Detection of anti-preS1 antibodies for recovery of hepatitis B patients by immunoassay

PreS1 Mutations Alter the Large HBsAg Antigenicity of a Hepatitis B Virus Strain Isolated in Bangladesh

Mutations in the hepatitis B virus (HBV) genome can potentially lead to vaccination failure, diagnostic escape, and disease progression. However, there are no reports on viral gene expression and large hepatitis B surface antigen (HBsAg) antigenicity alterations due to mutations in HBV isolated from a Bangladeshi population. Here, we sequenced the full genome of the HBV isolated from a clinically infected patient in Bangladesh. The open reading frames (ORFs) (P, S, C, and X) of the isolated HBV strain were successfully amplified and cloned into a mammalian expression vector. The HBV isolate was identified as genotype C (sub-genotype C2), serotype adr, and evolutionarily related to strains isolated in Indonesia, Malaysia, and China. Clinically significant mutations, such as preS1 C2964A, reverse transcriptase domain I91L, and small HBsAg N3S, were identified. The viral P, S, C, and X genes were expressed in HEK-293T and HepG2 cells by transient transfection with a native subcellular distribution pattern analyzed by immunofluorescence assay. Western blotting of large HBsAg using preS1 antibody showed no staining, and preS1 ELISA showed a significant reduction in reactivity due to amino acid mutations. This mutated preS1 sequence has been identified in several Asian countries. To our knowledge, this is the first report investigating changes in large HBsAg antigenicity due to preS1 mutations.

Vaccines targeting preS1 domain overcome immune tolerance in hepatitis B virus carrier mice

Strong tolerance to hepatitis B virus (HBV) surface antigens limits the therapeutic effect of the conventional hepatitis B surface antigen (HBsAg) vaccination in both preclinical animal models and patients with chronic hepatitis B (CHB) infection. In contrast, we observed that clinical CHB patients presented less immune tolerance to the preS1 domain of HBV large surface antigen. To study whether targeting the weak tolerance of the preS1 region could improve therapy gain, we explored vaccination with the long peptide of preS1 domain for HBV virions clearance. Our study showed that this preS1-polypeptide rather than HBsAg vaccination induced robust immune responses in HBV carrier mice. The anti-preS1 rapidly cleared HBV virions in vivo and blocked HBV infection to hepatocytes in vitro. Intriguingly, vaccination of preS1-polypeptide even reduced the tolerized status of HBsAg, opening a therapeutic window for the host to respond to the HBsAg vaccine. A sequential administration of antigenically distinct preS1-polypeptide and HBsAg vaccines in HBV carrier mice could finally induce HBsAg/hepatitis B surface antibody serological conversion and clear chronic HBV infection in carrier mice.

CONCLUSION

These results suggest that preS1 can function as a therapeutic vaccine for the control of CHB. (Hepatology 2017;66:1067-1082).

Inhibition of preS1-hepatocyte interaction by an array of recombinant human antibodies from naturally recovered individuals

Neutralizing monoclonal antibodies are being found to be increasingly useful in viral infections. In hepatitis B infection, antibodies are proven to be useful for passive prophylaxis. The preS1 region (21–47a.a.) of HBV contains the viral hepatocyte-binding domain crucial for its attachment and infection of hepatocytes. Antibodies against this region are neutralizing and are best suited for immune-based neutralization of HBV, especially in view of their not recognizing decoy particles. Anti-preS1 (21–47a.a.) antibodies are present in serum of spontaneously recovered individuals. We generated a phage-displayed scFv library using circulating lymphocytes from these individuals and selected four preS1-peptide specific scFvs with markedly distinct sequences from this library. All the antibodies recognized the blood-derived and recombinant preS1 containing antigens. Each scFv showed a discrete binding signature, interacting with different amino acids within the preS1-peptide region. Ability to prevent binding of the preS1 protein (N-terminus 60a.a.) to HepG2 cells stably expressing hNTCP (HepG2-hNTCP-C4 cells), the HBV receptor on human hepatocytes was taken as a surrogate marker for neutralizing capacity. These antibodies inhibited preS1-hepatocyte interaction individually and even better in combination. Such a combination of potentially neutralizing recombinant antibodies with defined specificities could be used for preventing/managing HBV infections, including those by possible escape mutants.

