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.

Prevention of de novo HBV infection by the presence of anti-HBs in transplanted patients receiving core antibody-positive livers

AIM： To analyze whether the presence of anti-HBs in liver transplant recipients is effective in preventing HBV infection. METHODS： Twenty-three patients receiving anti-HBc positive liver were studied. Nine recipients were anti-HBc positive as a result of previous HBV infection. Of them, one also received HBV vaccine during the pre-liver transplantation period. Fourteen recipients were anti-HBs positive due to HBV vaccine administered during the pretransplant period. Liver biopsy was obtained in 10/14 anti-HBc negative/anti-HBs positive recipients and in 4/9 anti-HBc positive recipients. RESULTS： After a mean foUow-up period of 46 months, 1 recipient with protective serum anti-HBs levels developed de novo HBV infection as a consequence of immune escape HBV mutants. Among the 14 vaccinated anti-HBc negative/anti-HBs positive recipients, 1/10 patients with available liver biopsy （10%） had liver HBV-DNA at 13 mo post-liver transplantation without serum viral markers and did not develop de novo HBV infection.The vaccinated anti-HBc positive recipient without HBV vaccine response was HBV-DNA positive in serum and liver, viral DNA was continuously negative in the following tests, so a spontaneous seroconversion was diagnosed. CONCLUSION： The presence of anti-HBs as a result of HBV vaccine or past HBV infection seems to be effective at protecting patients receiving livers from anti-HBc positive donors. However, the emergence of immune escape HBV mutants, which can evade the anti-HBs protection, should be considered as a risk of HBV infection.

The Experimental Study on Treating Transgenic HBV Mice with Recombined IL-2-PreS DNA Vaccine

The aim of this study is to investigate the feasibility and mechanism of hIL-2-preS DNA vaccine as prevention and therapeutic approach against Hepatitis B. Eukaryon expression vector involving hIL-2 and preS gene was constructed with recombinant technique and transferred into normal BALB/c mice and HBV transgenic mice (Tg-Mice) respectively. Then a series of detection were performed: detection of anti-preS2, HBs antibody and HBsAg in BALB/c mice and Tg-mice with ELISA, quantification of HBV DNA copies in HBV Tg-mice serum with real-time PCR, determination of hepatitis degree with immunopathological HE staining and detection of liver function. Anti-preS1 can be detected at 4 th , 6 th and 10 th week in inoculated BALB/c mice. Injection with gene gun gained an advantage over muscular and subcutaneous injection since it acquired just 1/10 inoculation quantity (10 μg/mouse). Highest expression of IgG2a at 4 th week suggested Th1-mediated immune response, which facilitated HBV cleaning. Of all inoculated HBV Tg-mice, 80% of them showed anti-preS2, HBs antibody positive and HBV DNA decreased, and 20% showed negative for HBsAg. HE staining to hepatic tissue showed obvious infiltration of inflammatory cells, swelling and granular degeneration of hepatocytes. In our study, IL-2-preS DNA vaccine which can provoke the humoral and cellular immune response and break the immune tolerance supports the designation and construction of new vaccine against HBV and specific immune remedy for HBV continuous infection.

Recent advances in DNA vaccine of hepatitis virus

Nucleic acid vaccine or DNA vaccine is a hopeful vac- cine to prevent and treat viral hepatitis. Problems exist in different DNA vaccines for HBV or HCV. Optimal animal model should be established study vaccine against hepatitis. Apart from the strategy to enhance the efficiency of DNA vaccine, combined use of cytokines or chemokines, different routes of inocu- lation, design of optimal vector, ISS insertion in the plasmid vectors, etc to enhance the efficiency of DNA vaccine are reviewed.

