Evaluation of recombinant Chinese avian hepatitis E virus (CaHEV) ORF2 and ORF3 proteins for protection of chickens against CaHEV infection

Avian hepatitis E virus (HEV) is the etiologic agent of big liver and spleen disease in chickens. In 2010, the Chinese avian HEV (CaHEV) strain was isolated from chickens and demonstrated to cause the decreased egg production in layer hens. No avian HEV commercial vaccine has yet been developed to prevent virus infection in China. In this study, recombinant CaHEV truncated ORF2 and complete ORF3 proteins were evaluated separately for immunoprotection of chickens against CaHEV infection. First, truncated ORF2 and complete ORF3 proteins were expressed in Escherichia coli. Next, 48 specific-pathogen-free chickens were randomly divided into three groups. One group was immunized with truncated ORF2 protein, the second group was immunized with recombinant ORF3 protein, while the third group (control) was mock-immunized with PBS. After booster immunization, chickens in all three groups were challenged intravenously with CaHEV infectious stock and assessed for viremia, fecal virus shedding, seroconversion, and gross hepatic lesions. In the ORF2 protein-immunized group, no chickens showed evidence of avian HEV infection. In the ORF3 protein-immunized group, nine chickens exhibited viremia and seven had fecal virus shedding. In the control group, all 16 chickens showed viremia and fecal virus shedding. However, the durations in chickens from the ORF3 protein group (2–4 weeks) were shorter than the ones from the control group (4–8 weeks). Moreover, no gross liver lesions emerged in the ORF2 protein group, while lesions observed in the ORF3 protein group were milder than in controls. Therefore, the ORF2 protein can confer complete immunoprotection against chicken CaHEV infection, while the ORF3 protein only confers partial immunoprotection.     

Immunization with recombinant ORF2 p551 protein protects common marmosets (Callithrix jacchus) against homologous and heterologous hepatitis E virus challenge

BackgroundHepatitis E virus (HEV) is a major causative agent of acute hepatitis worldwide, prompting continuous HEV vaccine efforts. Vaccine development is hampered by the lack of convenient animal models susceptible to infection with different HEV genotypes. We produced recombinant open reading frame 2 protein (pORF2; p551) of HEV genotype (GT) 3 and assessed its immunogenicity and protectivity against HEV challenge in common marmosets (Callithrix jacchus, CM).Methodsp551 with consensus sequence corresponding to amino acid residues 110–660 of HEV GT3 pORF2 was expressed in E. coli and purified by affinity chromatography. CMs were immunized intramuscularly with 20 μg of p551 VLPs with alum adjuvant (n = 4) or adjuvant alone (n = 2) at weeks 0, 3, 7 and 19. At week 27, p551-immunized and control animals were challenged with HEV GT1 or GT3 and thereafter longitudinally screened for markers of liver function, anti-HEV IgG and HEV RNA in feces and sera.ResultsPurified p551 formed VLPs with particle size of 27.71 ± 2.42 nm. Two immunizations with p551 induced anti-HEV IgG mean titer of 1:1810. Immunized CMs challenged with homologous and heterologous HEV genotype did not develop HEV infection during the follow-up. Control CMs infected with both HEV GT1 and GT3 demonstrated signs of HEV infection with virus shedding and elevation of the levels of liver enzymes. High levels of anti-HEV IgG persisted in vaccinated CMs and control CMs that resolved HEV infection, for up to two years post challenge.ConclusionsCMs are shown to be a convenient laboratory animal model susceptible to infection with HEV GT1 and GT3. Immunization with HEV GT3 ORF2/p551 triggers potent anti-HEV antibody response protecting CMs from homologous and heterologous HEV challenge. This advances p551 in VLPs as a prototype vaccine against HEV.     

