Hepatitis B Surface Antigen Isoforms: Their Clinical Implications, Utilisation in Diagnosis, Prevention and New Antiviral Strategies

The hepatitis B surface antigen (HBsAg) is a multifunctional glycoprotein composed of large (LHB), middle (MHB), and small (SHB) subunits. HBsAg isoforms have numerous biological functions during HBV infection-from initial and specific viral attachment to the hepatocytes to initiating chronic infection with their immunomodulatory properties. The genetic variability of HBsAg isoforms may play a role in several HBV-related liver phases and clinical manifestations, from occult hepatitis and viral reactivation upon immunosuppression to fulminant hepatitis and hepatocellular carcinoma (HCC). Their immunogenic properties make them a major target for developing HBV vaccines, and in recent years they have been recognised as valuable targets for new therapeutic approaches. Initial research has already shown promising results in utilising HBsAg isoforms instead of quantitative HBsAg for correctly evaluating chronic infection phases and predicting functional cures. The ratio between surface components was shown to indicate specific outcomes of HBV and HDV infections. Thus, besides traditional HBsAg detection and quantitation, HBsAg isoform quantitation can become a useful non-invasive biomarker for assessing chronically infected patients. This review summarises the current knowledge of HBsAg isoforms, their potential usefulness and aspects deserving further research.

Clinical efficacy of anti-SARS-CoV-2 monoclonal antibodies in preventing hospitalisation and mortality among patients infected with Omicron variants: A systematic review and meta-analysis

Until now, the treatment protocols for COVID-19 have been revised multiple times. The use and approval of therapeutic monoclonal antibodies (mAbs) for COVID-19 treatment represent exceptional achievements in modern science, technology and medicine. SARS-CoV-2 Omicron evasion of pre-existing immunity represents a serious public health problem nowadays. This systematic review with meta-analysis provided comprehensive and up-to-date evidence of the clinical efficacy of therapeutic anti-SARS-CoV-2 mAbs against Omicron subvariants in COVID-19 patients and included 10 articles. The prevalence of hospitalisation among Omicron-positive patients treated with anti-SARS-CoV-2 mAbs was 2.8% (89/3169) while it controls (Omicron-positive patients treated with other therapies) 11% (154/1371). There was a statistically significantly different number of hospitalisations between the two studied groups in favour of the anti-SARS-CoV-2 mAbs treated group. (OR = 0.56, 95% CI OR = 0.41-0.77, p < 0.001, respectively). Eight deaths (0.30%) out of 2619 Omicron-positive patients occurred in the anti-SARS-CoV-2 mAbs treated group, while in the control group (Omicron-positive patients treated with other therapies), 27 patients died out of 1401 (1.93%). There was a significantly different number of deaths between the two studied groups in favour of Omicron-positive patients treated with anti-SARS-CoV-2 mAbs (OR = 0.38, 95% CI OR = 0.17-0.85, p = 0.020). Using sotrovimab in treating Omicron-positive patients indicated a reduction of hospitalisation and mortality for 49% and 89% in favour of sotrovimab, respectively (OR = 0.51, 95% CI OR = 0.34-0.79, p = 0.002; OR = 0.11, 95% CI OR = 0.03-0.39, p = 0.001). We could only provide evidence of the positive impact in reducing hospitalisation and mortality rates when anti-SARS-CoV-2 mAbs were used to treat patients infected with Omicron variants BA.1 or BA.2 and not on other Omicron variants.

Immune Evasion of SARS-CoV-2 Emerging Variants: What Have We Learnt So Far?

Despite the slow evolutionary rate of SARS-CoV-2 relative to other RNA viruses, its massive and rapid transmission during the COVID-19 pandemic has enabled it to acquire significant genetic diversity since it first entered the human population. This led to the emergence of numerous variants, some of them recently being labeled "variants of concern" (VOC), due to their potential impact on transmission, morbidity/mortality, and the evasion of neutralization by antibodies elicited by infection, vaccination, or therapeutic application. The potential to evade neutralization is the result of diversity of the target epitopes generated by the accumulation of mutations in the spike protein. While three globally recognized VOCs (Alpha or B.1.1.7, Beta or B.1.351, and Gamma or P.1) remain sensitive to neutralization albeit at reduced levels by the sera of convalescent individuals and recipients of several anti-COVID19 vaccines, the effect of spike variability is much more evident on the neutralization capacity of monoclonal antibodies. The newly recognized VOC Delta or lineage B.1.617.2, as well as locally accepted VOCs (Epsilon or B.1.427/29-US and B1.1.7 with the E484K-UK) are indicating the necessity of close monitoring of new variants on a global level. The VOCs characteristics, their mutational patterns, and the role mutations play in immune evasion are summarized in this review.

