Antigen epitopes of animal coronaviruses:a mini-review

Coronaviruses are widespread in nature and can infect mammals and poultry,making them a public health concern.Globally,prevention and control of emerging and re-emerging animal coronaviruses is a great challenge.The mecha-nisms of virus-mediated immune responses have important implications for research on virus prevention and control.The antigenic epitope is a chemical group capable of stimulating the production of antibodies or sensitized lympho-cytes,playing an important role in antiviral immune responses.Thus,it can shed light on the development of diagnos-tic methods and novel vaccines.Here,we have reviewed advances in animal coronavirus antigenic epitope research,aiming to provide a reference for the prevention and control of animal and human coronaviruses.

Recent advances in the study of epitopes,allergens and immunologic cross-reactivity of edible mango

Mango(Mangifera indica L.)is a tropical fruit that is widely consumed as both fresh fruits and processed products around the world.The high incidence of mango allergy,on the other hand,has sparked widespread concern.Therefore,a summary and analysis of the current status and issues in mango allergen research can guide in-depth study on the mechanism of mango allergy and reveal effective desensitization methods.We described the incidence of fruit allergy,as well as the mechanism and clinical symptoms of mango allergy,in this review.We also looked into the structural properties of mango allergens,the effect of processing methods on mango allergens,prediction methods for mango allergen epitopes,and the current state of research on mango cross-reactive allergens and preventive measures.Finally,the research directions and ideas for the future are proposed and discussed.

The amino acids differences in epitopes may promote the different allergenicity of ovomucoid derived from hen eggs and quail eggs

Quail egg ovomucoid can inhibit activation of basophils and eosinophils,while hen egg ovomucoid has been shown to be a major allergen,named Gal d 1.At present,the differences in structure and function between two ovomucoid are unclear.We found the homology of ovomucoid in quail eggs and hen eggs reached77%.Compared with hen egg ovomucoid,the distribution of secondary structure was different in AA52-53,AA57-58,AA66-68,AA71-72,AA131-133,AA139-140,AA157-159 and AA184-185.Among 9 epitopes of egg ovomucoid,there were different amino acids from quail egg ovomucoid in 8 epitopes.Recombination quail egg ovomucoid had trypsin inhibition activity and quail egg ovomucoid didn't specifically bind to serum of eggs allergic patients.Quail egg ovomucoid can significantly inhibit RBL-2 H3 cells degranulation and protect cells morphology to a certain extent,indicating quail egg ovomucoid can inhibit cells activation and have potential anti-allergic effects,which is related to trypsin inhibitory activity.The difference in sensitization compare to hen egg ovomucoid may be due to amino acids differences affecting protein structure by changing antigenic epitopes.

Bioinformatics analysis of the structure and linear B-cell epitopes of aquaporin-3 from Schistosoma japonicum

Objective:To analyze the structure of aquaporins-3(AQP-3) from Schistosoma japonicum(SJAQP-3) using bioinformalical methods,and to provid of references for vaccine targets research.Methods:Protparam,BepiPred,TMHMM Server,MLRC,Geno3d,DNA star software packages were used to predict the physical and chemical properties,hydrophilicity plot, flexibility regions,antigenic index,surface probability plot,secondary structure,and tertiary structure of amino acid sequence of SJAQP-3.Results:SJAQP-3 had six transmembrane regions and two half-spanning helices that form a central channel.The half-spanning helices fold into the centre of the channel.Either of the half-spanning helix had a conserved motif of NPA common to all aquaporins.Predicted linear B-Cell epitopes were most likely at the N-terminal amino acid residues of Saa-7aa,59aa- 62aa,225aa-230aa,282aa -288aa,294aa -29Saa and 305aa -307aa area.59aa- 62aa,22Saa-230aa located outside the membrane,the others located inside the cell.Conclusions:SJAQP-3 is a integral membrane protein in Schistosoma japonicum tegument.There are six potential epitopes in SJ AQP-3.It might be a potential molecular target for the development of vaccines.

