Naturally occurring mutations in surface proteins of Hepatitis B virus(HBV) usually result in altered hepatitis B surface antigen(HBsAg) secretion efficiency.In the present study,we reported two conserved residues,M75...Naturally occurring mutations in surface proteins of Hepatitis B virus(HBV) usually result in altered hepatitis B surface antigen(HBsAg) secretion efficiency.In the present study,we reported two conserved residues,M75 and M103 with respect to HBsAg,mutations of which not only attenuated HBsAg secretion(M75 only),but also suppressed HBV genome replication without compromising the overlapping p-gene product.We also found M75 and M103 can initiate truncated surface protein(TSPs) synthesis upon over-expression of full-length surface proteins,which may possibly contribute to HBV genome replication.However,attempts to rescue replicationdefective HBV mutant by co-expression of TSPs initiated from M75 or M103 were unsuccessful,which indicated surface proteins rather than the putative TSPs were involved in regulation of HBV genome replication.展开更多
Hepatitis B virus(HBV) infection is a global public health concern. HBV causes chronic infection in patients and can lead to liver cirrhosis, hepatocellular carcinoma, and other severe liver diseases. Thus, understand...Hepatitis B virus(HBV) infection is a global public health concern. HBV causes chronic infection in patients and can lead to liver cirrhosis, hepatocellular carcinoma, and other severe liver diseases. Thus, understanding HBV-related pathogenesis is of particular importance for prevention and clinical intervention. HBV surface antigens are indispensable for HBV virion formation and are useful viral markers for diagnosis and clinical assessment. During chronic HBV infection, HBV genomes may acquire and accumulate mutations and deletions, leading to the expression of defective HBV surface antigens. These defective HBV surface antigens have been found to play important roles in the progression of HBV-associated liver diseases. In this review, we focus our discussion on the nature of defective HBV surface antigen mutations and their contribution to the pathogenesis of fulminant hepatitis B. The relationship between defective surface antigens and occult HBV infection are also discussed.展开更多
AIM To test whether a simple animal, Caenorhabditis elegans(C. elegans), can be used as an alternative model to study the interaction between hepatitis B virus antigens(HBs Ag) and host factors. METHODS Three plasmids...AIM To test whether a simple animal, Caenorhabditis elegans(C. elegans), can be used as an alternative model to study the interaction between hepatitis B virus antigens(HBs Ag) and host factors. METHODS Three plasmids that were able to express the large, middle and small forms of HBs Ags(LHBs Ag, MHBs Ag, and SHBs Ag, respectively) driven by a ubiquitous promoter(fib-1) and three that were able to express SHBs Ag driven by different tissue-specific promoters were constructed and microinjected into worms. The brood size, egglaying rate, and gonad development of transgenic worms were analyzed using microscopy. Levels of m RNA related to endoplasmic reticulum stress, enpl-1, hsp-4, pdi-3 and xbp-1, were determined using reverse transcription polymerase reaction(RT-PCRs) in three lines of transgenic worms and dithiothreitol(DTT)-treated wild-type worms. RESULTS Severe defects in egg-laying, decreases in brood size, and gonad retardation were observed in transgenic worms expressing SHBs Ag whereas moderate defects were observed in transgenic worms expressing LHBs Ag and MHBs Ag. RT-PCR analysis revealed that enpl-1, hsp-4 and pdi-3 transcripts were significantly elevated in worms expressing LHBs Ag and MHBs Ag and in wild-type worms pretreated with DTT. By contrast, only pdi-3 was increased in worms expressing SHBs Ag. To further determine which tissue expressing SHBs Ag could induce gonad retardation, we substituted the fib-1 promoter with three tissue-specific promoters(myo-2 for the pharynx, est-1 for the intestines and mec-7 for the neurons) and generated corresponding transgenic animals. Moderate defective phenotypes were observed in worms expressing SHBs Ag in the pharynx and intestines but not in worms expressing SHBs Ag in the neurons, suggesting that the secreted SHBs Ag may trigger a cross-talk signal between the digestive track and the gonad resulting in defective phenotypes. CONCLUSION Ectopic expression of three forms of HBs Ag that causes recognizable phenotypes in transgenic worms suggests that C. elegans can be used as an alternative model for studying virus-host interactions because the resulting phenotype is easily detected through microscopy.展开更多
