of identifying the possible way of reducing the menace and mitigating the risk of the virus. The models' positivity and boundedness were demonstrated using well-known theorems. Equating the differential equations to zero demonstrates the equilibria of the solutions i.e., the disease-free and endemic equilibrium. The next Generation Matrix method was used to compute the basic reproduction number for the models. Local and global stabilities of the models were shown via linearization and Lyapunov function methods respectively. The importance of testing and treatment on the dynamics of HBV were fully discussed in this paper. It was discovered that testing at the acute stage of the virus and chronic unaware state helps in better management of the virus.

The impact of testing and treatment on the dynamics of Hepatitis B virus.

Despite the intervention of WHO on vaccination for reducing the spread of Hepatitis B Virus (HBV), there are records of the high prevalence of HBV in some regions. In this paper, a mathematical model was formulated to analyze the acquisition and transmission process of the virus with the view of identifying the possible way of reducing the menace and mitigating the risk of the virus. The models' positivity and boundedness were demonstrated using well-known theorems. Equating the differential equations to zero demonstrates the equilibria of the solutions i.e., the disease-free and endemic equilibrium. The next Generation Matrix method was used to compute the basic reproduction number for the models. Local and global stabilities of the models were shown via linearization and Lyapunov function methods respectively. The importance of testing and treatment on the dynamics of HBV were fully discussed in this paper. It was discovered that testing at the acute stage of the virus and chronic unaware state helps in better management of the virus.

Dynamics of hepatitis C epidemic among people living with HIV in Estonia based on Estonian HIV cohort study

BackgroundEstonia has a typical Eastern European HIV epidemic where the most frequent co-infection is chronic hepatitis C (HCV). We aimed to describe the changes in HCV prevalence, the distribution of HCV genotypes (GT), and HCV treatment in Estonian people living with HIV over 15 years.MethodsWe used data of subjects included to the Estonian HIV Cohort Study (E-HIV) before 31st of December 2015. We compared two time periods—first, 1st of January 2000 to 31st of December 2008 when the HIV epidemic was mostly spreading among people who inject drugs (PWID) and second, 1st of January 2009 to 31st of December 2015 when HIV started to emerge to the general population.ResultsOf 4422 HIV positives 3708 (84%) had information about their HCV serostatus; 2706 (61%) were HCV seropositive, of latter 1625 (60%) were HCV RNA positive, 239 (9%) had their HCV GT determined, and 141 (5%) received treatment for HCV. The dominating subtypes were 1b (42%) and 3a (37%) followed by 1a (16%), and the few cases of 2 (1.5%). HCV prevalence was 1.5 times (95% CI 1.4–1.6) higher in subjects diagnosed with HIV in first as compared to those diagnosed in second period (84% vs 56%, respectively). There were more men and the median age at HIV diagnosis was lower in HIV/HCV co-infected than in HIV mono-infected patients (70% vs 47% and 24 years vs. 30 years, respectively; both p < 0.001).ConclusionThere is a decrease in HCV prevalence but it remains high among HIV positive PWID, suggesting that there is need for improvement of harm reduction programs among PWID.

Delayed hepatitis B epidemic model with stochastic analysis

Environmental factors such as, humidity and temperature pose significant impacts on the dynamics of hepatitis B virus (HBV). The stochastic modeling has been proved to be a powerful tool for revealing such impacts. With this motive, the present study enacts the formulation and analysis of a stochastic hepatitis B model considering a time-delay in the transmission coefficient, and CTL immune response class. Initially, the model is investigated for the existence of a unique global solution. By using the stochastic Lyapunov functional theory, the model was further analyzed for extinction and persistence of the disease. It is evident that the ergodic stationary distribution exists under certain condition. We infer that the white noise plays a significant role in controlling the infection. Relatively large noise guarantees the extinction of HBV. Similarly, it is inferred that the delay factor is responsible for the periodic occurrence and re-infection of the disease. Additionally, for providing a strong support to the theoretical results, sample trajectories were displayed at the end of the study.

