Anti-HBs after hepatitis B immunization with plasma-derived and recombinant DNA-derived vaccines: binding to mutant HBsAg

Higher disappearance rate of anti-HBs in Taiwanese freshers neonatally vaccinated with recombinant yeast hepatitis B vaccine

BACKGROUND & AIM

The aim of this study was to compare the long-term efficacy of infant recombinant yeast hepatitis B vaccine (Recombinant group) and infant plasma-derived one (Plasma group) in Taiwanese freshers.

METHODS

Recruited were a total of 38 377 freshmen who underwent university entrance health examinations from 2003 to 2015. Subjects were assigned into two groups-plasma type and recombinant type, according to the national neonatal hepatitis B immunization program. The seroprevalences of hepatitis B surface antigen, antibody against hepatitis B surface antigen, and antibody against hepatitis B core antigen in each group and gender were calculated. Multivariate logistic regression analysis was performed to compare the efficacy of two groups.

RESULTS

The HBsAg-positive rates in the plasma group and recombinant group were 1.5% and 0.3% respectively. The anti-HBs positive rates were 43.6% and 30.9%. The hepatitis B viral natural infection rates were 3.6% and 1.3%. Taking those who were born in July 1986-April 1992 as baseline group after adjustment for gender and age at hepatitis B markers checkup time, the efficacy of recombinant group in decreasing HBsAg positive rate, and decreasing hepatitis B virus natural infection rate was 71.0% (95% C.I.: 59.0-79.0%, P<.001) and 65.0% (95% C.I. 58.0-71.0%, P<.001) respectively. On the contrary, the seroprevalence of anti-HBs positive rate in recombinant group was 39.0% (95% C.I.: 36.0-42.0%, P<.001) lower than that of plasma group. (P<.001).

CONCLUSION

Higher disappearance rate of anti-HBs was noted in recombinant group than in plasma group when the subjects reached their youth and young adulthood in Taiwan.

Increased seroprevalence of HBV DNA with mutations in the s gene among individuals greater than 18 years old after complete vaccination

BACKGROUND & AIMS

Despite the success of a universal vaccination program against hepatitis B virus (HBV) in Taiwan, a small but substantial proportion of individuals remain infected by mutant viruses that escape the vaccine. We investigated the seroepidemiology and genotypic characteristic of HBV for long periods after neonatal vaccination.

METHODS

We measured hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc), and antibody to hepatitis B surface antigen (anti-HBs) in 1214 serum samples collected throughout Taiwan from individuals 0.6-87.8 years old in 2007. HBV DNA was detected using polymerase chain reaction and sequence analysis in vaccine recipients who tested positive for anti-HBc and/or HBsAg.

RESULTS

The overall seroprevalence of HBsAg and anti-HBc was significantly lower among individuals born after the initiation of the nationwide vaccination program (P < .001). However, we observed increasing seroprevalence of anti-HBc and isolated anti-HBs when subjects were grouped by age: at 10-14, 14-18, to 18-21 years of age, values were 0.4%, 1.9%, and 8.1% (P = .0135) and 43.7%, 55.4%, and 59.6% (P = .0093), respectively (χ(2) test for trend). A large increase was observed in the percentage of patients who tested positive for HBV DNA at 18-21 years of age (3.0% vs 0.2% [P = .002] for all eligible subjects and 5.7% vs 0.3% [P < .001] for subjects vaccinated with ≥3 doses). Five of 8 completely vaccinated individuals who were seropositive for HBV DNA carried variants with mutations in the S gene.

CONCLUSIONS

Universal vaccination effectively controls HBV infection in children and adolescents. However, after adolescence, there is a significant increase in the seroprevalence of anti-HBs, anti-HBc, and HBV DNA, indicating that new preventative strategies are needed for adults.

Molecular imprinting based composite cryogel membranes for purification of anti-hepatitis B surface antibody by fast protein liquid chromatography