Recombinant vaccine against hepatitis E: dose response and protection against heterologous challenge

Thirty-two rhesus monkeys were used to evaluate the dose response of a recombinant HEV vaccine, and the efficacy of the vaccine based on the ORF2 protein of the Pakistani strain for pre- and post-exposure vaccination against intravenous challenge with homologous or heterologous virus was examined. Post-exposure vaccination did not protect animals against hepatitis. Although primates vaccinated twice with 50-μg, 10-μg, 2-μg, or 0.4-μg doses of the recombinant 55 kDa ORF-2 protein were infected, they were protected from hepatitis when they were challenged with very high doses of the homologous strain of HEV. Primates vaccinated twice with a 50 μg dose of the recombinant protein were protected from hepatitis after heterologous challenge with the Mexican strain, the strain of HEV most genetically distant from the Pakistani strain.     

Protective immunity against influenza virus challenge by norovirus P particle-M2e and HA2-AtCYN vaccines in chickens

Development of a broadly reactive influenza vaccine that can provide protection against emerging type A influenza viruses is a big challenge. We previously demonstrated that a vaccine displaying the extracellular domain of the matrix protein 2 (M2e) on the surface loops of norovirus P-particle (M2eP) can partially protect chickens against several subtypes of avian influenza viruses. In the current study, a chimeric vaccine containing a conserved peptide from the subunit 2 of hemagglutinin (HA) glycoprotein (HA2) and Arabidopsis thaliana cyanase protein (AtCYN) (HA2-AtCYN vaccine) was evaluated in 2-weeks-old chickens. Depending on the route of administration, the HA2-AtCYN vaccine was shown to induce various levels of HA2-specific IgA in tears as well as serum IgG, which were associated with partial protection of chickens against tracheal shedding of a low pathogenicity H5N2 challenge virus. Furthermore, intranasal administration with a combination of HA2-AtCYN and M2eP vaccines resulted in enhanced protection compared to each vaccine alone. Simultaneous intranasal administration of the vaccines did not interfere with secretory IgA induction by each vaccine. Additionally, significantly higher M2eP-specific proliferative responses were observed in peripheral blood mononuclear cells of all M2eP-vaccinated groups when compared with the mock-vaccinated group. Although tripling the number of M2e copies did not enhance the protective efficacy of the chimeric vaccine, it significantly reduced immunodominance of P-particle epitopes without affecting the robustness of M2e-specific immune responses. Taken together, our data suggests that mucosal immunization of chickens with combinations of mechanistically different cross-subtype-conserved vaccines has the potential to enhance the protective efficacy against influenza virus challenge.     

戊型肝炎病毒ORF3蛋白功能的研究进展

戊型肝炎是一种由戊型肝炎病毒(HEV)引起的经肠道传播的病毒性肝炎。对HEV结构蛋白的深入研究有利于病毒感染机制的明确和疾病的预防。ORF3蛋白作为HEV结构蛋白之一,其具体功能目前仍不太清楚。一直以来,针对该蛋白的研究非常少,近年来研究发现HEV ORF3蛋白在细胞信号转导、病毒感染和免疫抑制等方面都有非常重要的作用。     

Assessment of the cross-protective capability of recombinant capsid proteins derived from pig, rat, and avian hepatitis E viruses (HEV) against challenge with a genotype 3 HEV in pigs