Hepatitis B virus (HBV) is one of the major causes of chronic hepatitis, cirrhosis and liver cancer. In combating HBV infections, HBV diagnosis and vaccination are therefore critical. The hepatitis B virus surface ant...Hepatitis B virus (HBV) is one of the major causes of chronic hepatitis, cirrhosis and liver cancer. In combating HBV infections, HBV diagnosis and vaccination are therefore critical. The hepatitis B virus surface antigen (HBsAg) is a key target molecule in developing vaccines and diagnostic systems. To date, although HBsAg has been expressed in bacteria, yeasts and mammalian cells, there are still limitations in the existing ones, which leave the necessity for searching new HBsAg production methods. In this study, a simple phage display-based method was developed to produce the purified full-length HBsAg molecules for further immunization studies. For this purpose, the HBsAg coding gene was cloned into a pCANTAB5E phagemid vector and expressed on the surface of M13 filamentous phages. The HBsAg-expressing phage nanosystem was then used as immunization agent in BALB/cJ mice. The ELISA results for sera obtained from mice immunized with HBsAg-displaying phage particles revealed an immune response against HBsAg. These results demonstrate the potential use of a full-length antigen to be displayed on phages as cost effective adjuvant-free immunization agents as an alternative to the highly purified and more expensive antigens conjugated with carrier molecules.展开更多
Occult hepatitis B virus(HBV)infection(OBI)is a challenging pathobiological and clinical issue that has been widely debated for several decades.By definition,OBI is characterized by the persistence of HBV DNA in the l...Occult hepatitis B virus(HBV)infection(OBI)is a challenging pathobiological and clinical issue that has been widely debated for several decades.By definition,OBI is characterized by the persistence of HBV DNA in the liver tissue(and in some cases also in the serum)in the absence of circulating HBV surface antigen(HBsAg).Many epidemiological and molecular studies have indicated that OBI is an important risk factor for hepatocellular carcinoma(HCC)development.OBI may exert direct pro-oncogenic effects through the activation of the same oncogenic mechanisms that are activated in the course of an HBsAg-positive infection.Indeed,in OBI as in HBV-positive infection,HBV DNA can persist in the hepatocytes both integrated into the host genome as well as free episome,and may maintain the capacity to produce proteins-mainly X protein and truncated preS-S protein-provided with potential transforming properties.Furthermore,OBI may indirectly favor HCC development.It has been shown that the persistence of very low viral replicative activity during OBI may induce mild liver necro-inflammation continuing for life,and substantial clinical evidence indicates that OBI canaccelerate the progression of liver disease towards cirrhosis that is considered the most important risk factor for HCC development.展开更多
AIM: To generate recombinant adenoviral vector con-taining calreticulin (CRT)-hepatitis B surface antigen (HBsAg) fusion gene for developing a safe, effective and HBsAg-specific therapeutic vaccine.METHODS: CRT and HB...AIM: To generate recombinant adenoviral vector con-taining calreticulin (CRT)-hepatitis B surface antigen (HBsAg) fusion gene for developing a safe, effective and HBsAg-specific therapeutic vaccine.METHODS: CRT and HBsAg gene were fused using polymerase chain reaction (PCR), endonuclease diges-tion and ligation methods. The fusion gene was cloned into pENTR/D-TOPO transfer vector after the base pairs of DNA (CACC) sequence