In the present study, we have focused our attention to prepare molecular imprinted composite cryogel membranes for purification of hepatitis B surface antibody (anti-HBs) by fast protein liquid chromatography. Before the preparation of the molecular imprinted composite cryogel membranes (MI-CMs) by free radical polymerization at sub-zero temperature, we have synthesized and characterized the anti-HBs imprinted particles. Then, the cryogel membranes (CMs) were characterized by swelling test, scanning electron microscopy and Fourier transform infrared spectroscopy. Prior to chromatographic purification studies, the effective parameters on the anti-HBs adsorption process were evaluated by investigating the dependency of the adsorption capacity on flow-rate, anti-HBs concentration, contact time and ionic strength. The maximum anti-HBs adsorption capacity was calculated as 701.4 mIU/g CM. The selectivity of the MI-CMs was shown by competitive adsorption of anti-HBs, total anti-hepatitis A antibody (anti-HAV) and total immunoglobulin E (IgE) adsorption studies. The MI-CMs have relative selectivity coefficients as 5.45 for anti-HBs/total anti-HAV and 9.05 for anti-HBs/total IgE, respectively. The phosphate buffer solution (pH 7.4) containing 1.0M NaCl was used for elution, almost completely, of adsorbed anti-HBs molecules. The MI-CMs could be used many times without any significant decrease in the adsorption capacity. The chromatographic purification performances of the MI-CMs were also investigated. The chromatographic parameters such as capacity and separation factors, the theoretical plate number and resolution of the MI-CMs were calculated as 5.48, 6.02, 1153.9, and 1.72 for anti-HBs molecules, respectively. As a conclusion, we can say that the MI-CMs could be used for specific purification of anti-HBs from anti-HBs positive human plasma.

HBV vaccine efficacy and detection and genotyping of vaccineé asymptomatic breakthrough HBV infection in Egypt

AIM

To evaluate the impact of mass vaccination against the hepatitis B virus (HBV) in Egypt, and to search for vaccinee asymptomatic breakthrough HBV infection and its genotype.

METHODS

Seven hundred serum samples from vaccinated children and adults (aged 2-47 years) were used for quantitative and qualitative detection of HBsAb by ELISA. Three hundred and sixty serum samples representing undetectable or low or high HBsAb were screened for markers of active HBV infection (HBsAg, HBcAb (IgG) and HBeAb by ELISA, plus HBsAg by AxSYM) and HBV-DNA genotyping by nested multiplex PCR and by DNA sequencing.

RESULTS

It was found that 65% of children aged 2-4 years, and 20.5% aged 4-13 years, as well as 45% adults were good responders to HBV vaccination mounting protective level HBsAb. Poor responders were 28%, 59.5% and 34%, and non-responders were 7%, 20% and 21% respectively, in the three studied groups. Markers of asymptomatic HBV infections were HBsAg detected by ELISA in 2.5% vs 11.39% by AxSYM. Other markers were HBcAb (IgG) in 1.38%, HBeAb in 0.83%, and HBV-DNA in 7.8%. All had HBV genotype E infection.

CONCLUSION

It is concluded that HBV vaccine is efficient in controlling HBV infection among children and adults. The vaccine breakthrough infection was by HBV genotype E. A booster dose of vaccine is recommended, probably four years after initial vaccination.

A review of multiple approaches towards an improved hepatitis B vaccine

BACKGROUND

Hepatitis B is a DNA virus that can cause liver inflammation, cirrhosis, and cancer in chronically infected and symptomatic carriers. Antiviral treatments are usually limited in their effectiveness in treating the disease states. Vaccination against hepatitis B in pediatric and adolescent populations has proven to be a generally effective means for preventing diseases that could be potentially caused by this virus. Some 5 - 10% of the vaccinees do not develop protective immunity against the virus. Therefore, a significant amount of effort has been made in many research laboratories across the world to increase the potency of the vaccine by various innovative means, e.g., increasing the immunogenicity of the antigen or through introduction of novel adjuvants that elicit strong humoral and cell-mediated immune responses.

OBJECTIVES/METHODS

The objective of this review is to highlight publications of significant developments that have been made over the past decade and efforts that are continuing towards producing an improved vaccine. A number of patents that protect novel hepatitis B vaccine formulations, including those claiming novel hepatitis B core antigen formulations and combinations of a vaccine with small molecule therapeutics, are discussed.

CONCLUSION

There have been promising developments in the area of new adjuvants and delivery systems. The practical need for reducing the total number of childhood vaccinations has driven development of, and patent filings on, multivalent and combination vaccine formulations in which the hepatitis B vaccine is included as one component. Efforts and some advances have also been made in the critical area of therapeutic application of the vaccine. The existence of a large population of already infected patients and the inadequacy of most of the current antiviral drugs against hepatitis B diseases have also inspired efforts to produce a vaccine that would be efficacious in clearing an exiting infection.

Acute hepatitis B virus infection by genotype F despite successful vaccination in an immune-competent German patient

BACKGROUND

Hepatitis B Virus (HBV) infection is a leading cause of chronic hepatitis and liver cirrhosis worldwide, and efficient protection can usually be achieved by vaccination that is based on recombinant HBsAg protein from HBV genotype A and D.

RESULTS

Here we report the case of a fully immune-competent German patient that acquired a symptomatic acute HBV infection during adulthood despite a complete and formally successful vaccination, which had resulted in anti-HBs titers considered protective. Further phylogentic analysis identified an infection with the rare genotype F of HBV, possibly acquired in Spain, without apparent aberrations in the immunodominant 'a' determinant domain of the envelope gene. However, sequence comparisons revealed that all reported genotype F isolates display marked differences from the other genotypes in this domain which serves as an epitope for humoral immune responses.