Hepatitis E virus (HEV), the causative agent of hepatitis E, is primarily transmitted via the fecal-oral route through contaminated water supplies, although many sporadic cases of hepatitis E are transmitted zoonotically via direct contact with infected animals or consumption of contaminated animal meats. Genotypes 3 and 4 HEV are zoonotic and infect humans and other animal species, whereas genotypes 1 and 2 HEV are restricted to humans. There exists a single serotype of HEV, although the cross-protective ability among the animal HEV strains is unknown. Thus, in this study we expressed and characterized N-terminal truncated ORF2 capsid antigens derived from swine, rat, and avian HEV strains and evaluated their cross-protective ability in a pig challenge model. Thirty, specific-pathogen-free, pigs were divided into 5 groups of 6 pigs each, and each group of pigs were vaccinated with 200μg of swine HEV, rat HEV, or avian HEV ORF2 antigen or PBS buffer (2 groups) as positive and negative control groups. After a booster dose immunization at 2 weeks post-vaccination, the vaccinated animals all seroconverted to IgG anti-HEV. At 4 weeks post-vaccination, the animals were intravenously challenged with a genotype 3 mammalian HEV, and necropsied at 4 weeks post-challenge. Viremia, fecal virus shedding, and liver histological lesions were compared to assess the protective and cross-protective abilities of these antigens against HEV challenge in pigs. The results indicated that pigs vaccinated with truncated recombinant capsid antigens derived from three animal strains of HEV induced a strong IgG anti-HEV response in vaccinated pigs, but these antigens confer only partial cross-protection against a genotype 3 mammalian HEV. The results have important implications for the efficacy of current vaccines and for future vaccine development, especially against the novel zoonotic animal strains of HEV.     

戊型肝炎病毒ORF3基因转染HeLa细胞及其稳定表达

目的 将戊型肝炎病毒ORF3基因转染HeLa细胞,建立能稳定表达ORF3蛋白(pORF3)的细胞株.方法 将ORF3基因片段克隆至真核表达质粒pcDNA3,构建重组质粒pcDNA3-ORF3.电穿孔法将其导入HeLa细胞中,G418筛选得到稳定抗性的细胞株,并用RT-PCR和Western印迹法分别从mRNA水平和蛋白水平检测ORF3的表达.结果 成功构建了重组表达质粒pcDNA3-ORF3,并筛选获得能稳定表达pORF3蛋白的HeLa细胞株.结论 pORF3蛋白能够在HeLa细胞中稳定表达,为进一步研究其生物学功能奠定了实验基础.     

戊型肝炎病毒基因Ⅳ型病毒样颗粒的表达和抗原性分析

目的表达戊型肝炎病毒(HEV)基因Ⅳ型(G4)结构蛋白ORF2截短的基因片段,观察病毒样颗粒(VLP)的装配情况,对纯化的VLP进行抗原性分析。方法为了制备HEV病毒样颗粒,将结构蛋白ORF2的N末端111个氨基酸残基截掉,然后将112至660共549个氨基酸残基的基因与杆状病毒基因重组,在昆虫细胞Tn5表达。首先用聚丙烯酰胺凝胶电泳和WesternBlotting检测基因是否正确表达,再用超速离心检测是否形成病毒样颗粒,最后用免疫电镜和ELISA分析病毒样颗粒的抗原特异性。结果含有截掉了N末端111个氨基酸残基的HEVG4的ORF2基因的重组杆状病毒感染昆虫细胞Tn5,除了可以表达最初的产物(相对分子质量为58×103的蛋白分子)外,也产生了一些可能经过宿主细胞酶类处理的蛋白分子,相对分子质量分别为57×103、56×103和54×103,并分泌到培养液中。经超速离心和密度梯度离心,电镜观察发现只有54×103的蛋白分子可以自行组装成VLP,颗粒直径为23~24nm,浮密度为1·285g/cm3,与HEVG1比较,G4VLP具有相同的大小和浮密度,但表达量低。G4VLP与HEV病人血清可以发生抗原抗体反应,用G4VLP作抗原可以检测HEV的G1、G3、G4型特异性IgM和IgG抗体。结论该研究证实截短的HEVG4的ORF2结构蛋白基因可以在重组杆状病毒表达系统高效表达。形成的VLP具有HEV病毒颗粒类似的抗原活性,可用于制备抗HEV诊断试剂和开发预防用疫苗。     

Recombinant infectious laryngotracheitis virus expressing Newcastle disease virus F protein protects chickens against infectious laryngotracheitis virus and Newcastle disease virus challenge