was added to the 5′ end. Adenoviral expression vector containing CRT-HBsAg fusion gene was constructed by homologous recombinan-tion. The human embryo kidney (HEK) 293A cells were transfected with linearized DNA plasmid of the recombi-nant adenoviral vector to package and amplify recombi-nant adenovirus. The recombinant adenovirus titer was characterized using the end-dilution assay. The expres-sion of the CRT/HBsAg fusion protein in Ad-CRT/HBsAg infected 293A cells was detected by Western blotting.RESULTS: The CRT-HBsAg fusion gene was char-acterized by PCR and sequencing and its length and sequence were confirmed to be accurate. The CRT-HB-sAg fusion gene recombinant pENTR/D-TOPO transfer vector was constructed. The recombinant adenoviral vector, Ad-CRT/HBsAg, was generated successfully. The titer of Ad-CRT/HBsAg was characterized as 3.9 × 1011 pfu/mL. The CRT-HBsAg fusion protein was ex-pressed by HEK 293A cells correctly. CONCLUSION: CRT/HBsAg fusion gene recombinant replication-defective adenovirus expression vector is constructed successfully and this study has provided an experimental basis for further studies of Hepatitis B vi-rus gene therapy.展开更多
目的:探讨低水平HBV-DNA乙肝患者乙肝病毒外膜大蛋白(hepatitis B virus large surface protein,LHBs)的表达及其意义,从而探讨LHBs是否可以用作乙型肝炎e抗原(hepatitis B e antigen,HBeAg)阴性乙型肝炎患者病毒复制程度的判定指标。方...目的:探讨低水平HBV-DNA乙肝患者乙肝病毒外膜大蛋白(hepatitis B virus large surface protein,LHBs)的表达及其意义,从而探讨LHBs是否可以用作乙型肝炎e抗原(hepatitis B e antigen,HBeAg)阴性乙型肝炎患者病毒复制程度的判定指标。方法:对83例HBeAg阴性的慢性乙型肝炎患者血清,采用ELISA进行LHBs检测,全自动免疫分析仪检测HBeAg,实时荧光定量PCR方法检测HBV DNA。分析HBV DNA无拷贝数组、低拷贝数组及高拷贝数组中LHBs的检出率以及HBV DNA不同拷贝数组与LHBs的相关性。结果:在HBV DNA无拷贝数组,LHBs的阳性率为6.38%;低拷贝数组,LHBs的阳性率为56.25%,吸光度值与拷贝数对数值没有显著的相关性(r=0.25,P=0.36);高拷贝数组,阳性率为95%,吸光度值与拷贝数对数值有良好相关性(r=0.90,P<0.0001)。结论:检测HBeAg阴性慢性乙型肝炎患者血清LHBs,有助于判断患者体内HBV的复制程度,但是否能够作为HBeAg阴性乙型肝炎抗病毒治疗终点的有效判定指标,尚有待进一步探讨。展开更多
The expression and secretion of preS containing hepatitis B surface antigen in vaccinia virus system was investigated. The human TK^- 143 cells were infected with the recombinant vaccinia viruses vTMS-1 or vTLS-1. Cel...The expression and secretion of preS containing hepatitis B surface antigen in vaccinia virus system was investigated. The human TK^- 143 cells were infected with the recombinant vaccinia viruses vTMS-1 or vTLS-1. Cells infected with vTMS-1, which contains the preS2+S gene, produced preS2 containing middle HBsAg proteins. Similarly, cells produced preS1 containing large HBsAg proteins upon infection with vTLS-1, which carries the preS1+preS2+S gene. The expression products could be secreted and form 22 nm particles. They reacted specifically with anti-preS1 and/or anti-preS2 monoclonal antibodies, and exhibited pHSA-receptor (for polymerized human serum albumin) activity. In addition, the major S components of hepatitis B surface antigen were also present in the products expressed by vTMS-1 and vTLS-1.展开更多
AIM: Most studies on the immune effect of gp96 were focused on its enhancement of CTLs. It is interesting to know whether gp96 could influence the humoral immune response, and whether the recombinant N-terminal fragme...AIM: Most studies on the immune effect of gp96 were focused on its enhancement of CTLs. It is interesting to know whether gp96 could influence the humoral immune response, and whether the recombinant N-terminal fragment of gp96 could substitute native gp96 to stimulate the immune system.METHODS: gp96 isolated from livers of normal mice and its N-terminal fragment (amino acid 22-355) expressed in E coli were used for immunization of BALb/c mice. Eight groups of mice received one of the following regiments subcutaneously in 100 μL phosphate buffered saline (PBS)at an interval of 3 wk. Group 1: PBS only; group 2:gp96 only; group 3: N-terminal fragment only; group 4: HBsAg only; group 5: HBsAg+gp96; group 6: HBsAg+N-terminalfragment; group 7: HBsAg+incomplete Freud's adjuvant; group 8: HBsAg+N-terminal fragment (95 ℃ heated for 30 min). Serum anti-HBsAg antibody levels were assayed by ELISA. CTL responses in splenocytes were analyzed by ELISPOT after the last vaccination.RESULTS: The average titer of serum anti-HBsAg antibodyin the mice immunized with HBsAg together with gp96 or its N-terminal fragment were much higher than those immunized with HBsAg alone detected by ELISA. The cellular immune response of the mice immunized with HBsAg together with gp96 or its N-terminal fragment was not different with those immunized with HBsAg alone measured by ELISPOT assay.CONCLUSION: gp96 or its N-terminal fragment greatly improved humoral immune response induced by HBsAg, but failed to enhance the CTL response, which demonstrated the potential of using gp96 or its N-terminal fragment as a possible adjuvant to augment humoral immune response against HBV infection.展开更多
