Development of a monoclonal antibody-based sandwich ELISA for detection of guinea pig interleukin-2

Interleukin 2 (IL-2) is a T cell proliferation factor released by Th0- and Th1-type helper T cells and is an essential cytokine for immune responses. In the present study, recombinant glutathione S-transferase (GST)-guinea pig IL-2 (GPIL-2) fusion protein was prepared by Escherichia coli (E. coli) and by using this protein as an immunogen, monoclonal antibodies (mAbs) against GPIL-2 were produced to establish a basis for a research on immune responses in guinea pigs. Three stable hybridoma cell lines were established, and specific binding of each mAb to recombinant GPIL-2 produced by E. coli and insect cells infected with recombinant baculovirus was shown by enzyme linked immunosorbent assay (ELISA) and/or immunoblot analysis. Isotype analyses of these mAbs revealed that all three mAbs were IgG1 and had kappa chain. Furthermore, assessment of their epitopes by competition binding assay indicated that the mAbs obtained in this study bound to three different epitopes. Thus, a sandwich ELISA based on the two mAbs specific to different GPIL-2 epitopes was developed for detection of GPIL-2, which had a sensitivity threshold of about 0.3 ng/ml of GPIL-2.     

Characterization of monoclonal antibodies to equine interleukin-10 and detection of T regulatory 1 cells in horses

Interleukin-10 (IL-10) terminates inflammatory immune responses and inhibits activation and effector functions of T-cells, monocytes, macrophages and dendritic cells. IL-10 has also been found to be a key cytokine expressed by subpopulations of regulatory T-cells. In this report, we describe the generation and characterization of three monoclonal antibodies (mAbs) to equine IL-10. The antibodies were found to be specific for equine IL-10 using different recombinant equine cytokine/IgG fusion proteins. Two of the anti-equine IL-10 mAbs were selected for ELISA to detect secreted IL-10 in supernatants of mitogen stimulated equine peripheral blood mononuclear cells (PBMC). The sensitivity of the ELISA for detecting secreted IL-10 was found to be around 200pg/ml. The production of intracellular IL-10 was measured in equine PBMC by flow cytometry. PBMC were stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin in the presence of the secretion blocker Brefeldin A. All three anti-IL-10 mAbs detected a positive population in PMA stimulated lymphocytes which was absent in the medium controls. Around 80% of the IL-10(+) cells were CD4(+). Another 15% were CD8(+) cells. Double staining with IL-4 or interferon-gamma (IFN-gamma) indicated that PMA and ionomycin stimulation induced 80% IL-10(+)/IFN-gamma(+) lymphocytes, while only 5% IL-10(+)/IL-4(+) cells were observed. By calculation, at least 60% of the IL-10(+)/IFN-gamma(+) cells were CD4(+) lymphocytes. This expression profile corresponds to the recently described T regulatory 1 (T(R)1) cell phenotype. In summary, the new mAbs to equine IL-10 detected native equine IL-10 by ELISA and flow cytometry and can be used for further characterization of this important regulatory cytokine in horses.     

Production and characterization of monoclonal antibodies reactive with the chicken interleukin-15 receptor alpha chain

We recently cloned the genes encoding chicken IL-15 and IL-15 receptor (R) alpha proteins. In this study, 12 monoclonal antibodies (mAbs) against recombinant chicken IL-15Ralpha were produced and characterized. By enzyme-linked immunosorbent assay (ELISA), all mAbs showed binding specificity for IL-15Ralpha, but not IL-2 or interferon-gamma, and identified a 25.0kDa protein by immunoblot analysis. Flow cytometric analysis revealed negligible expression of IL-15Ralpha on non-activated lymphocytes from the spleen, thymus or bursa, low but detectable expression on macrophages and high expression on concanavalin A-activated spleen lymphoblasts. Established chicken T cell (RP13) and macrophage (HD11) cell lines expressed substantially higher levels of IL-15Ralpha compared with a B cell line (RP9). Two mAbs inhibited IL-15 dependent proliferation of T cells suggesting that the tertiary structure of the protein domain of native IL-15Ralpha that binds to IL-15 is preserved in the recombinant receptor molecule. These mAbs will be useful reagents for further in vitro and in vivo studies of the biological functions of chicken IL-15 and its receptor.     

