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Chen X, Zhang H, Feng J, Zhang L, Zheng M, Luo H, Zhuo H, Xu N, Zhang X, Chen C, Qu P, Li Y. Comparative Genomic Analysis Reveals Genetic Diversity and Pathogenic Potential of Haemophilus seminalis and Emended Description of Haemophilus seminalis. Microbiol Spectr 2023; 11:e0477222. [PMID: 37382545 PMCID: PMC10434262 DOI: 10.1128/spectrum.04772-22] [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: 11/22/2022] [Accepted: 06/10/2023] [Indexed: 06/30/2023] Open
Abstract
Haemophilus seminalis is a newly proposed species that is phylogenetically related to Haemophilus haemolyticus. The distribution of H. seminalis in the human population, its genomic diversity, and its pathogenic potential are still unclear. This study reports the finding of our comparative genomic analyses of four newly isolated Haemophilus strains (SZY H8, SZY H35, SZY H36, and SZY H68) from human sputum specimens (Guangzhou, China) along with the publicly available genomes of other phylogenetically related Haemophilus species. Based on pairwise comparisons of the 16S rRNA gene sequences, the four isolates showed <98.65% sequence identity to the type strains of all known Haemophilus species but were identified as belonging to H. seminalis, based on comparable phenotypic and genotypic features. Additionally, the four isolates showed high genome-genome relatedness indices (>95% ANI values) with 17 strains that were previously identified as either "Haemophilus intermedius" or hemin (X-factor)-independent H. haemolyticus and therefore required a more detailed classification study. Phylogenetically, these isolates, along with the two previously described H. seminalis isolates (a total of 23 isolates), shared a highly homologous lineage that is distinct from the clades of the main H. haemolyticus and Haemophilus influenzae strains. These isolates present an open pangenome with multiple virulence genes. Notably, all 23 isolates have a functional heme biosynthesis pathway that is similar to that of Haemophilus parainfluenzae. The phenotype of hemin (X-factor) independence and the analysis of the ispD, pepG, and moeA genes can be used to distinguish these isolates from H. haemolyticus and H. influenzae. Based on the above findings, we propose a reclassification for all "H. intermedius" and two H. haemolyticus isolates belonging to H. seminalis with an emended description of H. seminalis. This study provides a more accurate identification of Haemophilus isolates for use in the clinical laboratory and a better understanding of the clinical significance and genetic diversity in human environments. IMPORTANCE As a versatile opportunistic pathogen, the accurate identification of Haemophilus species is a challenge in clinical practice. In this study, we characterized the phenotypic and genotypic features of four H. seminalis strains that were isolated from human sputum specimens and propose the "H. intermedius" and hemin (X-factor)-independent H. haemolyticus isolates as belonging to H. seminalis. The prediction of virulence-related genes indicates that H. seminalis isolates carry several virulence genes that are likely to play an important role in its pathogenicity. In addition, we depict that the genes ispD, pepG, and moeA can be used as biomarkers for distinguishing H. seminalis from H. haemolyticus and H. influenzae. Our findings provide some insights into the identification, epidemiology, genetic diversity, pathogenic potential, and antimicrobial resistance of the newly proposed H. seminalis.
