Contribution of Bordetella bronchiseptica Filamentous Hemagglutinin and Pertactin to Respiratory Disease in Swine

Abstract

Bordetella bronchiseptica is pervasive in swine populations and plays multiple roles in respiratory disease. Most studies addressing virulence factors of B. bronchiseptica are based on isolates derived from hosts other than pigs. Two well-studied virulence factors implicated in the adhesion process are filamentous hemagglutinin (FHA) and pertactin (PRN). We hypothesized that both FHA and PRN would serve critical roles in the adhesion process and be necessary for colonization of the swine respiratory tract. To investigate the role of FHA and PRN in Bordetella pathogenesis in swine, we constructed mutants containing an in-frame deletion of the FHA or the PRN structural gene in a virulent B. bronchiseptica swine isolate. Both mutants were compared to the wild-type swine isolate for their ability to colonize and cause disease in swine. Colonization of the FHA mutant was lower than that of the wild type at all respiratory tract sites and time points examined and caused limited to no disease. In contrast, the PRN mutant caused similar disease severity relative to the wild type; however, colonization of the PRN mutant was reduced relative to the wild type during early and late infection and induced higher anti-Bordetella antibody titers. Together, our results indicate that despite inducing different pathologies and antibody responses, both FHA and PRN are necessary for optimal colonization of the swine respiratory tract.

Cross-Species Protection Mediated by a Bordetella bronchiseptica Strain Lacking Antigenic Homologs Present in Acellular Pertussis Vaccines

“…While this species is eventually cleared from the lower respiratory tract, high numbers of bacteria are recovered from the nasal cavity up to 270 days postinoculation (22,40). Previous results have shown that loss of individual virulence factors (FHA, Fim, Prn, ACT, or BipA) has little, if any, effect on the ability of B. bronchiseptica to colonize the nasal cavity (12,28,31,39,49). Since Bordetella species express multiple adhesins and toxins, we hypothesized that while the lack of individual factors may not have an effect, simultaneous absence of five factors may result in a defect in nasal colonization.…”

“…Magnification, ϫ100. (12,28,31,39,49). We hypothesized that efficient nasopharyngeal colonization by bordetellae involves coordinated participation of multiple virulence factors.…”

Pertactin Is Required forBordetellaSpecies To Resist Neutrophil-Mediated Clearance

“…However, two different studies failed to reveal a role for PRN in facilitating B. pertussis attachment to mammalian cells (15,64). B. bronchiseptica PRN was also reported to function as an adhesin (13,47). In vivo studies are limited to three reports: Khelef et al and Roberts et al observed no difference between the abilities of wild-type and pertactin-deficient B. pertussis strains to colonize or grow in the murine respiratory tract (32,55), while Nicholson et al found that a B. bronchiseptica prn mutant displayed reduced lung colonization in pigs at day 56 postinoculation (but not at earlier time points) compared with wild-type bacteria (47).…”

“…B. bronchiseptica PRN was also reported to function as an adhesin (13,47). In vivo studies are limited to three reports: Khelef et al and Roberts et al observed no difference between the abilities of wild-type and pertactin-deficient B. pertussis strains to colonize or grow in the murine respiratory tract (32,55), while Nicholson et al found that a B. bronchiseptica prn mutant displayed reduced lung colonization in pigs at day 56 postinoculation (but not at earlier time points) compared with wild-type bacteria (47). Thus, despite 25 years of study and the commitment to include PRN in acellular pertussis vaccines, knowledge of how PRN contributes to Bordetella pathogenesis is rudimentary.…”

Porcine Respiratory Pathogens in Swine Farms Environment in Mexico

“…In this type of production, under normal conditions, the animals are concurrently infected by one or more respiratory viral or bacterial pathogens [1]- [3]. Respiratory diseases in pigs are the main health problem affecting the pork industry today, produce up to 50% mortality in farms, resulting in great economic losses [4] [5]. Only in United States, Porcine Reproductive and Respiratory Syndrome virus (PRRSV) produces losses of $560 million yearly.…”