The N-terminal 54 base pairs (encoding amino acid residues 2—19) within the preS1 region of the human hepatitis B virus surface antigen gene were deleted by site-directed mutagenesis. Unlike the wild type large surfa...The N-terminal 54 base pairs (encoding amino acid residues 2—19) within the preS1 region of the human hepatitis B virus surface antigen gene were deleted by site-directed mutagenesis. Unlike the wild type large surface antigen protein; when this mutated gene was expressed in monkey kidney cell line COS-M6, the protein product (S301 protein) could be secreted from the cells. Moreover, the inhibition of the secretion of the major surface antigen protein by this altered large surface antigen protein was greatly reduced, suggesting that the deleted region contained a retention sequence which prevented the secretion of the large surface antigen. However, the coexpression of the major S protein was essential for the secretion of the S301 protein. When coexpressed, the secretion of these two proteins was synchronous. Like the wild type large surface antigen protein, the S301 protein could be translocated into ertdoplasmic reticulum and glycosylated after its synthesis in COS cells. The S301 protein was thermostable and proteinase-resistant. It also retained the antigenicity of the large S and major S proteins. Given the fact that the S301 protein is readily secretable, stable and identical to the large S protein in terms of their antigenicity, it may be developed into a new generation of recombinant vaccine for the prevention of viral hepatitis.展开更多
The DNA fragments coding for preS2(120 146) and preS1(21 47) amplified by PCR were fused to both 5′ and 3′ ends of S gene at the position of amino acid 223. The fusion gene was placed downstream of the promoter P7.5...The DNA fragments coding for preS2(120 146) and preS1(21 47) amplified by PCR were fused to both 5′ and 3′ ends of S gene at the position of amino acid 223. The fusion gene was placed downstream of the promoter P7.5 of the universal vaccinia viral vector pGJP 5 and the recombinant vaccinia virus vS2SS1 was then selected by \%in vivo\% homogeneous recombination. Fusion protein S2SS1 could be expressed in the mammalian cells infected with vS2SS1. The investigation of expression, secretion, antigenicity and particle assembly of the S2SS1 protein demonstrated that S2SS1 protein could be assembled into particles which presented preS1, preS2 and S antigenicity and be efficiently secreted from the cells. It also showed that the level of its expression and secretion approached to that of the S protein expressed by the recombinant vaccinia virus.展开更多
基金supported by the National Basic Research Program of China(2007CB512900)
文摘Naturally occurring mutations in surface proteins of Hepatitis B virus(HBV) usually result in altered hepatitis B surface antigen(HBsAg) secretion efficiency.In the present study,we reported two conserved residues,M75 and M103 with respect to HBsAg,mutations of which not only attenuated HBsAg secretion(M75 only),but also suppressed HBV genome replication without compromising the overlapping p-gene product.We also found M75 and M103 can initiate truncated surface protein(TSPs) synthesis upon over-expression of full-length surface proteins,which may possibly contribute to HBV genome replication.However,attempts to rescue replicationdefective HBV mutant by co-expression of TSPs initiated from M75 or M103 were unsuccessful,which indicated surface proteins rather than the putative TSPs were involved in regulation of HBV genome replication.