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Affiliation(s)
- Xiaowei Chen
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Hanyun Zhang
- Department of Laboratory Medicine, The Affiliated Hexian Memorial Hospital of Southern Medical University, Guangzhou, China
| | - Junhui Feng
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Lei Zhang
- Guangzhou Kingmed Center for Clinical Laboratory, Guangzhou, China
| | - Minling Zheng
- Department of Clinical Laboratory, Guangdong Women and Children Hospital, Guangzhou, China
| | - Haimin Luo
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Clinical Laboratory, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Huiyan Zhuo
- Department of Laboratory Medicine, The Affiliated Hexian Memorial Hospital of Southern Medical University, Guangzhou, China
| | - Ning Xu
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Clinical Laboratory, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Xuan Zhang
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Clinical Laboratory, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Cha Chen
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Clinical Laboratory, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Pinghua Qu
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou, China
- Department of Clinical Laboratory, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Youqiang Li
- Department of Laboratory Medicine, The Affiliated Hexian Memorial Hospital of Southern Medical University, Guangzhou, China
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Garai P, Atack JM, Wills BM, Jennings MP, Bakaletz LO, Brockman KL. Adherence of Nontypeable Haemophilus influenzae to Cells and Substrates of the Airway Is Differentially Regulated by Individual ModA Phasevarions. Microbiol Spectr 2023; 11:e0409322. [PMID: 36511712 PMCID: PMC9927368 DOI: 10.1128/spectrum.04093-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 11/28/2022] [Indexed: 12/15/2022] Open
Abstract
Adherence of nontypeable Haemophilus influenzae (NTHi) to the host airway is an essential initial step for asymptomatic colonization of the nasopharynx, as well as development of disease. NTHi relies on strict regulation of multiple adhesins for adherence to host substrates encountered in the airway. NTHi encode a phase-variable cytoplasmic DNA methyltransferase, ModA, that regulates expression of multiple genes; a phasevarion (phase-variable regulon). Multiple modA alleles are present in NTHi, in which different alleles methylate a different DNA target, and each controls a different set of genes. However, the role of ModA phasevarions in regulating adherence of NTHi to the host airway is not well understood. This study therefore sought to investigate the role of four of the most prevalent ModA phasevarions in the regulation of adherence of NTHi to multiple substrates of the airway. Four clinical isolates of NTHi with unique modA alleles were tested in this study. The adherence of NTHi to mucus, middle ear epithelial cells, and vitronectin was regulated in a substrate-specific manner that was dependent on the ModA allele encoded. The adhesins Protein E and P4 were found to contribute to the ModA-regulated adherence of NTHi to distinct substrates. A better understanding of substrate-specific regulation of NTHi adherence by ModA phasevarions will allow identification of NTHi populations present at the site of disease within the airway and facilitate more directed development of vaccines and therapeutics. IMPORTANCE Nontypeable Haemophilus influenzae (NTHi) is a predominant pathogen of the human airway that causes respiratory infections such as otitis media (OM) and exacerbations in the lungs of patients suffering from chronic obstructive pulmonary disease (COPD). Due to the lack of a licensed vaccine against NTHi and the emergence of antibiotic-resistant strains, it is extremely challenging to target NTHi for treatment. NTHi adhesins are considered potential candidates for vaccines or other therapeutic approaches. The ModA phasevarions of NTHi play a role in the rapid adaptation of the pathogen to different environmental stress conditions. This study addressed the role of ModA phasevarions in the regulation of adherence of NTHi to specific host substrates found within the respiratory tract. The findings of this study improve our understanding of regulation of adherence of NTHi to the airway, which may further be used to enhance the potential of adhesins as vaccine antigens and therapeutic targets against NTHi.
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Affiliation(s)
- Preeti Garai
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - John M. Atack
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
- School of Environment and Science, Griffith University, Gold Coast, Queensland, Australia
| | - Brandon M. Wills
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Michael P. Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Lauren O. Bakaletz
- Abigail Wexner Research Institute, Center for Microbial Pathogenesis, Nationwide Children’s Hospital, Columbus, Ohio, USA
- College of Medicine, Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Kenneth L. Brockman
- Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Janoušková M, Straw ML, Su YC, Riesbeck K. Gene Expression Regulation in Airway Pathogens: Importance for Otitis Media. Front Cell Infect Microbiol 2022; 12:826018. [PMID: 35252035 PMCID: PMC8895709 DOI: 10.3389/fcimb.2022.826018] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
Otitis media (OM) is an inflammatory disorder in the middle ear. It is mainly caused by viruses or bacteria associated with the airways. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis are the three main pathogens in infection-related OM, especially in younger children. In this review, we will focus upon the multifaceted gene regulation mechanisms that are well-orchestrated in S. pneumoniae, H. influenzae, and M. catarrhalis during the course of infection in the middle ear either in experimental OM or in clinical settings. The sophisticated findings from the past 10 years on how the othopathogens govern their virulence phenotypes for survival and host adaptation via phase variation- and quorum sensing-dependent gene regulation, will be systematically discussed. Comprehensive understanding of gene expression regulation mechanisms employed by pathogens during the onset of OM may provide new insights for the design of a new generation of antimicrobial agents in the fight against bacterial pathogens while combating the serious emergence of antimicrobial resistance.