N-terminal myristoylation-dependent masking of neutralizing epitopes in the preS1 attachment site of hepatitis B virus

BACKGROUNDS & AIMS

The N-terminally myristoylated preS1 domain of the large hepatitis B surface protein (LHBs) mediates specific attachment of hepatitis B virus (HBV) to hepatocytes. Its B-cell epitopes leading to neutralization of infectivity are not yet characterized.

METHODS

We inserted C- and N-terminal preS1 peptides into the most immunogenic region of HBV core particles, therewith immunized Balb/c mice and determined binding properties and neutralization potential of resulting antibodies in vitro.

RESULTS

The particles with preS1 inserts were highly immunogenic and the corresponding anti-preS antibodies strongly bound to HBV particles from chronic carriers infected with different HBV genotypes A-F. However, antibodies binding to the C-terminal part of preS1 did not neutralize HBV infectivity for susceptible hepatocyte cultures. In contrast, antibodies elicited by the complete N-terminal attachment site of preS1(2-48) strongly neutralized with an IC50<3μg/ml of total immunoglobulin. Interestingly, antibodies against the very N-terminal part of preS1(1-21) could not neutralize infectivity although this sequence contains the most conserved and essential part of the attachment site. These antibodies reacted well with non-myristoylated preS1 peptides but only weakly with myristoylated preS1 peptides, natural HBsAg or HBV.

CONCLUSIONS

N-terminal myristic acid obviously favors a topology of LHBs that makes the most essential part of the preS1 attachment site inaccessible for neutralizing antibodies, whereas antibodies to neighbouring sequences neutralized very well. Thus, addition of the preS1(2-48) peptide in a highly immunogenic form to the current hepatitis B vaccine may improve protective immunity and reduce selection of escape mutations.

Demonstration of an association between detection of IgG antibody reactivity towards the C-terminal region of the preS1 protein of hepatitis B virus and the capacity to respond to interferon therapy in chronic hepatitis B

BACKGROUND AND AIM

The treatment of hepatitis B virus (HBV) remains complex, with somewhat unpredictable responses. The aim of this study was to determine the predictive value of the pretreatment presence of circulatory antibodies towards a synthetic peptide mimicking the amino acids 94-117 of the preS1 protein of HBV and the capacity to respond to alpha-inteferon (IFN-alpha) treatment.

METHODS

The anti preS1(94-117) antibodies were measured by a peptide-based enzyme-linked immunosorbent assay (ELISA) and the response to INF-alpha therapy was judged by the effect on the viral kinetics as measured by an assay based on quantitative polymerase chain reaction during the treatment and follow up.

RESULTS

We found a significant (P < 0.001) correlation between the pretreatment presence of anti preS1(94-117) antibodies and a decrease in viral levels on follow up after the end of IFN-alpha therapy. The combined response of HBV DNA suppression (P < 0.001), hepatitis B e antigen (HBeAg) loss (P < 0.0001), anti-HBe seroconversion (P < 0.005) and AST aminotransferase normalization (P < 0.01) was also highly associated with the pretreatment presence of anti preS1(94-117) antibodies.

CONCLUSION

The positive predictive value (PPV) of anti preS1(94-117) in determining a virological response was 83% and the negative predictive value (NPV) was 100%, indicating that in the absence of pretreatment anti preS1 reactivity virtually no patient has the capacity to respond to IFN-alpha therapy. Our findings may help to improve the efficacy of INF-alpha therapy for chronic hepatitis B (CHB) by guiding the selection of patients for treatment and optimizing the clinical management of the individual patient.