基金supported by the National Nature Science Foundation of China,No.31770180the Youth Innovation Promotion Association CAS,No.2016303
文摘Hepatitis B virus(HBV) infection is a global public health concern. HBV causes chronic infection in patients and can lead to liver cirrhosis, hepatocellular carcinoma, and other severe liver diseases. Thus, understanding HBV-related pathogenesis is of particular importance for prevention and clinical intervention. HBV surface antigens are indispensable for HBV virion formation and are useful viral markers for diagnosis and clinical assessment. During chronic HBV infection, HBV genomes may acquire and accumulate mutations and deletions, leading to the expression of defective HBV surface antigens. These defective HBV surface antigens have been found to play important roles in the progression of HBV-associated liver diseases. In this review, we focus our discussion on the nature of defective HBV surface antigen mutations and their contribution to the pathogenesis of fulminant hepatitis B. The relationship between defective surface antigens and occult HBV infection are also discussed.
基金Supported by Chang Gung Memorial Hospital,grants Nos.CMRPD1C0812,CMRPD1C0813 and BMRP742(to Lo SJ)
文摘AIM To test whether a simple animal, Caenorhabditis elegans(C. elegans), can be used as an alternative model to study the interaction between hepatitis B virus antigens(HBs Ag) and host factors. METHODS Three plasmids that were able to express the large, middle and small forms of HBs Ags(LHBs Ag, MHBs Ag, and SHBs Ag, respectively) driven by a ubiquitous promoter(fib-1) and three that were able to express SHBs Ag driven by different tissue-specific promoters were constructed and microinjected into worms. The brood size, egglaying rate, and gonad development of transgenic worms were analyzed using microscopy. Levels of m RNA related to endoplasmic reticulum stress, enpl-1, hsp-4, pdi-3 and xbp-1, were determined using reverse transcription polymerase reaction(RT-PCRs) in three lines of transgenic worms and dithiothreitol(DTT)-treated wild-type worms. RESULTS Severe defects in egg-laying, decreases in brood size, and gonad retardation were observed in transgenic worms expressing SHBs Ag whereas moderate defects were observed in transgenic worms expressing LHBs Ag and MHBs Ag. RT-PCR analysis revealed that enpl-1, hsp-4 and pdi-3 transcripts were significantly elevated in worms expressing LHBs Ag and MHBs Ag and in wild-type worms pretreated with DTT. By contrast, only pdi-3 was increased in worms expressing SHBs Ag. To further determine which tissue expressing SHBs Ag could induce gonad retardation, we substituted the fib-1 promoter with three tissue-specific promoters(myo-2 for the pharynx, est-1 for the intestines and mec-7 for the neurons) and generated corresponding transgenic animals. Moderate defective phenotypes were observed in worms expressing SHBs Ag in the pharynx and intestines but not in worms expressing SHBs Ag in the neurons, suggesting that the secreted SHBs Ag may trigger a cross-talk signal between the digestive track and the gonad resulting in defective phenotypes. CONCLUSION Ectopic expression of three forms of HBs Ag that causes recognizable phenotypes in transgenic worms suggests that C. elegans can be used as an alternative model for studying virus-host interactions because the resulting phenotype is easily detected through microscopy.
文摘Hepatitis B virus (HBV) is one of the major causes of chronic hepatitis, cirrhosis and liver cancer. In combating HBV infections, HBV diagnosis and vaccination are therefore critical. The hepatitis B virus surface antigen (HBsAg) is a key target molecule in developing vaccines and diagnostic systems. To date, although HBsAg has been expressed in bacteria, yeasts and mammalian cells, there are still limitations in the existing ones, which leave the necessity for searching new HBsAg production methods. In this study, a simple phage display-based method was developed to produce the purified full-length HBsAg molecules for further immunization studies. For this purpose, the HBsAg coding gene was cloned into a pCANTAB5E phagemid vector and expressed on the surface of M13 filamentous phages. The HBsAg-expressing phage nanosystem was then used as immunization agent in BALB/cJ mice. The ELISA results for sera obtained from mice immunized with HBsAg-displaying phage particles revealed an immune response against HBsAg. These results demonstrate the potential use of a full-length antigen to be displayed on phages as cost effective adjuvant-free immunization agents as an alternative to the highly purified and more expensive antigens conjugated with carrier molecules.
