Epitope Mapping of Human Polyclonal Antibodies to the fHbp Antigen of a Neisseria Meningitidis Vaccine by Hydrogen-Deuterium Exchange Mass Spectrometry (HDX-MS).

Antigen-antibody interactions play a key role in the immune response post vaccination and the mechanism of action of antibody-based biopharmaceuticals. 4CMenB is a multicomponent vaccine against Neisseria meningitidis serogroup B in which factor H binding protein (fHbp) is one of the key antigens. In this study, we use hydrogen/deuterium exchange mass spectrometry (HDX-MS) to identify epitopes in fHbp recognized by polyclonal antibodies (pAb) from two human donors (HDs) vaccinated with 4CMenB. Our HDX-MS data reveal several epitopes recognized by the complex mixture of human pAb. Furthermore, we show that the pAb from the two HDs recognize the same epitope regions. Epitope mapping of total pAb and purified fHbp-specific pAb from the same HD reveals that the two antibody samples recognize the same main epitopes, showing that HDX-MS based epitope mapping can, in this case at least, be performed directly using total IgG pAb samples that have not undergone Ab-selective purification. Two monoclonal antibodies (mAb) were previously produced from B-cell repertoire sequences from one of the HDs and used for epitope mapping of fHbp with HDX-MS. The epitopes identified for the pAb from the same HD in this study, overlap with the epitopes recognized by the two individual mAbs. Overall, HDX-MS epitope mapping appears highly suitable for simultaneous identification of epitopes recognized by pAb from human donors and to thus both guide vaccine development and study basic human immunity to pathogens, including viruses.

Identification of cocoonase and cocoonase like protein using polyclonal antibody of Antheraea mylitta cocoonase.

BACKGROUND: Cocoonase is a proteolytic enzyme released by silk moths during pupal adult emergence. Without damaging the silk fibroin, this enzyme dissolves the shell of the tasar cocoon by exclusively targeting the protein sericin. Prior to this study, there was no available antibody against Antheraea mylitta cocoonase to identify or screen out similar variants or cocoonase like protein. RESULTS: In the present study, naturally secreted A. mylitta cocoonase was purified and used to immunize New Zealand white rabbits. The developed polyclonal antibody of cocoonase was purified and its specific interaction with cocoonase was determined using Indirect ELISA. The confirmation of its specificity and immuno-reactivity was evaluated by western blot using native cocoonase of tasar silkworm A. mylitta. The efficacy and specificity of the polyclonal antibody were further verified and confirmed by western blot which was performed to detect ten different ecotypes of A. mylitta cocoonase. CONCLUSION: The developed antibody successfully detected the cocoonase of different ecotypes. Thus, in future this antibody can serve as one of the molecular detection method for cocoonase and cocoonase-like proteins.

Development of a label-free photoelectrochemical immunosensor for novel astrovirus detection.

Since 2017, an infectious goose gout disease characterized by urate precipitation in viscera, mainly caused by novel goose astrovirus (GoAstV) infection, has emerged in the main goose-producing region of China. The current challenge in managing goose gout disease is largely due to the absence of a rapid and efficient detection method for the GoAstV pathogen. Notably, the potential application of immunosensors in detecting GoAstV has not yet been explored. Herein, a label-free PEC immunosensor was fabricated by using purchased TiO2 as the photoactive material and antibody against GoAstV P2 proteins as the specific recognition element. First, we successfully expressed the capsid spike domain P2 protein of ORF2 from GoAstV CHSH01 by using the pET prokaryotic expression system. Meanwhile, the polyclonal antibody against GoAstV capsid P2 protein was produced by purified protein. To our knowledge, this is the first establishment and preliminary application of the label-free photoelectrochemical immunosensor method in the detection of AstV. The PEC immunosensor had a linear range of 1.83 fg mL-1 to 3.02 ng mL-1, and the limit of detection (LOD) was as low as 0.61 fg mL-1. This immunosensor exhibited high sensitivity, great specificity, and good stability in detecting GoAstV P2 proteins. To evaluate the practical application of the immunosensor in real-world sample detection, allantoic fluid from goose embryos was collected as test samples. The results indicated that of the eight positive samples, one false negative result was detected, while both negative samples were accurately detected, suggesting that the constructed PEC immunosensor had good applicability and practical application value, providing a platform for the qualitative detection of GoAstV.