Novel DNA vaccine based on hepatitis B virus core gene induces specific immune responses in Balb/c mice

AIM： To investigate the immunogenidty of a novel DNA vacoine, pSW3891/HBc, based on HBV core gene in Balb/c mice. METHODS： A novel DNA vaccine, pSW3891/HBc, encoding HBV core gene was constructed using a vector plasmid pSW3891. Balb/c mice were immunized with either pSW3891/HBc or empty vector DNA via gene gun. IgG anti-HBc responses in mouse sera were demonstrated by ELISA. Specific cytotoxicity of cytotoxic T lymphocytes （CTLs） of mice was quantitatively measured by lactate dehydrogenase release assay. RESULTS： HBcAg was expressed effectively in 293T cell line transiently transfected with pSW3891/HBc. Strong IgG anti-HBc responses were elicited in mice immunized with pSW3891/HBc. The end-point titers of anti-HBc reached the highest 1：97 200, 4 wk after the third immunization. The specific CTL killing with the highest specific lysis reached 73.25% at effector：target ratio of 20：1 in mice that received pSW3891/HBc DNA vaccine. CONCLUSION： pSW3891/HBc vaccination elicits specific anti-HBc response and induces HBc-specific CTL response in immunized Balb/c mice.

Seropositivity for Hepatitis B Virus, Vaccination Status and Response to Vaccine in a Cohort of Dental Students

Background: The development of a vaccine against hepatitis B virus (HBV) has been a major achievement in terms of prevention of HBV infection. To evaluate the immunological status against HBV of dental-profession students, we analysed the long-term immunogenicity and effectiveness of HBV vaccination in Italian dental students with different work seniorities, determining the influence of epidemiological variables on the immune response. Methods: This study, carried out from January 2014 to April 2016, involved 361 under- and post-graduate dental students attending the Second University of Naples. HBV serum markers were determined and multivariate logistic regression analysis was used to identify factors associated with the level of long-term immunogenicity. Results: Of the 361 subjects evaluated, 15 (4.2%) declared no history of vaccination. All vaccinated subjects were HBsAg/anti-HBc negative, with 86 (24.9%) having an anti-HBs titre <10 IU/L. The latter were younger, more likely to be attending undergraduate dental school, and more likely to have been vaccinated in infancy. Conclusion: The findings of this study suggest that assessment of HBV serum markers in workers potentially exposed to hospital infections is useful to identify small numbers of unvaccinated subjects or vaccinated subjects with low antibody titre, all of whom should be referred for a booster series of vaccinations.

Hepatitis B Virus (HBV) Infection in Patients at Pasteur Institute of Dakar in Senegal from 2016 to 2020: Prevalence and Seroprotection Level

Hepatitis B virus (HBV) infection is highly endemic in Senegal. Vaccination of all children against HBV was introduced in 1999 and included in Expanded Programme on Immunisation in 2005. The aim of this study was to assess the prevalence and immune status against HBV in patients received at Pasteur Institut in Dakar, Senegal. Methods: Between January 2016 and December 2020, patients aged between 1 and 96 years received laboratory were included in the study. Serum samples were analysed for HBV serology (HBs antigen: HBsAg, HBs antibody: HBsAb and HBc antibody: HBcAb) using ARCHITECT? analyser. Patients with anti-HBs antibody levels (HBsAb ≥ 10 IU/l) were considered seroprotected against HBV. Results: A total of 5629 patients were analysed with a mean age of 39 years and extremes from 1 to 96 years. The most represented age group was 31 - 45 years with 38.4%. HBsAg was present in 520 patients (9.2%) and was signed by sex and age group. Anti-HBc antibodies were found in 52.7% of patients and 1603 (28.48%) had isolated anti-HBs antibodies reflecting proportion of people vaccinated at the time of the study. However, 2143 patients (41.9%) had no seroprotection (HBsAb 10 IU/L) and 640 (12.6%) had strong seroprotection defined as HBsAb > 1000 IU/L. Conclusion: Our results show a significant presence of virus in Senegalese population and low vaccination coverage, especially in adults. Evaluation of HBsAb levels and provision of HBV booster shots should be considered for children in Senegal.

