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Wang S, Yang Y, Yue X, Liu Z, Yuan F, Yang K, Zhu J, Liu W, Tian Y, Wu Q, Gao T, Li C, Song H, Zhou D, Bei W. Preparation and Evaluation of Novel Epitope-Based ETEC K88-K99 Bivalent Vaccine. Vet Sci 2025; 12:381. [PMID: 40284883 PMCID: PMC12030781 DOI: 10.3390/vetsci12040381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2025] [Revised: 04/14/2025] [Accepted: 04/16/2025] [Indexed: 04/29/2025] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is one of the primary pathogens causing diarrhea in piglets, causing significant economic losses in the swine farming industry. Due to the numerous serotypes of ETEC, traditional vaccines fail to provide sufficient cross-protection, and subunit vaccines based on epitope design have emerged as a safer and more effective approach for prevention and control. Unlike vaccine development strategies that involve the tandem arrangement of multiple antigenic epitopes, this study used the K88-FaeG protein as a backbone and incorporated the antigenic epitopes of K99-FanC to achieve a better immunogenicity. By using bioinformatics software to predict B-cell linear epitopes (score of over 0.6), B-cell epitopes from three-dimensional structures (50% amino acid score of ≥0.2), and B-cell epitope IgG antibody subtypes, as well as docking analysis with Sus scrofa aminopeptidase N (APN) receptors, six antigenic epitopes of K99-FanC were selected. Through Western blotting and competitive ELISA, we confirmed that all six recombinant proteins exhibited binding capabilities to K88- and K99-positive serum. The ELISA results showed that the serum levels of specific IgG and IgA antibodies increased after immunization, with FaeG-Ep3 and FaeG-Ep5 inducing the highest antibody titers against FanC-IgG (Log2 = 14.96) and FaeG-IgG (Log2 = 17.96), respectively. Bacterial adhesion assays revealed that only FaeG-Ep3 effectively blocked the adhesion of both K99 and K88 to IPEC-J2 cells. Immunization challenge experiments showed that, in the unimmunized group, mice infected with K88 and K99 experienced weight loss (p < 0.05) with intestinal villus shedding and intestinal wall structural damage. However, in the FaeG-Ep3-immunized group, no significant weight loss occurred after infection, and the villus protection rate (83%) was the same as that in the FaeG and FanC immunized groups. Overall, the FaeG-Ep3 recombinant protein identified in this study shows potential vaccine application value and provides new insights for developing multivalent vaccines against ETEC.
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Affiliation(s)
- Shuangshuang Wang
- National Key Laboratory of Agricultural Microbial Resources Discovery and Utilization, Huazhong Agricultural University, Wuhan 430070, China; (S.W.); (X.Y.)
- The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Yuxin Yang
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Xinru Yue
- National Key Laboratory of Agricultural Microbial Resources Discovery and Utilization, Huazhong Agricultural University, Wuhan 430070, China; (S.W.); (X.Y.)
- The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Zewen Liu
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Fangyan Yuan
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Keli Yang
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Jiajia Zhu
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Wei Liu
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Yongxiang Tian
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Qiong Wu
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Ting Gao
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Chang Li
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Haofei Song
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Danna Zhou
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (Y.Y.); (Z.L.); (F.Y.); (K.Y.); (J.Z.); (W.L.); (Y.T.); (Q.W.); (T.G.); (C.L.); (H.S.)
| | - Weicheng Bei
- National Key Laboratory of Agricultural Microbial Resources Discovery and Utilization, Huazhong Agricultural University, Wuhan 430070, China; (S.W.); (X.Y.)
- The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, China
- Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan 430070, China
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Zhao H, Xu Y, Li X, Yin J, Li G, Zhao H, Li S, Li J, Wang L. Protective efficacy of a recombinant enterotoxin antigen in a maternal immunization model and the inhibition of specific maternal antibodies to neonatal oral vaccination. J Reprod Immunol 2023; 157:103946. [PMID: 37031607 DOI: 10.1016/j.jri.2023.103946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 02/19/2023] [Accepted: 04/03/2023] [Indexed: 04/11/2023]
Abstract
ETEC (enterotoxigenic Escherichia coli) infection is the leading cause of profuse watery diarrhea in mammals, especially among pre-weaning and post-weaning piglets in swine industry. Maternal immunization is a current rational strategy for providing protection to susceptive piglets and reducing the incidence of ETEC-associated diarrhea. Here we evaluated the protective efficiency of a recombinant antigen (MBP-SLS) fused by major enterotoxin subunits (STa-LTB-STb) via a maternal immunization model, and the impacts of maternal antibodies to neonatal oral vaccination were also investigated in the neonates. The high titers of specific IgG and sIgA in pups shown that the maternal antibodies could be transferred passively. Furthermore, the increases of IL-6 and IL-10 cytokines in breast milk and pup serum indicated that immunization on mother could effectively boost the immune system of neonates. Newborn rats from immunized mothers showed a 70% survival rate after ETEC infection. However, the mucosal immune responses of neonates were inhibited by the high level of maternal specific antibodies. Among the oral-vaccinated neonates, born from mock-immunized rats reached the highest survival after ETEC challenge. Collectively, the fusion MBP-SLS antigen could effectively induce strong immune responses in rats during pregnancy and the pups could receive passive protection through specific antibodies transferred via milk and placenta. However, the specific maternal antibodies exhibited an inhibition effect on the mucosal immune responses in offspring.
