Mucosal colonization of Mannheimia haemolytica capsular and adhesin mutants in cattle

ABSTRACT Mannheimia haemolytica (Mh) is a normal inhabitant of the upper respiratory tract of ruminants and is associated with bovine respiratory disease. Polysaccharide capsule and surface adhesins are suggested to function in adherence and colonization of M. haemolytica to the mucosa of the upper...

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Main Authors: Anna K. Goldkamp, Harish Menghwar, Carly Kanipe, Robert E. Briggs, Bradley O. Chriswell, Eduardo Casas, Michael L. Clawson, Fred M. Tatum, Rohana P. Dassanayake
Format: Article
Language:English
Published: American Society for Microbiology 2025-07-01
Series:Microbiology Spectrum
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Online Access:https://journals.asm.org/doi/10.1128/spectrum.00684-25
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author Anna K. Goldkamp
Harish Menghwar
Carly Kanipe
Robert E. Briggs
Bradley O. Chriswell
Eduardo Casas
Michael L. Clawson
Fred M. Tatum
Rohana P. Dassanayake
author_facet Anna K. Goldkamp
Harish Menghwar
Carly Kanipe
Robert E. Briggs
Bradley O. Chriswell
Eduardo Casas
Michael L. Clawson
Fred M. Tatum
Rohana P. Dassanayake
author_sort Anna K. Goldkamp
collection DOAJ
description ABSTRACT Mannheimia haemolytica (Mh) is a normal inhabitant of the upper respiratory tract of ruminants and is associated with bovine respiratory disease. Polysaccharide capsule and surface adhesins are suggested to function in adherence and colonization of M. haemolytica to the mucosa of the upper respiratory tract. M. haemolytica serotype 1 mutant strains containing deletions of either the capsule biosynthetic gene cluster (∆cap) or putative adhesin genes (∆adh123) were created using a temperature-sensitive plasmid and tested for colonization in a calf challenge model. Two treatment groups were used in the study: Sham-Mh-BHV-1 (SMB; intranasal administration of uninfected cell culture lysate/supernatant [sham; S] 4 days before intranasal M. haemolytica inoculation, and intranasal inoculation of bovine-herpesvirus-1 [BHV-1] 20 days post-Mh) and BHV-1-Mh-Sham (BMS; intranasal inoculation of BHV-1 4 days before intranasal Mh inoculation and intranasal sham administration 20 days post-Mh). A mixture of wild-type M. haemolytica parent strain, ∆cap, and ∆adh123 mutants was included in the Mh inoculum. Animals were observed for clinical signs and nasal colonization for approximately 7 weeks. The ∆adh123 mutant and parent strain colonized the nasopharynx, whereas the ∆cap mutant was not detected after 1 day post-inoculation. The ∆adh123 mutant colonized the nasopharynx at significantly higher levels (P < 0.0001) compared to wild type. Higher colonization of ∆adh123 was also found in palatine tonsils. These findings suggest a requirement of capsule in long-term colonization and an advantage for ∆adh123 in colonization over the parent strain.IMPORTANCEUnderstanding the colonization dynamics of Mannheimia haemolytica is crucial for developing effective prevention and treatment strategies for bovine respiratory disease (BRD), a significant cause of economic loss in the cattle industry. This study highlights the role of capsular polysaccharide and surface adhesins in nasopharyngeal colonization. These findings demonstrate that the deletion of putative surface adhesins leads to enhanced colonization compared to the wild-type strain, while mutants containing a deletion of the capsule biosynthetic gene cluster failed to establish long-term colonization. These results suggest that targeting bacterial adhesion mechanisms could influence bacterial persistence and immune response, offering potential avenues for controlling BRD.