实时定量PCR测定治疗性HBV DNA疫苗工程菌的质粒拷贝数

目的 比较不同的定量方法和总DNA制备方法对实时定量PCR(real-time quantitative PCR, qPCR)测定治疗性HBV DNA疫苗工程菌的质粒拷贝数(plasmid copy number, PCN)的影响,为建立快速简便的治疗性HBV DNA疫苗工程菌的PCN测定方法提供参考。方法 通过试剂盒提取法、Triton X-100煮沸法和培养基煮沸法分别制备总DNA样品用于qPCR检测,使用绝对定量方法和相对定量方法计算不同制备方法样品的PCN,并对测定结果进行统计学分析。结果 试剂盒提取法制备的样品经绝对定量和相对定量计算PCN,结果分别为43.10±4.02和42.92±3.98,显著低于Triton X-100煮沸法的结果(69.32±6.51和68.58±6.42)以及培养基煮沸法的结果(75.73±7.46和76.15±7.50)。任一样品制备方法,比较其绝对定量和相对定量结果,差异均无统计学意义。结论 qPCR的绝对定量和相对定量计算方法都适用于治疗性HBV DNA疫苗工程菌PCN测定,Triton X-100煮沸法更适合于总DNA模板制备。

计划免疫后出生献血者乙肝无症状慢性感染血清学与分子生物学特征分析

目的了解深圳地区计划免疫后出生献血者乙肝病毒无症状慢性感染情况,分析其血清学和分子生物学特征。方法将1992年之后出生的无偿献血者的HBsAg ELISA阳性血液标本进行乙肝两对半检测和核酸大容量提取,对其BCP/PC区及S区进行巢式PCR扩增及qPCR定量检测,并对产物进行基因测序及序列分析。结果2020年12月—2022年1月共收集46632份计划免疫后出生无偿献血者标本,其中含男性31612份,女性15020份。通过常规筛查得到ELISA阳性标本99份,经化学发光、巢式PCR、实时荧光PCR等方法检测,61份确证HBsAg阳性,阳性率0.13%(61/46632)。其中男性49份,阳性率0.16%,女性12份,阳性率0.08%(P<0.05)。50/61份标本获得S序列,经系统进化树分析,其中B型46份[92%(46/50),男性38份,女性8份],C型4份[8%(4/50),男性3份,女性1份]。S区突变频率高的分别N40S(8/46,17.39%),G44E(7/46,15.22%),Q129H/R(6/46,13.04%),Y161F/S(7/46,15.22%),V179A(4/46,8.70%),S53L(2/4,50%),C69T(2/4,50%),I126S/T(2/4,50%)。其中免疫逃逸突变有Q129R和T/I126A/N/S/T。结论乙肝疫苗接种能大大降低献血者的乙肝表面抗原阳性率,提高输血安全性。高频率的免疫逃逸突变也成为血液安全潜在风险,需要进一步探讨研究。

治疗型双质粒HBV DNA疫苗的构建及其鉴定

为构建以人白细胞介素 2 /γ干扰素(hIL 2 /hIFN γ)融合基因为佐剂的治疗型HBVDNA疫苗 ,采用DNA重组技术分别构建含有HBV包膜中蛋白 (preS2 ·S)抗原和hIL 2 /hIFN γ融合蛋白的真核表达质粒即pcDNAS2 ·S和pcDNAIIF ,酶谱和测序分析表明克隆的preS2 ·S和hIL 2 /hIFN γ融合蛋白基因片段的方向、序列与预期相符。用脂质体转染试剂转染COS 7细胞 ,并用ELISA检测转染细胞培养上清中目的基因表达水平。结果显示 ,质粒转染后 4 8h达峰值 ,分别为HBsAg(P/N) =7.6 3、IL 2 =1 0 .35ng/ml、IFN γ =7.90ng/ml。以CTLL 2依赖细胞株/MTT比色法和微量细胞病变抑制法 (WISH VSV)检测pcDNAIIF转染后 4 8h培养上清中IL 2及IFN γ活性 ,结果分别为 998U/ml和 2 4 9U/ml。证明构建的重组质粒pcDNAS2 ·S和pcDNAIIF结构正确 。

