Virological Response to Tenofovir Disoproxil Fumarate in HIV-Positive Patients with Lamivudine-Resistant Hepatitis B Virus Coinfection in an Area Hyperendemic for Hepatitis B Virus Infection

N-Heterocycles as Promising Antiviral Agents: A Comprehensive Overview

Viruses are a real threat to every organism at any stage of life leading to extensive infections and casualties. N-heterocycles can affect the viral life cycle at many points, including viral entrance into host cells, viral genome replication, and the production of novel viral species. Certain N-heterocycles can also stimulate the host's immune system, producing antiviral cytokines and chemokines that can stop the reproduction of viruses. This review focused on recent five- or six-membered synthetic N-heterocyclic molecules showing antiviral activity through SAR analyses. The review will assist in identifying robust scaffolds that might be utilized to create effective antiviral drugs with either no or few side effects.

Current practice and recommendations for management of hepatitis B virus in people living with HIV in Asia

BACKGROUND

The prevalence of HIV and hepatitis B virus (HBV) co-infection is higher in Asia than in Europe and North America and varies significantly between different regions within Asia. Important routes of transmission of both these infections include high-risk unprotected sexual contact, intravenous drug use, and transmission of maternal infection perinatally or in early childhood. While life expectancy among people living with HIV has been extended with effective antiretroviral therapy (ART), HBV-induced liver injury and complications have emerged as a leading cause of morbidity and mortality in people living with HIV.

OBJECTIVES

This article describes the prevalence of co-infection, current clinical practice, and recommendations for the management of people living with HIV-HBV co-infection in Asia.

RESULTS AND CONCLUSIONS

Screening for HBV should occur at the time of HIV diagnosis; however, HBV screening rates in people living with HIV in Asia vary widely by region. Similarly, people with HBV should be screened for HIV before initiation of HBV antiviral therapy. People with HIV-HBV co-infection should be assessed for liver damage and risk factors for liver disease and be monitored regularly for liver complications and HBV DNA. Medical treatment with ART is lifelong and includes tenofovir and lamivudine or emtricitabine, unless intolerant or contraindicated, as these are active against both HIV and HBV. HBV vaccination programmes are effective in reducing co-infection rates. Mother-to-child transmission can be prevented through measures such as vaccination, antenatal screening, and treatment of pregnant women who are infected.

Virological responses to tenofovir-alafenamide-containing antiretroviral therapy in people living with HIV co-infected with lamivudine-resistant or lamivudine-susceptible hepatitis B virus

BACKGROUND

Data on the effectiveness of tenofovir alafenamide (TAF) against lamivudine-resistant (LAM-R) hepatitis B virus (HBV) among patients co-infected with human immunodeficiency virus (HIV) and HBV are limited.

METHODS

Between April and December 2018, HIV-positive patients co-infected with LAM-R or lamivudine-susceptible (LAM-S) HBV who switched from tenofovir-disoproxil-fumarate-containing antiretroviral therapy (ART) to TAF-containing ART were followed for 96 weeks. Plasma HBV and HIV loads, HBV serological markers, and liver function before and after the switch were analysed.

RESULTS

In total, 182 patients co-infected with HIV and HBV were included in this study: 45 with LAM-R HBV and 137 with LAM-S HBV. At baseline, 28.9% and 7.4% of patients in the LAM-R and LAM-S groups, respectively, tested positive for hepatitis B virus envelope antigen (HBeAg) (P<0.001), and the respective percentages of patients who had achieved plasma HBV DNA <20 IU/mL were 95.5% and 97.1%. At weeks 48 and 96, 100% and 94.9% of patients in the LAM-R group, respectively, and 97.1% and 95.6% of patients in the LAM-S group, respectively, maintained plasma HBV DNA <20 IU/mL. Lamivudine resistance of HBV and baseline hepatitis B virus surface antigen (HBsAg) level were associated with HBsAg decrement at week 96 at a degree of 0.25 log₁₀ IU/mL [95% confidence interval (CI) 0.059-0.246] and 0.22 log₁₀ IU/mL (per 1-log₁₀IU/mL increase, 95% CI 0.018-0.101), respectively. At week 96, 2.2% (4/182) of patients had HBsAg loss; no patients in the LAM-R group and 25.0% (2/8) of patients in the LAM-S group had HBeAg seroconversion.

CONCLUSIONS

Switching to TAF-containing regimens maintained high rates of HBV viral suppression in patients co-infected with either LAM-R or LAM-S HBV. The decrease in HBsAg was minimal, and HBsAg seroconversion occurred infrequently.