Identification of the immunogenic domains in HBsAg preS1 region using overlapping preS1 fragment fusion proteins

AIM: The incorporation of hepatitis B virus (HBV) preS1 region into epitope-based vaccines against HBV has been accepted widely, but the incorporate site and size of preS1 sequence is controversial. Therefore our purpose was to further investigate its immunogenic domains for the epitope-based hepatitis B vaccine design.

METHODS: Eight GST fusion proteins containing overlapping preS1 fragments in preS1 (21-119) region were expressed in E.coli. Using these purified fusion proteins, the immunogenic domains in preS1 region were identified in detail in mice and humans by Western blot analysis and ELISA.

RESULTS: The results in mice showed that the immu-nogenic domains mainly existed in preS1 (21-59) and preS1 (95-109). Similarly, these fragments had strong immunogenicity in humans; whereas the other parts except for preS1 (60-70) also had some immunogenicity. More importantly, a major immunogenic domain, preS1 (34-59), which has much stronger immunogenicity, was identified. Additionally, the antibodies against some preS1 fragments, especially preS1 (34-59), were speculated to be virus-neutralizing.

CONCLUSION: Eight GST fusion proteins containing overlapping preS1 fragments were prepared successfully. They were used for the study on the immunogenic dom-ains in preS1 (21-119) region. The preS1 (34-59) fragm-ents were the major immunogenic domains in the preS1 region, and the antibodies against these fragments were speculated to be virus-neutralizing. Therefore, the incorporation of preS1 (34-59) fragments into epitope-based HBV vaccines may be efficient for enhancement of immune response. Additionally, the results also imply that there are more complex immune responses to preS1 region and more abundant immunogenic domains in humans.

N-acetyl cysteine therapy in acute viral hepatitis

AIM: To investigate the effect of N-acetyl cysteine (NAC) on acute viral hepatitis (AVH).

METHODS: We administered 200 mg oral NAC three times daily (600 mg/day) to the study group and placebo capsules to the control group. All patients were hospitalized and diagnosed as AVH. Blood total and direct bilirubin, ALT, AST, alkaline phosphatese, albumin and globulin levels of each patient were measured twice weekly until total bilirubin level dropped under 2 mg/dl, ALT level under 100 U/L, follow up was continued and then the patients were discharged.

RESULTS: A total of 41(13 female and 28 male) AVH patients were included in our study. The period for normalization of ALT and total bilirubin in the study group was 19.7 ± 6.9 days and 13.7 ± 8.5 days respectively. In the control group it was 20.4 ± 6.5 days and 16.9 ± 7.8 days respectively (P > 0.05).

CONCLUSION: NAC administration effected neither the time necessary for normalization of ALT and total bilirubin values nor duration of hospitalization, so we could not suggest NAC for the treatment of icteric AVH cases. However, our results have shown that this drug is not harmful to patients with AVH.

Detection of T lymphocyte subsets and mIL-2R on surface of PBMC in patients with hepatitis B

AIM: To study the levels of T lymphocyte subsets and membrane interleukin-2 receptor (mIL-2R) on surface of peripheral blood mononuclear cells (PBMCs) of patients with hepatitis B and its role in the pathogenesis of hepatitis B.

METHODS: The levels of T lymphocyte subsets and mIL-2R in PBMC before and after being stimulated with PHA were detected by biotin-streptavidin (BSA) technique in 196 cases of hepatitis B.