HBV壳聚糖微球疫苗鼻腔免疫的初步研究

目的 研究HBV表面抗原亚单位微球疫苗及DNA微球疫苗鼻腔免疫的效果 ,为新型鼻腔疫苗的研制提供实验基础。方法 选取HBV表面抗原亚单位疫苗及HBVDNA疫苗作为模型 ,以壳聚糖作为载体 ,通过沉淀 凝聚法制备壳聚糖微球疫苗 ,分别通过鼻腔、腹腔及肌肉免疫小鼠 ,在不同时间点收集小鼠血清 ,用ELISA检测血清中抗HBVIgG ,分析不同免疫途径的免疫效果。结果 在HBV亚单位微球疫苗免疫组中 ,腹腔与鼻腔免疫效果差异无显著意义 ;而在HBVDNA疫苗免疫组中 ,肌肉免疫后 12周IgG达到峰值 ,随后开始出现下降趋势 ;而微球疫苗则在 16周才达峰值 ,且鼻腔免疫组要高于肌肉免疫组。结论 鼻腔免疫可作为亚单位疫苗及DNA疫苗的免疫途径 ,且相对于DNA疫苗而言 ,壳聚糖微球具有保护作用及缓释作用。

含HBV PreS2/S的抗体化乙肝基因疫苗可增强乙肝病毒特异性CTL应答

目的:构建乙肝病毒抗原PreS2/S和抗体Fc段的融合分子,观察该抗体化的乙肝疫苗诱导特异性细胞免疫应答的能力及状况。方法:用PCR的方法扩增乙肝病毒抗原PreS2/S和鼠IgG1Fc段基因,依次克隆到载体上;体外转染小鼠肌细胞,观察表面抗原转录水平和蛋白水平的表达情况;基因免疫小鼠,观察其诱导的特异性CTL免疫应答状况。结果:基因克隆融合分子经酶切和测序鉴定构建成功;体外转染实验表明融合分子可以在肌肉细胞中表达;免疫小鼠脾脏细胞用特异性抗原刺激后能产生很强的细胞免疫应答,其中特异性CTL反应明显增强。结论:基于抗体Fc段的抗体化乙肝疫苗能增强机体对HBV的特异性CTL反应,有利于打破HBV感染导致的免疫耐受。

治疗性HBV DNA疫苗诱导健康Balb/c小鼠细胞免疫应答的实验研究

目的探讨治疗性HBVDNA疫苗对健康Balb/c小鼠表达Th1类细胞免疫应答的影响。方法治疗性HBVDNA疫苗(pS2·S+pFP)以剂量(50μg+50μg)/只对Balb/c小鼠进行接种,以酶联免疫斑点法(ELISPOT)、流式细胞术(FACS)分析特异性分泌IFN-γ阳性T细胞的免疫效果。结果免疫6周时,实验组用HBsAg刺激后其诱生的IFN-γ细胞频数(34±15.3)较不用HBsAg组(4±4.4)高(P<0.05,t=5.65),也较同期空载体免疫对照组(3±3.6)高(P<0.05,t=5.21);治疗性HBVDNA疫苗诱导小鼠CD4+T细胞表达IFN-γ的百分比实验组[(0.28±0.17)%]与对照组[(0.20±0.03)%]比较,无显著性差异(P>0.05,t=0.21);而诱导CD8+T细胞表达IFN-γ的百分比实验组[(0.69±0.08)%]与对照组[(0.24±0.12)%]比较,具显著性差异(P<0.05,t=4.167)。结论治疗性HBVDNA疫苗能有效诱导T细胞分泌HBsAg特异性IFN-γ因子,并以CD8+T细胞分泌占优而发挥细胞免疫应答的优势。