Monoclonal anti-equine IgE antibodies with specificity for different epitopes on the immunoglobulin heavy chain of native IgE

In this study we describe the generation of monoclonal antibodies (mAbs), which recognize different epitopes of the equine IgE constant heavy chain. Equi-murine recombinant IgE (rIgE), composed of the murine V(H)186.2 heavy chain variable region, linked to the equine IgE constant heavy chain and expressed together with the murine lambda(1) chain in J558L cells was used to immunize BALB/C mice. A total of 17 different mAbs were obtained, which recognized the rIgE heavy chain constant region. None of the mAbs reacted with monoclonal equine isotypes IgM, IgG1 (IgGa), IgG3 (IgG(T)), IgG4 (IgGb) or isolated equine light chains, IgGc and IgA from horse serum, or the native mAb B1-8delta, expressing the same heavy chain variable regions and light chains. One of the mAbs (alphaIgE-132) recognized the recombinant equine IgE, but did not recognize any protein in equine serum, i.e. native IgE. A total of 16 mAbs detected a serum protein of approximately 210,000Da on Western blots, corresponding to the expected MW of native IgE. In addition, one of the mAbs (alphaIgE-176) detected a protein of 76,000Da under reducing conditions, most likely the equine IgE heavy chain. According to binding inhibition studies, the equine IgE specific mAbs recognize at least two different epitopes of the equine IgE. In an ELISA using two anti-IgE mAbs which recognized different epitopes, no significant differences in the concentration of total serum IgE could be detected between adult Icelandic horses with IgE-mediated type I allergy (summer eczema) and healthy control animals. In Icelandic horse foals, no serum IgE could be measured 6 months post partum. All anti-IgE mAbs recognized a small population (1.3+/-0.5%) of leukocytes from adult Icelandic horses by surface immunofluorescence, but no cells could be detected in foal blood. The stained leukocytes from adult horses could be enriched by magnetic cell sorting and contained 32% basophils, 53% monocytes and/or large lymphocytes, 13% small lymphocytes and 2% eosinophils.     

Development and characterization of mouse monoclonal antibodies reactive with chicken interleukin-2 receptor αlpha chain (CD25)

This study was carried out to develop and characterize mouse monoclonal antibodies (mAbs) against chicken CD25 (chCD25), the alpha chain of the interleukin-2 (IL-2) receptor. A recombinant chimeric chCD25/IgG4 fusion protein was expressed in Chinese hamster ovary (CHO) cells and isolated from spent cell culture medium by protein G affinity chromatography. Purified chCD25 protein was used to immunize mice, from which 54 stable hybridomas secreting chCD25 mAbs were produced. Two mAbs, chCD25-32 and chCD25-54, with high binding affinity for chCD25-expressing CHO cells were selected for further characterization. By flow cytometry, both mAbs detected cells in the spleen, bursa of Fabricius, intestinal duodenum, and immunostained established chicken T cell, B cell, and macrophage cell lines. Both mAbs reacted with a 55 kDa protein on Western blots of lysates from concanavalin A (Con A)-stimulated spleen mononuclear cells. Intraperitoneal injection of chickens with bacterial lipopolysaccharide increased the percentage of chCD25(+) spleen cells by approximately 4-fold compared with untreated animals. In vitro stimulation of spleen cells with Con A increased the percentage of chCD25(+) cells by up to 50-fold compared with cells treated with medium alone. Finally, the chCD25-32 mAb suppressed IL-2-driven spleen cell proliferation and reduced IL-2-induced nitric oxide production. These mAbs may be useful for future investigation of chicken regulatory T cells.     

Epitopes of the T19 lymphocyte surface antigen are extensively conserved in ruminants.

The reactivity of five monoclonal antibodies (mAbs SBU-T19, 197, IL-A29, CC-15 and CC-39) specific for the T19 molecule on sheep and cattle CD4-CD8- T cells was compared. MAbs SBU-T19 and 197 were shown to recognise separate epitopes on T19. All mAbs reacted with lymphocytes from several different ruminant species and the tissue distribution and frequency of positive cells was similar in each case. None of the mAbs reacted with horse, pig or camel lymphocytes. The extensive conservation of T19 epitopes in ruminants during the mammalian radiation could indicate an important role for this molecule in the ruminant immune system.     