Prediction of T cell and B cell epitopes of the 22-, 47-, 56-, and 58-kDa proteins of Orientia tsutsugamushi

Objective:To predict B cell and T cell epitopes of 22-kDa,47-kDa,56-kDa and 58-kDa proteins.Methods:The sequences of 22-kDa,47-kDa,56-kDa and 58-kDa proteins which were derived from Orientia tsutsugamushi were analyzed by SOPMA,DNAstar,Bcepred,ABCpred,NetMHC,NetMHCⅡand IEDB.The 58-kDa tertiary structure model was built by MODELLER9.17.Results:The 22-kDa B-cell epitopes were located at positions 194-200,20-26 and 143-154,whereas the T-cell epitopes were located at positions 154-174,95-107,17-25 and 57-65.The 47-kD a protein B-cell epitopes were at positions 413-434,150-161 and 283-322,whereas the T-cell epitopes were located at positions 129-147,259-267,412-420 and 80-88.The 56-kDa protein B-cell epitopes were at positions 167-173,410-419 and 101-108,whereas the T-cell epitopes were located at positions 88-104,429-439,232-240 and 194-202.The 58-kDa protein B-cell epitopes were at positions 312-317,540-548 and 35-55,whereas the T-cell epitopes were located at positions 415-434,66-84 and 214-230.Conclusions:We identified candidate epitopes of 22-kDa,47-kDa,56-kDa and 58-kDa proteins from Orientia tsutsugamushi.In the case of 58-kDa,the dominant antigen is displayed on tertiary structure by homology modeling.Our findings will help target additional recombinant antigens with strong specificity,high sensitivity,and stable expression and will aid in their isolation and purification.

Prediction of promiscuous T-cell epitopes in the Zika virus polyprotein:An in silico approach

Objective:To predict immunogenic promiscuous T-cell epitopes from the polyprotein of the Zika virus using a range of bioinformatics tools.To date,no epitope data are available for the Zika virus in the IEDB database.Methods:We retrieved nearly 54 full length polyprotein sequences of the Zika virus from the NCBI database belonging to different outbreaks.A consensus sequence was then used to predict the promiscuous T cell epitopes that bind MHC 1 and MHC II alleles using Propred1 and Propred immunoinformatic algorithms respectively.The antigencity predicted score was also calculated for each predicted epitope using the Vaxi Jen 2.0 tool.Results:By using Pro Pred1,23 antigenic epitopes for HLA class I and 48 antigenic epitopes for HLA class II were predicted from the consensus polyprotein sequence of Zika virus.The greatest number of MHC class I binding epitopes were projected within the NS5(21%),followed by Envelope(17%).For MHC class II,greatest number of predicted epitopes were in NS5(19%) followed by the Envelope,NS1 and NS2(17% each).A variety of epitopes with good binding affinity,promiscuity and antigenicity were predicted for both the HLA classes.Conclusion:The predicted conserved promiscuous T-cell epitopes examined in this study were reported for the first time and will contribute to the imminent design of Zika virus vaccine candidates,which will be able to induce a broad range of immune responses in a heterogeneous HLA population.However,our results can be verified and employed in future efficacious vaccine formulations only after successful experimental studies.

Prediction of promiscuous T cell epitopes in RNA dependent RNA polymerase of Chikungunya virus

Objective: To explore RNA dependent RNA polymerase of Chikungunya virus(CHIKV) and develop T cell based epitopes with high antigenicity and good binding affinity for the human leukocyte antigen(HLA) classes as targets for epitopes based CHIKV vaccine. Methods: In this study we downloaded 371 non-structural protein 4 protein sequences of CHIKV belonging to different regions of the world from the US National Institute of Allergy and Infectious Diseases(NIAID) virus pathogen resource database. All the sequences were aligned by using CLUSTALW software and a consensus sequence was developed by using Uni Pro U Gene Software version 1.2.1. PropredⅠand Propred software were used to predict HLAⅠ and HLAⅡ binding promiscuous epitopes from the consensus sequence of non-structural protein 4 protein. The predicted epitopes were analyzed to determine their antigenicity through Vaxijen server version 2.0. All the HLAⅠ binding epitopes were scanned to determine their immunogenic potential through the Immune Epitope Database(IEDB). All the predicted epitopes of our study were fed to IEDB database to determine whether they had been tested earlier. Results: Twenty two HLA class Ⅱ epitopes and eight HLA classⅠepitopes were predicted. The promiscuous epitopes WMNMEVKII at position 486–494 and VRRLNAVLL at 331–339 were found to bind with 37 and 36 of the 51 HLA class Ⅱ alleles respectively. Epitope MANRSRYQS at position 58–66 and epitopes YQSRKVENM at positions 64–72 were predicted to bind with 12 and 9 HLAⅠI alleles with antigenicity scores of 0.754 9 and 1.013 0 respectively. Epitope YSPPINVRL was predicted to bind 18 HLAⅠ alleles and its antigenicity score was 1.425 9 and immunogenicity score was 0.173 83. This epitope is very useful in the preparation of a universal vaccine against CHIKV infection. Conclusions: Epitopes reported in this study showed promiscuity, antigenicity as well as good binding affinity for the HLA classes. These epitopes will provide the baseline for development of efficacious vaccine for CHIKV.