Current Trends and Limitations in Dengue Antiviral Research

Dengue is the most prevalent arthropod-borne viral disease worldwide and affects approximately 2.5 billion people living in over 100 countries. Increasing geographic expansion of Aedes aegypti mosquitoes (which transmit the virus) has made dengue a global health concern. There are currently no approved antivirals available to treat dengue, and the only approved vaccine used in some countries is limited to seropositive patients. Treatment of dengue, therefore, remains largely supportive to date; hence, research efforts are being intensified for the development of antivirals. The nonstructural proteins, 3 and 5 (NS3 and NS5), have been the major targets for dengue antiviral development due to their indispensable enzymatic and biological functions in the viral replication process. NS5 is the largest and most conserved nonstructural protein encoded by flaviviruses. Its multifunctionality makes it an attractive target for antiviral development, but research efforts have, this far, not resulted in the successful development of an antiviral targeting NS5. Increase in structural insights into the dengue NS5 protein will accelerate drug discovery efforts focused on NS5 as an antiviral target. In this review, we will give an overview of the current state of therapeutic development, with a focus on NS5 as a therapeutic target against dengue.

Growing Preferences towards Analog-based Drug Discovery

BACKGROUND

The major concern of today's time is the developing resistance in most of the clinically derived pathogenic micro-organisms for available drugs through several mechanisms. Therefore, there is a dire need to develop novel molecules with drug-like properties that can be effective against the otherwise resistant micro-organisms.

METHODS

New drugs can be developed using several methods like structure-based drug design, ligandbased drug design, or by developing analogs of the available drugs to further improve their effects. However, the smartness is to opt for the techniques that have comparatively less expenditure, lower failure rates, and faster discovery rates.

RESULTS

Analog-Based Drug Design (ABDD) is one such technique that researchers worldwide are opting to develop new drug-like molecules with comparatively lower market values. They start by first designing the analogs sharing structural and pharmacological similarities to the existing drugs. This method embarks on scaffold structures of available drugs already approved by the clinical trials, but are left ineffective because of resistance developed by the pathogens.

CONCLUSION

In this review, we have discussed some recent examples of anti-fungal and anti-bacterial (antimicrobial) drugs that were designed based on the ABDD technique. Also, we have tried to focus on the in silico tools and techniques that can contribute to the designing and computational screening of the analogs, so that these can be further considered for in vitro screening to validate their better biological activities against the pathogens with comparatively reduced rates of failure.

Hepatitis B virus drug resistance mutations in HIV/HBV co-infected children in Windhoek, Namibia

In patients who are HIV infected, hepatitis B virus (HBV) infection is an important co-morbidity. However, antiretroviral options for HIV/HBV co-infected children are limited and, at the time of this study, only included lamivudine. These children may remain on this regimen for many years until late adolescence. They are at high risk of developing HBV drug resistance and uncontrolled HBV disease. The aim of this study was to characterize HBV infection in HIV/HBV co-infected children. Known HIV-infected/HBsAg-positive children, previously exposed to lamivudine monotherapy against HBV, and their mothers were recruited at the Katutura Hospital paediatric HIV clinic in Windhoek, Namibia. Dried blood spot and serum samples were collected for HBV characterization and serological testing, respectively. Fifteen children and six mothers participated in the study. Eight of the 15 children (53.3%) tested HBV DNA positive; all eight children were on lamivudine-based ART. Lamivudine-associated resistance variants, together with immune escape mutants in the surface gene, were identified in all eight children. Resistance mutations included rtL80I, rtV173L, rtL180M, rtM204I/V and the overlapping sE164D, sW182*, sI195M and sW196LS variants. HBV strains belonged to genotypes E (6/8, 75%) and D3 (2/8, 25%). Further analysis of the HBV core promoter region revealed mutations associated with reduced expression of HBeAg protein and hepatocarcinogenesis. All six mothers, on HBV-active ART containing tenofovir and lamivudine, tested HBV DNA negative. This study confirms the importance of screening HIV-infected children for HBV and ensuring equity of drug access to effective HBV treatment if co-infected.

