A basis for vaccine development: Comparative characterization of Haemophilus influenzae outer membrane vesicles

Roier, Sandro; Blume, Thomas W.; Klug, Lisa; Wagner, Gabriel E.; Elhenawy, Wael; Zangger, Klaus; Ruth, Peter; Reidl, Joachim; Daum, Günther; Feldman, Mario F.; Schild, Stefan

doi:10.1016/j.ijmm.2014.12.005

Cited by 47 publications

(67 citation statements)

References 78 publications

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“…Most of the vesicles were 20 to 30 nm in diameter with somewhat larger vesicles occasionally observed. These vesicles are very similar in appearance and physical dimension to naturally released OMVs purified by other groups from other NTHi strains (25,32,33).…”

Section: Resultssupporting

confidence: 57%

“…2 and 3). As noted above, each of these proteins was also detected in the NTHi OMV preparations previously characterized by others (25,32,33). Each of these proteins has been demonstrated capable of inducing functionally active antibodies in vitro and in vivo (14,35,(37)(38)(39).…”

Section: Discussionmentioning

confidence: 76%

“…NTHi OMVs have been reported to contain a number of major and minor outer membrane proteins (25,32,33). The major outer membrane proteins of Haemophilus influenzae, including proteins P1, P2, P5, and P6, were originally defined based upon their presence in sarcosyl-insoluble membrane preparations and by their migration in SDS-polyacrylamide gels (34).…”

Section: Resultsmentioning

confidence: 99%

“…Two research groups have previously characterized representative naturally released NTHi OMVs in detail (25,32,33). These groups defined the protein content of their OMVs using tandem mass spectrometry and found them to be enriched in several of the major outer membrane proteins, including P2 (35), P5 (36), and P6 (37), as well as in the high molecular weight HMW1/HMW2 proteins (14).…”

Section: Discussionmentioning

confidence: 99%

“…Several different methods have been described in the literature for purification of outer membrane vesicles from Gram-negative bacteria, including those of NTHi (24,25,32,33). When we initiated our project, we attempted to recover so-called naturally released outer membrane vesicles from culture supernatants of our NTHi strains grown in bulk liquid culture, but recovery of vesicles was negligible.…”

Section: Discussionmentioning

confidence: 99%

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Immunogenicity of Nontypeable Haemophilus influenzae Outer Membrane Vesicles and Protective Ability in the Chinchilla Model of Otitis Media

Winter

Barenkamp

2017

Clin Vaccine Immunol

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Outer membrane vesicles (OMVs) produced by Gram-negative bacteria are enriched in several outer membrane components, including major and minor outer membrane proteins and lipooligosaccharide. We assessed the functional activity of nontypeable Haemophilus influenzae (NTHi) OMV-specific antisera and the protective ability of NTHi OMVs as vaccine antigens in the chinchilla otitis media model. OMVs were purified from three HMW1/HMW2-expressing NTHi strains, two of which were also engineered to overexpress Hia proteins. OMV-specific antisera raised in guinea pigs were assessed for their ability to mediate killing of representative NTHi in an opsonophagocytic assay. The three OMV-specific antisera mediated killing of 18 of 65, 24 of 65, and 30 of 65 unrelated HMW1/HMW2-expressing NTHi strains. Overall, they mediated killing of 39 of 65 HMW1/HMW2-expressing strains. The two Hia-expressing OMV-specific antisera mediated killing of 17 of 25 and 14 of 25 unrelated Hia-expressing NTHi strains. Overall, they mediated killing of 20 of 25 Hiaexpressing strains. OMVs from prototype NTHi strain 12 were used to immunize chinchillas and the course of middle ear infection was monitored following intrabullar challenge with the homologous strain. All control animals developed culturepositive otitis media, as did two of three HMW1/HMW2-immunized animals. All OMVimmunized animals, with or without supplemental HMW1/HMW2 immunization, were completely protected against otitis media. NTHi OMVs are the first immunogens examined in this model that provided complete protection with sterile immunity after NTHi strain 12 challenge. These data suggest that NTHi OMVs hold significant potential as components of protective NTHi vaccines, possibly in combination with HMW1/HMW2 proteins. KEYWORDS Haemophilus influenzae, outer membrane vesicles, vaccines Nontypeable Haemophilus influenzae (NTHi) organisms are small Gram-negative bacteria that colonize the upper respiratory tract of humans beginning at a very early age (1). Although these organisms are normally commensals, when host defenses are compromised by underlying medical conditions such as malnutrition, immunodeficiency, chronic lung disease, or acute viral infection, disease caused by NTHi may develop (2, 3). Among children in the developed world, NTHi infections are currently responsible for an estimated 40 to 50% of the cases of acute otitis media and an even higher percentage of cases of chronic and recurrent disease (4, 5). Among adults, particularly among patients with chronic obstructive pulmonary disease, NTHi infections are a major cause of illness, especially during the acute exacerbations that often characterize this disease (6). A vaccine capable of preventing disease caused by these organisms would offer substantial benefit to the adult and pediatric populations alike.NTHi vaccine development efforts are ongoing in many laboratories. A large number