Investigation of 4-hydroxynonenal-delved Epitopes on Apolipoprotein B in Human Serum

hydroxynonenal(HNE) is one of the important products generated in lipid peroxidation. An enzyme linked immunoassay for HNE derived epitopes on apolipoprotein B(apo B) was established and 263 human sera were measured. The mean expression of HNE epitopes in men(156.5 mg/L, n=157) was higher than that in women(147.6 mg/L, n=106). In the subjects less than 70 years of age the serum levels of HNE epitopes increased with the age. Expression of HNE epitopes on apo B in serum positively related to serum contents of ferritin, total cholesterol, triglycerides, and low density lipoprotein cholesterol(LDL C). In addition, mean level of HNE epitopes on apo B in patients with coronary heart disease (CHD, 183.5 mg/L, n=103) was higher than that of controls(133.3 mg/L, n=160). This difference was statistically significant. A multiple regression analysis furth showed that serum concentration of LDL C and HNE epitopes were positively related to CHD as well as the age, but high density lipoprotein cholesterol and female were negatively related to CHD. Thus, increased expression of HNE epitopes on apo B might be an independent risk factor of CHD. \ \

Genome-wide comparison inferred the origin and evolution of B-cell epitopes on the proteins of human influenza A virus

The novel strain H1N1 caused the outbreak of first pandemic influenza in 21 century. Now it is a common component of current seasonal influenza viruses. The recent transmission and plentiful genome sequences available provided a good opportunity to study the origin and evolution of epitopes on the proteins of human influenza virus. In the present study, the B-cell epitope compositions in the pandemic strains, circulating traditional seasonal strains, swine strains as well as highly virulent avian strain H5N1 were identified with the aid of the Immune Epitope DataBase (IEDB) and were compared at genomic level. A total of 14210 distinct sequences down-loaded from NCBI database were used for analysis. Some epitopes on proteins HA or NA, not conserved in recent seasonal strains, were found in 2009 pandemic strains but existed in the early human strains (1919-1935). The pandemic strain shared higher conserved epitopes with “bird flu” virus H5N1than classic human seasonal strains. The epitopes that could exist at common antigenic regions of HA protein are needed to further identify. The genetic exchanges between human and swine population by transmission was very active but the princepal side of the transmission could be from swine to human. These results provided valuable information on influenza A virus evolution and transmission by means of epitope analysis at genomic level.

Theoretical Study of Continuous B-Cell Epitopes with Developed BP Neural Network

In order to identify continuous B-cell epitopes effectively and to increase the success rate of experimental identification, the modified Back Propagation artificial neural network (BP neural network) was used to predict the continuous B-cell epitopes, and finally the predictive model for the B-cells epitopes was established. Comparing with the other predictive models, the prediction performance of this model is more excellent (AUC = 0.723). For the purpose of verifying the performance of the model, the prediction to the SWISS PROT NUMBER: P08677 was carried on, and the satisfying results were obtained.

Expression of cancer-testis antigen CT10 gene mRNA in hepatocellular carcinoma and prediction of HLA - A2 restricted CTL epitopes of CT10

Objective To investigate the expression of cancer-testis antigen CT10 gene mRNA in hepatocellular carcinoma and predict the HLA-A2-restricted CTL epitopes of CT10. Methods The expression of CT10 mRNA was detected by using RT - PCR in HCC tissues and the corresponding adjacent non-HCC tissues from 45 HCC patients, among those 3 samples selected randomly from CT10 PCR positive products were sequenced. HLA - A2-restricted CTL epitopes of CT10 was predicted by peptide supermotif prediction combined with quantitative motif. Results CT10 mRNA was detectable in 19/45 (42. 2%) of HCC samples, while the corresponding adjacent non-HCC tissue were all negative in expression of CT10 mRNA. In addition, The DNA sequence confirmed that the RT- PCR products were truly CT10 cDNA. No June 2003 Vol12 No2 relationship was found between the expression of CT10 and demographic and clinical features such as age, sex, tumor size, degree of tumor differentiation, serum α-fetoprotein level and infection of hepatitis B virus or

