Antibody Persistence and Safety through 6 Months after Heterologous Orally Aerosolised Ad5-nCoV in individuals primed with two-dose CoronaVac previously

BackgroundHeterologous orally administered adenovirus type-5 vector-based COVID-19 vaccine (Ad5-nCoV) in individuals who were primed with two-dose CoronaVac (an inactivated SARS-CoV-2 vaccine, by Sinovac) previously, has been reported to be safe and highly immunogenic within 28 days post-boosting. However, antibody persistence and safety up to 6 months of this regimen are not been reported yet. MethodsThis is a randomized, open label, single-center trial on safety and immunogenicity of heterologous boost immunization with an orally administered aerosolised Ad5-nCoV vs. homologous boost immunization with CoronaVac after two-dose priming with CoronaVac in Chinese adults aged 18 years and older (NCT05043259). We followed the participants in this trial, including 140 in the low-dose aerosolised Ad5-nCoV group, 139 in the high-dose aerosolised Ad5-nCoV group, and 140 in the CoronaVac group for 6 months. Neutralising antibodies (NAbs) against live wild-type SARS-CoV-2 virus and omicron variant, and receptor-binding domain (RBD)-specific IgG antibodies were detected in serum samples collected at 28 days, 3 months, and 6 months after the booster dose. Serious adverse events (SAEs) were documented till month 6. ResultsThe low-dose and high-dose heterologous boost immunisation groups had NAb GMTs against live wild-type SARS-CoV-2 of 1937.3 [95% CI 1466.9, 2558.4] and 1350.8 [95% CI 952.6, 1915.3], which were 26.4 folds and 18.4 folds higher than that the CoronaVac group did (73.5 [95% CI 52.3, 103.3]) at 28 days. The low-dose and high-dose heterologous boost immunisation groups had NAb GMTs against live wild-type SARS-CoV-2 of 530.1 (95% CI 412.5, 681.1) and 457.6 (95%CI 349.4, 599.2), which were 26.0 folds and 22.4 folds higher than that the CoronaVac group did (20.4 [95%CI 14.3, 29.1]) at 3 months, respectively. At 6 months, the low-dose and high-dose heterologous booster groups had NAb GMTs against live wild-type SARS-CoV-2 of 312.9 (95% CI 237.7, 411.8) and 251.1 (95% CI 178.2, 354.0), which were 30.1 folds and 24.1 folds higher than the CoronaVac group did (10.4 [95% CI 7.8, 14.0]), respectively. Additionally, the low-dose and high-dose heterologous booster groups had NAb GMTs against live omicron variant of 52.0 (95% CI 37.2, 72.6) and 23.1 (95% CI 15.7, 33.9) at 28 days, 27.9 (95% CI 18.8, 41.3) and 23.3 (95% CI 16.2, 33.3) at 3 months, 16.0 (95% CI 10.9, 23.5) and 12.0 (95% CI 8.5, 16.8) at 6 months, respectively. However, nearly all participants had no detectable NAbs for omicron variant in the CoronaVac group at either 28 days, 3 months, or 6 months. No vaccine-related SAEs were observed. ConclusionsThese data suggested that heterologous aerosolised Ad5-nCoV following two-dose CoronaVac priming was safe and persistently more immunogenic than three-dose CoronaVac, although immune responses waned over time.

Heterologous prime-boost immunization with CoronaVac and Convidecia

BackgroundThe safety and immunogenicity of heterologous prime-boost COVID-19 vaccine regimens with one shot of a recombinant adenovirus type-5-vectored COVID-19 vaccine Convidecia has not been reported. MethodsWe conducted a randomized, controlled, observer-blinded trial of heterologous prime-boost immunization with CoronaVac and Convidecia in healthy adults 18-59 years of age. Eligible participants who were primed with one or two doses of CoronaVac were randomly assigned at a 1:1 ratio to receive a booster dose of Convidecia or CoronaVac. Participants were masked to the vaccine received but not to the three-dose or two-dose regimen. The occurrences of adverse reactions within 28 days after the vaccination were documented. The geometric mean titers of neutralizing antibodies against live SARS-CoV-2 virus were measured at 14 and 28 days after the booster vaccination. ResultsBetween May 25 and 26, 2021, a total of 300 participants were enrolled. Participants who received a booster shot with a heterologous dose of Convidecia reported increased frequencies of solicited injection-site reactions than did those received a homogeneous dose of CoronaVac, but frequencies of systemic reactions. The adverse reactions were generally mild to moderate. The heterologous immunization with Convidecia induced higher live viral neutralizing antibodies than did the homogeneous immunization with CoronaVac (197.4[167.7, 232.4] vs. 33.6[28.3, 39.8] and 54.4[37. 9, 78.0] vs. 12.8[9.3, 17.5]) at day 14 in the three- and two-dose regimen cohort, respectively. ConclusionsThe heterologous prime-boost regimen with Convidecia after the priming with CoronaVac was safe and significantly immunogenic than a homogeneous boost with CoronaVac (ClinicalTrials.gov, number NCT04892459).