Establishment of enzyme-linked immunosorbent assay for aristolochic acid.

In recent years, the nephrotoxicity and carcinogenicity of aristolochic acid have attracted worldwide attention, and the traditional Chinese medicine containing this ingredient has been banned in many places, affecting the TCM industry. To meet this challenge, researchers have developed various detection methods, such as high-performance liquid chromatography, gas chromatography-mass spectrometry and thin-layer chromatography. A rapid detection method must therefore be developed to ensure safety. A polyclonal antibody capable of recognizing aristolochic acid was prepared, and an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was established to detect the amount of aristolochic acid in the sample to be measured. Methods Using 1-(4-chlorophenyl) cyclobutylamine as a hapten, immunogens and coating antigens were obtained by coupling with bovine serum albumin (BSA) and chicken ovalbumin (OVA) using the active ester method. UV scanning confirmed the successful coupling of the conjugate, and New Zealand white rabbits were immunized. The obtained antibody serum was screened for the best antibody by ic-ELISA detection. Use the chessboard method to determine three optimal combinations of original coating concentration and antibody dilution ratio, establish a standard curve for each combination to obtain the best combination, and establish a rapid detection method. Finally, the standard aristolochic acid A was added to the purchased apple vinegar and canned coffee for recycling experiments to verify the detection method.By changing the antigen antibody concentration, the antibody showed the highest sensitivity to aristolochic acid standard at the original coating, 1000-fold dilution, IC50 of 24.88 ng/mL, limit of detection IC10 of 3.19 ng/mL, and detection range IC20-IC80 of 6.81-90.91 ng/mL. The recovery experiments under this conditions yielded a recovery rate of 92%-105%, within reasonable limits, indicating the success of the ELISA rapid detection method. Conclusion The enzyme-linked immunoassay method established in this paper can quickly detect the content of aristolochic acid in the sample to be tested, and the antibody prepared by this method has good broad-spectrum and can detect other aristolochic acid, such as aristolochic acid A, aristolochic acid B, aristolochic acid C, and aristolochic acid D.

Preparation of polyclonal antibodies to chicken P62 protein and its application in nephropathogenic infectious bronchitis virus-infected chickens.

p62, also known as SQSTM1, has been shown to be closely related to the coronavirus. However, it remains unclear on the relationship between p62 and NIBV infection. Moreover, there are no available antibodies against the chicken p62 protein. Thus, this study aimed to prepare p62 polyclonal antibody and investigate the correlation between the p62 protein and NIBV infection. Here, PET-32a-p62 prokaryotic fusion expression vector was constructed for prokaryotic protein expression, and then p62 polyclonal antibody was prepared by immunizing rabbits. Lastly, these antibodies were then utilized in Western blotting (WB), immunohistochemistry (IHC), and immunofluorescence (IF) assays. The results showed that we successfully prepared chicken p62 polyclonal antibody. Meanwhile, WB and IF demonstrated that the expression of p62 showed a trend of first increase and then decrease after NIBV infection. IHC showed that the expression of p62 in the spleen, lung, kidney, bursa of Fabricius and trachea of chickens infected with NIBV in 11 dpi was significantly higher than that of normal chickens. Taken together, this study successfully prepared a polyclonal antibody for chicken p62 protein and confirmed its application and expression in chickens, as well as the expression of p62 in tissues after NIBV infection.

Preparation of polyclonal antibody against thrombospondin 2 recombinant protein and its functional verification in pulmonary hypertension syndrome in broilers.

Cell migration regulated by Thrombospondin 2 (THSB2) is important for the development of pulmonary artery remodeling, but the mechanism by which THBS2-mediated cell migration regulates the development of pulmonary artery remodeling in broiler ascites syndrome (AS) is unclear. In addition, the lack of chicken THBS2 antibodies makes it difficult to study the mechanism in depth. In our study, we used recombinant gene technology, protein purification, and other techniques to obtain mouse anti-chicken THBS2 antibody and analyze its expression in broilers, ascites broilers and other animals. The results showed that we immunized mouse with recombinant THBS2 protein and obtained an antibody titer of 1:204,800, and the addition of astragalus polysaccharide as an immunomodulator during immunization significantly increased the titer of the antibody. Western blotting (WB) and immunofluorescence results showed that the THBS2 was significantly down-regulated in the ascites broiler. The THBS2 antibody we prepared can also detect THBS2 protein in duck, mouse, goat, and rabbit tissues. These results provide a foundation for further investigation of the role of THBS2 in pulmonary artery remodeling in broiler ascites syndrome and a powerful tool for studying the role of THBS2 in AS.

