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Sun J, Huang Y, Li X, Xu X, Cui X, Hao F, Ji Q, Chen C, Bao G, Liu Y. Characterization and immunological effect of outer membrane vesicles from Pasteurella multocida on macrophages. Appl Microbiol Biotechnol 2024; 108:238. [PMID: 38407600 PMCID: PMC10896778 DOI: 10.1007/s00253-024-13060-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/11/2024] [Accepted: 02/06/2024] [Indexed: 02/27/2024]
Abstract
Pasteurella multocida is an important bacterial pathogen that can cause diseases in both animals and humans. Its elevated morbidity and mortality rates in animals result in substantial economic repercussions within the livestock industry. The prevention of diseases caused by P. multocida through immunization is impeded by the absence of a safe and effective vaccine. Outer membrane vesicles (OMVs) secreted from the outer membrane of Gram-negative bacteria are spherical vesicular structures that encompass an array of periplasmic components in conjunction with a diverse assortment of lipids and proteins. These vesicles can induce antibacterial immune responses within the host. P. multocida has been shown to produce OMVs. Nonetheless, the precise characteristics and immunomodulatory functions of P. multocida OMVs have not been fully elucidated. In this study, OMVs were isolated from P. multocida using an ultrafiltration concentration technique, and their morphology, protein constitution, and immunomodulatory properties in RAW264.7 cells were studied. Transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) revealed that the OMVs exhibited typical spherical and bilayered lipid vesicular architecture, exhibiting an average diameter of approximately 147.5 nm. The yield of OMVs was 2.6 × 1011 particles/mL. Proteomic analysis revealed a high abundance of membrane-associated proteins within P. multocida OMVs, with the capability to instigate the host's immune response. Furthermore, OMVs stimulated the proliferation and cellular uptake of macrophages and triggered the secretion of cytokines, such as TNF-ɑ, IL-1β, IL-6, IL-10, and TGF-β1. Consequently, our results indicated that OMVs from P. multocida could directly interact with macrophages and regulate their immune function in vitro. These results supported the prospective applicability of P. multocida OMVs as a platform in the context of vaccine development. KEY POINTS: • Preparation and characterization of P. multocida OMVs. • P. multocida OMVs possess a range of antigens and lipoproteins associated with the activation of the immune system. • P. multocida OMVs can activate the proliferation, internalization, and cytokine secretion of macrophages in vitro.
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Affiliation(s)
- Jiaying Sun
- College of Life Sciences, China Jiliang University, Zhejiang, 310018, Hangzhou, China
| | - Yee Huang
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Zhejiang, 310021, Hangzhou, China
| | - Xuefeng Li
- College of Life Sciences, China Jiliang University, Zhejiang, 310018, Hangzhou, China
| | - Xiangfei Xu
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Zhejiang, 310021, Hangzhou, China
| | - Xuemei Cui
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Zhejiang, 310021, Hangzhou, China
| | - Fangjiao Hao
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Zhejiang, 310021, Hangzhou, China
| | - Quanan Ji
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Zhejiang, 310021, Hangzhou, China
| | - Chun Chen
- College of Life Sciences, China Jiliang University, Zhejiang, 310018, Hangzhou, China
| | - Guolian Bao
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Zhejiang, 310021, Hangzhou, China.
| | - Yan Liu
- Institute of Animal Husbandry and Veterinary Science, Zhejiang Academy of Agricultural Sciences, Zhejiang, 310021, Hangzhou, China.
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Robi DT, Mossie T, Temteme S. A Comprehensive Review of the Common Bacterial Infections in Dairy Calves and Advanced Strategies for Health Management. VETERINARY MEDICINE (AUCKLAND, N.Z.) 2024; 15:1-14. [PMID: 38288284 PMCID: PMC10822132 DOI: 10.2147/vmrr.s452925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Accepted: 01/16/2024] [Indexed: 01/31/2024]
Abstract
Dairy farming faces a significant challenge of bacterial infections in dairy calves, which can have detrimental effects on their health and productivity. This review offers a comprehensive overview of the most prevalent bacterial infections in dairy calves, including Escherichia coli, Salmonella typhimurium, Salmonella dublin, Salmonella enterica, Clostridium perfringens, Pasteurella multocida, Listeria monocytogenes, Mycoplasma bovis, and Haemophilus somnus. These pathogens can cause various clinical signs and symptoms, leading to diarrhea, respiratory distress, septicemia, and even mortality. Factors such as management practices, environmental conditions, and herd health influence the incidence and severity of the infections. Efficient management and prevention strategies include good colostrum and nutrient feeding, early detection, appropriate treatment, hygiene practices, and supportive care. Regular health monitoring and diagnostic tests facilitate early detection and intervention. The use of antibiotics should be judicious to prevent antimicrobial resistance and supportive care such as fluid therapy and nutritional support promotes recovery. Diagnostic methods, including immunological tests, culture, polymerase chain reaction (PCR), and serology, aid in the identification of specific pathogens. This review also explores recent advancements in the diagnosis, treatment, and prevention of bacterial infections in dairy calves, providing valuable insights for dairy farmers, veterinarians, and researchers. By synthesizing pertinent scientific literature, this review contributes to the development of effective strategies aimed at mitigating the impact of bacterial infections on the health, welfare, and productivity of young calves. Moreover, more research is required to enhance the understanding of the epidemiology and characterization of bacterial infections in dairy calves.