In vitro inactivation of SARS-CoV-2 by commonly used disinfection products and methods.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is currently a global pandemic, and there are limited laboratory studies targeting pathogen resistance. This study aimed to investigate the effect of selected disinfection products and methods on the inactivation of SARS-CoV-2 in the laboratory. We used quantitative suspension testing to evaluate the effectiveness of the disinfectant/method. Available chlorine of 250 mg/L, 500 mg/L, and 1000 mg/L required 20 min, 5 min, and 0.5 min to inactivate SARS-CoV-2, respectively. A 600-fold dilution of 17% concentration of di-N-decyl dimethyl ammonium bromide (283 mg/L) and the same concentration of di-N-decyl dimethyl ammonium chloride required only 0.5 min to inactivate the virus efficiently. At 30% concentration for 1 min and 40% and above for 0.5 min, ethanol could efficiently inactivate SARS-CoV-2. Heat takes approximately 30 min at 56 °C, 10 min above 70 °C, or 5 min above 90 °C to inactivate the virus. The chlorinated disinfectants, Di-N-decyl dimethyl ammonium bromide/chloride, ethanol, and heat could effectively inactivate SARS-CoV-2 in the laboratory test. The response of SARS-CoV-2 to disinfectants is very similar to that of SARS-CoV.

Toilets dominate environmental detection of SARS-CoV-2 virus in a hospital

BackgroundRespiratory and faecal aerosols play a suspected role in transmitting the SARS-CoV-2 virus. We performed extensive environmental sampling in a dedicated hospital building for Covid-19 patients in both toilet and non-toilet environments, and analysed the associated environmental factors. MethodsWe collected data of the Covid-19 patients. 107 surface samples, 46 air samples, two exhaled condensate samples, and two expired air samples were collected were collected within and beyond the four three-bed isolation rooms. We reviewed the environmental design of the building and the cleaning routines. We conducted field measurement of airflow and CO2 concentrations. FindingsThe 107 surface samples comprised 37 from toilets, 34 from other surfaces in isolation rooms (ventilated at 30-60 L/s), and 36 from other surfaces outside isolation rooms in the hospital. Four of these samples were positive, namely two ward door-handles, one bathroom toilet-seat cover and one bathroom door-handle; and three were weakly positive, namely one bathroom toilet seat, one bathroom washbasin tap lever and one bathroom ceiling-exhaust louvre. One of the 46 air samples was weakly positive, and this was a corridor air sample. The two exhaled condensate samples and the two expired air samples were negative. InterpretationThe faecal-derived aerosols in patients toilets contained most of the detected SARS-CoV-2 virus in the hospital, highlighting the importance of surface and hand hygiene for intervention. FundingThe work were partially supported by the National Natural Science Foundation of China (no 41977370), the Research Grants Council of Hong Kongs (no 17202719) (no C7025-16G), and Scientific Research Fund of Jiangsu Provincial Department of Health (no S21017002).

HTCC as a highly effective polymeric inhibitor of SARS-CoV-2 and MERS-CoV

The beginning of 2020 brought us information about the novel coronavirus emerging in China. Rapid research resulted in the characterization of the pathogen, which appeared to be a member of the SARS-like cluster, commonly seen in bats. Despite the global and local efforts, the virus escaped the healthcare measures and rapidly spread in China and later globally, officially causing a pandemic and global crisis in March 2020. At present, different scenarios are being written to contain the virus, but the development of novel anticoronavirals for all highly pathogenic coronaviruses remains the major challenge. Here, we describe the antiviral activity of previously developed by us HTCC compound (N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride), which may be used as potential inhibitor of currently circulating highly pathogenic coronaviruses - SARS-CoV-2 and MERS-CoV.