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Affiliation(s)
- Hong Zhao
- School of Bioengineering, Dalian University of Technology, Dalian 116024, China
| | - Yongping Xu
- School of Bioengineering, Dalian University of Technology, Dalian 116024, China; Dalian SEM Bio-Engineering Technology Co. Ltd., Dalian 116620, China; Center for Food Safety of Animal Origin, Ministry of Education, Dalian University of Technology, Dalian 116600, China
| | - Xiaoyu Li
- School of Bioengineering, Dalian University of Technology, Dalian 116024, China
| | - Jiajun Yin
- Affiliated Zhongshan Hospital of Dalian University, Dalian 116001, China
| | - Gen Li
- School of Bioengineering, Dalian University of Technology, Dalian 116024, China
| | - Haofei Zhao
- School of Bioengineering, Dalian University of Technology, Dalian 116024, China
| | - Shuying Li
- Dalian SEM Bio-Engineering Technology Co. Ltd., Dalian 116620, China; Center for Food Safety of Animal Origin, Ministry of Education, Dalian University of Technology, Dalian 116600, China
| | - Jibin Li
- Dalian SEM Bio-Engineering Technology Co. Ltd., Dalian 116620, China
| | - Lili Wang
- School of Bioengineering, Dalian University of Technology, Dalian 116024, China.
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Golchin M, Aitken R. Isolation by phage display of recombinant antibodies able to block adherence of Escherichia coli mediated by the K99 colonisation factor. Vet Immunol Immunopathol 2007; 121:321-31. [PMID: 18036670 DOI: 10.1016/j.vetimm.2007.10.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 09/26/2007] [Accepted: 10/04/2007] [Indexed: 10/22/2022]
Abstract
K99 fimbriae are important for intestinal colonisation by bovine strains of enterotoxigenic Escherichia coli. The mode of action of this colonisation factor is well understood and specific immune responses are protective. K99 was therefore chosen for this study as a model to test if antibodies with anti-adhesion activity could be isolated from recombinant libraries using phage display techniques. Potentially, this strategy could be used to understand better the action of bacterial colonisation factors and aid the design of therapies (e.g. vaccines, purified protein products or bacteria bearing colonisation-blocking antibodies) to inhibit bacterial adherence. The major fimbrial subunit from K99, FanC, was purified from a clinical E. coli isolate. The protein was coated to plastic immunotubes and used as a target for selection of antibodies from the Tomlinson I and J libraries of single chain (scFv) antibodies. Clones able to recognise K99 were isolated by iterative rounds of binding, elution and amplification. scFv antibodies chosen from the resulting panel were purified and their specificity confirmed by ELISA. Pre-incubation of several scFvs with bacteria expressing K99 fimbriae inhibited the agglutination of erythrocytes. Further investigation by microscopy confirmed that when E. coli expressing K99 were exposed to scFv antibodies, the binding of bacteria to erythrocytes was blocked with high efficiency. The study showed that recombinant antibodies were able to block the action of a bacterial colonisation factor and hence that phage display techniques might be applied to the identification of less well-characterised virulence factors and the analysis of their structure and function.