Dynamics of Hepatitis E Virus (HEV) Antibodies and Development of a Multifactorial Model To Improve the Diagnosis of HEV Infection in Resource-Limited Settings.

Serological markers are important for the diagnosis of hepatitis E virus (HEV) infection. This study aims to compare the diagnostic performance of the anti-HEV IgM and the HEV antigen (Ag) assays and establish a multifactorial model to improve the diagnosis of current HEV infection when HEV RNA detection is not available. A total of 809 serum samples, including 325 anti-HEV IgM-positive and 484 anti-HEV IgM-negative samples, were tested for HEV RNA. The anti-HEV IgM assay had very high sensitivity (99.4%) but moderate accuracy (79.2%) and specificity (74.3%). By retrospective follow-up of 58 patients with sequential samples (n = 143) tested for anti-HEV antibodies, we found anti-HEV IgM remained positive for more than 10 months in some HEV-infected patients, when HEV RNA was already undetectable; thus, decision solely based on anti-HEV IgM may lead to misdiagnosis. In contrast, the HEV Ag assay had very high specificity (100%). However, the detection efficiency of HEV Ag greatly diminished when the HEV RNA level was low or the anti-HEV IgG level was high. By logistic regression, a model integrating anti-HEV IgM, alanine aminotransferase, and HEV Ag was proposed, and the cutoff value was determined based on the testing results of the 143 sequential samples. The model was further evaluated with 67 randomly selected IgM-positive samples from single-visit patients. Overall, the model outperformed the anti-HEV IgM or the HEV Ag assay in the diagnosis of current HEV infection (sensitivity/specificity/accuracy, 89.5%/95.2%/91.9%). The area under the receiver operating characteristics curve of the model was greater than 0.97.

A fractional order model for the transmission dynamics of hepatitis B virus with two-age structure in the presence of vaccination

In this study, we proposed a fractional order model of hepatitis B virus transmission dynamics with two-age structure under vaccination. A qualitative analysis of the model is performed. Basic reproduction number of the model is determined. Local stability conditions of disease-free equilibrium point are proven by using fractional Ruth-Hurwitz conditions. Global stability conditions of both disease-free and endemic equilibrium points are shown by constructing appropriate Lyapunov functions. Sensitivity analysis was done by using normalized forward sensitivity index approach. Numerical simulation is performed to investigate the effect of memory on hepatitis B disease dynamics by varying order of derivatives and to simulate the effects of vaccinating newborns immediately after birth, vaccinating children and adult vaccination. Then, we compared their effects on hepatitis B disease dynamics in the sense of control and elimination. It is observed that the number of infective individuals decreases faster and even falls to zero over a long run for the model with memory than memory-less model. Comparing results between vaccination of different ages show that increasing newborn vaccination immediately after birth has the highest effect on hepatitis B disease control.

Mathematical modelling of the transmission dynamics of hepatitis B virus in the presence of imperfect vaccination

Mathematical modelling of the transmission dynamics of hepatitis B virus in the presence of imperfect vaccination

Analysis of a Fractional Reaction-Diffusion HBV Model with Cure of Infected Cells

In this paper, we propose a fractional reaction-diffusion model in order to better understand the mechanisms and dynamics of hepatitis B virus (HBV) infection in human body. The infection transmission is modeled by Hattaf–Yousfi functional response, and the fractional derivative is in the sense of Caputo. The global stability of the model equilibria is analyzed by means of Lyapunov functionals. Finally, numerical simulations are presented to support our analytical results.