Monoclonal antibodies suitable for incorporation into a competitive enzyme-linked immunosorbent assay (ELISA) for detection of specific antibodies to Leptospira interrogans serovar pomona

Monoclonal antibodies (mAb) were produced by fusing Sp2/0-Ag14 myeloma cells with spleen cells from BALB/c and ND4 mice that were immunized with killed Leptospira interrogans serovar pomona whole cells. Thirty hybridomas which produced antibodies (of the IgG1, IgG2a, IgG2b, or IgG3 isotype) that bound to epitopes on the serovar pomona whole cell antigen were identified by an indirect enzyme-linked immunosorbent assay (ELISA). Twenty-eight of these 30 mAbs cross-reacted in the indirect ELISA with at least one whole cell antigen prepared from 12 other pathogenic Leptospira serovars, and/or with whole cell antigen from the non-pathogenic Leptospira biflexa serovar patoc. The two serovar pomona-specific mAbs, which were designated M897 and M898, were obtained from the ND4 mouse and were both of the IgG1 isotype. In competitive ELISAs, M897 and M898 were inhibited from binding to the pomona antigen by bovine sera with anti-serovar pomona microscopic agglutination test (MAT) titres ranging from 100 to 6400. No significant inhibition was observed with pomona MAT-negative sera or with sera from animals experimentally infected with serovars canicola, copenhageni, grippotyphosa, hardjo type hardjobovis or sejroe. The epitopes recognized by M897 and M898 were both highly susceptible to sodium meta-periodate oxidation, indicating a carbohydrate composition. Neither of these mAbs reacted in immunoblots with the separated components of the serovar pomona whole cell antigen.     

Functional characterization of a swine CD4(+)/CD8(+) double positive lymphoblastoid T-cell line with a CD25(+)/CD45RA(-) phenotype generated in vitro with interleukin-2

A dual expressing (CD4(+)/CD8(+)) porcine lymphoblastoid T-cell line (pIL-2d) generated from peripheral blood mononuclear (MN) cells shown to be highly responsive to exogenous interleukin-2 (IL-2) was characterized. The swine MN cells were initially stimulated with concanavalin A (Con A), and sub-passaged using decreasing amounts of conditioned medium (CM), which was prepared from culture fluids of Con A activated porcine MN cells, until a steady growth was observed. The resulting pIL-2d cells require exogenous IL-2 from CM and are highly responsive to recombinant human IL-2 (rhIL-2). The pIL-2d cells exhibited a specific, dose-dependent proliferative response to stimulation with IL-2. The specificity of this proliferative response was confirmed to be IL-2 induced by its inhibition with an anti-swine IL-2 receptor (alpha-swIL-2R) monoclonal antibody (mAb). Furthermore, the pIL-2d cells are highly responsive to exogenous IL-2 contained in culture fluids derived from antigen-driven blastogenic tests performed with lymphocytes of vaccinated swine. This property makes the pIL-2d cells an ideal functional adjunct to immunochemical or molecular tests that are commonly used to measure total porcine IL-2. Interestingly, the phenotype of the pIL-2d cells after five or more passages was shown by flow cytometric analysis to be CD4(+)/CD8(+)/CD45RA(-)/CD25(+) and to remain unchanged thereafter. Although, the mechanism of selection and maintenance of the CD4(+)/CD8(+) DP cells developed here remains unclear, our data suggest that an oligoclonal or polyclonal expansion and maintenance of cells of this phenotype was mediated by exogenous IL-2.     