Biological features of hepatitis B virus strains associated with fulminant hepatitis

Accumulating evidence suggests that hepatitis B virus (HBV) biological features may influence the course and clinical manifestations of infection and possibly the development of fulminant hepatitis (FH). Since HBV is not a cytocidal virus, virus-induced liver damage results from an interplay between the virus replication and the host's defense. Therefore, viral factors contributing to enhanced replication, induction of a stronger immune attack or apoptosis of hepatocytes could be crucial in development of FH. Numerous mutations in basal core promoter, pre-C, C and S regions of the HBV genome contribute to development of FH by different mechanisms, including enhanced viral replication, the loss of a decoy for immune response, unbalanced expression of viral proteins and retention of unprocessed cytotoxic proteins in hepatocytes.

Increased systemic sST2 in patients with end stage renal disease contributes to milder liver damage during HCV infection

INTRODUCTION

Hepatitis C Virus (HCV) is the leading cause of chronic liver disease and is a serious global health problem. Hepatitis C infection is highly prevalent in patients with end stage renal disease (ESRD), due to frequent exposure to blood and blood products, nosocomial transmission of HCV, and prolong hemodialysis duration. The aim of the study was to evaluate the influence of IL-33/ST2 signaling pathway on severity of the liver disease in ESRD HCV+ patients.

METHODOLOGY

Blood samples from patients with end stage renal disease (ESRD) and hepatitis C infection (HCV), 20 patients with HCV infection, 20 patients with ESRD and 20 healthy control donor patients were taken for the examination of biochemical parameters, for the determination of the serum cytokine concentration, and for the molecular diagnostics of HCV.

RESULTS

Systemic sST2 positively correlated with serum level of urea and creatinine, respectively. Serum sST2 was significantly increased in ESRD HCV+ patients in comparison to HCV+ group. sST2/IL-1, sST2/IL-4 and sST2/IL-23 ratios were significantly increased in serum of ESRD HCV+ patients in comparison to HCV+ patients. Significantly higher systemic level of sST2 and sST2/IL-1 and sST2/IL-4 ratios were measured in ESRD patients compared to non-ESRD patients.

CONCLUSION

These results suggested that elevated level sST2, as the consequence of renal failure, causes less destruction of liver in HCV infection.

Immune-Escape Hepatitis B Virus Mutations Associated with Viral Reactivation upon Immunosuppression

Hepatitis B virus (HBV) reactivation occurs as a major complication of immunosuppressive therapy among persons who have recovered from acute hepatitis and those who have controlled chronic infection. Recent literature data emphasize the presence of a high degree of S gene variability in HBV isolates from patients who developed reactivation. In reactivated HBV, the most frequently detected mutations belong to the second loop of “a” determinant in HBsAg. These mutations were identified to be immune escape and responsible for vaccine- and diagnostic-escape phenomena. Their emergence clearly provides survival in the presence of a developed humoral immune response and is often associated with impaired serological diagnosis of HBV reactivation. The knowledge of their existence and roles can elucidate the process of reactivation and strongly highlights the importance of HBV DNA detection in monitoring all patients with a history of HBV infection who are undergoing immunosuppression. This review discusses the possible influence of the most frequently found immune-escape mutations on HBV reactivation.

Analysis of variability of urinary excreted JC virus strains in patients infected with HIV and healthy donors