Identification of the epitopes on HCV core protein recognized by HLA-A2 restricted cytotoxic T lymphocytes

AIM To identify hepatitis C virus (HCV) core protein epitopes recognized by HLA-A2 restricted cytotoxic T lymphocyte (CTL).METHODS Utilizing the method of computer prediction followed by a 4 h 51 Cr-release assay confirmation.RESULTS The results showed that peripheral blood mononuclear cells (PBMC) obtained from two HLA-A2 positive donors who were infected with HCV could lyse autologous target cells labeled with peptide 'ALAHGVFAL (core TS0-158)'.The rates of specific lysis of the cells from the two donors were 37.5% and 15.8%,respectively. Blocking of the CTL response with anti-CD4 mAb caused no significant decrease of the specific lysis.But blocking of CTL response with anti-CD8 mAb could abolish the Iysis.CONCLUSION The peptide (core 150 - 158 ) is the candidate epitope recognized by HLA-A2 restricted CTL.

Catalytic domain of PDC-E2 contains epitopes recognized by antimitochondrial antibodies in primary biliary cirrhosis

AIM:To search for further immunodominant peptides of the pyruvate dehydrogenase complex E2-component (PDC-E2) recognized by antimitochondrial antibodies (AMA) in primary biliary cirrhosis (PBC). METHODS:Sera from 95 patients with PBC were tested by enzyme-linked immunosorbent assay against 33 synthetic overlapping peptides (25 amino acids; aa) covering the entire length of the E2-subunit of PDC-E2. Furthermore,the inner lipoyl peptide 167-184 was used in an unlip oylated and a lipoylated form as well as coupled to ovalbumin. Sera from 11 AMA negative/ANA posit ive PBC patients,63 patients with other liver disorders and 22 healthy blood donors served as controls.RESULTS:Of the 95 PBC-sera,74% reacted with the peptide 475-499 and 58% with the pept ide 407-431 located within the catalytic domain of PDC-E2. Patients with other disorders or healthy controls were positive in only up to 18%. Antibodies to the unlipoylatedand lip oylated pept ide 167-184 within the inner lipoyl domain were found in only 5% and 11% of the PBC sera,respectively; using ovalbumin-coupled peptides,the incidence increased up to 57% (unlipoylated form). CONCLUSION:Peptides within the catalytic site of PDC-E2 rather than the previously reported lipoyl binding peptide 167-184 may represent major immunodomin ant epitopes recognized by AMA in PBC.

Bioinformatics analysis and characteristics of envelop glycoprotein E epitopes of dengue virus

The major envelope glycoprotein E of dengue (DEN) virus plays a central role in the biology of flaviviruses. It is capable of inducing a protective immune response in vivo and responsible for the viral binding to the cellular receptor. The crystal structures of glycoprotein E ectodomains have already been determined. However, it is still un-clear where the well-defined B-cell epitopes for glycoprotein E which induce the neutralizing an-tibodies locates. Thus, in order to characterize the role of glycoprotein E in the pathogenesis of dengue virus infection, we first used network servers (http://bio.dfci. harvard.edu/Tools/ &http://www. imtech. res. in) to predict and analyze the well defined B-cell and T-cell epitopes of the glycoprotein of the DEN-1 HAWAII strain. Then based on the highly conserved envelop glyco-protein amino acids, the hydrophilicity, antigenic-ity, accessibility and flexibility of envelop glyco-protein E were further predicted by using Biotic softwares (DNASTAR) and network servers (http://bio. dfci.harvard.edu/Tools/), the secondary structure was putatively obtained. In our study, the sequence at 281-295 amino acid (aa) for den-gue virus type 1 HAWAII strain and the sequence at 345-359, 383-397 for dengue virus type 2 NGC strain were predicted as the more prevalent epi-topes by using multiple parameters and different analysis softwares, respectively. Two epitopes of DEN-2 and one of DEN-1 locate on the domain Ш and domainⅡ of the protein E, respectively. Sub-sequently, further studies will be carried out to examine the antigenicity and protection of the synthetic peptides with higher scores in the av-erage antigen index (AI) and better hydrophilic properties determined by our data.

