| 1. |
- Janson, Håkan, et al.
(författare)
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Protein D, the glycerophosphodiester phosphodiesterase from Haemophilus influenzae with affinity for human immunoglobulin D, influences virulence in a rat otitis model
- 1994
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 62:11, s. 4848-4854
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Tidskriftsartikel (refereegranskat)abstract
- A mutant lacking the ability to express the surface-exposed lipoprotein protein D was constructed by linker insertion and deletion mutagenesis of a cloned DNA insert containing the protein D structural gene from a nontypeable Haemophilus influenzae strain (NTHi). An isogenic NTHi mutant was isolated after transformation of genetically competent bacteria. The transformant was unreactive to a protein D-specific monoclonal antibody in a colony immunoassay. In addition, the mutant lacked the ability to synthesize detectable levels of protein D by protein staining, immunoblot methods, glycerophosphodiester phosphodiesterase activity, and binding studies of radiolabelled immunoglobulin D. The isogenic protein D-deficient mutant was compared with its parental strain for its ability to induce experimental otitis media in rats challenged with bacteria. An approximately 100-times-higher concentration of the mutant compared with that of the wild-type strain was required in order to cause otitis among all rats challenged with that given dose. The protein D mutant exhibited a generation time that was equal to that of the wild-type strain in complex broth medium. No difference in lipopolysaccharide expression was found between the mutant and the parental strain. These results suggest that protein D may influence the pathogenesis of NTHi in the upper respiratory tract.
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| 2. |
- Melhus, Åsa, et al.
(författare)
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Nontypeable and encapsulated Haemophilus influenzae yield different clinical courses of experimental otitis media
- 1994
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Ingår i: Acta Oto-Laryngologica. - 0001-6489 .- 1651-2251. ; 114:3, s. 289-294
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Tidskriftsartikel (refereegranskat)abstract
- Middle ears of male Sprague-Dawley rats were injected with suspensions of thirteen Haemophilus influenzae strains of different sero- and biotypes and at various concentrations. Systemic and local changes were monitored by clinical observations, otomicroscopy, and analysis of bacterial samples from blood and middle ears. Two patterns of response were recognized, a nontypeable and an encapsulated pattern. The nontypeable H. influenzae middle ear infection required a high bacterial dose and was well past its peak 8 days after challenge, when the encapsulated H. influenzae otitis media was still purulent. The most severe infections were caused by H. influenzae type b strains. The overall mortality rate was zero and the animals recovered without permanent deterioration or otomicroscopically discernable changes. The results of this study show the rat to be a suitable animal model for the study of H. influenzae otitis media.
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