文摘Occult hepatitis B virus(HBV)infection(OBI)is a challenging pathobiological and clinical issue that has been widely debated for several decades.By definition,OBI is characterized by the persistence of HBV DNA in the liver tissue(and in some cases also in the serum)in the absence of circulating HBV surface antigen(HBsAg).Many epidemiological and molecular studies have indicated that OBI is an important risk factor for hepatocellular carcinoma(HCC)development.OBI may exert direct pro-oncogenic effects through the activation of the same oncogenic mechanisms that are activated in the course of an HBsAg-positive infection.Indeed,in OBI as in HBV-positive infection,HBV DNA can persist in the hepatocytes both integrated into the host genome as well as free episome,and may maintain the capacity to produce proteins-mainly X protein and truncated preS-S protein-provided with potential transforming properties.Furthermore,OBI may indirectly favor HCC development.It has been shown that the persistence of very low viral replicative activity during OBI may induce mild liver necro-inflammation continuing for life,and substantial clinical evidence indicates that OBI canaccelerate the progression of liver disease towards cirrhosis that is considered the most important risk factor for HCC development.
基金Supported by Grants from National Natural Science Foundation of China, No. 30901344
文摘AIM: To generate recombinant adenoviral vector con-taining calreticulin (CRT)-hepatitis B surface antigen (HBsAg) fusion gene for developing a safe, effective and HBsAg-specific therapeutic vaccine.METHODS: CRT and HBsAg gene were fused using polymerase chain reaction (PCR), endonuclease diges-tion and ligation methods. The fusion gene was cloned into pENTR/D-TOPO transfer vector after the base pairs of DNA (CACC) sequence was added to the 5′ end. Adenoviral expression vector containing CRT-HBsAg fusion gene was constructed by homologous recombinan-tion. The human embryo kidney (HEK) 293A cells were transfected with linearized DNA plasmid of the recombi-nant adenoviral vector to package and amplify recombi-nant adenovirus. The recombinant adenovirus titer was characterized using the end-dilution assay. The expres-sion of the CRT/HBsAg fusion protein in Ad-CRT/HBsAg infected 293A cells was detected by Western blotting.RESULTS: The CRT-HBsAg fusion gene was char-acterized by PCR and sequencing and its length and sequence were confirmed to be accurate. The CRT-HB-sAg fusion gene recombinant pENTR/D-TOPO transfer vector was constructed. The recombinant adenoviral vector, Ad-CRT/HBsAg, was generated successfully. The titer of Ad-CRT/HBsAg was characterized as 3.9 × 1011 pfu/mL. The CRT-HBsAg fusion protein was ex-pressed by HEK 293A cells correctly. CONCLUSION: CRT/HBsAg fusion gene recombinant replication-defective adenovirus expression vector is constructed successfully and this study has provided an experimental basis for further studies of Hepatitis B vi-rus gene therapy.
文摘目的:探讨低水平HBV-DNA乙肝患者乙肝病毒外膜大蛋白(hepatitis B virus large surface protein,LHBs)的表达及其意义,从而探讨LHBs是否可以用作乙型肝炎e抗原(hepatitis B e antigen,HBeAg)阴性乙型肝炎患者病毒复制程度的判定指标。方法:对83例HBeAg阴性的慢性乙型肝炎患者血清,采用ELISA进行LHBs检测,全自动免疫分析仪检测HBeAg,实时荧光定量PCR方法检测HBV DNA。分析HBV DNA无拷贝数组、低拷贝数组及高拷贝数组中LHBs的检出率以及HBV DNA不同拷贝数组与LHBs的相关性。结果:在HBV DNA无拷贝数组,LHBs的阳性率为6.38%;低拷贝数组,LHBs的阳性率为56.25%,吸光度值与拷贝数对数值没有显著的相关性(r=0.25,P=0.36);高拷贝数组,阳性率为95%,吸光度值与拷贝数对数值有良好相关性(r=0.90,P<0.0001)。结论:检测HBeAg阴性慢性乙型肝炎患者血清LHBs,有助于判断患者体内HBV的复制程度,但是否能够作为HBeAg阴性乙型肝炎抗病毒治疗终点的有效判定指标,尚有待进一步探讨。
文摘The expression and secretion of preS containing hepatitis B surface antigen in vaccinia virus system was investigated. The human TK^- 143 cells were infected with the recombinant vaccinia viruses vTMS-1 or vTLS-1. Cells infected with vTMS-1, which contains the preS2+S gene, produced preS2 containing middle HBsAg proteins. Similarly, cells produced preS1 containing large HBsAg proteins upon infection with vTLS-1, which carries the preS1+preS2+S gene. The expression products could be secreted and form 22 nm particles. They reacted specifically with anti-preS1 and/or anti-preS2 monoclonal antibodies, and exhibited pHSA-receptor (for polymerized human serum albumin) activity. In addition, the major S components of hepatitis B surface antigen were also present in the products expressed by vTMS-1 and vTLS-1.