In immunocompromised individuals, especially in patients with T cell immunodeficiency, reactivation of JCPyV can cause serious life-threatening diseases. Nowadays, HIV infection is one of the most important factor for reactivation of JCPyV and the development of of the progressive multifocal leukoencephalopathy (PML). Mutations in the outer loops of the VP1 region can lead to the selection of the viral variants with changed tropism and increased pathological potential. The aims of this study were to determine sequence variation and amino acid changes within VP1 loops and the structure of non-coding control region (NCCR) of urinary excreted JCPyV isolates among HIV-infected patients and healthy donors. Single urine samples from 114 HIV-infected patients and 120 healthy donors were collected. PCR was performed for amplification of VP1 and NCCR. Amplified fragments were directly sequenced and analyzed by using bioinformatics tools. Nucleotide substitutions were detected within DE and EF loops and in the β-sheets of both studied groups. In HIV-infected patients group, 70% of mutations were detected within receptor domains. Among healthy donors, one mutation was identified within β-sheets while the remaining were located within receptor domains. The most prevalent mutation was L157V in both groups. Analysis of NCCR revealed that all isolates had archetype structure with some minor changes. Since single point mutations at specific place within outer loop of VP1 region can cause formation of variants with changed receptor specificity, identification of these mutations in HIV-infected patients can help to single out those with higher risk for development of polyomavirus-associated diseases.

Analysis of the Variability of Epstein-Barr Virus Genes in Infectious Mononucleosis: Investigation of the Potential Correlation with Biochemical Parameters of Hepatic Involvement

Background

Primary Epstein-Barr virus (EBV) infection is usually asymptomatic, although at times it results in the benign lymphoproliferative disease, infectious mononucleosis (IM), during which almost half of patients develop hepatitis. The aims of the present study are to evaluate polymorphisms of EBV genes circulating in IM isolates from this geographic region and to investigate the correlation of viral sequence patterns with the available IM biochemical parameters.

Methods

The study included plasma samples from 128 IM patients. The genes EBNA2, LMP1, and EBNA1 were amplified using nested-PCR. EBNA2 genotyping was performed by visualization of PCR products using gel electrophoresis. Investigation of LMP1 and EBNA1 included sequence, phylogenetic, and statistical analyses.

Results

The presence of EBV DNA in plasma samples showed correlation with patients’ necessity for hospitalization (p=0.034). The majority of EBV isolates was genotype 1. LMP1 variability showed 4 known variants, and two new deletions (27-bp and 147-bp). Of the 3 analyzed attributes of LMP1 isolates, the number of 33-bp repeats less than the reference 4.5 was the only one that absolutely correlated with the elevated levels of transaminases. EBNA1 variability was presented by prototype subtypes. A particular combination of EBNA2, LMP1, and EBNA1 polymorphisms, deleted LMP1/P-thr and non-deleted LMP1/P-ala, as well as genotype 1/ 4.5 33-bp LMP1 repeats or genotype 2/ 4.5 33-bp LMP1 repeats showed correlation with elevated AST (aspartate aminotransferase) and ALT (alanine transaminase).

Conclusions

This is the first study which identified the association between EBV variability and biochemical parameters in IM patients. These results showed a possibility for the identification of hepatic related diagnostic EBV markers.

Molecular characterization of BK virus in patients infected with human immunodeficiency virus

Immunosuppression seems to be the most important cause of BKPyV reactivation. Recently, a spectrum of diseases associated with BKPyV infection has been reported in HIV-infected patients. BKPyV isolates can be classified into four subtypes based on nucleotide polymorphisms within VP1 coding region. Mutations within the BC loop of the VP1 may be associated with an increase in the viral pathogenicity. The aims of this study were to determine prevalence and distribution of BKPyV subtypes, sequence variation and mutations within VP1 among HIV-infected patients and healthy donors. Urine samples from 114 HIV-infected patients and 120 healthy donors were collected. PCR followed by sequence analysis was carried out using primers specific for VP1 and NCRR of the virus genome. The predominant BKPyV subtype was I, followed by IV. In isolates from HIV-infected patients, the majority of non-synonymous alterations were located within the BC loop. BKV sequences from healthy donors showed non-synonymous alterations outside of the receptor loops in the β-sheets. The higher frequency of mutations in the BC loop of VP1 protein was detected among HIV-infected patients. The most frequent mutation was E82D. All HIV-infected patients who harbored mutations had CD4(+) cell counts less than 200 cell/mm(3). It seems that immunosuppression is a very important factor for BKPyV reactivation that can increase viral replication rate and leads to higher frequency of mutations in the BC loop of the VP1. These mutations may change receptor specificity, and further studies are needed to determine the effect of these mutations on the biological properties of the BKPyV.