RESULTS: In patients with hepatitis B, the levels of CD₃⁺, CD₄⁺ cells, and the ratio of CD₄⁺ cells/CD₈⁺ cells were lower, but the level of CD₈⁺ cells was higher than those in normal controls (42.20 ± 6.01 vs 65.96 ± 6.54, 38.17 ± 5.93 vs 41.73 ± 6.40, 0.91 ± 0.28 vs 1.44 ± 0.31, 39.86 ± 6.36 vs 30.02 ± 4.54, P < 0.01). The total expression level of mIL-2R in PBMC before and after being stimulated with PHA was also lower than those in normal controls (3.47 ± 1.55 vs 4.52 ± 1.49, 34.03 ± 2.94 vs 37.95 ± 3.00, P < 0.01). In all the patients with hepatitis B, the levels of T lymphocyte subsets and mIL-2R in PBMC with HBV-DNA (+) were lower than those with HBV-DNA (-), which were significantly different (39.57 ± 7.11 vs 44.36 ± 5.43, 34.36 ± 7.16 vs 40.75 ± 5.87, 37.82 ± 6.54 vs 41.72 ± 6.21, 0.88 ± 0.33 vs 0.99 ± 0.27, 2.82 ± 1.62 vs 3.85 ± 1.47, 31.56 ± 3.00 vs 35.84 ± 2.83, P < 0.01). In addition, the levels of CD₃⁺, CD₄⁺, CD₈⁺ cells, the ratio of CD₄⁺ cells/CD₈⁺ cells and mIL-2R among different courses of hepatitis B were all significantly different (F = 3723.18, P < 0.01. F = 130.43, P < 0.01. F = 54.01, P < 0.01. F = 2.99, P < 0.05. F = 7.16, P < 0.01).

CONCLUSION: Both cellular and humoral immune functions are obviously in disorder in patients with hepatitis B, which might be closely associated with the chronicity in patients.

Expression of HLA-I on HepG2 cells by hepatitis B virus nucleocapsid mutants

AIM

To study the expression of HLA-I/antigen peptide complex on HepG2 cells transfected with HBV (adr) wild type and nucleocapsid protein mutants.

METHODS

The site-directed mutation was performed to introduce nucleocapsid protein point mutations V60 and L97 into 1.2 copies of HBV genome plasmid p3.8 Ⅱ. After identification of DNA sequence and biological activities, the plasmid p3.8Ⅱ and mutant plasmid constructs were subcloned respectively into EB virus based vector EBO-plpp for stable expression. The vector constructed EBO-wild type, EBO-V60, and EBO-L97 were analyzed by restriction enzyme digestion and DNA sequenceing, then transfected into HepG2 cells via the liposome technique, respectively. HBV antigen in their culture supernatants was quantified by Abbott kits. The cells were stained with murine monoclonal antibody anti-HLA-ABC conjugated directly to FITC, and expression of HLA-I on their membrane was analyzed by flow-cytometry.

RESULTS

Restriction enzyme digestion of 3 vector constructs showed two bands similar to HBV 1.2 copies genome and EBO vector, respectively. Analysis of DNA sequence confirmed the mutated nucleotides of EBO-V60 and EBO-L97 (i.e nt2078 C→G, nt2189 A→C). The expression of HBeAg S/CO in culture supernatant of EBO-wild type was much higher than that of mutant EBO-V60 and EBO-L97, while the expression of HBsAg S/N in three constructs had similar level, indicating similar transfecting rate in this experiment. The expression of HLA-I on HepG2 cells transfected with EBO empty vector was at low level. Fluorescence intensity of HLA-I expression of transfected cells was elevated by EBO-wild type (18.2), while that of L97 was increased to 34.5 and V60 declined to 3.4.

CONCLUSION

HBV might enhance the expression of HLA-I/antigen peptide complex on HepG2 cells. Hot-spot mutations of HBV nucleocapsid protein L97 and V60 could influence the expression level of HLA-I on host cells.

Successful rescuing a pregnant woman with severe hepatitis E infection and postpartum massive hemorrhage

AIM: To sum up the experience of the successful therapy for the severe hepatitis of pregnant woman with postpartum massive hemorrhage.

METHODS: The advanced therapeutic methods including the bilateral uterine artery embolism, hemodialysis and artificial liver support therapy were performed with comprehensive medical treatments and the course of the successful rescuing the patient was analyzed.

RESULTS: Through the hospitalization of about two mouths the patient and her neonatus had gotten the best of care in our department and pediatric department separately. Both of them were discharged in good condition.