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Short B, Carson S, Devlin AC, Reihill JA, Crilly A, MacKay W, Ramage G, Williams C, Lundy FT, McGarvey LP, Thornbury KD, Martin SL. Non-typeable Haemophilus influenzae chronic colonization in chronic obstructive pulmonary disease (COPD). Crit Rev Microbiol 2021; 47:192-205. [PMID: 33455514 DOI: 10.1080/1040841x.2020.1863330] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Haemophilus influenzae is the most common cause of bacterial infection in the lungs of chronic obstructive pulmonary disease (COPD) patients and contributes to episodes of acute exacerbation which are associated with increased hospitalization and mortality. Due to the ability of H. influenzae to adhere to host epithelial cells, initial colonization of the lower airways can progress to a persistent infection and biofilm formation. This is characterized by changes in bacterial behaviour such as reduced cellular metabolism and the production of an obstructive extracellular matrix (ECM). Herein we discuss the multiple mechanisms by which H. influenzae contributes to the pathogenesis of COPD. In particular, mechanisms that facilitate bacterial adherence to host airway epithelial cells, biofilm formation, and microbial persistence through immune system evasion and antibiotic tolerance will be discussed.
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Affiliation(s)
- Bryn Short
- University of the West of Scotland, Paisley, United Kingdom
| | - Stephen Carson
- School of Pharmacy, Queen's University Belfast, Belfast, United Kingdom
| | - Anna-Claire Devlin
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - James A Reihill
- School of Pharmacy, Queen's University Belfast, Belfast, United Kingdom
| | - Anne Crilly
- University of the West of Scotland, Paisley, United Kingdom
| | - William MacKay
- University of the West of Scotland, Paisley, United Kingdom
| | - Gordon Ramage
- Glasgow Biofilm Research Group, Oral Sciences, School of Medicine, Dentistry and Nursing, University of Glasgow, Glasgow, United Kingdom
| | - Craig Williams
- University of the West of Scotland, Paisley, United Kingdom
| | - Fionnuala T Lundy
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Lorcan P McGarvey
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Keith D Thornbury
- Smooth Muscle Research Group, Dundalk Institute of Technology, Dundalk, Ireland
| | - S Lorraine Martin
- School of Pharmacy, Queen's University Belfast, Belfast, United Kingdom
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Haemophilin-Producing Strains of Haemophilus haemolyticus Protect Respiratory Epithelia from NTHi Colonisation and Internalisation. Pathogens 2021; 10:pathogens10010029. [PMID: 33401487 PMCID: PMC7823694 DOI: 10.3390/pathogens10010029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/28/2020] [Accepted: 12/28/2020] [Indexed: 11/17/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) is a significant respiratory tract pathogen responsible for infections that collectively pose a substantial health and socioeconomic burden. The clinical course of these infections is largely dictated by NTHi interactions with host respiratory epithelia, and thus, approaches that disrupt colonisation and invasion may have significant therapeutic potential. Survival, successful host–cell interactions, and pathogenesis are reliant on NTHi’s ability to sequester host-derived haem. Previously, we demonstrated the therapeutic potential of exploiting this haem-dependence using a closely related competitor bacterium, Haemophilus haemolyticus (Hh). Hh strains capable of producing the novel haem-binding protein haemophilin (Hpl) possessed potent inhibitory activity by restricting NTHi access to haem in a broth co-culture environment. Here, we extend this work to cell culture models that more closely represent the human respiratory epithelium and show that Hh strains with high levels of hpl expression protect epithelial cell line monolayers against adhesion and invasion by NTHi. Inhibitory activity was dependent on the level of Hpl production, which was stimulated by NTHi challenge and nasopharyngeal cell exposure. Provided these protective benefits translate to in vivo applications, Hpl-producing Hh may have probiotic utility against NTHi infections by inhibiting requisite nasopharyngeal colonisation.