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Affiliation(s)
- Mehdi Golchin
- Division of Infection and Immunity, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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Piller KJ, Clemente TE, Jun SM, Petty CC, Sato S, Pascual DW, Bost KL. Expression and immunogenicity of an Escherichia coli K99 fimbriae subunit antigen in soybean. PLANTA 2005; 222:6-18. [PMID: 15609046 DOI: 10.1007/s00425-004-1445-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Accepted: 10/30/2004] [Indexed: 05/15/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) cause acute diarrhea in humans and farm animals, and can be fatal if the host is left untreated. As a potential alternative to traditional needle vaccination of cattle, we investigated the feasibility of expressing the major K99 fimbrial subunit, FanC, in soybean (Glycine max) for use as an edible subunit vaccine. As a first step in this developmental process, a synthetic version of fanC was optimized for expression in the cytosol and transferred to soybean via Agrobacterium-mediated transformation. Western analysis of T(0) events revealed the presence of a peptide with the expected mobility for FanC in transgenic protein extracts, and immunofluorescense confirmed localization to the cytosol. Two T(0) lines, which accumulated FanC to levels near 0.5% of total soluble protein, were chosen for further molecular characterization in the T(1) and T(2) generations. Mice immunized intraperitoneally with protein extract derived from transgenic leaves expressing synthetic FanC developed significant antibody titers against bacterially derived FanC and produced antigen-specific CD4(+) T lymphocytes, demonstrating the ability of transgenic FanC to function as an immunogen. These experiments are the first to demonstrate the expression and immunogenicity of a model subunit antigen in the soybean system, and mark the first steps toward the development of a K99 edible vaccine to protect against ETEC.
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Affiliation(s)
- Kenneth J Piller
- Department of Biology, University of North Carolina-Charlotte, 9201 University City Boulevard, Charlotte, NC 28223, USA.
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Jay CM, Bhaskaran S, Rathore KS, Waghela SD. Enterotoxigenic K99+ Escherichia coli attachment to host cell receptors inhibited by recombinant pili protein. Vet Microbiol 2004; 101:153-60. [PMID: 15223119 DOI: 10.1016/j.vetmic.2004.03.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2003] [Revised: 03/04/2004] [Accepted: 03/04/2004] [Indexed: 11/21/2022]
Abstract
Most enterotoxigenic Escherichia coli (ETEC) isolated from neonatal cattle with diarrhea (enteric colibacillosis) exhibit the colonization factor antigen, K99. The K99 pili are necessary for the bacteria to bind to a receptor, N-glycolylneuraminic acid-GM3 on the host cells in the small intestine where the bacteria multiply and secrete toxins that cause the diarrhea. When the attachment of the ETEC to host cell is inhibited, the bacteria do not accumulate sufficiently in the gut to cause disease. Since purified K99 pili block K99+ ETEC from binding to host epithelia, three recombinant K99 proteins of different sizes were developed and produced to demonstrate inhibition with in vitro competitive binding assays. The full-length recombinant protein, rK99-476 inhibited the binding of ETEC with an activity similar to that of the native purified K99, whereas the truncated recombinant K99 protein had no inhibitory activity. Thus this binding activity of rK99-476, which is specific and effective in blocking the receptors on the host cells, may be able to competitively inhibit K99+ ETEC infections in cattle.
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Affiliation(s)
- Christopher M Jay
- Department of Veterinary Pathobiology, Texas Veterinary Medical Center, Texas A&M University, College Station, TX 77843, USA.
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Verdonck F, Cox E, Schepers E, Imberechts H, Joensuu J, Goddeeris BM. Conserved regions in the sequence of the F4 (K88) fimbrial adhesin FaeG suggest a donor strand mechanism in F4 assembly. Vet Microbiol 2004; 102:215-25. [PMID: 15327796 DOI: 10.1016/j.vetmic.2004.06.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2003] [Revised: 06/07/2004] [Accepted: 06/14/2004] [Indexed: 10/26/2022]
Abstract
Oral immunization of newly weaned piglets with recombinant F4 (K88) fimbrial adhesin FaeG induces a F4-specific immune response, significantly reducing F4+ Escherichia coli excretion following challenge. In order to use FaeG subunits in an oral vaccine against F4+ enterotoxigenic E. coli, it is necessary to determine the conservation of the adhesin subunit. Hereto, the faeG sequence was determined of 21 F4ac+ E. coli field isolates from piglets with diarrhoea and subsequently compared with these of the reference strain GIS26 and previously reported FaeG sequences from F4ab, F4ac and F4ad antigenic variant strains. The FaeG amino acid sequence was 96-100% homologous within each F4 serotype, but only 92 and 88% when the F4ab and F4ad antigenic variants were compared with the F4ac antigenic variant. Furthermore, the conserved regions of the adhesin suggest a donor strand mechanism in F4 fimbriae assembly as reported for type 1 and P pili. In conclusion, the results of the reported experiments support the usefulness FaeG in an oral subunit vaccine against F4+ E. coli infections or as a mucosal carrier since the adhesin is conserved among F4+ E. coli field isolates.
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Affiliation(s)
- F Verdonck
- Laboratory of Veterinary Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium.
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