CONCLUSION: The key points for a successful therapy of the pregnant woman with severe hepatitis are termination of the pregnancy and the control of their various complications. It was suggested that the proper combination of these measures of modern therapy would race against time for renewing of hepatic and renal functions.

Investigation of HGV and TTV infection in sera and saliva from non-hepatitis patients with oral diseases

AIM: To determine the frequencies of HGV and TTV infections in serum and saliva samples of non-hepatitis patients with oral diseases in Hangzhou area, and to understand the correlation between detected results of HGV RNA and/or TTV DNA in sera and in saliva from the same patients.

METHODS: RT-nested PCR for HGV RNA detection and semi-nested PCR for TTV DNA detection were performed in the serum and saliva samples from 226 non-hepatitis patients with oral diseases, and nucleotide sequence analysis.

RESULTS: Twenty-seven (11.9%) and 21 (9.3%) of the 226 serum samples were only positive for HGV RNA and TTV DNA, respectively. 10 (4.4%) and 9 (3.9%) of the 226 saliva samples were only positive for HGV RNA and TTV DNA, respectively. And 7 (3.1%) of the serum samples and 2 (0.9%) of the saliva samples showed the positive amplification results for both HGV RNA and TTV DNA. 12 saliva samples from the 34 patients (35.3%) with HGV or HGV/TTV viremia and 11 saliva samples from the 28 patients (39.3%) with TTV or HGV/TTV viremia were HGV RNA detectable, respectively, including two patients positive for both HGV RNA and TTV DNA in serum and saliva samples. No saliva samples from the 226 patients were found to be HGV RNA or TTV DNA detectable while their serum samples were negative for HGV or TTV. Homologies of the nucleotide sequences of HGV and TTV amplification products from the serum and saliva samples of the two patients compared with the reported sequences were 88.65%-91.49% and 65.32%-66.67%, respectively. In comparison with the nucleotide sequences of amplification products between serum and from saliva sample from any one of the two patients, the homologies were 98.58% and 99.29% for HGV, and were 98.65% and 98.20% for TTV, respectively.

CONCLUSION: Relatively high carrying rates of HGV and/or TTV in the sera of non-hepatitis patients with oral diseases in Hangzhou area are demonstrated. Parts of the carriers are HGV and/or TTV positive in their saliva. The results of this study indicate that dentists may be one of the populations with high risk for HGV and/or TTV infection, and by way of saliva HGV and TTV may be transmitted among individuals.

The comparison of antibody response to different hepatitis b vaccines with and without pre-S2 antigen in children with cancer

Children with cancer are at an increased risk of hepatitis B infection and chronic liver disease. Since hepatitis B vaccines containing pre-S2 antigen has been recently reported as being more efficient in providing immunization in healthy individuals, the authors compared antibody response to pre-S2-containing vaccine with no-pre-S2-containing hepatitis B vaccine, when given in double doses to 100 children receiving chemotherapy. Patients, aged 1 to 16 years with negative HBV serology, were vaccinated with 2 different types of HBV vaccines between 1997 and 1999. Group 1 received Gen Hevac B containing pre-S2 (n = 41) in a dose of 20 microg for patients younger than 10 years old and 40 microg for older patients. Group 2 was vaccinated at the same dose with hepatitis B vaccines not containing pre-S2 antigen. All vaccinations were repeated at 0, 1, and 6 months. Serum samples were drawn for determination of anti-HBs titers at 1, 3, 6, and 8 months. After the third dose of vaccine, the seroconversion rate was 72% in group 1 and 62% in group 2. The anti-HBs levels were higher in the group receiving pre-S2-containing hepatitis B vaccine. However, the difference between groups was not statistically significant (p > .05). The administration of pre-S2-containing hepatitis B vaccines may give a better seroconversion and higher antibody response to vaccination in children with cancer. But a further large-scale study is needed to confirm this finding.