Adjuvant effect enhancement of porcine interleukin-2 packaged into solid lipid nanoparticles

In this paper, we investigated the enhancement of adjuvant effects of porcine IL-2 (pIL-2) by packaging it into a solid lipid nanoparticle (SLN) delivery system. SLN–pIL-2 was prepared using hydrogenated castor oil and Polylactide-co-glycolide by double emulsion solvent evaporation methods (w/o/w). In animal trials, BALB/c mice were immunized with inactivated foot and mouth disease virus (FMDV) antigen combined with the SLN–pIL-2 adjuvant on days 0 and 14. Antibody titer, splenocyte proliferation, and secretion of IFN-γ and IL-4 cytokines were determined. Our results showed that SLN–pIL-2 could significantly enhance FMDV-specific antibody level compared with recombinant pIL-2 alone (p < 0.05). In addition, SLN–pIL-2 significantly increased the proliferative responses of antigen-specific spleen cells. Furthermore, SLN–pIL-2 induced the secretion of IFN-γ at a level higher than that induced by recombinant pIL-2 alone. Our results indicate that packaging recombinant pIL-2 in SLNs can be an effective way of boosting the effectiveness of pIL-2 as an adjuvant to enhance immune responses of vaccines.     

鸡Toll样受体15单克隆抗体的制备及其初步应用

旨在制备鸡Toll样受体15 (ChTLR15)的特异性单克隆抗体(mAb),并初步应用.利用PCR技术扩增ChTLR15第162-386位氨基酸,克隆于载体pET-30a中进行诱导表达,获得高纯度的重组ChTLR15 (162-386 aa)蛋白.然后采用皮下多点注射方式将ChTLR15免疫6周龄的雌性BALB/c小...     

Production and characterization of monoclonal antibodies to (poly100)S1 protein of avian infectious bronchitis virus

Fragments within S1 genes ((poly100)S1) of infectious bronchitis virus (IBV) strains ZJ971, M41 and SC021202 (SC) were subcloned into a prokaryotic expression vector and expressed in Escherichia coli. Monoclonal antibodies (mAbs) against the recombinant (poly100)S1 proteins were produced, characterized and used to analyse epitopes on the S1 subunit of IBV. Nine mAbs raising from the three (poly100)S1 proteins recognized five different epitopes of the S1 subunit, designated as S1-A, B, C, D and E. Epitopes S1-C and S1-D are common for the three IBV strains, while S1-A and S1-B exist on ZJ971 and M41 strains, and S1-E was a strain-specific epitope for SC strain. Immunocytochemistry indicated that all the mAbs to the (poly100)S1 proteins can react with the homologous S1 glycoprotein expressed in Vero cells. Moreover neutralization test demonstrated that only mAbs 6E2, 4F9 and 6G4 had neutralization activity for the homologous IBV. These mAbs to (poly100)S1 protein were potential candidates for detecting and distinguishing IBV strains, and also used to examine antigenic variation of the S1 protein.     

猪圆环病毒2型衣壳蛋白优势B细胞表位重组蛋白免疫原性研究

猪圆环病毒2型(PCV-2)衣壳蛋白(Cap)是研制基因工程疫苗和血清抗体检测方法的主要候选抗原。为筛选免疫原性强的Cap抗原表位,将定位在Cap上的6个B细胞线性表位的编码基因序列重新组合,命名为R1234、R1235、R1236、R2345、R2346和R3456,然后克隆至pET32a原核表达载体,转化到大肠埃希菌中进行诱导表达。通过对表达和纯化条件的优化,最终获得6个多抗原表位串联体的重组蛋白。Western blot和间接ELISA结果显示,6组重组表位蛋白均能被PCV-2阳性血清特异性识别,具有良好的反应原性。将其与完整Cap分别免疫Balb/c小鼠,检测免疫后血清中特异性抗体和细胞因子水平以及脾脏淋巴细胞中CD4^+和CD8^+T淋巴细胞的比例。结果表明,R2346组合刺激机体产生的特异性抗体和细胞因子IFN-γ、IL-4的水平明显高于其他组,脾脏淋巴细胞中CD4^+和CD8^+T淋巴细胞含量与对照组相比显著增加(P<0.05),说明该重组蛋白能够刺激体液免疫和细胞免疫反应。因此,筛选获得的R2346重组表位蛋白可以作为研制PCV-2多表位基因工程疫苗和血清抗体诊断方法的候选抗原,用于PCV-2的预防和控制工作中。     

