Viral quasispecies of hepatitis B virus in patients with YMDD mutation and lamivudine resistance may not predict the efficacy of lamivudine/adefovir rescue therapy

Antivirals for prevention of hepatitis B virus mother-to-child transmission in human immunodeficiency virus positive pregnant women co-infected with hepatitis B virus

BACKGROUND

Hepatitis B virus (HBV)-human Immunodeficiency virus (HIV) co-infection promotes an aggressive disease course of HBV infection. In the only available non-Cochrane systematic review on antiviral therapy during pregnancy for prevention of mother-to-child transmission of HBV, none of the women studied had HBV-HIV co-infection but were either HBV- or HIV-seropositive. Treatment of HBV alone may develop HIV-strains that are resistant to non-nucleoside reverse transcriptase inhibitors. Accordingly, co-treatment of the HIV infection is recommended.

OBJECTIVES

To evaluate the benefits and harms of tenofovir-based antiviral combination regimens versus placebo, tenofovir alone, or non-tenofovir-based antiviral regimen either alone or in combination with HBV for the prevention of mother-to-child transmission of HBV in HIV-positive pregnant women co-infected with HBV.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Central Register of Controlled Trials, MEDLINE Ovid, Embase Ovid, LILACS (Bireme), Science Citation Index Expanded (Web of Science), and Conference Proceedings Citation Index-Science (Web of Science) on 30 January 2023. We manually searched the reference lists of included trials, searched on-line trial registries, and contacted experts in the field and pharmaceutical companies for any further potential trials.

SELECTION CRITERIA

We aimed to include randomised clinical trials comparing tenofovir-based antiviral combination regimens (anti-HIV regimen with lopinavir-ritonavir therapy, or any other antiviral therapy, and two drugs with activity against HBV, specifically, tenofovir alafenamide (TAF) or tenofovir disoproxil fumarate (TDF), plus lamivudine or emtricitabine) with placebo alone, or tenofovir alone, or non-tenofovir-based antiviral regimen (zidovudine, lamivudine, telbivudine, emtricitabine, entecavir, lopinavir-ritonavir, or any other antiviral therapy) either alone or in combination with at least two other antivirals.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Primary outcomes included all-cause infant mortality, proportion of infants with serious adverse events, proportion of infants with HBV mother-to-child transmission, all-cause maternal mortality, and proportion of mothers with serious adverse events. Secondary outcomes included proportion of infants with adverse events not considered serious, proportion of mothers with detectable HBV DNA (deoxyribonucleic acid) (before delivery), maternal hepatitis B e antigen (HBeAg) to HBe-antibody seroconversion (before delivery) and maternal adverse events not considered serious. We used RevMan Web to carry out analyses and presented results, where feasible, using a random-effects model and risk ratios (RR) with 95% confidence intervals (CIs). We performed sensitivity analysis. We assessed risk of bias using predefined domains, assessed the certainty of the evidence using GRADE, controlled risk of random errors with Trial Sequential Analysis, and presented outcome results in a summary of findings table.

MAIN RESULTS

Five completed trials were included, of which four trials contributed data to one or more of the outcomes. They included a total of 533 participants randomised to tenofovir-based antiviral combination regimens (196 participants) versus control (337 participants). The control groups received non-tenofovir-based antiviral regimens either as zidovudine alone (three trials) or as a combination of zidovudine, lamivudine and lopinavir-ritonavir (five trials). None of the trials used placebo or tenofovir alone. All trials were at unclear risk of bias. Four trials used intention-to-treat analyses. In the remaining trial, two participants in the intervention group and two in the control group were lost to follow-up. However, the outcomes of these four participants were not described. Tenofovir-based antiviral combination regimen versus control We are very uncertain about the effect of a tenofovir-based antiviral combination regimen versus control on all-cause infant mortality (RR 2.24, 95% CI 0.72 to 6.96; participants = 132; trials = 1; very low-certainty evidence); proportion of infants with serious adverse events (RR 1.76, 95% CI 1.27 to 2.43; participants = 132; trials = 1; very low-certainty evidence), and proportion of mothers with serious adverse events (RR 0.90, 95% CI 0.62 to 1.32; participants = 262; trials = 2; very low-certainty evidence). No trial reported data on the proportion of infants with HBV mother-to-child transmission and all-cause maternal mortality. We are also very uncertain about the effect of tenofovir-based antiviral combination regimens versus control on the proportion of infants with adverse events not considered serious (RR 0.94, 95% CI 0.06 to 13.68; participants = 31; trials = 1; very low-certainty evidence), and proportion of mothers with detectable HBV DNA (before delivery) (RR 0.66, 95% CI 0.42 to 1.02; participants = 169; trials = 2; very low-certainty evidence). No trial reported data on maternal hepatitis B e antigen (HBeAg) to HBe-antibody seroconversion (before delivery) and maternal adverse events not considered serious. All trials received support from industry.

AUTHORS' CONCLUSIONS

We do not know what the effects of tenofovir-based antiviral combination regimens are on all-cause infant mortality, proportion of infants with serious adverse events and proportion of mothers with serious adverse events, proportion of infants with adverse events not considered serious, and proportion of mothers with detectable HBV DNA before delivery because the certainty of evidence was very low. Only one or two trials, with insufficient power, contributed data for analyses. We lack randomised clinical trials at low risk of systematic and random errors, and fully reporting all-cause infant mortality, serious adverse events and reporting on clinical and laboratory outcomes, such as infants with HBV mother-to-child transmission, all-cause maternal mortality, maternal hepatitis B e antigen (HBeAg) to HBe-antibody seroconversion before delivery and maternal adverse events not considered serious.

Impact of RNA Virus Evolution on Quasispecies Formation and Virulence

RNA viruses are known to replicate by low fidelity polymerases and have high mutation rates whereby the resulting virus population tends to exist as a distribution of mutants. In this review, we aim to explore how genetic events such as spontaneous mutations could alter the genomic organization of RNA viruses in such a way that they impact virus replications and plaque morphology. The phenomenon of quasispecies within a viral population is also discussed to reflect virulence and its implications for RNA viruses. An understanding of how such events occur will provide further evidence about whether there are molecular determinants for plaque morphology of RNA viruses or whether different plaque phenotypes arise due to the presence of quasispecies within a population. Ultimately this review gives an insight into whether the intrinsically high error rates due to the low fidelity of RNA polymerases is responsible for the variation in plaque morphology and diversity in virulence. This can be a useful tool in characterizing mechanisms that facilitate virus adaptation and evolution.