以HBc颗粒为呈现载体的HBV多表位复合基因真核表达载体的构建

目的 构建以HBVHBc颗粒为呈现载体的HBV多表位复合基因真核表达质粒 ,以探讨HBV基因免疫的新途径。方法 PCR扩增HBc第 1～ 72aa及 93～ 183aa编码序列并定向克隆至pcDNA3.1的NheⅠ /XhoⅠ位点 ,构建真核表达载体pHBcdM。合成HBV多表位基因并插入HBc原脊区基因位点 ,构建HBc Mep融合基因真核表达质粒。经PCR、酶切及序列测定等方法筛选阳性质粒。结果 双酶切及测序结果证实阳性质粒正确克隆了约 885bp、编码HBc与HBV多表位的复合基因。结论 成功构建了以HBc颗粒为呈现载体的HBV多表位复合基因真核表达载体pHBc Mep ,为研究pHBc Mep作为DNA疫苗的免疫活性奠定基础。

治疗性双质粒HBV DNA疫苗工程菌的中试发酵工艺研究

目的研究双质粒HBV DNA疫苗工程菌的中试发酵工艺。方法首先通过计算质粒拷贝数，检测工程菌DH5α/pS2．S和DH5α/pFP在传代过程中的遗传稳定性，通过摇瓶培养确定培养基组成，再在30L发酵罐内，通过改变培养基成分、培养时间、补料方式，确定最佳发酵参数。并将确定的最佳发酵参数应用于50L发酵罐连续3批中试规模的发酵，同时考察在发酵培养过程中质粒稳定性和超螺旋质粒DNA的比例。结果工程菌DH5α/pS2．S和DH5α/pFP在连续传代30次后，质粒拷贝数保持稳定。确定最佳发酵参数为以甘油为碳源的培养基培养，梯度恒速流加方式补料，培养时间为10h。通过3批稳定发酵，最终可获得湿菌58．0～71．8g／L，质粒含量可达到1．11～1．58mg／g菌，超螺旋质粒DNA的比例达93％以上。结论已建立了稳定的双质粒HBV DNA疫苗工程菌中试发酵工艺，为进一步规模化生产奠定了基础。

高复制HBV转基因小鼠模型对抗乙型肝炎病毒药物的效应研究

目的:研究高复制HBV转基因小鼠模型对抗乙肝病毒药物的效应评价。方法:选用抗乙肝药物拉咪呋啶、大剂量重组乙肝蛋白疫苗、α-1b型干扰素和RNA干扰在转基因小鼠进行药效及作用机制评价。结果:拉咪呋啶、重组乙肝疫苗、α-1b型干扰素均可使HBV转基因小鼠血清中HBV DNA滴度显著降低。其中后两者还可提高机体脾细胞IL-2和IFN-γ的水平及使分泌IFN-γ脾细胞Elispot斑点数明显增加。将RNA干扰表达载体pU6-siHBV质粒尾静脉注入小鼠体内。注射后5d血清HBsAg下降56.7%,抑制作用持续14d。肝脏免疫组化显示HBcAg阳性细胞明显减少,但血清HBV DNA定量无明显降低。结论:本近交系高复制HBV转基因小鼠模型对抗乙肝药物药效学评估是可靠、可行的。