OPTIMAL CONTROL ANALYSIS OF THE EFFECT OF TREATMENT, ISOLATION AND VACCINATION ON HEPATITIS B VIRUS

Hepatitis B infection is a serious health issue and a major cause of deaths worldwide. This infection can be overcome by adopting proper treatment and control strategies. In this paper, we develop and use a mathematical model to explore the effect of treatment on the dynamics of hepatitis B infection. First, we formulate and use a model without control variables to calculate the basic reproduction number and to investigate basic properties of the model such as the existence and stability of equilibria. In the absence of control measures, we prove that the disease free equilibrium is locally asymptotically stable when the basic reproduction number is less than unity. Also, using persistent theorem, it is shown that the infection is uniformly persistent, whenever the basic reproduction number is greater than unity. Using optimal control theory, we incorporate into the model three time-dependent control variables and investigate the conditions required to curtail the spread of the disease. Finally, to illustrate the effectiveness of each of the control strategies on disease control and eradication, we perform numerical simulations. Based on the numerical results, we found that the first two strategies (treatment and isolation strategy) and (vaccination and isolation strategy) are not very effective as a long term control or eradication strategy for HBV. Hence, we recommend that in order to effectively control the disease, all the control measures (isolation, vaccination and treatment) must be implemented at the same time.

Spatiotemporal Dynamics of a Generalized HBV Infection Model with Capsids and Adaptive Immunity

In this study, we propose and analyze a new mathematical model formulated by partial differential equations in order to better understand the mechanisms and dynamics of hepatitis B virus (HBV) infection in vivo. The proposed model incorporates the intracellular HBV DNA-containing capsids, spatial diffusion in both capsids and viruses, and adaptive immune response exerted by cytotoxic T lymphocytes and antibodies. Further, the infection process is modeled by a general incidence function that includes many cases existing in the literature. We first show the global existence, uniqueness, positivity and boundedness of solutions. The global stability and instability of equilibria are established by means of Lyapunov’s direct and indirect methods. Finally, numerical simulations are presented to illustrate the dynamical behaviors of the model and to support the theoretical results.

Epidemiology and Risk Factors for Chlamydia trachomatis, Treponema pallidum,Hepatitis B Virus and Hepatitis C Virus in the Maraj? Archipelago, Brazilian Amazon

Background: The dynamics of hepatitis B virus, hepatitis C virus, Treponema pallidum and Chlamydia trachomatis infections were investigated in four municipalities of the Marajó Archipelago.Methods: Epidemiological characteristics and detection of specific antibodies were investigated in 1,208 resident persons. Persistence was defined by the presence of HBsAg and viral RNA.Results: Prevalence of antibodies was 30.9% (C. trachomatis), 8.9% (T. pallidum), 12.4% (anti-HBc/IgG) and 1.3% (anti-hepatitis C virus). Vaccination coverage for hepatitis B virus was 19.8%. C. trachomatis infection was significantly associated among women, 28 to 37 years old. T. pallidum was significantly associated with older age (>68 years), being separated or widowed and illiterate persons. hepatitis B virus was significantly associated with males, 48 to 57 years old and those with low educational level. Consumption of alcoholic beverages and use of illicit drugs were more likely to be infected with C. trachomatis. More than one sexual partner and absence of condoms during sexual intercourse were risk factors for T. pallidum infections.Discussion: The transmission of infections will only be interrupted by the consistent application of measures including health education, routine examination, immediate treatment and recognition of risk factors associated with infections.Conclusion: Severe infectious agents circulate in areas far from large urban centers where population have restricted access to healthcare providers.

Influence of Intracellular Delay on the Dynamics of Hepatitis C Virus

In this paper, we present a delay induced model for hepatitis C virus incorporating the healthy and infected hepatocytes as well as infectious and noninfectious virions. The model is mathematically analyzed and characterized, both for the steady states and the dynamical behavior of the model. It is shown that time delay does not affect the local asymptotic stability of the uninfected steady state. However, it can destabilize the endemic equilibrium, leading to Hopf bifurcation to periodic solutions with realistic data sets. The model is also validated using 12 patient data obtained from the study, conducted at the University of Sao Paulo Hospital das clinicas.