Prevalence and mutational patterns of lamivudine-resistant HBV strains in chronically infected Serbian patients

This study aimed to determine the prevalence and mutational patterns of lamivudine-resistant hepatitis B virus (HBV) strains in chronically infected Serbian patients. The study included 154 patients on long-term lamivudine monotherapy. Resistance-associated mutations were identified by direct sequencing of the S/P gene. The genotypic resistance to lamivudine was confirmed in 54.5% of patients. Three primary resistance-associated mutations were found: rtM204V (55.9%), rtM204I (40.5%), rtA181T (3.6%) and two compensatory mutations rtV173L (17.8%) and rtL180M (67.8%). Seven mutational patterns were discovered with rtL180M+rtM204V being dominant (41.6%). The presence of resistance associated mutations was correlated to the older age of patients, the presence of clinically relevant HBsAg mutations and higher values of viral load. No correlation with HBV genotypes, subgenotypes or HBsAg subtypes was observed. High prevalence of resistance supports the use of genotypic testing in monitoring patients on lamivudine therapy and selecting those who would benefit from therapy with newly developed nucleos(t)ide analogs.

Nijmegen breakage syndrome and chronic polyarthritis

We report on pediatric patient with Nijmegen breakage syndrome (NBS), a rare DNA repair disorder characterized by microcephaly, immunodeficiency and predisposition to malignant lymphomas, who developed juvenile idiopathic arthritis (JIA)-like polyarthritis. In patients with primary immunodeficiencies (PID), septic arthritis due to pyogenic bacteria or mycoplasmal arthritis are the most common osteoarticular manifestations. In certain PID, chronic, non-infectious arthritis resembling rheumatoid arthritis may occur. In our patient microbiologic cultures of synovial fluid including Mycoplasma spp. were negative. At first, because of suspected mycoplasmal arthritis we used macrolides and doxycycline combined with hydroxychloroquine but without therapeutic response. However, the use of rituximab led to remission of her polyarthritis lasting for 9 months. Autoimmune features were rarely reported in NBS. An occurrence of JIA-like, chronic polyarthritis in NBS, a DNA repair disorder characterized by decreased tolerance of immunosuppressive drugs such as methotrexate and a high natural risk for lymphomas, makes therapeutic approach even more complex.

The influence of single and combined IL28B polymorphisms on response to treatment of chronic hepatitis C

BACKGROUND

Three single nucleotide polymorphisms (SNPs) near IL28B gene were shown to be highly predictive of sustained virological response (SVR) in patients with chronic hepatitis C virus (HCV) infection.

OBJECTIVES

This study attempted to demonstrate the role of single and combined IL28B polymorphisms (rs8099917, rs12979860 and rs12980275) and other host and viral factors in predicting response to treatment, in Caucasian patients infected with HCV genotype 1.

STUDY DESIGN

The IL28B genotypes at 3 SNPs were determined in 106 patients who underwent standard 48-week therapy and out of which 55.7% achieved SVR.

RESULTS

Patients carrying genotypes CCrs12979860 or AArs12980275 were 3.5 and 3 times more likely to achieve SVR, respectively. Genotypes GGrs8099917 and TTrs12979860 were identified as predictors of treatment failure. The presence of IL28B profiles including at least one of the favourable genotypes was identified as the most important factor associated with SVR, followed by younger age and lower grade of histological activity. Of all patients who achieved SVR, 88.1% was carrying one of these IL28B profiles. The strongest PPV of single SNPs for achieving SVR was observed for CCrs12979860 (76.9%). The presence of GGrs8099917 showed the strongest NPV of 85.7%. The correlation of SNPs with other host and viral factors revealed association of TTrs8099917 and lower AST levels.

CONCLUSIONS

Results of this study confirm that all investigated IL28B polymorphisms are associated with treatment response and that presence of any of the favourable IL28B genotypes can be considered independent pretreatment determinant of the effectiveness of therapy.

Multiple sclerosis: individualized disease susceptibility and therapy response

Multiple sclerosis (MS) is a heterogeneous disease in which diverse genetic, pathological and clinical backgrounds lead to variable therapy response. Accordingly, MS care should be tailored to address disease traits unique to each person. At the core of personalized management is the emergence of new knowledge, enabling optimized treatment and disease-modifying therapies. This overview analyzes the promise of genetic and nongenetic biomarkers in advancing decision-making algorithms to assist diagnosis or in predicting the disease course and therapy response in any given MS patient.