Asian consensus recommendations on optimizing the diagnosis and initiation of treatment of hepatitis B virus infection in resource-limited settings

Asia has an intermediate-to-high prevalence of and high morbidity and mortality from hepatitis B virus (HBV) infection. Optimization of diagnosis and initiation of treatment is one of the crucial strategies for lowering disease burden in this region. Therefore, a panel of 24 experts from 10 Asian countries convened, and reviewed the literature, to develop consensus guidance on diagnosis and initiation of treatment of HBV infection in resource-limited Asian settings. The panel proposed 11 recommendations related to diagnosis, pre-treatment assessment, and indications of therapy of HBV infection, and management of HBV-infected patients with co-infections. In resource-limited Asian settings, testing for hepatitis B surface antigen may be considered as the primary test for diagnosis of HBV infection. Pre-treatment assessments should include tests for complete blood count, liver and renal function, hepatitis B e-antigen (HBeAg), anti-HBe, HBV DNA, co-infection markers and assessment of severity of liver disease. Noninvasive tests such as AST-to-platelet ratio index, fibrosis score 4 or transient elastography may be used as alternatives to liver biopsy for assessing disease severity. Considering the high burden of HBV infection in Asia, the panel adopted an aggressive approach, and recommended initiation of antiviral therapy in all HBV-infected, compensated or decompensated cirrhotic individuals with detectable HBV DNA levels, regardless of HBeAg status or alanine transaminase levels. The panel also developed a simple algorithm for guiding the initiation of treatment in noncirrhotic, HBV-infected individuals. The recommendations proposed herein, may help guide clinicians, to optimize the diagnosis and improvise the treatment rates for HBV infection in Asia.

Brief Report: Outcome of Acute Hepatitis B Virus Infection in HIV-1-Infected Patients: Possible Factors Associated With Resolution or Chronicity

BACKGROUND

HIV-1 infection impairs cellular immunity, causing a detrimental effect on the natural course of hepatitis B virus (HBV) infection. HBV vaccination is less effective in HIV-1-infected patients. This study aimed to gain insight into HIV-1 infection with persistence of hepatitis B surface antigen (HBsAg) defining chronic hepatitis B infection (CBI) after a primary infection and the possible associated factors.

SETTING

Division of Infectious Diseases, San Raffaele Hospital, Italy.

METHODS

This retrospective study analyzed HIV-1-infected patients diagnosed with acute hepatitis B infection (AHB) based on clinical or laboratory records. CBI was defined as a positive HBsAg result recorded >6 months after an AHB diagnosis. Multivariate logistic regression was applied to assess factors (evaluated at AHB diagnosis) that were associated with CBI.

RESULTS

Of 63 HIV-1-infected patients with AHB, 23 (36.5%) developed CBI. On multivariate analysis, CBI risk was less likely in patients with HIV-RNA of >50 copies/mL (adjusted odds ratio = 0.03, 95% confidence interval: 0.001 to 0.58, P = 0.021). Dually acting antiretroviral treatment, including one or more drugs active against HIV/HBV (lamivudine, emtricitabine, and tenofovir), seemed to be protective in terms of the clinical outcome of CBI (adjusted odds ratio = 0.07, 95% confidence interval: 0.01 to 1.02, P = 0.050). Among the 23 patients with CBI, 15 (65.2%) lost the hepatitis B e-antigen, while 11 (47.8%) had HBsAg seroclearance during follow-up.

CONCLUSIONS

In HIV-1-infected subjects with AHB, the persistence of HBsAg seemed to occur frequently. Factors associated with a lower CBI risk were detectable HIV load and the use of dually acting antiretroviral treatment during AHB.

Hepatitis B virus seroprevalence among HIV-infected patients receiving combination antiretroviral therapy three decades after universal neonatal hepatitis B immunization program in Taiwan

BACKGROUND/PURPOSE

This multicenter study aimed to evaluate the seroprevalence of hepatitis B virus (HBV) and the use of combination antiretroviral therapy (cART) among patients receiving HIV care in Taiwan.

METHODS

We retrospectively reviewed the medical records of HIV-infected adult patients who initiated cART at 11 designated hospitals in Taiwan between 2012 and 2016. The clinical information collected included serological profiles on HBV, hepatitis C virus (HCV), and syphilis, plasma HIV RNA load, nadir CD4 cell count, and antiretrovirals with activity against both HBV and HIV (tenofovir disoproxil fumarate [TDF], lamivudine [LAM], and emtricitabine [FTC]).

RESULTS

We analyzed 1800 HIV-infected patients; 1742 (96.8%) were male and 794 (44.1%) were born after July, 1986, when nationwide universal neonatal HBV vaccination was implemented. HBsAg positive results were 11.6% (209/1800), which decreased significantly from 18.1% (182/1006) in those born before July 1986 to 3.4% (27/794) in those born after. In multivariable analysis, HBsAg positivity was significantly associated with age (adjusted odds ratio [aOR] 1.06, 95% confidence interval [CI] 1.05-1.08), CD4≧200 cells/μL (aOR 0.73, 95% CI 0.53-0.99), and HCV seropositivity (aOR 1.62, 95% CI 1.06-2.50). Of 209 HBV/HIV-coinfected patients, 31.1% started cART containing only LAM with anti-HBV activity, while 68.9% started cART containing TDF plus LAM or coformulated TDF/FTC.