In this study, we isolated and identified an infectious laryngotracheitis virus (ILTV) that was naturally avirulent in specific pathogen-free (SPF) chickens, with the aim of developing a more efficacious vaccine against ILTV and Newcastle disease virus (NDV). We constructed a US9-deleted ILTV mutant based on this avirulent ILTV, and then constructed a recombinant ILTV (designated ILTV-ΔUS9-F) expressing the fusion protein (F) of the genotype VII NDV based on the US9-deleted ILTV mutant. Expression of the F protein in ILTV-ΔUS9-F-infected cells was confirmed by indirect immunofluorescence assay and western blotting. The inserted F gene was stably expressed in ILTV-ΔUS9-F. The growth kinetics of ILTV-ΔUS9-F were comparable to those of the wild-type ILTV strain. Vaccination of SPF chickens with ILTV-ΔUS9-F produced no clinical signs but did induce low levels of NDV-specific enzyme-linked immunosorbent assay and neutralizing antibodies. A single vaccination with 10⁴ plaque-forming units (PFU) of ILTV-ΔUS9-F provided good protection against both genotype VII and IX NDVs based on clinical signs, similar to the protection provided by the commercial live La Sota vaccine. Notably, ILTV-ΔUS9-F limited the replication and shedding of genotype VII NDV from oropharyngeal swabs more efficiently than the La Sota vaccine. In addition, vaccination with lower doses (10³ and 10² PFU) of ILTV-ΔUS9-F also provided sufficient clinical protection. These results indicated that ILTV-ΔUS9-F may be a bivalent vaccine candidate against both ILTV and NDV.     

广西地区野鼠戊型肝炎病毒相关抗体的血清流行病学

目的调查广西地区野鼠有无戊型肝炎病毒感染以及相关抗体的阳性率。方法利用HEV核衣壳蛋白的不同多肽片断作为包被抗原,采用酶免疫法测定广西地区556只各种野鼠外周血抗-HEV。结果556只各种野鼠中,共有90只(16.2%)抗-HEV阳性。其中,353只褐家鼠中,68只(19.3%)阳性,152只黄胸鼠中,22只(14.5%)阳性,两组阳性率差异无显著意义(P>0.1);51只其他鼠类(板齿鼠、竹鼠、鼷鼠、小家鼠)均未测出抗-HEV。不同地区鼠类的抗体阳性率不同,农村明显高于城市(P<0.05),卫生状况差的地点鼠类抗体阳性率最高。结论广西地区的野鼠中大约16%有抗-HEV抗体存在,这些野鼠感染过HEV或HEV相关病毒,但这些鼠类是否构成相关病毒的宿主还有待于进一步的研究。     

Long lasting immunity in chickens induced by a single shot of influenza vaccine prepared from inactivated non-pathogenic H5N1 virus particles against challenge with a highly pathogenic avian influenza virus

An influenza vaccine was prepared from inactivated whole particles of the non-pathogenic strain A/duck/Hokkaido/Vac-1/04 (H5N1) virus using an oil adjuvant containing anhydromannitol-octadecenoate-ether (AMOE). The vaccine was injected intramuscularly into five 4-week-old chickens, and 138 weeks after vaccination, they were challenged intranasally with 100 times 50% chicken lethal dose of the highly pathogenic avian influenza (HPAI) virus A/chicken/Yamaguchi/7/04 (H5N1). All 5 chickens survived without exhibiting clinical signs of influenza, although 2 days post-challenge, 3 vaccinated chickens shed limited titres of viruses in laryngopharyngeal swabs.     