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Mokrzan EM, Ahearn CP, Buzzo JR, Novotny LA, Zhang Y, Goodman SD, Bakaletz LO. Nontypeable Haemophilus influenzae newly released (NRel) from biofilms by antibody-mediated dispersal versus antibody-mediated disruption are phenotypically distinct. Biofilm 2020; 2:100039. [PMID: 33447823 PMCID: PMC7798465 DOI: 10.1016/j.bioflm.2020.100039] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 11/02/2020] [Accepted: 11/12/2020] [Indexed: 02/08/2023] Open
Abstract
Biofilms contribute significantly to the chronicity and recurrence of bacterial diseases due to the fact that biofilm-resident bacteria are highly recalcitrant to killing by host immune effectors and antibiotics. Thus, antibody-mediated release of bacteria from biofilm residence into the surrounding milieu supports a powerful strategy to resolve otherwise difficult-to-treat biofilm-associated diseases. In our prior work, we revealed that antibodies directed against two unique determinants of nontypeable Haemophilus influenzae (NTHI) [e.g. the Type IV pilus (T4P) or a bacterial DNABII DNA-binding protein, a species-independent target that provides structural integrity to bacterial biofilms] release biofilm-resident bacteria via discrete mechanisms. Herein, we now show that the phenotype of the resultant newly released (or NRel) NTHI is dependent upon the specific mechanism of release. We used flow cytometry, proteomic profiles, and targeted transcriptomics to demonstrate that the two NRel populations were significantly different not only from planktonically grown NTHI, but importantly, from each other despite genetic identity. Moreover, each NRel population had a distinct, significantly increased susceptibility to killing by either a sulfonamide or β-lactam antibiotic compared to planktonic NTHI, an observation consistent with their individual proteomes and further supported by relative differences in targeted gene expression. The distinct phenotypes of NTHI released from biofilms by antibodies directed against specific epitopes of T4P or DNABII binding proteins provide new opportunities to develop targeted therapeutic strategies for biofilm eradication and disease resolution.
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Affiliation(s)
- Elaine M Mokrzan
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Christian P Ahearn
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - John R Buzzo
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Laura A Novotny
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Yan Zhang
- Department of Biomedical Informatics, The Ohio State University College of Medicine, Columbus, OH, USA.,The Ohio State University Comprehensive Cancer Center (OSUCCC - James), Columbus, OH, USA
| | - Steven D Goodman
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Lauren O Bakaletz
- Center for Microbial Pathogenesis, Abigail Wexner Research Institute at Nationwide Children's Hospital, Columbus, OH, USA.,Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA
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Nontypeable Haemophilus influenzae Type IV Pilus Mediates Augmented Adherence to Rhinovirus-Infected Human Airway Epithelial Cells. Infect Immun 2020; 88:IAI.00248-20. [PMID: 32540869 DOI: 10.1128/iai.00248-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/09/2020] [Indexed: 12/15/2022] Open
Abstract
Human rhinovirus (hRV) is frequently detected in the upper respiratory tract, and symptomatic infection is associated with an increased nasopharyngeal bacterial load, with subsequent development of secondary bacterial diseases. Nontypeable Haemophilus influenzae (NTHI) is a commensal bacterial species of the human nasopharynx; however, in the context of prior or concurrent upper respiratory tract viral infection, this bacterium commonly causes multiple diseases throughout the upper and lower respiratory tracts. The present study was conducted to determine the mechanism(s) by which hRV infection promotes the development of NTHI-induced diseases. We showed that hRV infection of polarized primary human airway epithelial cells resulted in increased adherence of NTHI, due in part to augmented expression of CEACAM1 and ICAM1, host cell receptors to which NTHI binds via engagement of multiple adhesins. Antibody blockade of these host cell receptors significantly reduced NTHI adherence. With a specific focus on the NTHI type IV pilus (T4P), which we have previously shown binds to ICAM1, an essential adhesin and virulence determinant, we next showed that T4P-directed antibody blockade significantly reduced NTHI adherence to hRV-infected airway cells and, further, that expression of this adhesin was required for the enhanced adherence observed. Collectively, these data provide a mechanism by which "the common cold" promotes diseases due to NTHI, and they add further support for the use of PilA (the majority subunit of T4P) as a vaccine antigen, since antibodies directed against PilA are expected to limit the notably increased bacterial load associated with hRV coinfection and thereby to prevent secondary NTHI-induced diseases of the respiratory tract.