ASFV pp62 Protein Has 9 Dominant B-T Cell Combined Epitopes

[Objective]The paper was to study the basic characteristics of the pp62 protein of the African swine fever virus strain Pig/HLJ/2018,and to provide more basic data for the study of the virus.[Method]We used the ProtParam program to analyze the physical and chemical properties of the pp62 protein.TMHMM-2.0 and SignalP-5.0 were used to analyze protein transmembrane region and signal peptide,and Lasergene 7.0 Protean program was used to study protein antigen index,hydrophilicity,surface accessibility and titration curve.Protein N-glycosylation site and O-glycosylation site came out with NetNGlyc-1.0 and NetOGlyc-4.0 online servers.Then,PSIPRED-4.0,NetSurfP-2.0,and PSRSM were used to analyze protein secondary structure,BepiPred1.0 and IEDB tools were used to analyze protein B-cell epitopes,and NetMHC 4.0 and NetMHCpan tools were used to analyze protein T-cell epitopes.And we used Swiss-Model to analyze the high-level structure of the protein,the EzMol tool to visually analyze B-T cell combined epitopes,and finally,MEGA 7.0 to analyze the genetic evolutionary relationship of the protein.[Result]The pp62 protein of African swine fever viral strain Pig/HLJ/2018 had a molecular weight of 60.5 kDa.It was a hydrophilic acid labile protein,and had no transmembrane region and signal peptide.There were 5 N-glycosylation sites and 4 O-glycosylation sites.Analysis of the secondary structure of the protein showed that the proportions of helix,coil and strands were 45.5%,41.7%and 12.8%,respectively.The study of dominant epitopes revealed that there were 14 dominant B-cell epitopes and 16 dominant T-cell epitopes.And 9 dominant B-T cell combined epitopes located on the surface of the protein molecule were found.The phylogenetic tree constructed with the pp62 protein showed that the evolutionary relationship of Pig/HLJ/2018 strain was the closest to Georgia/2007/1,which belonged to genotype II.[Conclusion]The results will provide basic information for pp62 research.

MAPPING EPITOPES OF HUMAN PAPILLOMAVIRUS TYPE 16 L1 PROTEIN WITH A PHAGE DISPLAY EPITOPE LIBRARY

The objective of this study is to map epitopes on HPMAPV16 L1 protein and provide information to the design of HPV16 prophylactic peptide vaccine. The epitopes on L1 protein were screenedby polyclonal and two monoclonal antibodies (BS and F4G3) against RPV16 L1 protin from a 6-merfd phage display epitope library with the method or immuuo-afrinity screening (Biopauuing). Aferthree rounds or Bio-Panning, the Positive phages were detected by L1 antibodies again with ELISA.The positive phages reacted strongly with L1 antibodies were then identified by DNA sequencing.Three mimotopes have been screened by polycloual and two monoclonal antibodies. The mimotope(LSLFSC) reacted with mouoclonal antibody B8 showed 50% pomology with the sequence 270275a. a (DSLFFY) of prototype HPV16 L1. Another mimotope (LTSSYS) reacted with polyclonalantibodies had 66% pomology with the L1 sequence 516~521a. A(TTSSTS), also a mimotope (DRWDRF) was found had the bomologic RF with the known L1 sequence 441 ~446a. a. The mimotopesLSLFSC and DRWDRF were adjacent to the epitopes at 267~269a. a and 422~441 a. a reported byother researchers Previously. Our results suggest that there might be a batch of epitopes on HPV16L1 ppotein, and the predominant epitopes of HPV16 L1 protein are located in the above two domains. These results will be helpful for design or HPV16 prophylactic peatide vaccines and HPVpolyvalent vaccines.