乙肝疫苗免疫献血者人群HBV感染的分子生物学特性研究

目的探讨乙肝疫苗免疫献血者人群中HBV感染的分子生物学特性及其HBsAg＋／抗．HBs＋发生机制。方法从13504（人）份无偿献血者标本中，收集HBsAg＋／HBVDNA＋者58例，应用巢式．聚合酶链反应技术获得其中35例Pre—S／S基因片段并测序、基因分型；采用荧光定量聚合酶链反应技术测定58例阳性标本的病毒载量，通过咨询随访，确认其中的接种乙肝疫苗后HBsAg＋／抗-HBs＋／抗-HBc＋者，并与对应基因型的HBsAg＋／抗。HBs-／抗HBc＋毒株Pre—S／S序列比对，分析其变异特征。结果深圳地区无偿献血者HBV检出率为0．43％（58／13504），HBV感染率约为1．90％（26／13707）；35例Pre—S／S区扩增成功的标本基因型B、C构成比分别为42．86％（15／35）、57．14％（20／35），其中5例HBsAg＋／抗．HBs＋／抗-HBc＋标本均为基因曰型，抗-HBs滴度（10．45—88．76）（中位数21．54）mlU／mL，病毒载量为（3．8～5．5）X10’（中位数6．7x10。）IU／mL。HBsAg＋／抗一HBs＋组除了Pre—S1基因区，Pre．S／S、Pre．S2、S、MHRl、MHR2、a抗原决定簇基因的氨基酸置换率均明显高于HBsAg＋／抗HBs一组各区（P〈0．05），以主要亲水1区（MHRl）和Pre．s2区的氨基酸变异率最高（3．11％、4．36％），MHRl区出现少见的N40S、P62L变异，在主要亲水2区（MHR2）有60％（3／5）标本为高度保守，20％（1／5）标本在整个Pre-SIS区没发生变异。未发现a抗原决定簇常见G145R变异。结论接种乙肝疫苗后出现HBsAg＋／抗-HBs＋的机制与Pre-S／S区变异，特别是MHRl、Pre．s2区变异增多有重要关联，基因B型的HBVDNA可能在乙肝疫苗免疫压力下更易发生变异而导致抗-HBs与HBsAg不能中和。

应用S基因转染的Sp2/0细胞作为靶细胞研究HBV基因疫苗的细胞免疫应答

构建编码ＨＢｓＡｇ 蛋白的重组真核表达质粒ｐＣＲ３－１Ｓ作为ＨＢＶ 基因疫苗， 免疫接种Ｂａ１ｂ／ｃ 小鼠。以重组质粒ｐＣＲ３－１Ｓ转染的Ｓｐ２／０ 细胞作为靶细胞， 采用５１Ｃｒ ４ｈ 释放法， 体外检测免疫小鼠的淋巴细胞杀伤功能。结果显示， 与空载体对照组相比较， ＨＢＶ基因疫苗可诱导Ｂａｌｂ／ｃ 小鼠产生ＨＢＶ 特异性细胞毒性Ｔ 细胞应答（ Ｐ＞ ０－０５） ， 提示以Ｓｐ２／０ 基因转染的细胞作为靶细胞， 检测免疫Ｂａｌｂ／ｃ 小鼠淋巴细胞的杀伤功能是可靠的。

抗HBV的治疗性双质粒DNA疫苗的构建及初步药效学研究

目的:构建抗乙型肝炎病毒(HBV)的治疗性DNA疫苗并进行体外、体内鉴定。方法:采用PCR技术扩增含有HBV包膜中蛋白(preS2.S)抗原基因和hIL-2/hIFN-γ融合蛋白的基因,将目的基因分别亚克隆于pVAX1真核表达载体,并进行酶切和测序分析;转染双质粒于COS-7细胞检测基因及蛋白表达情况;利用Combinatotial Extension(CE)软件模建分析佐剂质粒表达融合蛋白的空间结构;双质粒联合在体电脉冲技术(EP)注射BALB/c小鼠以检测特异性的体液和细胞免疫应答。结果:经酶谱和测序分析表明,构建的双质粒pVAX1/S2.S(pS2.S)和pVAX1/IL-2IFN-γ(pIIF)的基因片段的方向、序列完全正确;ELISA法定量检测双质粒转染COS-7细胞后48小时目的基因(preS2.S和hIL-2/hIFN-γ)的蛋白表达水平较高,HBsAg、IL-2、IFN-γ的含量分别为45.1、10.03、11.5ng/ml;模拟空间结构分析表明佐剂质粒的融合蛋白中两细胞因子的活性部位均裸露在外;小鼠免疫试验结果表明,疫苗pS2.S能诱导健康小鼠的保护性抗-HBs的抗体产生,且具有剂量相关性;佐剂pIIF可显著增强疫苗pS2.S质粒的免疫效果;在EP辅助作用下,质粒pS2.S和pIIF共肌注BALB/c小鼠,低剂量就能诱导较强特异性的细胞和体液免疫。结论:成功构建了抗HBV的DNA疫苗pS2.S及佐剂pIIF质粒,并具有较特异的体内外活性。