Heterologous prime-boost immunization of Newcastle disease virus vectored vaccines protected broiler chickens against highly pathogenic avian influenza and Newcastle disease viruses

Avian Influenza virus (AIV) is an important pathogen for both human and animal health. There is a great need to develop a safe and effective vaccine for AI infections in the field. Live-attenuated Newcastle disease virus (NDV) vectored AI vaccines have shown to be effective, but preexisting antibodies to the vaccine vector can affect the protective efficacy of the vaccine in the field. To improve the efficacy of AI vaccine, we generated a novel vectored vaccine by using a chimeric NDV vector that is serologically distant from NDV. In this study, the protective efficacy of our vaccines was evaluated by using H5N1 highly pathogenic avian influenza virus (HPAIV) strain A/Vietnam/1203/2004, a prototype strain for vaccine development. The vaccine viruses were three chimeric NDVs expressing the hemagglutinin (HA) protein in combination with the neuraminidase (NA) protein, matrix 1 protein, or nonstructural 1 protein. Comparison of their protective efficacy between a single and prime-boost immunizations indicated that prime immunization of 1-day-old SPF chicks with our vaccine viruses followed by boosting with the conventional NDV vector strain LaSota expressing the HA protein provided complete protection of chickens against mortality, clinical signs and virus shedding. Further verification of our heterologous prime-boost immunization using commercial broiler chickens suggested that a sequential immunization of chickens with chimeric NDV vector expressing the HA and NA proteins following the boost with NDV vector expressing the HA protein can be a promising strategy for the field vaccination against HPAIVs and against highly virulent NDVs.     

Enhanced cross-lineage protection induced by recombinant H9N2 avian influenza virus inactivated vaccine

Background

Antigenic drift of H9N2 low pathogenic avian influenza viruses (AIV) may result in vaccination failure in the poultry industry and thus a cross-protective vaccine against H9N2 AIV is highly desirable.

HBV外膜蛋白2型重组腺相关病毒免疫原性

目的观察乙型肝炎病毒(HBV)外膜大蛋白(LP)基因的2型重组腺相关病毒(rAAV-2-LP)在Balb/c小鼠体内的免疫原性。方法以5×1011的rAAV-2-LP单次肌肉注射接种Balb/c小鼠,RT-PCR扩增肝脏组织中HBV外膜大蛋白基因cDNA;RIA法检测血清中表面抗体(抗-HBs)滴度;51Cr释放分析检测细胞毒性T淋巴细胞(CTL)活性。结果HBV外膜大蛋白基因已整合到肝细胞染色体DNA,rAAV-LP接种小鼠后第20 d,小鼠体内可出现针对HBV外膜大蛋白特异性CTL,第30 d,血清中可检测到表面抗体。结论rAAV可以介导HBV外膜大蛋白基因转移到小鼠肝细胞;rAAV-2-LP免疫小鼠可以同时诱导体液和细胞免疫反应的出现。基于rAAV-2载体的HBV疫苗,对于防止HBV感染,尤其是作为慢性乙型肝炎的治疗性疫苗可能具有潜在的应用价值。     

A dual vaccine candidate against norovirus and hepatitis E virus

Norovirus (NoV) and hepatitis E virus (HEV) are both enterically-transmitted viruses causing gastroenteritis and hepatitis, respectively, in humans. While a vaccine against HEVs recently became available in China, there is no prophylactic or therapeutic approach against NoVs. Both NoV and HEV have surface protrusions formed by dimers of the protruding (P) domains of the viral capsids, which is responsible for virus–host interactions and eliciting viral neutralizing antibody. We developed in this study a bivalent vaccine against the two viruses through a recently developed polyvalent complex platform. The dimeric P domains of NoV and HEV were fused together, designated as NoV P⁻-HEV P, which was then linked with the dimeric glutathione-S-transferase (GST). After expression and purification in E. coli, the GST-NoV P⁻-HEV P fusion protein assembled into polyvalent complexes with a mean size of 1.8 μm, while the NoV P⁻-HEV P formed oligomers ranging from 100 to 420 kDa. Mouse immunization study demonstrated that both GST-NoV P⁻-HEV P and NoV P⁻-HEV P complexes induced significantly higher antibody titers to NoV P⁻ and HEV P, respectively, than those induced by a mixture of the NoV P⁻ and HEV P dimers. Furthermore, the complex-induced antisera exhibited significantly higher neutralizing activity against HEV infection in HepG2/3A cells and higher blocking activity on NoV P particles binding to HBGA receptors than those of the dimer-induced antisera. Thus, GST-NoV P⁻-HEV P and NoV P⁻-HEV P complexes are promising dual vaccine candidates against both NoV and HEV.     