A data-driven drug repositioning framework discovered a potential therapeutic agent targeting COVID-19

The global spread of SARS-CoV-2 requires an urgent need to find effective therapeutics for the treatment of COVID-19. We developed a data-driven drug repositioning framework, which applies both machine learning and statistical analysis approaches to systematically integrate and mine large-scale knowledge graph, literature and transcriptome data to discover the potential drug candidates against SARS-CoV-2. The retrospective study using the past SARS-CoV and MERS-CoV data demonstrated that our machine learning based method can successfully predict effective drug candidates against a specific coronavirus. Our in silico screening followed by wet-lab validation indicated that a poly-ADP-ribose polymerase 1 (PARP1) inhibitor, CVL218, currently in Phase I clinical trial, may be repurposed to treat COVID-19. Our in vitro assays revealed that CVL218 can exhibit effective inhibitory activity against SARS-CoV-2 replication without obvious cytopathic effect. In addition, we showed that CVL218 is able to suppress the CpG-induced IL-6 production in peripheral blood mononuclear cells, suggesting that it may also have anti-inflammatory effect that is highly relevant to the prevention immunopathology induced by SARS-CoV-2 infection. Further pharmacokinetic and toxicokinetic evaluation in rats and monkeys showed a high concentration of CVL218 in lung and observed no apparent signs of toxicity, indicating the appealing potential of this drug for the treatment of the pneumonia caused by SARS-CoV-2 infection. Moreover, molecular docking simulation suggested that CVL218 may bind to the N-terminal domain of nucleocapsid (N) protein of SARS-CoV-2, providing a possible model to explain its antiviral action. We also proposed several possible mechanisms to explain the antiviral activities of PARP1 inhibitors against SARS-CoV-2, based on the data present in this study and previous evidences reported in the literature. In summary, the PARP1 inhibitor CVL218 discovered by our data-driven drug repositioning framework can serve as a potential therapeutic agent for the treatment of COVID-19.

Pyroptosis induced by different Enteroviruses infection in SH-SY5Y cell / 中华实验和临床病毒学杂志

Objective@#To investigate the pyroptosis induced by different enteroviruses in human neuroblastoma cells SH-SY5Y and the differences among them.@*Methods@#SH-SY5Y cells were infected with nine strains of enterovirus respectively, including enterovirus A71 (EV-A71), Coxsackievirus A (CA), Coxsackievirus B (CB), Echovirus (Echo). The cellular morphology of infected and control groups were observed and activity of Caspase-1 of infected and control groups were detected by flow cytometry at 48 h post infection.@*Results@#The activity of Caspase-1 induced by EV-A71 was higher than control (P<0.001), and the activity of Caspase-1 induced by EV-A71 isolated from severe case was significantly higher than that induced by EV-A71 isolated from common case (P<0.001). The activity of Caspase-1 induced by CA was at a lower level. The activity of Caspase-1 induced by CB and Echo were both significantly higher than that induced by EV-A71 and control (P<0.001). Cytopathic effects (CPE) were found to be related with the activity of Caspase-1.@*Conclusions@#EV-A71, CB and Echo all could induce pyroptosis mediated by Caspase-1 in SH-SY5Y cells, but the ability of CA to induce pyroptosis was at a lower level, which may provide evidences for further study on mechanism of neuropathy caused by enterovirus.

Clinical features and molecular characteristics of influenza A (H1N1) viral pneumonia in 17 elderly patients / 中华实验和临床病毒学杂志

Objective@#To analyze the clinical manifestations and results of etiological examinations of 17 elderly patients with influenza A (H1N1) viral pneumonia, and to understand the clinical features of pneumonia and molecular characteristics of influenza A (H1N1) virus infection in the elderly.@*Methods@#The elderly patients with pneumonia who were hospitalized in the Department of Respiratory Diseases of Nanjing First Hospital from January 2018 to March were enrolled. The cases were confirmed by nucleic acid examination for influenza virus and the clinical data were collected. After the amplification of the whole genome of influenza virus, the high throughput sequencing and bioinformatics analysis were performed.@*Results@#The mean age of the 17 enrolled patients was 73.8±10.8. All of them had at least 1 underlying disease, and 7 cases had co-infection. Respiratory symptoms and fever were the most prominent clinical manifestations. Lesions in both lungs were found in 76.5% of the patients. The result of high throughput sequencing showed that all the viruses were highly homologous to the vaccine strain, and the HA gene belonged to the 6B.1 subgroup. Furthermore, three variations of antigenic locus (H138Y, S74R and S164T in HA) and a drug-resistant variation (H275Y in NA) were detected in the circulating strains.@*Conclusions@#Elderly patients with influenza A (H1N1) virus pneumonia often have underlying diseases and are prone to have co-infection. The molecular characteristics of the virus and the variation of key amino acid loci should be closely monitored in order to provide evidence for epidemic prevention and clinical antiviral treatment.