基金Supported by the Major State Basic Research Development Program of China, Program 973, Grant No. 2001CB510001
文摘AIM: Most studies on the immune effect of gp96 were focused on its enhancement of CTLs. It is interesting to know whether gp96 could influence the humoral immune response, and whether the recombinant N-terminal fragment of gp96 could substitute native gp96 to stimulate the immune system.METHODS: gp96 isolated from livers of normal mice and its N-terminal fragment (amino acid 22-355) expressed in E coli were used for immunization of BALb/c mice. Eight groups of mice received one of the following regiments subcutaneously in 100 μL phosphate buffered saline (PBS)at an interval of 3 wk. Group 1: PBS only; group 2:gp96 only; group 3: N-terminal fragment only; group 4: HBsAg only; group 5: HBsAg+gp96; group 6: HBsAg+N-terminalfragment; group 7: HBsAg+incomplete Freud's adjuvant; group 8: HBsAg+N-terminal fragment (95 ℃ heated for 30 min). Serum anti-HBsAg antibody levels were assayed by ELISA. CTL responses in splenocytes were analyzed by ELISPOT after the last vaccination.RESULTS: The average titer of serum anti-HBsAg antibodyin the mice immunized with HBsAg together with gp96 or its N-terminal fragment were much higher than those immunized with HBsAg alone detected by ELISA. The cellular immune response of the mice immunized with HBsAg together with gp96 or its N-terminal fragment was not different with those immunized with HBsAg alone measured by ELISPOT assay.CONCLUSION: gp96 or its N-terminal fragment greatly improved humoral immune response induced by HBsAg, but failed to enhance the CTL response, which demonstrated the potential of using gp96 or its N-terminal fragment as a possible adjuvant to augment humoral immune response against HBV infection.
基金This research was supported in part by U. S. Public Health Service Grants CA-70175 and CA-2243 to J. Mertz from the U. S. National Institute of Health.
文摘The N-terminal 54 base pairs (encoding amino acid residues 2—19) within the preS1 region of the human hepatitis B virus surface antigen gene were deleted by site-directed mutagenesis. Unlike the wild type large surface antigen protein; when this mutated gene was expressed in monkey kidney cell line COS-M6, the protein product (S301 protein) could be secreted from the cells. Moreover, the inhibition of the secretion of the major surface antigen protein by this altered large surface antigen protein was greatly reduced, suggesting that the deleted region contained a retention sequence which prevented the secretion of the large surface antigen. However, the coexpression of the major S protein was essential for the secretion of the S301 protein. When coexpressed, the secretion of these two proteins was synchronous. Like the wild type large surface antigen protein, the S301 protein could be translocated into ertdoplasmic reticulum and glycosylated after its synthesis in COS cells. The S301 protein was thermostable and proteinase-resistant. It also retained the antigenicity of the large S and major S proteins. Given the fact that the S301 protein is readily secretable, stable and identical to the large S protein in terms of their antigenicity, it may be developed into a new generation of recombinant vaccine for the prevention of viral hepatitis.
文摘The DNA fragments coding for preS2(120 146) and preS1(21 47) amplified by PCR were fused to both 5′ and 3′ ends of S gene at the position of amino acid 223. The fusion gene was placed downstream of the promoter P7.5 of the universal vaccinia viral vector pGJP 5 and the recombinant vaccinia virus vS2SS1 was then selected by \%in vivo\% homogeneous recombination. Fusion protein S2SS1 could be expressed in the mammalian cells infected with vS2SS1. The investigation of expression, secretion, antigenicity and particle assembly of the S2SS1 protein demonstrated that S2SS1 protein could be assembled into particles which presented preS1, preS2 and S antigenicity and be efficiently secreted from the cells. It also showed that the level of its expression and secretion approached to that of the S protein expressed by the recombinant vaccinia virus.