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Affiliation(s)
- Dereje Tulu Robi
- Ethiopian Institute of Agricultural Research, Tepi Agricultural Research Center, Tepi, Ethiopia
| | - Tesfa Mossie
- Ethiopian Institute of Agriculture Research, Jimma Agriculture Research Center, Jimma, Ethiopia
| | - Shiferaw Temteme
- Ethiopian Institute of Agricultural Research, Tepi Agricultural Research Center, Tepi, Ethiopia
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Yang X, Fu Q, Zhang W, An Q, Zhang Z, Li H, Chen X, Chen Z, Cheng Y, Chen S, Man C, Du L, Chen Q, Wang F. Overexpression of Pasteurella multocida OmpA induces transcriptional changes and its possible implications for the macrophage polarization. Microb Pathog 2023; 183:106212. [PMID: 37353176 DOI: 10.1016/j.micpath.2023.106212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 06/07/2023] [Accepted: 06/20/2023] [Indexed: 06/25/2023]
Abstract
Pasteurella multocida (P. multocida) is a highly infectious, zoonotic pathogen. Outer membrane protein A (OmpA) is an important virulence component of the outer membrane of P. multocida. OmpA mediates bacterial biofilm formation, eukaryotic cell infection, and immunomodulation. It is unclear how OmpA affects the host immune response. We estimated the role of OmpA in the pathogenesis of P. multocida by investigating the effect of OmpA on the immune cell transcriptome. Changes in the transcriptome of rat alveolar macrophages (NR8383) upon overexpression of P. multocida OmpA were demonstrated. A model cell line for stable transcription of OmpA was constructed by infecting NR8383 cells with OmpA-expressing lentivirus. RNA was extracted from cells and sequenced on an Illumina HiSeq platform. Key gene analysis of genes in the RNA-seq dataset were performed using various bioinformatics methods, such as gene ontology enrichment analysis, Kyoto Encyclopedia of Genes and Genomes enrichment analysis, Gene Set Enrichment Analysis, and Protein-Protein Interaction Analysis. Our findings revealed 1340 differentially expressed genes. Immune-related pathways that were significantly altered in rat alveolar macrophages under the effect of OmpA included focal adhesion, extracellular matrix and vascular endothelial growth factor signaling pathways, antigen processing and presentation, nucleotide oligomerization domain-like receptor and Toll-like receptor signaling pathways, and cytokine-cytokine receptor interaction. The key genes screened were Vegfa, Igf2r, Fabp5, P2rx1, C5ar1, Nedd4l, Gas6, Cxcl1, Pf4, Pdgfb, Thbs1, Col7a1, Vwf, Ccl9, and Arg1. Data of associated pathways and altered gene expression indicated that OmpA might cause the conversion of rat alveolar macrophages to M2-like. The related pathways and key genes can serve as a reference for OmpA of P. multitocida and host interaction mechanism studies.
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Affiliation(s)
- Xiaohong Yang
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Qiaoyu Fu
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Wencan Zhang
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Qi An
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Zhenxing Zhang
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Hong Li
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Xiangying Chen
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Zhen Chen
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Yiwen Cheng
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Si Chen
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Churiga Man
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China
| | - Li Du
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China.
| | - Qiaoling Chen
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China.
| | - Fengyang Wang
- Hainan Key Lab of Tropical Animal Reproduction, Breeding and Epidemic Disease Research, Animal Genetic Engineering Key Lab of Haikou, School of Animal Science and Technology, Hainan University, Haikou, Hainan, China.