CONCLUSIONS

The rare HBV genotype F, as detected in this immune-competent, previously vaccinated patient, has marked sequences differences in the envelope/polymerase gene. Therefore, current HBV vaccines based on genotype A and D may not result in full protective immunity towards viral strains from genotype F.

Hepatitis B virus vaccination of blood donors--what costs may be expected?

Although the risk of transfusion-transmitted hepatitis B virus (TT-HBV) infection is very low, it still exists. Therefore, introduction of further precautions to reduce this risk is discussed at present. However, so far no data are available about the HBV vaccination status among blood donors (BDs). We compared HBV vaccination status of apheresis donors (ADs) of a university based and whole BDs (WBDs) of a Red Cross blood donation service using a standardized questionnaire. On the basis of these data, the estimated costs over 10 years for HBV vaccination were calculated for two different strategies and compared with the costs for HBV nucleic acid amplification technology (NAT) testing. 22.3% of the WBDs and 41.2% of the ADs indicated having received at least one HBV vaccine dose. This difference was related to the different demographic structures of the two BD populations (BDPs). With regard to the primary costs for the blood donation service, HBV vaccination of BDs could be an alternative to HBV NAT testing, especially for BDPs with an already high HBV vaccination rate and a high donation frequency.

Incidence of HBV variants with a mutation at nt551 among hepatitis B patients in Nanjing and its neighbourhood

AIM: To investigate the epidemiology of hepatitis B virus (HBV) strains with a mutation at nt551 in surface gene among hepatitis B patients in Nanjing and its neighbourhood.

METHODS: By using mutation-specific polymerase chain reaction (msPCR) established by our laboratory for amplifying HBV DNAs with a mutation at nt551, 117 serum samples taken from hepatitis B patients were detected.

RESULTS: The results showed that 112 samples were positive for nt551A, 4 samples were positive for nt551G. One sample was positive for nt551T. No nt551C of HBV DNA was found. The incidence of HBsAg mutants with G, C, T, A at nt551 among 117 samples was 3.42%, 0%, 0.85%, 95.73%, respectively.

CONCLUSION: In Nanjing and its neighbourhood, hepatitis B patients are mainly infected with wild genotype HBV. The incidence of mutants with a mutation at nt551 in HBV genome is significantly lower than that in wild genotype HBV DNA (P<0.01). The necessity of adding components of HBsAg mutants to HBV vaccine needs further investigation.

Hepatitis B virus (HBV) vaccine-induced escape mutants of HBV S gene among children from Qidong area, China

Hepatitis B virus (HBV) infection is the main factor, which induces hepatocellular carcinoma (HCC) in Qidong high-risk area, China. To prevent HBV infection is the most important strategy to inhibit the HCC carcinogenesis. A large project was performed in Qidong area to protect newborn babies from the HBV infection that 80,000 children born between 1984 and 1990 were vaccinated. After three times of follow-up studies, 15 screened children were found to have symptoms of illness showing persistent elevation of serum glutamic-pyruvic transaminase (ALT). From these previously collected data, we found that the ALT levels of five vaccinees with negative hepatitis B surface antigen (HBsAg) were significantly higher than those of 10 vaccinees with positive HBsAg. Furthermore, with the passage of time, the difference of ALT levels between the two groups (HBsAg negative and positive groups) diminishes. After cloning and sequencing of the HBsAg "a" epitope coding sequences, we found that mutations in "a" epitope were correlated with the absence of detectable anti-HBsAg, while no mutations were seen in the anti-HBsAg positive infections. We also found that majority of point mutations were occurred in the coding sequences of the first loop structure in "a" epitope. The structure of double loop conformation in "a" epitope was conservative, and important for HBV antigenicity. These changes in a double loop conformation would escape neutralization by vaccine-induced antibody.

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A mutation specific polymerase chain reaction for detecting hepatitis B virus genome mutations at nt551

AIM: The hepatitis B surface antigen (HBsAg) is considered to be one of the best markers for the diagnosis of acute and chronic HBV infection. But in some patients, this antigen cannot be detected by routine serological assays despite the presence of virus. One of the most important explanations for the lack of detectable HBsAg is that mutations which occur within the “a” determinant of HBV S gene can alter expression of HBsAg and lead to changes of antigenicity and immunogenicity of HBsAg accordingly. As a result, these mutants cannot be detected by diagnosis assays. Thus, it is essential to find out specific and sensitive methods to test the new mutants and further investigate their distribution. This study is to establish a method to investigate the distribution of the HBsAg mutant at nt551.