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spelling doaj-art-df4cf6f3aaa846608b16b7af0805d63b2025-08-20T03:14:57ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972025-07-0113710.1128/spectrum.00684-25Mucosal colonization of Mannheimia haemolytica capsular and adhesin mutants in cattleAnna K. Goldkamp0Harish Menghwar1Carly Kanipe2Robert E. Briggs3Bradley O. Chriswell4Eduardo Casas5Michael L. Clawson6Fred M. Tatum7Rohana P. Dassanayake8Ruminant Diseases and Immunology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, USARuminant Diseases and Immunology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, USAInfectious Bacterial Diseases Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, USARuminant Diseases and Immunology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, USARuminant Diseases and Immunology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, USARuminant Diseases and Immunology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, USAGenetics, Breeding, and Animal Health Research Unit, United States Department of Agriculture, Agricultural Research Service, U.S. Meat Animal Research Center, Clay Center, Nebraska, USARuminant Diseases and Immunology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, USARuminant Diseases and Immunology Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, USAABSTRACT Mannheimia haemolytica (Mh) is a normal inhabitant of the upper respiratory tract of ruminants and is associated with bovine respiratory disease. Polysaccharide capsule and surface adhesins are suggested to function in adherence and colonization of M. haemolytica to the mucosa of the upper respiratory tract. M. haemolytica serotype 1 mutant strains containing deletions of either the capsule biosynthetic gene cluster (∆cap) or putative adhesin genes (∆adh123) were created using a temperature-sensitive plasmid and tested for colonization in a calf challenge model. Two treatment groups were used in the study: Sham-Mh-BHV-1 (SMB; intranasal administration of uninfected cell culture lysate/supernatant [sham; S] 4 days before intranasal M. haemolytica inoculation, and intranasal inoculation of bovine-herpesvirus-1 [BHV-1] 20 days post-Mh) and BHV-1-Mh-Sham (BMS; intranasal inoculation of BHV-1 4 days before intranasal Mh inoculation and intranasal sham administration 20 days post-Mh). A mixture of wild-type M. haemolytica parent strain, ∆cap, and ∆adh123 mutants was included in the Mh inoculum. Animals were observed for clinical signs and nasal colonization for approximately 7 weeks. The ∆adh123 mutant and parent strain colonized the nasopharynx, whereas the ∆cap mutant was not detected after 1 day post-inoculation. The ∆adh123 mutant colonized the nasopharynx at significantly higher levels (P < 0.0001) compared to wild type. Higher colonization of ∆adh123 was also found in palatine tonsils. These findings suggest a requirement of capsule in long-term colonization and an advantage for ∆adh123 in colonization over the parent strain.IMPORTANCEUnderstanding the colonization dynamics of Mannheimia haemolytica is crucial for developing effective prevention and treatment strategies for bovine respiratory disease (BRD), a significant cause of economic loss in the cattle industry. This study highlights the role of capsular polysaccharide and surface adhesins in nasopharyngeal colonization. These findings demonstrate that the deletion of putative surface adhesins leads to enhanced colonization compared to the wild-type strain, while mutants containing a deletion of the capsule biosynthetic gene cluster failed to establish long-term colonization. These results suggest that targeting bacterial adhesion mechanisms could influence bacterial persistence and immune response, offering potential avenues for controlling BRD.https://journals.asm.org/doi/10.1128/spectrum.00684-25Mannheimia haemolyticacapsuleadhesincolonizationisogenic mutantsvirulence factors
spellingShingle Anna K. Goldkamp
Harish Menghwar
Carly Kanipe
Robert E. Briggs
Bradley O. Chriswell
Eduardo Casas
Michael L. Clawson
Fred M. Tatum
Rohana P. Dassanayake
Mucosal colonization of Mannheimia haemolytica capsular and adhesin mutants in cattle
Microbiology Spectrum
Mannheimia haemolytica
capsule
adhesin
colonization
isogenic mutants
virulence factors
title Mucosal colonization of Mannheimia haemolytica capsular and adhesin mutants in cattle
title_full Mucosal colonization of Mannheimia haemolytica capsular and adhesin mutants in cattle
title_fullStr Mucosal colonization of Mannheimia haemolytica capsular and adhesin mutants in cattle
title_full_unstemmed Mucosal colonization of Mannheimia haemolytica capsular and adhesin mutants in cattle
title_short Mucosal colonization of Mannheimia haemolytica capsular and adhesin mutants in cattle
title_sort mucosal colonization of mannheimia haemolytica capsular and adhesin mutants in cattle
topic Mannheimia haemolytica
capsule
adhesin
colonization
isogenic mutants
virulence factors
url https://journals.asm.org/doi/10.1128/spectrum.00684-25
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