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Mahboob S, Ullah N, Farhan Ul Haque M, Rauf W, Iqbal M, Ali A, Rahman M. Genomic characterization and comparative genomic analysis of HS-associated Pasteurella multocida serotype B:2 strains from Pakistan. BMC Genomics 2023; 24:546. [PMID: 37710174 PMCID: PMC10500850 DOI: 10.1186/s12864-023-09626-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 08/26/2023] [Indexed: 09/16/2023] Open
Abstract
BACKGROUND Haemorrhagic septicaemia (HS) is a highly fatal and predominant disease in livestock, particularly cattle and buffalo in the tropical regions of the world. Pasteurella multocida (P. multocida), serotypes B:2 and E:2, are reported to be the main causes of HS wherein serotype B:2 is more common in Asian countries including Pakistan and costs heavy financial losses every year. As yet, very little molecular and genomic information related to the HS-associated serotypes of P. multocida isolated from Pakistan is available. Therefore, this study aimed to explore the characteristics of novel bovine isolates of P. multocida serotype B:2 at the genomic level and perform comparative genomic analysis of various P. multocida strains from Pakistan to better understand the genetic basis of pathogenesis and virulence. RESULTS To understand the genomic variability and pathogenomics, we characterized three HS-associated P. multocida serotype B:2 strains isolated from the Faisalabad (PM1), Peshawar (PM2) and Okara (PM3) districts of Punjab, Pakistan. Together with the other nine publicly available Pakistani-origin P. multocida strains and a reference strain Pm70, a comparative genomic analysis was performed. The sequenced strains were characterized as serotype B and belong to ST-122. The strains contain no plasmids; however, each strain contains at least two complete prophages. The pan-genome analysis revealed a higher number of core genes indicating a close resemblance to the studied genomes and very few genes (1%) of the core genome serve as a part of virulence, disease, and defense mechanisms. We further identified that studied P. multocida B:2 strains harbor common antibiotic resistance genes, specifically PBP3 and EF-Tu. Remarkably, the distribution of virulence factors revealed that OmpH and plpE were not present in any P. multocida B:2 strains while the presence of these antigens was reported uniformly in all serotypes of P. multocida. CONCLUSION This study's findings indicate the absence of OmpH and PlpE in the analyzed P. multocida B:2 strains, which are known surface antigens and provide protective immunity against P. multocida infection. The availability of additional genomic data on P. multocida B:2 strains from Pakistan will facilitate the development of localized therapeutic agents and rapid diagnostic tools specifically targeting HS-associated P. multocida B:2 strains.
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Affiliation(s)
- Sadia Mahboob
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad, 38000, Punjab, Pakistan
| | - Nimat Ullah
- Atta-Ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), Islamabad, 44000, Pakistan
| | | | - Waqar Rauf
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad, 38000, Punjab, Pakistan
| | - Mazhar Iqbal
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad, 38000, Punjab, Pakistan.
| | - Amjad Ali
- Atta-Ur-Rahman School of Applied Biosciences (ASAB), National University of Sciences and Technology (NUST), Islamabad, 44000, Pakistan.
| | - Moazur Rahman
- Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad, 38000, Punjab, Pakistan.
- School of Biological Sciences, University of the Punjab, Lahore, 54590, Pakistan.
- Centre of Excellence in Molecular Biology, University of the Punjab, Lahore, 53700, Pakistan.
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Zhou G, Tian J, Tian Y, Ma Q, Li Q, Wang S, Shi H. Recombinant-attenuated Salmonella enterica serovar Choleraesuis vector expressing the PlpE protein of Pasteurella multocida protects mice from lethal challenge. BMC Vet Res 2023; 19:128. [PMID: 37598169 PMCID: PMC10439597 DOI: 10.1186/s12917-023-03679-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 07/27/2023] [Indexed: 08/21/2023] Open
Abstract
BACKGROUND Bacterial surface proteins play key roles in pathogenicity and often contribute to microbial adhesion and invasion. Pasteurella lipoprotein E (PlpE), a Pasteurella multocida (P. multocida) surface protein, has recently been identified as a potential vaccine candidate. Live attenuated Salmonella strains have a number of potential advantages as vaccine vectors, including immunization with live vector can mimic natural infections by organisms, lead to the induction of mucosal, humoral, and cellular immune responses. In this study, a previously constructed recombinant attenuated Salmonella Choleraesuis (S. Choleraesuis) vector rSC0016 was used to synthesize and secrete the surface protein PlpE of P. multocida to form the vaccine candidate rSC0016(pS-PlpE). Subsequently, the immunogenicity of S. Choleraesuis rSC0016(pS-PlpE) as an oral vaccine to induce protective immunity against P. multocida in mice was evaluated. RESULTS After immunization, the recombinant attenuated S. Choleraesuis vector can efficiently delivered P. multocida PlpE protein in vivo and induced a specific immune response against this heterologous antigen in mice. In addition, compared with the inactivated vaccine, empty vector (rSC0016(pYA3493)) and PBS immunized groups, the rSC0016(pS-PlpE) vaccine candidate group induced higher antigen-specific mucosal, humoral and mixed Th1/Th2 cellular immune responses. After intraperitoneal challenge, the rSC0016(pS-PlpE) immunized group had a markedly enhanced survival rate (80%), a better protection efficiency than 60% of the inactivated vaccine group, and significantly reduced tissue damage. CONCLUSIONS In conclusion, our study found that the rSC0016(pS-PlpE) vaccine candidate provided good protection against challenge with wild-type P. multocida serotype A in a mouse infection model, and may potentially be considered for use as a universal vaccine against multiple serotypes of P. multocida in livestock, including pigs.