Immunologic evaluation of 10 different adjuvants for use in vaccines for chickens against highly pathogenic avian influenza virus

Avian influenza viruses (AIV) are a threat to poultry production worldwide. Vaccination is utilized as a component of control programs for both high pathogenicity (HP) and low pathogenicity (LP) AIV. Over 95% of all AIV vaccine used in poultry are inactivated, adjuvanted products. To identify the best formulations for chickens, vaccines were prepared with beta-propiolactone (BPL) inactivated A/British Columbia/314514-1/2004 H7N3 LP AIV using ten commercially available or experimental adjuvants. Each vaccine formulation was evaluated for immunogenicity in chickens. Challenge studies with an antigenically homologous strain of HPAIV were conducted to compare protection against mortality and measure reductions in virus levels in oral swabs. The four best adjuvants from the studies with BPL inactivated antigen were selected and tested identically, but with vaccines prepared from formalin inactivated virus. Mineral and vegetable oil based adjuvants generally induced the highest antibody titers with 100% seroconversion by 3 weeks post vaccination. Chitosan induced positive antibody titers in 100% of the chickens, but the titers were significantly lower than those of most of the oil based adjuvants. Antibody levels from calcium phosphate and alginate adjuvanted groups were similar to those of non-adjuvanted virus. All groups that received adjuvanted vaccines induced similar levels of protection against mortality (0–20%) except the groups vaccinated with calcium phosphate adjuvanted vaccines, where mortality was similar (70%) to groups that received non-adjuvanted inactivated virus or no vaccine (60–100% mortality). Virus shedding in oral swabs was variable among the treatment groups. Formalin inactivated vaccine induced similar antibody titers and protection against challenge compared to BPL inactivated vaccine groups. These studies support the use of oil adjuvanted vaccines for use in the poultry industry for control for AIV.     

Recombinant Newcastle disease virus expressing H9 HA protects chickens against heterologous avian influenza H9N2 virus challenge

In order to produce an efficient poultry H9 avian influenza vaccine that provides cross-protection against multiple H9 lineages, two Newcastle disease virus (NDV) LaSota vaccine strain recombinant viruses were generated using reverse genetics. The recombinant NDV-H9Con virus expresses a consensus-H9 hemagglutinin (HA) that is designed based on available H9N2 sequences from Chinese and Middle Eastern isolates. The recombinant NDV-H9Chi virus expresses a chimeric-H9 HA in which the H9 ectodomain of A/Guinea Fowl/Hong Kong/WF10/99 was fused with the cytoplasmic and transmembrane domain of the fusion protein (F) of NDV. Both recombinant viruses expressed the inserted HA stably and grew to high titers. An efficacy study in chickens showed that both recombinant viruses were able to provide protection against challenge with a heterologous H9N2 virus. In contrast to the NDV-H9Chi virus, the NDV-H9Con virus induced a higher hemagglutination inhibition titer against both NDV and H9 viruses in immunized birds, and efficiently inhibited virus shedding through the respiratory route. Moreover, sera collected from birds immunized with either NDV-H9Con or NDV-H9Chi were able to cross-neutralize two different lineages of H9N2 viruses, indicating that NDV-H9Con and NDV-H9Chi are promising vaccine candidates that could provide cross-protection among different H9N2 lineage viruses.     