Development and characterization of mouse monoclonal antibodies reactive with chicken CD80

This study was carried out to develop and characterize mouse monoclonal antibodies (mAbs) against chicken CD80 (chCD80). A recombinant plasmid containing a chCD80/horse IgG4 fusion gene was constructed and expressed in CHO cells to produce recombinant chCD80/IgG4 protein. Chicken CD80 was purified from the chCD80/IgG4 fusion protein following enterokinase digestion, and used to immunize BALB/c mice, resulting in 158 hybridomas that produced mAbs against chCD80. Three mAbs with high binding specificity for recombinant chCD80/IgG4-transfected CHO cells were identified by flow cytometry, and one of these (#112) was selected for further characterization. Immunoprecipitation of CD80/IgG4-CHO cell extract, or lipopolysaccharide (LPS)-treated monocytes identified 35.0 kDa proteins. Immunohistochemical analysis revealed chCD80-expressing cells exclusively in the bursal follicles at the outer portion of the cortex, and throughout the red pulp and the outer boundary of the white pulp in the spleen. By immunofluorescence microscopy, chCD80 was observed on intestinal dendritic cells. LPS treatment of bursa or spleen monocytes for 24 or 48 h increased chCD80 expression. Finally, addition of chCD80 mAb to Con A-stimulated spleen cells inhibited the expression of major histocompatibility complex class II antigens and IL-2-driven proliferation of lymphoblast cells. In summary, these chCD80 mAbs will serve as valuable immunological reagents for basic and applied poultry immunology research.     

Generation and characterization of monoclonal antibodies to equine NKp46

The immunoreceptor NKp46 is considered to be the most consistent marker of NK cells across mammalian species. Here, we use a recombinant NKp46 protein to generate a panel of monoclonal antibodies that recognize equine NKp46. The extracellular region of equine NKp46 was expressed with equine IL-4 as a recombinant fusion protein (rIL-4/NKp46) and used as an immunogen to generate mouse monoclonal antibodies (mAbs). MAbs were first screened by ELISA for an ability to recognize NKp46, but not IL-4, or the structurally related immunoreceptor CD16. Nine mAbs were selected and were shown to recognize full-length NKp46 expressed on the surface of transfected CHO cells as a GFP fusion protein. The mAbs recognized a population of lymphocytes by flow cytometric analysis that was morphologically similar to NKp46+ cells in humans and cattle. In a study using nine horses, representative mAb 4F2 labeled 0.8-2.1% PBL with a mean fluorescence intensity consistent with gene expression data. MAb 4F2+ PBL were enriched by magnetic cell sorting and were found to express higher levels of NKP46 mRNA than 4F2- cells by quantitative RT-PCR. CD3-depleted PBL from five horses contained a higher percentage of 4F2+ cells than unsorted PBL. Using ELISA, we determined that the nine mAbs recognize three different epitopes. These mAbs will be useful tools in better understanding the largely uncharacterized equine NK cell population.     

Monoclonal antibodies against chicken interleukin-6

Monoclonal antibodies (mAb) were produced against a recombinant (r) chicken interleukin-6 (IL-6). Eight mAbs produced were tested for isotype; ability to inhibit recombinant forms of chicken (ch), human (h) and murine (m) IL-6; and recognition of rchIL-6 by Western immunoblotting. The mAb isotypes were represented by IgG1 (one), IgG2a (six) and IgG2b (one). In a mouse B9 hybridoma cell bioassay with rmIL-6, four mAbs effectively inhibited activity of rmIL-6. Further bioassays with the four mAbs at varying concentrations showed that two of these mAbs (1.20.7 and 1.26.4) were quite effective at inhibiting rmIL-6. Recombinant forms of ch, h and mIL-6 were all tested in a bioassay with the most potent inhibiting mAb (1.26.4), and this mAb was effective in inhibiting all three recombinant IL-6 proteins. Western immunoblotting revealed identification of the original IL-6 immunogen used for mAb production. Based upon inhibition of IL-6 activity in a standard bioassay and IL-6 recognition by Western immunoblotting, mAb 1.26.4 was judged the most useful antibody for future studies and applications.     