CONCLUSIONS

The overall prevalence of HBV/HIV coinfection remained high among HIV-infected patients in Taiwan. Despite recommendations of the HIV treatment guidelines for the management of HBV infection, a substantial proportion of HIV/HBV-coinfected patients received cART containing only LAM for HBV infection.

Impact of antiretroviral therapy containing tenofovir disoproxil fumarate on the survival of patients with HBV and HIV coinfection

BACKGROUND

Tenofovir disoproxil fumarate (TDF) is active against both HBV and HIV. Whether the introduction of TDF-containing combination antiretroviral therapy (cART) has improved the outcome of HIV/HBV-coinfected patients remains unclear in areas of higher HBV endemicity.

METHODS

We retrospectively reviewed medical records of newly diagnosed antiretroviral-naïve HIV-infected patients between 2007 and 2015. Four groups of patients were defined, according to the HBV status and availability of TDF for HIV treatment in Taiwan in 2011. The primary outcome was all-cause mortality.

RESULTS

During the 9-year study period, 1,723 HIV-infected patients were included, with a median age of 31 years and baseline CD4 count of 273 cells per μL. The HBV seroprevalence had declined from 18.1% (125/692) in the pre-TDF era to 10.1% (104/1031) in the post-TDF era. The respective mortality rate for HIV/HBV-coinfected and HIV-monoinfected patients in the pre-TDF era was 23.2 (95% CI, 12.5-43.1) and 9.6 (95% CI, 6.1-15.0) deaths per 1000 person-years of follow-up [PYFU], and the respective mortality rate in the post-TDF era was 15.7 (95% CI, 7.0-34.8) and 8.0 (95% CI, 5.5-11.6) deaths per 1000 PYFU. The adjusted hazard ratio for mortality in multivariate Cox proportional-hazards regression analysis among HIV/HBV-coinfected patients compared to HIV-monoinfected patients was 2.79 (95% CI, 1.25-6.22) in pre-TDF era and 1.11 (95% CI, 0.45-2.72) in post-TDF era.

CONCLUSIONS

In this country of high HBV endemicity, the adverse impact of chronic HBV infection on the survival observed in the pre-TDF era has significantly diminished among HIV/HBV-coinfected patients compared to HIV-monoinfected patients in the era of TDF-containing cART.

Long-term virological and serologic responses of chronic hepatitis B virus infection to tenofovir disoproxil fumarate-containing regimens in patients with HIV and hepatitis B coinfection

BACKGROUND

Data regarding the durability of HBV viral suppression with combination antiretroviral therapy (cART) containing tenofovir disoproxil fumarate (TDF) combined with lamivudine (3TC) or emtricitabine (FTC) in HIV/HBV-coinfected patients are scarce in hyperendemic areas of chronic HBV infection.

METHODS

Between 2004 and 2016, HIV/HBV-coinfected Taiwanese with available baseline HBV DNA load were retrospectively reviewed. Determinations of plasma HBV DNA load, HBV serologic markers (HBsAg, anti-HBs, HBeAg, and anti-HBe), and liver function were performed after initiation of cART. Factors associated with time to undetectable HBV DNA load were explored.

RESULTS

A total of 366 patients were included according to cART history: Group 1, 3TC as the only anti-HBV therapy (n = 73); Group 2, TDF-containing cART as initial therapy (n = 127); and Group 3, switch of 3TC-based to TDF-containing cART (n = 166). At year 5, HBV suppression was achieved in 77.8%, 95.7%, and 95.7% of Groups 1, 2 and 3, respectively. In multivariate Cox regression analysis, TDF ( ± 3TC or FTC) but not 3TC alone as initial anti-HBV therapy was significantly associated with HBV suppression (adjusted hazard ratio [aHR] 2.635; 95% CI 1.720-4.037), while HBeAg positivity at baseline was associated with failure to achieve HBV suppression (aHR 0.293; 95% CI 0.178-0.482). Loss of HBsAg occurred in 15 patients (4.1%), with 7 (1.9%) seroconversion to anti-HBs positivity, while HBeAg seroconversion occurred in 11 (16.9%) of 65 HBeAg-positive patients.

CONCLUSIONS

TDF-containing cART achieved durable HBV viral suppression in HIV/HBV-coinfected patients and HBeAg positivity at baseline was associated with failure to achieve HBV suppression despite long-term TDF-containing cART.