Structure and function of vasa gene in gonadal gametogenesis of Pacific abalone.

Pacific abalone (Haliotis discus hannai) is a marine gastropod mollusc with significant economic importance in both global fisheries and aquaculture. However, studies exploring the gonadal development and regulatory mechanisms of Haliotis discus hannai are limited. This study aimed to explore whether the vasa gene acted as a molecular marker for germ cells. Initially, the vasa gene was successfully cloned using the cDNA-end rapid amplification technique. The cloned gene had a 2478-bp-long open reading frame and encoded 825 amino acids. Then, a recombinant expression vector was constructed based on the Vasa protein, and an 87-kDa recombinant protein was prepared. Subsequently, a polyclonal antibody was prepared using the purified recombinant protein. The enzyme-linked immunosorbent assay (ELISA) confirmed the titer of the antibody to be ≥512 K. The immunohistochemical analysis revealed that Vasa was widely expressed in oogonia, Stage I oocytes, spermatogonia, and primary spermatocytes. The specific expression of Vasa in the hermaphroditic gonads of abalone was assessed using western blotting to investigate the effects of different photoperiods (12 L:12D, 24 L:0D, 18 L:6D, and 6 L:18D) on the gonadal development of abalone (P < 0.05), with higher expression levels observed in the ovarian proliferative and spermary maturing stages compared with other developmental stages (P < 0.05). Additionally, Vasa exhibited the highest expression in the spermary and ovary under a photoperiod of 18 L:6D (P < 0.05). These data demonstrated the key role of Vasa in developing germ cells in abalone. They shed light upon the molecular mechanism through which the photoperiod influenced Vasa expression and regulated gonadal development in abalone. The findings might provide theoretical references for analyzing the differentiation pattern of abalone germ cells and the genetic improvement and conservation of germplasm resources.

[Preparation and preliminary application of the polyclonal antibody against Toxoplasma gondii dense granule protein 24].

OBJECTIVE: To prepare and characterize the mouse polyclonal antibody against the dense granule protein 24 (GRA24) of Toxoplasma gondii, and explore its preliminary applications. METHODS: The GRA24 coding sequences of different T. gondii strains were aligned using the MEGA-X software, and the dominant peptide of the GRA24 protein was analyzed with the Protean software. The base sequence encoding this peptide was amplified using PCR assay and ligated into the pET-28a vector, and the generated GRA24 truncated protein was transformed into Escherichia coli BL21. After induction by isopropyl-beta-D-thiogalactopyranoside (IPTG), the expression and purification of the recombinant GRA24 protein was analyzed using sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE). BALB/c mice were immunized by subcutaneous injection with the purified recombinant GRA24 truncated protein to generate the polyclonal antibody, and the titer of the polyclonal antibody was measured using enzyme linked immunosorbent assay (ELISA). The specificity of the polyclonal antibody was tested using Western blotting, and the intracellular localization of the polyclonal antibody was investigated using immunofluorescence assay (IFA). RESULTS: SDS-PAGE showed successful construction of the recombinant expression plasmid, and Coomassie brilliant blue staining showed the generation of the high-purity recombinant GRA24 truncated protein. ELISA measured that the titer of the polyclonal antibody against the GRA24 truncated protein was higher than 1:208 400, and Western blotting showed that the polyclonal antibody was effective to recognize the endogenous GRA24 proteins of different T. gondii strains and specifically recognize the recombinant GRA24 truncated protein. Indirect IFA showed that the GRA24 protein secreted 16 hour following T. gondii invasion in host cells. CONCLUSIONS: The polyclonal antibody against the T. gondii GRA24 protein has been successfully prepared, which has a widespread applicability, high titers and a high specificity. This polyclonal antibody is available for Western blotting and IFA, which provides the basis for investigating the function of the GRA24 protein.

