Bordetella holmesii is recognized as the third causative agent of pertussis (whooping cough) in addition to Bordetella pertussis and Bordetella parapertussis. Pertussis caused by B. holmesii is not rare around the world. However, to date, there is no effective vaccine against B. holmesii. We examined the protective potency of pertussis vaccines available in Japan and vaccines prepared from B. holmesii. A murine model of respiratory infection was exploited to evaluate protective potency. No Japanese commercial pertussis vaccines were effective against B. holmesii. In contrast, a wBH vaccine and an aBH vaccine prepared from B. holmesii were both protective. Passive immunization with sera from mice immunized with aBH vaccine established protection against B. holmesii, indicating that B. holmesii-specific serum antibodies might play an important role in protection. Immuno-proteomic analysis with sera from mice immunized with aBH vaccine revealed that the sera recognized a BipAlike protein of B. holmesii. An aBH vaccine prepared from a BipA-like protein-deficient mutant strain did not have a protective effect against B. holmesii. Taken together, our results suggest that the BipAlike protein plays an important role in the protective efficacy of aBH vaccine.Key words BipA-like protein, Bordetella holmesii, pertussis, whooping cough.Pertussis (whooping cough) is a highly contagious respiratory disease caused, in most cases, by Bordetella pertussis. Introduction of effective pertussis vaccines has dramatically reduced the incidence of pertussis caused by B. pertussis worldwide (1). However, current pertussis vaccines are not effective against other causative agents of pertussis, such as B. parapertussis and B. holmesii (2-5). Our previous studies showed that effective vaccines against B. parapertussis can be prepared from formalin-inactivated whole cells or FHA of B. parapertussis (3). The goal of the present study was to develop effective vaccines against respiratory infection by B. holmesii.Bordetella holmesii was first reported in 1995 after isolation from a patient with sepsis, and it is recognized as a causative agent of systemic infection, mainly in immunocompromised hosts (6). During the past decade, B. holmesii has also been isolated from patients with pertussis-like symptoms (7,8). Recent epidemiological studies suggest that pertussis caused by B. holmesii List of Abbreviations: 2D PAGE, two dimensional polyacrylamide gel electrophores; aBH, acellular vaccine prepared from Bordetella holmesii; BG agar, Bordet-Gengou agar; BH2Sm r -4BipA, BipA-like protein deficient-mutant of B. holmesii; CFU, colony-forming units; CasS/S, Stainer Scholte medium supplemented with 0.25 (w/v) Casamino acids; DPBS, Dulbecco's modified phosphate-buffered saline (À) pH 7.4; DTT, dithiothreitol; DTaP, diphtheriatetanus acellular pertussis vaccine; FHA, filamentous hemagglutinin; FIM, fimbriae; HE, hematoxylin-eosin; Incubation buffer, washing buffer containing 10% (w/v) skimmed milk; PFGE, pulse field gel electrophoresis; PRN, ...

Culture supernatants of Bordetella pertussis are a brilliant yellow; however, the structure and biological role of the responsible pigment have not been investigated. In this study, a brilliant yellow-colored fraction was extracted from culture supernatants of B. pertussis and analyzed by HPLC. UV-visible spectral analysis and mass spectrometry identified the brilliant yellow pigment as riboflavin. Riboflavin production was high in lag and early log phases and riboflavin was found to enhance growth of B. pertussis in low-density cultures. Riboflavin production is not regulated by the BvgAS system. In addition, it was found that other Bordetella species, such as B. parapertussis, B. holmesii and B. bronchiseptica, also release riboflavin into their culture supernatants. This is the first report that B. pertussis secrets riboflavin to the extracellular space and that riboflavin may promote its growth. The mechanism may be associated with pathogenesis of B. pertussis.