Viral RNA-Dependent RNA Polymerase Inhibitor 7-Deaza-2'-C-Methyladenosine Prevents Death in a Mouse Model of West Nile Virus Infection

West Nile virus (WNV) is a medically important emerging arbovirus causing serious neuroinfections in humans and against which no approved antiviral therapy is currently available. In this study, we demonstrate that 2'-C-methyl- or 4'-azido-modified nucleosides are highly effective inhibitors of WNV replication, showing nanomolar or low micromolar anti-WNV activity and negligible cytotoxicity in cell culture. One representative of C2'-methylated nucleosides, 7-deaza-2'-C-methyladenosine, significantly protected WNV-infected mice from disease progression and mortality. Twice daily treatment at 25 mg/kg starting at the time of infection resulted in 100% survival of the mice. This compound was highly effective, even if the treatment was initiated 3 days postinfection, at the time of a peak of viremia, which resulted in a 90% survival rate. However, the antiviral effect of 7-deaza-2'-C-methyladenosine was absent or negligible when the treatment was started 8 days postinfection (i.e., at the time of extensive brain infection). The 4'-azido moiety appears to be another important determinant for highly efficient inhibition of WNV replication in vitro However, the strong anti-WNV effect of 4'-azidocytidine and 4'-azido-aracytidine was cell type dependent and observed predominantly in porcine kidney stable (PS) cells. The effect was much less pronounced in Vero cells. Our results indicate that 2'-C-methylated or 4'-azidated nucleosides merit further investigation as potential therapeutic agents for treating WNV infections as well as infections caused by other medically important flaviviruses.

Hepatitis B infection among HIV infected individuals in Gabon: Occult hepatitis B enhances HBV DNA prevalence

In Gabon, a central African country, human immunodeficiency virus (HIV) and hepatitis B virus (HBV) are endemic. In a recent study, conducted in a semi-urban area (Franceville, Gabon), HBV infection was found to be more prevalent among HIV infected individuals. This study aims to investigate the prevalence and genetic diversity of hepatitis B virus infection among HIV infected individuals, predominantly under antiretroviral therapy, living in fully urbanized area: Libreville, capital of Gabon. Serological and molecular tests were performed to detect HBV infection among patients living with HIV/AIDS (PLHA). We used Monolisa HBsAg ULTRA, Anti-HBc Plus and Anti-HBs Plus EIA kits for serological analyses. HBV DNA viral load (HBV DNA VL) was determined by real time PCR and molecular characterization of HBV strains was performed by sequencing and phylogenetic analysis of partial HBV surface and core genes. At all, 70.2% of patients were under antiretroviral therapy. The prevalence of HBsAg was 8.8% (43/487). Detectable HBV DNA was found in 69.7% (30/43) of HBsAg positive patients and in 17.5% (24/137) HBsAg negative patients. HBV DNA VL was significantly higher among patient with CD4 cell counts less than 200 cells/mm³ than those with CD4 cell counts greater than 500 cells/mm³ (p = 0.008). We confirmed the presence of HBV sub-genotypes QS-A3 (40%), and A4 (20%) and HBV-E genotype (40%). The percentage of resistance to Lamivudine was high (40%) and varied according to the M204V/I motif. Occult hepatitis B infection (OBI) was found in patients with isolated HBcAb and among patients who had completed their HBsAg seroconversion. We detected HBV DNA for one patient without any HBV serological marker. This study provides a new landmark for the comprehension of HBV infection in PLHA in urban areas. OBI enhances HBV DNA prevalence and should be investigated in all HBsAg negative individuals.

Nucleoside analogs as a rich source of antiviral agents active against arthropod-borne flaviviruses

Nucleoside analogs represent the largest class of small molecule-based antivirals, which currently form the backbone of chemotherapy of chronic infections caused by HIV, hepatitis B or C viruses, and herpes viruses. High antiviral potency and favorable pharmacokinetics parameters make some nucleoside analogs suitable also for the treatment of acute infections caused by other medically important RNA and DNA viruses. This review summarizes available information on antiviral research of nucleoside analogs against arthropod-borne members of the genus Flavivirus within the family Flaviviridae, being primarily focused on description of nucleoside inhibitors of flaviviral RNA-dependent RNA polymerase, methyltransferase, and helicase/NTPase. Inhibitors of intracellular nucleoside synthesis and newly discovered nucleoside derivatives with high antiflavivirus potency, whose modes of action are currently not completely understood, have drawn attention. Moreover, this review highlights important challenges and complications in nucleoside analog development and suggests possible strategies to overcome these limitations.