Monoclonal antibodies reactive with chicken interleukin-17

Chicken interleukin-17 (chIL-17) gene was previously characterized through cloning from a chicken intestinal expressed sequence tag (EST) cDNA library. To further investigate the biological properties of chIL-17, six monoclonal antibodies (mAbs) against a bacterially expressed chIL-17 recombinant protein were produced and their binding specificities characterized. Antibodies which were initially selected on the basis of their specific binding reactivity with recombinant chIL-17 in ELISA were further characterized by Western blot analysis. Monoclonal antibodies specific for chIL-17 identified 20 and 21kDa protein bands in the culture supernatant and cell lysate of CU205 cells. These mAbs also recognized specific bands for chIL-17 in the cell lysate from conconavalin A (Con A)-activated, but not from normal splenic lymphocytes. Furthermore, these mAbs detected a 16kDa protein in the lysate of CU205 cells treated with tunicamycin and stained an intracellular protein in CU205 cells in flow cytometric analysis. Together, these results indicate that these new mAbs are specific for chIL-17 and will be a useful tool for structural and immunological studies of IL-17 in poultry.     

Monoclonal antibodies to equine CD23 identify the low-affinity receptor for IgE on subpopulations of IgM+ and IgG1+ B-cells in horses

CD23, also called FcεRII, is the low-affinity receptor for IgE and has first been described as a major receptor regulating IgE responses. In addition, CD23 also binds to CD21, integrins and MHC class II molecules and thus has a much wider functional role in immune regulation ranging from involvement in antigen-presentation to multiple cytokine-like functions of soluble CD23. The role of CD23 during immune responses of the horse is less well understood. Here, we expressed equine CD23 in mammalian cells using a novel IL-4 expression system. Expression resulted in high yield of recombinant IL-4/CD23 fusion protein which was purified and used for the generation of monoclonal antibodies (mAbs) to equine CD23. Seven anti-CD23 mAbs were further characterized. The expression of the low-affinity IgE receptor on equine peripheral blood mononuclear cells was analyzed by flow cytometric analysis. Cell surface staining showed that CD23 is mainly expressed by a subpopulation of equine B-cells. Only a very few equine T-cells or monocytes expressed CD23. CD23(+) B-cells were either IgM(+) or IgG1(+) cells. All CD23(+) cells were also positive for cell surface IgE staining suggesting in vivo IgE binding by the receptor. Two of the CD23 mAbs detected either the complete extracellular region of CD23 or a 22kDa cleavage product of CD23 by Western blotting. The new anti-CD23 mAbs provide valuable reagents to further analyze the roles of CD23 during immune responses of the horse in health and disease.     

抗犬瘟热病毒重组核衣壳蛋白单克隆抗体的制备及鉴定

以纯化的重组犬瘟热病毒(CDV)N蛋白免疫BALB/c小鼠,应用常规杂交瘤技术获得两株能稳定分泌特异性单克隆抗体的杂交瘤细胞系,分别命名为A_4C_6C_(12)和A_5B_8H_7。间接ELISA检测腹水效价分别为1:10~6、1:10~5;亚类鉴定结果分别为IgG2a、IgG2b,轻链均为κ型;Western blot和ELISA分析结果显示2株单克隆抗体均能与重组N蛋白和CDV发生反应,而与犬细小病毒及犬腺病毒等无交叉反应;ELISA叠加试验的增值结果表明两株单克隆抗体识别的抗原位点不同。特异性抗CDV-rN的单克隆抗体的获得,为进一步用于临床诊断研究奠定了基础。     

Analysis of Immune Response Induced by Recombinant Lactobacillus reuteri Expressing Cap Protein of Porcine Circovirus Type 2 in Mice