Cloning and expression profiling of voltage-gated sodium channel gene (VGSC) from Spodoptera frugiperda.

Spodoptera frugiperda is a long-distance migratory pest with strong dispersal ability, fast reproduction speed and destructive feeding, so it is difficult to prevent and control. Pyrethroid insecticides are commonly used in pest insects control, And since the voltage-gated sodium channel (VGSC) serves as a major target of pyrethroids, it is important to study this gene for pest control. VGSC is an integral transmembrane protein consisting of approximately 2,000 amino acid residues found in neurons, myocytes, endocrine cells, and ovarian cells and involved in the initiation and propagation of excitable cellular action potentials. In this study, the cDNA sequence of the VGSC was identified from S. frugiperda by rapid amplification of cDNA ends (RACE) which contained an open reading frame of 6,261 bp encoding a protein of 2,086 amino acids. The molecular weight of this protein was predicted to be 236 kDa, and the theoretical isoelectric point was 5.21. A phylogenetic tree constructed based on lepidopteran insects showed that the VGSC of S. frugiperda was most closely relative to that of Spodoptera litura. VGSC is a highly conserved protein with Ion channel conserved structural domains of transmembrane proteins. qPCR showed that the VGSC gene was highly expressed in the epidermis of 2nd instar larvae, and its expression level was low in other tissues, such as the foregut and Malpighian tubules. In addition, VGSC was also detected in the prepupal stage, then gradually increased in abundance after entering the adult stage, peaked at the adult males on the 4th day of pupal stage, and decreased afterwards. The recombinant plasmid of pSumo-mut-VGSC was constructed and induced to express a His tag fused VGSC protein. Polyclonal antibodies were prepared from purified recombinant VGSC protein. The antibody was ELISA-titered, and the western blotting results showed that it specifically recognized VGSC, whether it was recombinant or endogenous protein. These results have laid the foundation for future studies on the physiological function of this gene in the growth and development of S. frugiperda.

Development of an immunoassay based on a specific antibody for the detection of diphenyl ether herbicide fomesafen.

Fomesafen belongs to the diphenyl ether herbicide, and is widely used in the control of broadleaf weeds in crop fields due to its high efficiency and good selectivity. The residual of fomesafen in soil has a toxic effect on subsequent sensitive crops and the microbial community structure because of its long residual period. Therefore, an efficient method for detecting fomesafen is critical to guide the correct and reasonable use of this herbicide. Rapid and sensitive immunoassay methods for fomesafen is unavailable due to the lack of specific antibody. In this study, a specific antibody for fomesafen was generated based on rational design of haptens and a sensitive immunoassay method was established. The half maximal inhibitory concentration (IC50) of the immunoassay was 39 ng/mL with a linear range (IC10-90) of 1.92-779.8 ng/mL. In addition, the developed assay had a good correlation with the standard UPLC-MS/MS both in the spike-recovery studies and in the detection of real soil samples. Overall, the developed indirect competitive enzyme immunoassay reported here is important for detecting and quantifying fomesafen contamination in soil and other environmental samples with good sensitivity and high reproducibility.

Identification of the grass carp interleukin-23 receptor and its proinflammatory role in intestinal inflammation.

The interleukin 23 receptor (IL-23R) is associated with a variety of inflammatory diseases in humans and other mammals. However, whether IL-23R is involved in inflammatory diseases in teleost fish is less understood. Thus, to investigate the potential involvement of IL-23R in fish inflammatory diseases, the full-length cDNA of IL-23R from grass carp Ctenopharyngodon idella was cloned and used to generate a recombinant protein (rgcIL-23R) containing the extracellular domain of IL-23R, against which a polyclonal antibody (rgcIL-23R pAb) was then developed. qPCR analysis revealed that IL-23R mRNA was significantly upregulated in most grass carp tissues in response to infection with Gram-negative Aeromonas hydrophila. Treatment with rgcIL-23R significantly induced IL-17A/F1 expression in C. idella kidney (CIK) cells. By contrast, knockdown of IL-23R caused significant decreases in IL-23R, STAT3, and IL-17N expression in CIK cells after lipopolysaccharide (LPS) stimulation. Similarly, rgcIL-23R pAb treatment effectively inhibited the LPS-induced increase in the expression of IL-23 subunit genes and those of the IL-23/IL-17 pathway in CIK cells. Furthermore, intestinal symptoms identical to those caused by A. hydrophila were induced by anal intubation with rgcIL-23R, but suppressed by rgcIL-23R pAb. Therefore, these results suggest that IL-23R has a crucial role in the regulation of intestinal inflammation and, thus, is a promising target for controlling inflammatory diseases in farmed fish.