METHODS: A mutation specific polymerase chain reaction (msPCR) was established for amplifying HBV DNA with a mutation at nt551. Four sets of primer pairs, P551A-PPS, P551G-PPS, P551C-PPS and P551T-PPS, with the same sequences except for one base at 3’ terminus were designed and synthesized according to the known HBV genome sequences and the popular HBV subtypes, adr and adw, in China. At the basis of regular PCR method, we explored the specific conditions for amplifying HBV DNAs with a mutation at nt551 by regulating annealing temperature and the concentration of these primers. 126 serum samples from patients of hepatitis B were collected, among which 16 were positive for HBV S DNA in the nested PCR amplification. These 16 HBV S DNAs were detected by using the msPCR method.

RESULTS: When the annealing temperature was raised to 71 °C, nt551A and nt551G were amplified specifically by P551A-PPS and P551G-PPS; At 72 °C and 5 pmole of the primers (each) in reaction of 25 μl volume, nt551C and nt551T were amplified specifically by P551C-PPS and P551T-PPS. 16 of HBV S gene fragments were characterized by using this method. 14 of them were positive for nt551A, one was positive for nt551G, and the other one was positive for nt551T. The results were confirmed by nucleotide sequencing.

CONCLUSION: The mutation specific polymerase chain reaction is a specific and sensitive method for detecting the mutations of HBV genome at nt551.

A novel hepatitis B virus mutant with A-to-G at nt551 in the surface antigen gene

AIM: Hepatitis B surface antigen (HBsAg) mutant of hepatitis B virus (HBV) is one of the important factors that result in immune escape and cause failure of immunization. In this study we reported and characterized a novel HBV mutant with A-to-G at nt551 and intended to provide theoretical data for prevention of HBV infection in China.

METHODS: A methodology comprising polymerase chain reaction (PCR) amplifying, M13 bacteriophage cloning and nucleotide sequencing was used to analyze the sera of the pediatric patient who was hepatitis B (HB) immune failure. Expression plasmids containing the mutant S gene and a wild-type (adr) S gene were constructed respectively and the recombinant HBsAg were expressed in COS-7 cells under the regulation of SV40 early promoter. The recombinant proteins were investigated for their immunological reactivity with different monoclonal antibodies (mAb) against 'a' determinant and vaccine-raised human neutralizing antibodies.

RESULTS: It was found that there was a new point mutation at nt551 of the HBV (adr) genome from A to G, leading to a substitution of methionine (Met) to valine (Val) at position 133 in the 'a' determinant of HBsAg. Compared to the wild-type HBsAg, the binding activity of the muant HBsAg to mAbs (A6, A11 and S17) and to vaccine-raised human anti-hepatitis B surface antibody (anti-HBs) decreased significantly.

CONCLUSION: According to the facts that the patient has been immunized with HB vaccine and that the serum is anti-HBs positive and HBsAg negative, and based on the nucleotide sequence analysis of the mutant HBV S gene and its alteration of antigenicity, the HBV is considered to be a new vaccine-induced immune escape mutant different from the known ones.

Hepatitis B surface antigen (HBsAg) derived from yeast cells (Hansenula polymorpha) used to establish an influence of antigenic subtype (adw2, adr, ayw3) in measuring the immune response after vaccination

As a product of western world biotechnology the yeast (Saccharomyces cerevisiae) hepatitis B vaccine was introduced as antigenic subtype adw2. However, an HBsAg/adw2-vaccine may provide a good but not "optimal" immunologic response for infection with heterologous virus strains. The availability of the yeast Hansenula polymorpha HBsAg in three different antigenic forms (adw2, ayw3 and adr) enabled us to investigate the influence of variant amino acids in the binding of immune anti-HBs after vaccination. Hansenula-derived HBsAg was standardised on the basis of protein content at >95% purity. Standardisation was controlled by monoclonal anti-HBs binding in a well-conserved region. Sera were obtained after immunisation with type adw, ayw and adr vaccines. Direct binding of immune antibodies to homologous antigen (in EIA) was higher than to heterologous antigen except for the adr-related antibodies. Since the binding of the WHO reference anti-HBs was strongly reduced for the ayw and adr compared to the adw antigen, a similar binding profile for the three antigens on protein basis could result in 2-3-fold different anti-HBs level expressed in IU/l. Inhibition of Hansenula-derived HBsAg binding to solid phase monoclonal anti-HBs in enzyme immunoassays after incubation with serum anti-HBs confirmed the differential binding of serum anti-HBs with variant Hansenula-derived HBsAg. This variant (antigenic subtype) dependent reactivity of anti-HBs in immunoassays in combination with a variant specific WHO standard may limit the application of the threshold levels of 10 and 100 IU/l for seroconversion and seroprotection.