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Section: Resultssupporting

confidence: 57%

Section: Discussionmentioning

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

Immunogenicity of Nontypeable Haemophilus influenzae Outer Membrane Vesicles and Protective Ability in the Chinchilla Model of Otitis Media

Winter

Barenkamp

2017

Clin Vaccine Immunol

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Host–pathogen interactions of nontypeable Haemophilus influenzae: from commensal to pathogen

2016

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Nontypeable Haemophilus influenzae (NTHi) is a commensal microbe often isolated from the upper and lower respiratory tract. This bacterial species can cause sinusitis, acute otitis media in preschool children, exacerbations in patients suffering from chronic obstructive pulmonary disease, as well as conjunctivitis and bacteremia. Since the introduction of a vaccine against H. influenzae serotype b in the 1990s, the burden of H. influenzae‐related infections has been increasingly dominated by NTHi. Understanding the ability of NTHi to cause infection is currently an expanding area of study. NTHi is able to exert differential binding to the host tissue through the use of a broad range of adhesins. NTHi survival in the host is multifaceted, that is, using virulence factors involved in complement resistance, biofilm, modified immunoglobulin responses, and, finally, formation and utilization of host proteins as a secondary strategy of increasing the adhesive ability.

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The activity of the quorum sensing regulator HapR is modulated by the bacterial extracellular vesicle (BEV)‐associated protein ObfA of Vibrio cholerae

Ebenberger,

Cakar,

Chen

et al. 2024

J of Extracellular Vesicle

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Vibrio cholerae, a facultative human pathogen and causative agent of the severe diarrheal disease cholera, transits between the human intestinal tract and aquatic reservoirs. Like other bacterial species, V. cholerae continuously releases bacterial extracellular vesicles (BEVs) from its surface, which have been recently characterised for their role during in vivo colonisation. However, between epidemic outbreaks, V. cholerae persists in the biofilm mode for extended periods in aquatic reservoirs, which enhances environmental fitness and host transition. In this study, we investigated the effect of V. cholerae BEVs on biofilm formation, a critical feature for ex vivo survival. In contrast to BEVs from planktonic cultures, our results show that physiological concentrations of BEVs from dynamic biofilm cultures facilitate V. cholerae biofilm formation, which could be linked to a proteinaceous factor. Comparative proteomic analyses of planktonic‐ and biofilm‐derived BEVs identified a previously uncharacterised outer membrane protein as an abundant component of dynamic biofilm‐derived BEVs, which was found to be responsible for the BEV‐dependent enhancement of biofilm production. Consequently, this protein was named outer membrane‐associated biofilm facilitating protein A (ObfA). Comprehensive molecular studies unravelled ObfA as a negative modulator of HapR activity. HapR is a key transcriptional regulator of the V. cholerae quorum sensing (QS) cascade acting as a potent repressor of biofilm formation and virulence. Consistently, obfA mutants not only exhibited reduced biofilm production but also reduced colonisation fitness. Surprisingly, our results demonstrate that ObfA does not affect HapR through the canonical QS system but via the Csr‐cascade altering the expression of the small regulatory RNAs CsrC and CsrD. In summary, this study elucidates a novel intraspecies BEV‐based communication in V. cholerae that influences biofilm formation and colonisation fitness via a new regulatory pathway involving HapR, Csr‐cascade and the BEV‐associated protein ObfA.

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A basis for vaccine development: Comparative characterization of Haemophilus influenzae outer membrane vesicles

Cited by 47 publications

References 78 publications

Immunogenicity of Nontypeable Haemophilus influenzae Outer Membrane Vesicles and Protective Ability in the Chinchilla Model of Otitis Media

Immunogenicity of Nontypeable Haemophilus influenzae Outer Membrane Vesicles and Protective Ability in the Chinchilla Model of Otitis Media

Host–pathogen interactions of nontypeable Haemophilus influenzae: from commensal to pathogen

The activity of the quorum sensing regulator HapR is modulated by the bacterial extracellular vesicle (BEV)‐associated protein ObfA of Vibrio cholerae

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