Anti-SARS-CoV-2 glyco-humanized polyclonal antibody XAV-19: phase II/III randomized placebo-controlled trial shows acceleration to recovery for mild to moderate patients with COVID-19.

Introduction: XAV-19 is a glyco-humanized swine polyclonal antibody targeting SARS-CoV-2 with high neutralizing activity. The safety and clinical efficacy of XAV-19 were investigated in patients with mild to moderate COVID-19. Methods: This phase II/III, multicentric, randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate the safety and clinical efficacy of XAV-19 in patients with a seven-point WHO score of 2 to 4 at randomization, i.e., inpatients with COVID-19 requiring or not requiring low-flow oxygen therapy, and outpatients not requiring oxygen (EUROXAV trial, NCT04928430). Adult patients presenting in specialized or emergency units with confirmed COVID-19 and giving their consent to participate in the study were randomized to receive 150 mg of XAV-19 or placebo. The primary endpoint was the proportion of patients with aggravation within 8 days after treatment, defined as a worsening of the seven-point WHO score of at least one point between day 8 and day 1 (inclusion). The neutralization activity of XAV-19 against variants circulating during the trial was tested in parallel. Results: From March 2021 to October 2022, 279 patients received either XAV-19 (N = 140) or placebo (N = 139). A slow enrollment and a low rate of events forced the termination of the premature trial. XAV-19 was well tolerated. Underpowered statistics did not allow the detection of any difference in the primary endpoint between the two groups or in stratified groups. Interestingly, analysis of the time to improvement (secondary endpoint) showed that XAV-19 significantly accelerated the recovery for patients with a WHO score of 2 or 3 (median at 7 days vs. 14 days, p = 0.0159), and even more for patients with a WHO score of 2 (4 days vs. 14 days, p = 0.0003). The neutralizing activity against Omicron and BA.2, BA.2.12.1, BA.4/5, and BQ.1.1 subvariants was shown. Discussion: In this randomized placebo- controlled trial with premature termination, reduction of aggravation by XAV-19 at day 8 in patients with COVID-19 was not detectable. However, a significant reduction of the time to improvement for patients not requiring oxygen was observed. XAV-19 maintained a neutralizing activity against SARS-CoV-2 variants. Altogether, these data support a possible therapeutic interest for patients with mild to moderate COVID-19 requiring anti-SARS-CoV-2 neutralizing antibodies. Clinical Trial Registration: https://clinicaltrials.gov/, identifier NCT04928430; https://www.clinicaltrialsregister.eu/about.html (EudraCT), identifier 2020-005979-12.

Evaluation of species-specific polyclonal antibodies to detect and differentiate between Neospora caninum and Toxoplasma gondii.

Neosporosis and toxoplasmosis are major causes of abortion in livestock worldwide, leading to substantial economic losses. Detection tools are fundamental to the diagnosis and management of those diseases. Current immunohistochemistry (IHC) tests, using sera raised against whole parasite lysates, have not been able to distinguish between Toxoplasma gondii and Neospora caninum. We used T. gondii and N. caninum recombinant proteins, expressed in Escherichia coli and purified using insoluble conditions, to produce specific polyclonal rabbit antisera. We aimed to develop species-specific sera that could be used in IHC on formalin-fixed, paraffin-embedded (FFPE) tissue sections to improve the diagnosis of ruminant abortions caused by protozoa. Two polyclonal rabbit sera, raised against recombinant proteins, anti-Neospora-rNcSRS2 and anti-Toxoplasma-rTgSRS2, had specificity for the parasite they were raised against. We tested the specificity for each polyclonal serum using FFPE tissue sections known to be infected with T. gondii and N. caninum. The anti-Neospora-rNcSRS2 serum labeled specifically only N. caninum-infected tissue blocks, and the anti-Toxoplasma-rTgSRS2 serum was specific to only T. gondii-infected tissues. Moreover, tissues from 52 cattle and 19 sheep previously diagnosed by lesion profiles were tested using IHC with our polyclonal sera and PCR. The overall agreement between IHC and PCR was 90.1% for both polyclonal anti-rNcSRS2 and anti-rTgSRS2 sera. The polyclonal antisera were specific and allowed visual confirmation of protozoan parasites by IHC, but they were not as sensitive as PCR testing.