The purpose of this study was to construct a recombinant Lactobacillus reuteri (L. reuteri) expressing the cap protein of porcine circovirus type 2 (PCV2) and evaluate its effect on immune response in mice. The cap protein gene of PCV2b strain isolated and stored in the laboratory was amplified by PCR. A recombinant strain pPG-T7 g10-PPT-cap / L. reuteri expressing the cap protein was constructed using L. reuteri of pig origin as the host strain and explored the immune effect of BALB/c mice with recombinant bacteria orogastrically. Indirect ELISA was used to determine the level of antigen-specific IgG antibodies in the serum of mice after immunization, the levels of antigen-specific sIgA antibodies in stool, nasal wash, reproductive tract wash, and intestinal mucus, and the levels of various cytokines in mouse serum; MTT method was used to detect mouse spleen lymphocyte proliferation levels; flow cytometry (FCM) was used to detect the levels of CD4⁺ T cells and CD8⁺ T cells in mouse spleen lymphocytes; fluorescence quantitative PCR was used to detect the viral load of organs in challenged mice after immunization. The results showed that the serum levels of IgG antibodies in the mice of the oral immune recombinant strain group (OIG) were significantly higher than those in the control group (P<0.01); the levels of sIgA antibodies in the stool, nasal wash, reproductive tract wash, and intestinal mucus of the mice in OIG were significantly higher than those in the control group (P<0.01); Compared with the control group, the levels of cytokines in the serum of OIG were as follows: The levels of IFN-γ, IL-2, IL-4, IL-12 increased, the levels of IL-10 decreased, and the levels of IFN-α did not change significantly; Incubation of PCV2 and mouse spleen lymphocytes in vitro showed that the proliferation stimulating index of spleen lymphocytes in OIG was significantly higher than that of the control group (P<0.01); FCM results showed that CD4⁺ T cells and CD8⁺ T cells were higher than those of the control group; the results of fluorescent quantitative PCR showed that compared with the control group, the viral load in the OIG was significantly lower than that of the control group. In summary, the recombinant L. reuteri expressing the PCV2 cap protein were successfully constructed, and the constructed recombinant L. reuteri can stimulate mice to produce humoral and cellular immune responses after oragastrical immunization, and can exert a certain immune protection effect.     

表达猪圆环病毒2型cap蛋白的重组罗伊氏乳酸杆菌在小鼠诱导的免疫应答分析

旨在构建表达猪圆环病毒2型（PCV2）cap蛋白的重组罗伊氏乳酸杆菌（Lactobacillus reuteri,L.reuteri）,并评价其在小鼠体内诱导的免疫应答效果。利用PCR扩增实验室分离保存的PCV2b型毒株的cap蛋白基因,以猪源L.reuteri为宿主菌,构建表达cap蛋白的重组菌株pPG-T7 g10-PPT-cap/L.reuteri,通过口服免疫BALB/c小鼠。采用间接ELISA方法测定免疫后小鼠血清中抗原特异性IgG抗体水平,粪便、鼻腔洗液、生殖道洗液、肠黏液中抗原特异性sIgA抗体水平,小鼠血清中各细胞因子水平;MTT法检测小鼠脾淋巴细胞增殖水平;流式细胞技术检测小鼠脾淋巴细胞中CD4⁺T细胞、CD8⁺T细胞的水平;荧光定量PCR检测免疫后攻毒的小鼠体内器官的病毒载量。结果显示,口服免疫重组乳酸菌组小鼠血清IgG抗体水平显著高于对照组（P<0.01）;小鼠粪便、鼻腔洗液、生殖道洗液、肠黏液中sIgA抗体水平显著高于对照组（P<0.01）;小鼠血清中细胞因子水平和对照组相比,IFN-γ、IL-2、IL-4、IL-12水平升高,IL-10水平降低,IFN-α无显著变化;体外孵育PCV2和小鼠脾淋巴细胞结果表明,重组乳酸菌组小鼠脾淋巴细胞增殖刺激指数显著高于对照组（P<0.01）;流式细胞技术检测结果显示,口服免疫重组乳酸菌组小鼠脾细胞中CD4⁺T细胞、CD8⁺T细胞含量高于对照组;荧光定量PCR结果显示,相比于对照组,口服免疫重组乳酸菌组小鼠体内的病毒载量明显低于对照组。综上所述,本研究成功构建了表达PCV2 cap蛋白的重组罗伊氏乳酸杆菌,经口服途径免疫动物,构建的重组乳酸杆菌能够刺激小鼠产生体液免疫和细胞免疫应答,且具有一定的免疫保护效果。