Carboxy-terminal sequence variation of LMP1 gene in Epstein-Barr-virus-associated mononucleosis and tumors from Serbian patients

Seven strains of Epstein-Barr virus (EBV) are defined based on C-terminal sequence variations of the latent membrane protein 1 (LMP1). Some strains, especially those with a 30-bp deletion, are thought to be related to tumorigenic activity and geographical localization. The aims of the study were to determine the prevalence of different LMP1 strains and to investigate sequence variation in the C-terminal region of LMP1 in Serbian isolates. This study included 53 EBV-DNA-positive plasma and tissue block samples from patients with mononucleosis syndrome, renal transplantation, and tumors, mostly nasopharyngeal carcinoma. The sequence of the 506-bp fragment of LMP1 C terminus was used for phylogenetic analyses and identification of LMP1 strains, deletions, and mutations. The majority of isolates were non-deleted (66%), and the rest had 30-bp, rare 69-bp, or yet unknown 27-bp deletions, which were not related to malignant or non-malignant isolate origin. However, the majority of 69-bp deletion isolates were derived from patients with nasopharyngeal carcinoma. Less than five 33-bp repeats were found in the majority of non-deleted isolates (68.6%), whereas most 69-bp deletion isolates (75%) had five or six repeats. Serbian isolates were assigned to four LMP1 strains: B95-8 (32.1%), China 1 (24.5%), North Carolina (NC; 18.9%), and Mediterranean (Med; 24.5%). In NC isolates, three new mutations unique for this strain were identified. EBV EBNA2 genotypes 1 and 2 were both found, with dominance of genotype 1 (90.7%). This study demonstrated noticeable geographical-associated characteristics in the LMP1 C terminus of investigated isolates.

Prevalence of hepatitis B virus MHR mutations and their correlation with genotypes and antiviral therapy in chronically infected patients in Serbia

Understanding the prevalence and diversity of HBsAg variants in a population is fundamental to assay design and planning vaccination programs. It has been shown that mutations within the S gene, caused by selection or natural variation, can lead to false-negative results in assays for HBsAg, or have clinical implications, such as evading anti-HBV immunoglobulin therapy or vaccine-induced immunity. The region of HBsAg where most of these mutations occur is known as the major hydrophilic region (MHR). The aim of this study was to determine the prevalence and mutational patterns of MHR mutations in patients with chronic hepatitis B, and their correlation with patient characteristics, viral factors and antiviral therapy. The study comprised 164 plasma samples from patients with chronic hepatitis B, of which, 34.8% were on long-term lamivudine monotherapy. Direct sequencing of part of the S/pol gene was used for identification of HBsAg mutations, HBV genotypes, subgenotypes and HBsAg subtypes. The overall frequency of MHR mutations was 22.6%, but it varied significantly between untreated and treated patients (16.8% vs. 33.3%). The most frequent substitution was at position 120 (9.1%) whereas the most common vaccine-escape position, 145, was affected in 1.8% of isolates. The presence of MHR mutations was correlated with genotype D, subgenotype D3, and ayw2/ayw3 HBsAg subtypes and to older age (>40 years). It is concluded that natural viral variability present in a geographical region, duration of infection, and antiviral therapy are among the major factors associated with the occurrence of MHR mutations.

Distribution of HBV genotypes, subgenotypes and HBsAg subtypes among chronically infected patients in Serbia

Hepatitis B virus (HBV) has been classified into eight genotypes (some of them further divided into two or more subgenotypes) and nine HBsAg subtypes, distinctly distributed geographically. The aim of this study was to gain insight into the distribution of HBV genotypes, subgenotypes and HBsAg subtypes among HBV chronically infected patients in Serbia, since there were no previously published data on this subject. Eighty-nine plasma samples that gave a positive result in a nested PCR were included for genotype identification. Genotyping was performed by direct sequencing of the part of the S/pol gene, and the HBsAg subtype was deduced from the HBsAg sequence. Two HBV genotypes, A and D, were encountered in Serbia, with genotype D (D - 82%, A - 18%) and subgenotype D3 (47.9%) being prevalent. Genotype D isolates had three assigned subtypes (ayw2, ayw3, ayw4), with ayw2 found to be the most prevalent (ayw2 - 53.4%, ayw3 - 43.8%, ayw4 - 1.4%). Genotype A isolates belonged to the A2 subgenotype and the HBsAg subtype adw2, as expected for samples from European population. The results correspond to country's geographical position, being in close proximity to the Mediterranean basin and on the main route between the Middle East and Central Europe.