Optimization of DAC-ELISA and IC-RT-PCR using the developed polyclonal antibody and one-step RT-PCR assays for detection of Indian citrus ringspot virus in kinnow orange of Punjab, India.

Indian citrus ringspot virus (ICRSV), a member of the Mandarivirus genus, causes citrus ringspot disease, impacting kinnow orange quality and yield. Early and accurate detection methods are crucial before visible symptoms manifest in plants. In this study, a 507 bp partial coat protein gene (pCPG) segment was amplified from infected kinnow leaf tissues, cloned into a pET28a vector, and transformed into E. coli BL21(DE3) cells. Induced with IPTG, the cells overexpressed a recombinant partial coat protein (rpCP) of approximately 23 kDa, purified using Ni-NTA resin via affinity chromatography. Validated in western blot with an anti-His antibody, rpCP was used to generate an ICRSV-specific polyclonal antibody (PAb) in rabbits. PAb, optimized at 1:1000 dilution, successfully detected ICRSV in infected kinnow orange leaf extracts via DAC-ELISA and IC-RT-PCR assays. ICRSV was detectable in sample dilutions up to 1:640 and 1:10240 (w/v, g mL-1) by DAC-ELISA and IC-RT-PCR, respectively. One-step RT-PCR assays were also optimized, confirming the presence of ICRSV by amplifying a 507 bp pCPG fragment from total RNA extracted from kinnow orange leaves, with dilution up to 1:5120 (w/v, g mL-1). The result demonstrated that IC-RT-PCR has a 16-fold and 2-fold higher sensitivity than DAC-ELISA and one-step RT-PCR assays.

The Ability of Antibody against Truncated Matrix Metalloproteinase 9 Peptide to Evaluate the Native Protein on Tear Drops of Dry Eye Disease Patients by a Point-of-Care Diagnostic System.

Purpose: To obtain a reactive and specific antibody against truncated matrix metalloproteinase 9 (MMP-9), that has reactivity toward the native protein. Precision, accuracy, specificity, and sensitivity were evaluated using a point-of-care test. Methods: An in silico study was used to confirm the anti peptide truncated MMP-9 is against native MMP-9. After an antibody titer assessment, purification, and characterization, the anti MMP-9 was assessed. The cut-off value was determined using the purified gelatinases of the supernatant HCT 116 cell line. The supernatant was purified by preparative native-polyacrylamide gel electrophoresis based on charge and size of the proteins. Furthermore, quality control (QC) of the results were performed following standard densitometry methods. Results: A truncated MMP-9 is the major epitope peptide that can trigger the immune system to scavenge for a specific and reactive antibody against the native MMP-9. The MMP-9 native protein is purified from the supernatant of the HCT 116 cell line and the commercially available, full-length MMP-9. The cut-off value was estimated at 30 µg/mL. QC results indicated that the specificity was 80%, sensitivity was 96.7%, accuracy was 91%, and precision was 91.66%. The area under curve was 0.827 (P < 0.001). The positive predictive value was 83%, and the negative predictive value was 96%. Conclusions: The antibody against the synthetic epitope peptide can detect the native MMP-9. Native MMP-9 is considered the main biomarker in an immunoassay POCT and is used to diagnose dry eye disease (DED). In accordance with QC results, MMP-9 point of care test can be utilized for screening patients suffering from DED.