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Affiliation(s)
- Guodong Zhou
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China
| | - Jiashuo Tian
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China
| | - Yichen Tian
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China
| | - Qifeng Ma
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China
| | - Quan Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China
| | - Shifeng Wang
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611-0880, USA
| | - Huoying Shi
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China.
- Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, China.
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, Yangzhou University (JIRLAAPS), Yangzhou, China.
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Prajapati A, Chanda MM, Dhayalan A, Yogisharadhya R, Chaudhary JK, Mohanty NN, Shivachandra SB. Variability in in vitro biofilm production and antimicrobial sensitivity pattern among Pasteurella multocida strains. BIOFOULING 2020; 36:938-950. [PMID: 33059484 DOI: 10.1080/08927014.2020.1833192] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/28/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
Biofilm production, hitherto an uncharacterized feature among circulating Pasteurella multocida strains, was studied along with the antibiotic susceptibility pattern. On the basis of biofilm formation ability, all the strains were categorized into four groups under six different culture conditions: strong biofilm-forming (22%), moderate (19%), weak (51%), and non-adherent (7%). Strains from serogroups A and B formed significant biofilms in at least one culture condition whereas strains from serogroup D were unable to form biofilms. All strains were found to be susceptible to tetracycline. In addition, the correlation between diverse factors (host, capsule type, clinical condition and the tadD gene) as well as antimicrobial susceptibility in biofilm production were analyzed by Joint distribution models, and showed that enrofloxacin and azithromycin resistant strains were positively correlated with strong biofilm production.
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Affiliation(s)
- Awadhesh Prajapati
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru, Karnataka, India
| | - Mohammed Mudassar Chanda
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru, Karnataka, India
| | - Arul Dhayalan
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru, Karnataka, India
| | - Revanaiah Yogisharadhya
- ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru, Karnataka, India
| | - Jitendra Kumar Chaudhary
- College of Veterinary Sciences and Animal Husbandry, Central Agricultural University (CAU), Aizwal, Mizoram, India
| | - Nihar Nalini Mohanty
- CCS-National Institute of Animal Health (NIAH), Baghpat, Uttar Pradesh (UP), India
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Lindholm M, Min Aung K, Nyunt Wai S, Oscarsson J. Role of OmpA1 and OmpA2 in Aggregatibacter actinomycetemcomitans and Aggregatibacter aphrophilus serum resistance. J Oral Microbiol 2018; 11:1536192. [PMID: 30598730 PMCID: PMC6225413 DOI: 10.1080/20002297.2018.1536192] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/03/2018] [Accepted: 10/10/2018] [Indexed: 12/27/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans and Aggregatibacter aphrophilus belong to the HACEK group of fastidious Gram-negative organisms, a recognized cause of infective endocarditis. A. actinomycetemcomitans is also implicated in aggressive forms of periodontitis. We demonstrated that A. aphrophilus strains, as A. actinomycetemcomitans are ubiquitously serum resistant. Both species encode two Outer membrane protein A paralogues, here denoted OmpA1 and OmpA2. As their respective pangenomes contain several OmpA1 and OmpA2 alleles, they represent potential genotypic markers. A naturally competent strain of A. actinomycetemcomitans and A. aphrophilus, respectively were used to elucidate if OmpA1 and OmpA2 contribute to serum resistance. Whereas OmpA1 was critical for survival of A. actinomycetemcomitans D7SS in 50% normal human serum (NHS), serum resistant ompA1 mutants were fortuitously obtained, expressing enhanced levels of OmpA2. Similarly, OmpA1 rather than OmpA2 was a major contributor to serum resistance of A. aphrophilus HK83. Far-Western blot revealed that OmpA1AA, OmpA2AA, and OmpA1AP can bind to C4-binding protein, an inhibitor of classical and mannose-binding lectin (MBL) complement activation. Indeed, ompA1 mutants were susceptible to these pathways, but also to alternative complement activation. This may at least partly reflect a compromised outer membrane integrity but is also consistent with alternative mechanisms involved in OmpA-mediated serum resistance.
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Affiliation(s)
- Mark Lindholm
- Oral Microbiology, Department of Odontology, Umeå University, Umeå, Sweden
| | - Kyaw Min Aung
- Department of Molecular Biology and the Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Sun Nyunt Wai
- Department of Molecular Biology and the Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Jan Oscarsson
- Oral Microbiology, Department of Odontology, Umeå University, Umeå, Sweden
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