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Nontypeable Haemophilus influenzae Responds to Virus-Infected Cells with a Significant Increase in Type IV Pilus Expression. mSphere 2020; 5:5/3/e00384-20. [PMID: 32461275 PMCID: PMC7253600 DOI: 10.1128/msphere.00384-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHI) is the predominant bacterial causative agent of many chronic and recurrent diseases of the upper and lower respiratory tracts. NTHI-induced chronic rhinosinusitis, otitis media, and exacerbations of cystic fibrosis and chronic obstructive pulmonary disease often develop during or just after an upper respiratory tract viral infection. We have developed a vaccine candidate immunogen for NTHI-induced diseases that targets the majority subunit (PilA) of the type IV twitching pilus (T4P), which NTHI uses to adhere to respiratory tract epithelial cells and that also plays a role in disease. Here, we showed that NTHI cocultured with virus-infected respiratory tract epithelial cells express significantly more of the vaccine-targeted T4P than NTHI that encounters mock-infected (healthy) cells. These results strongly suggest that a vaccine strategy that targets the NTHI T4P will be effective under the most common predisposing condition: when the human host has a respiratory tract virus infection. Nontypeable Haemophilus influenzae (NTHI) colonizes the human nasopharynx, but when the host immune response is dysregulated by upper respiratory tract (URT) virus infection, NTHI can gain access to more distal airway sites and cause disease. The NTHI type IV pilus (T4P) facilitates adherence, benign colonization, and infection, and its majority subunit PilA is in clinical trials as a vaccinogen. To further validate the strategy of immunization with PilA against multiple NTHI-induced diseases, it is important to demonstrate T4P expression under microenvironmental conditions that predispose to NTHI infection of the airway. Because URT infection commonly facilitates NTHI-induced diseases, we examined the influence of ongoing virus infection of respiratory tract epithelial cells on NTHI T4P expression in vitro. Polarized primary human airway epithelial cells (HAEs) were sequentially inoculated with one of three common URT viruses, followed by NTHI. Use of a reporter construct revealed that NTHI upregulated pilA promoter activity when cultured with HAEs infected with adenovirus (AV), respiratory syncytial virus (RSV), or rhinovirus (RV) versus that in mock-infected HAEs. Consistent with these results, pilA expression and relative PilA/pilin abundance, as assessed by quantitative reverse transcription-PCR (qRT-PCR) and immunoblot, respectively, were also significantly increased when NTHI was cultured with virus-infected HAEs. Collectively, our data strongly suggest that under conditions of URT virus infection, PilA vaccinogen induction of T4P-directed antibodies is likely to be highly effective against multiple NTHI-induced diseases by interfering with T4P-mediated adherence. We hypothesize that this outcome could thereby limit or prevent the increased load of NTHI in the nasopharynx that characteristically precedes these coinfections. IMPORTANCE Nontypeable Haemophilus influenzae (NTHI) is the predominant bacterial causative agent of many chronic and recurrent diseases of the upper and lower respiratory tracts. NTHI-induced chronic rhinosinusitis, otitis media, and exacerbations of cystic fibrosis and chronic obstructive pulmonary disease often develop during or just after an upper respiratory tract viral infection. We have developed a vaccine candidate immunogen for NTHI-induced diseases that targets the majority subunit (PilA) of the type IV twitching pilus (T4P), which NTHI uses to adhere to respiratory tract epithelial cells and that also plays a role in disease. Here, we showed that NTHI cocultured with virus-infected respiratory tract epithelial cells express significantly more of the vaccine-targeted T4P than NTHI that encounters mock-infected (healthy) cells. These results strongly suggest that a vaccine strategy that targets the NTHI T4P will be effective under the most common predisposing condition: when the human host has a respiratory tract virus infection.
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