Preparation of rabbit polyclonal antibody and development and identification of quantitative ELISA detection method for pertussis toxin / 中国生物制品学杂志

@#Objective To prepare rabbit polyclonal antibodies against pertussis toxin(PT) and develop a double antibody sandwich ELISA for quantitative determination of PT antigen,identify and apply the method.Methods The rabbit polyclonal antibody against PT was prepared by immunizing Chinchilla rabbit with PT using traditional method.The reaction conditions of ELISA system were optimized,the double antibody sandwich ELISA method for quantitative determi-nation of PT was developed,and the specificity,linearity,accuracy,precision and sensitivity were verified.The developed method was used to detect PT antigen content in fimbriae proteins(FIM) stock solution of samples during detoxification and other purification process of pertussis antigen.Results The working condition of double antibody sandwich ELISA for detection of PT antigen content was the coating concentration of PT rabbit polyclonal antibody of 1 μg/mL,and the enzyme-labeled antibody dilution of 1:8 000.This detection system showed specific reaction with PT purified protein,but had no cross reaction with filamentous hemagglutinin,diphtheria toxoid and tetanus toxoid;the linear detection range of the developed double antibody sandwich ELISA was within 25—400 ng/mL;the recovery rates of PT at high,moderate and low concentrations were 103.27%,91.48% and 103.52%,respectively;both the intra-and inter-coefficients of variation(CVs)were less than 10%;the sensitivity of the method was 20.719 ng/mL,and the detection limit was 41.438 ng/mL.Thirty-five batches of samples were detected under five different detoxification process conditions and at different sampling time points,and the changes of antigen content were all consistent with the trend of detoxification reaction.Conclusion The PT rabbit polyclonal antibody was successfully prepared,and a double antibody sandwich ELISA with high precision and accuracy was developed for the quantitative determination of PT antigen content,which can be used for the antigen content detection of chemically detoxified samples in the production process of component DPT vaccines.

Preparation of rabbit polyclonal antibody and development and identification of quantitative ELISA detection method for pertussis toxin / 中国生物制品学杂志

@#Objective To prepare rabbit polyclonal antibodies against pertussis toxin(PT) and develop a double antibody sandwich ELISA for quantitative determination of PT antigen,identify and apply the method.Methods The rabbit polyclonal antibody against PT was prepared by immunizing Chinchilla rabbit with PT using traditional method.The reaction conditions of ELISA system were optimized,the double antibody sandwich ELISA method for quantitative determi-nation of PT was developed,and the specificity,linearity,accuracy,precision and sensitivity were verified.The developed method was used to detect PT antigen content in fimbriae proteins(FIM) stock solution of samples during detoxification and other purification process of pertussis antigen.Results The working condition of double antibody sandwich ELISA for detection of PT antigen content was the coating concentration of PT rabbit polyclonal antibody of 1 μg/mL,and the enzyme-labeled antibody dilution of 1:8 000.This detection system showed specific reaction with PT purified protein,but had no cross reaction with filamentous hemagglutinin,diphtheria toxoid and tetanus toxoid;the linear detection range of the developed double antibody sandwich ELISA was within 25—400 ng/mL;the recovery rates of PT at high,moderate and low concentrations were 103.27%,91.48% and 103.52%,respectively;both the intra-and inter-coefficients of variation(CVs)were less than 10%;the sensitivity of the method was 20.719 ng/mL,and the detection limit was 41.438 ng/mL.Thirty-five batches of samples were detected under five different detoxification process conditions and at different sampling time points,and the changes of antigen content were all consistent with the trend of detoxification reaction.Conclusion The PT rabbit polyclonal antibody was successfully prepared,and a double antibody sandwich ELISA with high precision and accuracy was developed for the quantitative determination of PT antigen content,which can be used for the antigen content detection of chemically detoxified samples in the production process of component DPT vaccines

Preparation and preliminary application of the polyclonal antibody against Toxoplasma gondii dense granule protein 24 / 中国血吸虫病防治杂志