Etiological analysis of influenza surveillance data in Yangzhou from 2012 to 2017 / 中华实验和临床病毒学杂志

Objective@#To find out the characteristics and regularity trend of influenza activity according to the analyses of influenza surveillance data in Yangzhou from 2012 to 2017, and to provide scientific supports for predicting and controlling the pandemic outbreak of influenza effectively.@*Methods@#The influenza samples were collected from Northern Jiangsu People′s Hospital, Yangzhou First People's Hospital and Gaoyou People’s Hospital, using fluorescent RT-PCR method to detect influenza virus nucleic acid and classifying influenza virus subtypes. Finally, the surveillance data from January, 2012 to December, 2017 of influenza like illness (ILI) cases of Yangzhou were analyzed.@*Results@#Totally 18 083 throat swabs of ILI specimens were collected from 2012—2017 in Yangzhou, 1 983 samples were positive (10.97%), the difference in positive rates of adjacent years was statistically significant (χ2=167.93, P<0.001). In Yangzhou city, influenza virus kept activative in whole year. The influenza epidemic season was winter-spring and summer, accounting for 83.61% of all positive cases, with type A influenza prevalent throughout all year and type B influenza mainly prevalent in spring and winter, each subtype showed alternating prevalence. The influenza virus infection occurred in every age group. The highest positive rate was 16.33% in the age group of 10-19 years and the lowest was 8.52% in the age group of 20-29 years among all detected age groups.@*Conclusions@#From 2012 to 2017, the epidemic of influenza in Yangzhou was obviously seasonal and all the subtypes of influenza were in prevalent status alternately. The high-risk groups of Influenza were infants and teenagers who under the age of 19 years. So a long-term influenza surveillance is much needed for the early warning and forecasting the spread of influenza.

Genetic origin of avian influenza A H7N4 virus causing a case of human infection in China , 2018 / 中华微生物学和免疫学杂志

Objective To analyze the molecular characteristics and genetic origin of a novel avian influenza A H7N4 virus casuing a case of human infection in China. Methods Specimens were collected from the patient and chickens and ducks kept by the patient and neighbours and then detected by real-time quantitative PCR. The original specimens and virus isolates were analyzed by next-generation sequencing technology to obtain viral whole-genome sequences. Pairwise sequence alignments and phylogenetic analysis were performed by BLASTs,ClustalX and MEGA 6. 1 softwares. Results In January 2018, a human case infected with avian influenza A H7N4 virus was confirmed. Seven H7N4 viruses were isolated from speci-mens collected from chicken and ducks kept in the patient`s backyard. H7N4 virus was a novel reassortant vi-rus with all eight gene fragments derived from wild waterfowl in Eurasia. HA protein contained a single basic amino acid residue R in cleavage site, suggesting that H7N4 virus was low pathogenic. The receptor-binding sites of HA had QSG at 226-228 residues, which indicated that the virus retained avian-type receptor speci-ficity (SAα2-3Gal). Different from H7N4 viruses in avian, the virus isolated from the patient had substitu-tion at position 627 ( E→K) in PB2 protein, which might increase its adaptation in human host. Conclusion This study reported a case of human infection with a novel reassortant avian influenza A H7N4 virus, which revealed that the traditional backyard breeding models might facilitate cross-species transmission of avian in-fluenza viruses in southern China.

Rapid detection of human adenovirus by recombinase polymerase amplification assay and lateral flow dipstick / 中华实验和临床病毒学杂志

Objective@#To establish a rapid and sensitive isothermal amplification assay for the detection of human Adenovirus.@*Methods@#Primers and probe used for recombinase polymerase amplification(RPA)were designed based on the conserved region of the adenoviruses hexon gene. After optimizing the reaction temperature and times, the products of RPA were detected by capillary electrophoresis and lateral flow dipstick(LFD). Sensitivity and specicity of the assay were evaluated. The diagnostic value of the RPA-LFD assay was verified using clinical samples which were simultaneously tested by real time PCR assay.@*Results@#The analytical sensitivity of RPA-LFD assay was 2 copies DNA molecules per reaction and no cross reaction with other pathogens was observed. Compared with real-time PCR assay, the sensitivity, and specificity of the present assay were all 100%.@*Conclusions@#The RPA-LFD assay developed in this study has the characteristics of high specificity, sensitivity, rapid and no requirement of expensive equipment which provided a new tool for rapid detection of human adenovirus.