Recombinant Newcastle disease virus expressing the infectious bronchitis virus S1 gene protects chickens against Newcastle disease virus and infectious bronchitis virus challenge

The recombinant LaSota strain expressing a chimeric IBV S1 gene (rLaSota-S1) was constructed with the S1 gene of the LX4 type IBV ck/CH/LDL/091022. The expression of the S1 protein was detected by an indirect immunofluorescence assay and Western blotting. The rLaSota-S1 strain was slightly attenuated, and its growth dynamics were similar to that of the parental LaSota strain. Vaccination of specific pathogen-free chickens with the rLaSota-S1 strain induced NDV hemagglutination inhibition antibodies, and it protected chickens from challenge with virulent NDV. In addition, vaccination with the rLaSota-S1 strain induced IBV-specific IgG antibodies and cellular immunity; however, a single vaccination provided partial protection with reduced virus shedding. Better protection efficiency was observed after a booster vaccination, which resulted in higher antibody titers, significantly fewer disease symptoms, and reduced virus replication and shedding. Our results suggest that the rLaSota-S1 strain is a bivalent vaccine candidate against both NDV and IBV.     

Construction and immunogenicity of recombinant swinepox virus expressing capsid protein of PCV2

To explore development of a vaccine against PCV2 infections, the gene of capsid protein (Cap) was inserted into the swinepox virus (SPV) genome by homologous recombination. The recombinant swinepox virus expressing capsid protein (rSPV-cap) was verified by PCR, western blot and immunofluorescence assays. To evaluate the immunogenicity of rSPV-cap, twenty-four PCV2 seronegative minipigs were immunized with rSPV-cap, wild type SPV (wtSPV; negative control), or PBS (challenge control). After inoculation with PCV2, pigs in the rSPV-cap immunized group showed significantly higher average daily weight gain (ADG) and shorter fever duration compared with the wtSPV treated group (P<0.05). Cap-specific antibody in the rSPV-cap immunized group increased dramatically after vaccination and increased continuously over time. PCV2 genomic copies in the serum of rSPV-cap immunized pigs were significantly less compared with the wtSPV treated group at all time points after inoculation (P<0.01). Significant reduction in gross lung lesion scores, histopathological lung lesion scores, and lymph node lesion scores were noted in the rSPV-cap immunized group compared with the wtSPV treated group (P<0.01). The results suggested that the recombinant rSPV-cap provided pigs with significant protection from PCV2-associated disease; thus, it offers proof-of-principle for the development of a vaccine for the prevention of PCV2-associated disease in pigs.     

Robust manufacturing and comprehensive characterization of recombinant hepatitis E virus-like particles in Hecolin

The hepatitis E virus (HEV) vaccine, Hecolin^®, was licensed in China for the prevention of HEV infection and HEV-related diseases with demonstrated safety and efficacy 0005 and 0010. The vaccine is composed of a truncated HEV capsid protein, p239, as the sole antigen encoded by open reading frame 2 and produced using Escherichia coli platform. The production of this virus-like particle (VLP) form of the antigen was successfully scaled up 50-fold from a bench scale to a manufacturing scale. Product consistency was demonstrated using a combination of biophysical, biochemical and immunochemical methods, which revealed comparable antigen characteristics among different batches. Particle size of the nanometer scale particulate antigen and presence of key epitopes on the particle surface are two prerequisites for an efficacious VLP-based vaccine. The particle size was monitored by several different methods, which showed diameters between 20 and 30 nm for the p239 particles. The thermal stability and aggregation propensity of the antigen were assessed using differential scanning calorimetry and cloud point assay under heat stress conditions. Key epitopes on the particulate antigen were analyzed using a panel of murine anti-HEV monoclonal antibodies (mAbs). The immuno reactivity to the mAbs among the different antigen lots was highly consistent when analyzed quantitatively using a surface plasmon resonance technique. Using a sandwich ELISA to probe the integrity of two different epitopes in the antigen, the specific antigenicity of multiple batches was assessed to demonstrate consistency in these critical product attributes. Overall, our findings showed that the antigen production process is robust and scalable during the manufacturing of Hecolin^®.