Objective To prepare and characterize the mouse polyclonal antibody against the dense granule protein 24 (GRA24) of Toxoplasma gondii, and explore its preliminary applications. Methods The GRA24 coding sequences of different T. gondii strains were aligned using the MEGA-X software, and the dominant peptide of the GRA24 protein was analyzed with the Protean software. The base sequence encoding this peptide was amplified using PCR assay and ligated into the pET-28a vector, and the generated GRA24 truncated protein was transformed into Escherichia coli BL21. After induction by isopropyl-beta-D-thiogalactopyranoside (IPTG), the expression and purification of the recombinant GRA24 protein was analyzed using sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE). BALB/c mice were immunized by subcutaneous injection with the purified recombinant GRA24 truncated protein to generate the polyclonal antibody, and the titer of the polyclonal antibody was measured using enzyme linked immunosorbent assay (ELISA). The specificity of the polyclonal antibody was tested using Western blotting, and the intracellular localization of the polyclonal antibody was investigated using immunofluorescence assay (IFA). Results SDS-PAGE showed successful construction of the recombinant expression plasmid, and Coomassie brilliant blue staining showed the generation of the high-purity recombinant GRA24 truncated protein. ELISA measured that the titer of the polyclonal antibody against the GRA24 truncated protein was higher than 1:208 400, and Western blotting showed that the polyclonal antibody was effective to recognize the endogenous GRA24 proteins of different T. gondii strains and specifically recognize the recombinant GRA24 truncated protein. Indirect IFA showed that the GRA24 protein secreted 16 hour following T. gondii invasion in host cells. Conclusions The polyclonal antibody against the T. gondii GRA24 protein has been successfully prepared, which has a widespread applicability, high titers and a high specificity. This polyclonal antibody is available for Western blotting and IFA, which provides the basis for investigating the function of the GRA24 protein.

Prokaryotic expression of variable region protein of adeno-associated virus 9 capsid and preparation of polyclonal antibody / 中国生物制品学杂志

@#Objective To express and purify the protein of variable region of adeno-associated virus 9(AAV9) capsid in prokaryotic cells,and prepare rabbit polyclonal antibody against it.Methods DNA sequence encoding variable region of AAV9 capsid protein was designed,synthesized and inserted into prokaryotic expression vector pET-30a. The obtained plasmid pET-30a-AAV-VR was transformed to E.coli BL21(DE3),induced by IPTG to express the multivalent antigenic peptide and purified by Ni-NTA resin under denaturation conditions. Male Japanese large-eared white rabbits were immunized with the AAV9 variable region protein after dialysis and renaturation to prepare polyclonal antibody,which was determined for the antibody potency by indirect ELISA,and for the specificity by Western blot and cellular immunofluorescence.Results The recombinant prokaryotic expression plasmid pET-30a-AAV-VR expressing the variable region of AAV9 capsid was constructed correctly as identified by XhoⅠ and BglⅡ digestion. The expressed protein was recognized by His tag antibody after purification with a relative molecular mass of about 20 000. The potency of rabbit polyclonal antibody was 1∶10 240 000,which specifically recognize AAV9 capsid protein.Conclusion The capsid variable region protein of AAV9 was successfully expressed and rabbit polyclonal antibody with high potency was prepared,which laid a foundation of the subsequent development of AAV vector and the research of AAV biological function.

Preparation and efficacy evaluation of polyclonal antibodies against serum albumin of five species / 中国生物制品学杂志

@#Objective To prepare polyclonal antibodies against the serum albumin of human,cattle,sheep,pig and horse,and evaluate their efficacy in the identification of human serum albumin(HSA). Methods The specific polypeptides of human,cattle,sheep,pig and horse serum albumin were prepared by bioinformatics and polypeptide synthesis method,which were coupled with keyhole limpet hemocyanin(KLH)to prepare the peptide antigen after the purity was identified by high performance liquid chromatography(HPLC). Male New Zealand white rabbits were immunized with polypeptide antigens of five species subcutaneously,with 2 for each kind of antigen. The antiserum was then obtained and purified by Protein A affinity chromatography to prepare the polyclonal antibody. The titers and specificity of the polyclonal antibodies were determined by ELISA and Western blot respectively,and the prepared five species of serum albumin were used to identify HSA products. Results The synthetic peptides of human,cattle,sheep,pig and horse serum albumin had a purity of over 91%,and the corresponding polyclonal antibodies all had the titer of 1∶160 000,which showed specific binding with the corresponding antigens and effectively identified the HSA products. Conclusion The polyclonal antibodies of human cattle,sheep,pig and horse serum albumin prepared in this study have good specificity and the preparation process is simple and rapid,suitable for the mass production,which lays a foundation of the development of HSA rapid identification kit.