Elimination of murine and human T-cell epitopes in recombinant immunotoxin eliminates neutralizing and anti-drug antibodies in vivo

Antibodies against the toxin portion of recombinant immunotoxins （RIT） reduce their efficacy and pose a potential safety risk. To overcome this problem we mutated the very immunogenic immunotoxin SSIP to produce LMB-T20, a de-immunized RIT that has the eight human T-cell epitopes in SSIP modified or removed. To determine the effect of T-cell epitope removal in vivo we mapped the T-cell epitopes in immune-competent BALB/c mice and found that these mice recognize two epitopes. One corresponds to the human immunodominant T-cell epitope and the other to a human subdominant epitope; both were eliminated in LMB-T20. We found that mice immunized with LMB-T20 did not have T-cell activation and did not develop anti-drug antibodies （ADA）, whereas mice immunized with SSIP, showed T-cell activation, and developed ADA detected by both ELISA and drug neutralizing assays. The ability of the mice treated with LMB-T20 to respond to other antigens was not compromised. We conclude that elimination of T-cell epitopes is sufficient to prevent formation of antibodies to an immunogenic foreign protein.

Construction and characterization of an HCV-derived multi-epitope peptide antigen containing B-cell HVR1 mimotopes and T-cell conserved epitopes

Hepatitis C(HCV) genome is highly variable,particularly in the hypervariable region 1 (HVR1) of its E2 envelope gene.The variability of HCV genome has been a major obstacle for de-veloping HCV vaccines.Due to B-cell HVR1 mimotopes mimicking the antigenicity of natural HVR1 epitopes and some T-cell epitopes from the consensus sequence of HCV genes conserving among the different HCV genotypes,we synthesized an minigene of HCV-derived multi-epitope peptide an-tigen(CMEP) ,which contains 9 B-cell HVR1 mimotopes in E2,2 conserved CTL epitopes in C,1 conserved CTL epitope in NS3 and 1 conserved Th epitope in NS3.This minigene was cloned into a GST expression vector to generate a fusion protein GST-CMEP.The immunogenic properties of CEMP were characterized by HCV infected patients' sera,and found that the reactivity frequency reached 75%.The cross reactivity of anti-CEMP antibody with different natural HVR1 variants was up to 90%.Meanwhile,we constructed an HCV DNA vaccine candidate,plasmid pVAX1.0-st-CMEP carrying the recombinant gene(st) of a secretion signal peptide and PADRE universal Th cell epitope sequence in front of the CMEP minigene.Immunization of rabbits with pVAX1.0-st-CMEP resulted in the production of antibody,which was of the same cross reactivity as the fusion protein GST-CMEP.Our findings indicate that the HCV-derived multi-epitope peptide antigen in some degree possessed the characteristics of neutralizing HCV epitopes,and would be of the value as a candidate for the development of HCV vaccines.

Partial protection induced by phage library-selected peptides mimicking epitopes of Schistosoma japonicum

Objective To obtain peptide mimicking epitopes of Schistosoma japonicum (S.japonicum) through screening of a phage peptide library and to test their potential for induction of protection. Methods S.japonicum infected sera from Microtus fortis (IMFS) and normal sera from Microtus fortis (NMFS) were used respectively to screen a 12-mers random peptide library by testing the reactivity of anti-S.japonicum serum with the phagotopes. After three rounds of biopanning, the pooled phages were used to immunize mice, after which challenge infection was performed. Results Of 12 randomly picked clones, 10 clones selected using IMFS and 7 clones selected using NMFS were shown to be antigenic. Significant reduction in adult worms (22.6%) and a high reduction (68.9%) in liver eggs were achieved following immunization with phages screened with IMFS. However, no protection was elicited by those selected with NMFS. Conclusion The results show that the phagotopes are both antigenic and immunogenic, suggesting a potential use of phage displayed peptide as novel vaccines against S. japonicum.

DNA-based immunization against hepatitis B surface antigen carrying preS epitopes

Three plasmid expression vectors containing modified hepatitis B surface antigen (HBsAg) carrying pres epitopes were constructed. Transient expression after in vitro transfection in COS-M6 cells showed that under the transcriptional control of the human cytomegalovirus (CMV) immediate early promoter, fusion genes expressed the modified HBV envelope proteins which were efficiently secreted into culture medium and presented HBsAg, preS1 and preS2 antigenicity. DNA-based immunization with these plasmids carrying pres sequences induced anti-HBs antibody in BALB/c mice. The titers of anti-HBs antibody were higher than those appeared in mice immunized with plasmid carrying S gene only. DNA injection with plasmids containing preS1 sequences elicited also high titers of anti-preS1 antibody. Moreover, the antipreS1 antibodies were found to appear earlier than anti-HBs antibodies.