Application of CRISPR/Cas9 genome editing technology for inhibition of hepatitis B virus replication / 中华微生物学和免疫学杂志

Objective To evaluate the practicability of using CRISPR/Cas9 genome editing tech-nology for inhibition of hepatitis B virus ( HBV) replication. Methods Two sgRNA targeting sites were de-signed for the S region of HBV genome. The CRISPR/Cas9 expression plasmids specific for HBV were con-structed and then transfected into a cell line expressing HBV genome(HepG2-N10). The cytotoxicity of cells transfected with different expression plasmids were detected by MTT assay. The levels of hepatitis B surface antigen ( HBsAg ) were determined by using chemiluminescent immunoassay ( CLIA ) . The expression of HBV at mRNA level was analyzed by quantitative real-time PCR ( qRT-PCR) . The qPCR was performed for the detection of extracellular and intracellular HBV DNA. The next-generation sequencing ( NGS) Illumina MiSeq Platform was used to analyze HBV genome editing. Results No significant cytotoxic effects were de-tected in HepG2-N10 cells transfected with different expression plasmids. Compared with the cells carrying pCas-Guide-GFP-Scramble, the levels of HBsAg in the supernatants of transfected cell culture harboring pCas-Guide-GFP-G1 and pCas-Guide-GFP-G2 were decreased by 24. 2% (P0. 05), respectively. The levels of HBsAg in cells transfected with pCas-Guide-GFP-G1 and pCas-Guide-GFP-G2 were respectively decreased by 16. 4% (P>0. 05) and 32. 1% (P>0. 05) as compared with that of pCas-Guide-GFP-Scramble transfected group. The expression of HBV at mRNA level was inhibited as indica-ted by the results of qRT-PCR. Moreover, the levels of extracellular HBV DNA were respectively suppressed by 23% (P>0. 05) and 35% (P0. 05) and 18% (P>0. 05). Different types of insertion/deletion mutation were de-tected in HBV genome by high-throughput sequencing. Conclusion HBV-specific CRISPR/Cas9 system could inhibit the expression of HBV gene and the replication of virus. Therefore, the CRISPR/Cas9 genome editing technology might be used as a potential tool for the treatment of persistent HBV infection.

Diagnostic value of detection of IgM antibodies to EV71-infection patients / 中华微生物学和免疫学杂志

Objective To evaluate the diagnostic value of detection of IgM antibodies to EV71-infection patients,and compared characterisation of RT-PCR,IgM capture ELISA and neutralization test.Methods Virus RNA,neutralization titer and IgM antibody in 115 EV71-infection patients were detected by EV71 real-time RT-PCR kit( EV71-PCR kit),neutralization test,and EV71 IgM-capture ELISA kit (EV71-IgM kit),respectively.Results Using EV71-IgM kit,the detection rate was 80.9％ (93/115,95％ CI:72.5-87.6) among the 115 EV71-infection patients,and was 2.6％ among the 228 healthy children.Simultaneously,sera collected after 1-2 day of disease onset showed an IgM positivity of 70.4％ (38/ 54).The positive rate of EV71-PCR among these patients was 82.6％ (95/115,95％ CI:74.4-89.0),so there was no statistically significant differences between it and EV71-IgM kit.In addition,the detection rate in EV71-infection patients could increase to 92.2％ by combined detection of EV71-PCR and EV71-IgM kit.Conclusion EV71-IgM kit was a rapid and valuable way for the early diagnosis of EV71 infection,and could significantly improve detection rate for EV71 infection by combining with EV71-PCR kit.

Preparation of the RNAse-resistant virus particles containing the partial gene fragments of avian influenza virus H5N1 and its application / 中国人兽共患病学报

To prepare the RNAse-resistant virus particles containing the partial gene fragments of avian influenza virus H5N1 for use as RNA standard and control in RNA virus detection, the genes coding the coat protein and maturase of E.coli bacteriophage MS2 were amplified by PCR and then cloned into prokaryotic expression vector pET32a to construct the intermediate vector pET32a-MS2. In addition, the gene sequences coding hemagglutinin (HA), neuraminidase(NA) and M protein of the H5N1 virus were also cloned separately to the down-stream of plasmid pET32a-MS2, thus constructing the prokaryotic expression vectors pET32a-NS2-HA, pET32a-MS2-NA and pET32a-MS2-M. These recombinant plasmids were then transformed separately to E.coli BL21(DE3) with induction by IPTG. to express the virus-like particles. The virus-like particles observed under electron microscopy were identified by RT-PCR ,while their stability was confirmed by real-time RT-PCR. In this way, the virus-like particles were successively constructed and identified through PCR amplification, enzymolysis identification and sequencing analysis. These virus-like particles observed under electron microscopy appeared to be circular in shape with a diameter of about 50 nm. Their stability was proved to be rather good. From these observations, it is apparent that these virus-like particles can be used as RNA standard and quality control in the detection of avian influenza virus H5N1.

Genetic Analysis and Rescue of a Triple-reassortant H3N2 Influenza A Virus Isolated From Swine in Eastern China / 中国病毒学·英文版

One influenza H3N2 virus, A/swine/Shandong/3/2005 (Sw/SD/3/2005), was isolated from pigs with respiratory disease on a farm in eastern China. Genetic analysis revealed that Sw/SD/3/2005 was a triple-reassortant virus with a PB2 gene from human-like HIN1, NS from classical swine H1NI, and the remaining genes from human-like H3N2 virus. These findings further support the concept that swine can serve as reservoir or mixing vessels of influenza virus strains and maintain genetic and antigenic stability of viruses. Furthermore, we have successfully established a reverse genetics system based on eight plasmids and rescued Sw/SD/3/2005 through cell transfection. HI tests and RT-PCR confirmed that the rescued virus maintained the biological properties of the wild type Sw/SD/3/2005. The successful establishment of the reverse genetics system of Sw/SD/3/2005 will enable us to conduct extensive studies of the molecular evolution of H3N2 influenza viruses in swine.

Purification and functional characterization of enterohemorrhagic Escherichia coli O157: H7 Shiga toxinⅡ / 中华传染病杂志

Objective To purify Shiga toxin Ⅱ (STX Ⅱ) of enterohaemorrhagic Escherichia coli (EHEC) O157: H7 by affinity chromatography, and characterize its biological function. Methods The immno-affinity chromatography column was prepared by STX Ⅱ A subunit-specific antibody S1D8 coupling to Sepharose 4B matrix. The purity and specificity of STX Ⅱ molecule secreted by EHEC O157:H7 were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot, respectively. The purified toxin was serially diluted and the toxic activities to Vero cell line and mice were observed. The 50% cytotoxic dose (CD50) for Vero cell line and 100% lethal dose (LD100) for mice were calculated. The protection effect of anti-STX Ⅱ polysera to the mice against the purified toxin challenge was also observed. Results STX Ⅱ was successfully purified from culture supernatant of EHEC O157:H7 using affinity chromatography scheme. The relative molecular weights of STX Ⅱ A and B subunits were 32 000 and 7 500 confirmed by SDS-PAGE, respectively. The purified toxin could react with monoclonal antibodies against STX Ⅱ A and B subunits, respectively.The toxin was cytotoxic to Vero cell with CD50 of 20 ng/L and lethal to mice with LD100 of 5 ng.The toxin could be neutralized by anti-STX Ⅱ polysera in vivo. Conclusion STX Ⅱ is successfully purified and its toxic effects are confirmed in both cell line and mouse model.

Preparation and immunological properties of hepatitis B virus surface antigen-tetanus toxoid conjugate vaccine / 中华微生物学和免疫学杂志

Objective To prepare and study the immunogenicity of hepatitis B virus surface anti-gen (HBsAg)-tetanus toxoid (TT) conjugate vaccine. Methods Tr was activated by cyangen bromide and reacted with adipic acid dihydrazide, then HBsAg-TT conjugate was prepared by carbediimide. Conjugate, HBsAg or hepatitis B vaccine was injected subcutaneously into mice. Anti-HBsAg and HBsAg-specific T cell response elicited by these immunogens were assayed. Results New HBsAg-TT conjugate elicited higher levels of anti-HBsAg and HBsAg positive conversion rates after the immunization than did HBsAg alone or hepatitis B vaccine. Conjugate induced mesdy antibodies of the IgG2a subclass, while HBsAg alone or hepa-titis B vaccine mainly elicited anti-HBsAg in the IgG1 subclass. The number of IFN-γand IL-2 secreting T cells induced by conjugate was also significantly higher than that did by HBsAg or hepatitis B vaccine. Con-clusion This study indicated new HBsAg-TT conjugate can induce both stronger humoral and TH1 type of cellular immune response.