title: Brucella abortus nicotinamidase (PncA) contributes to its intracellular replication and infectivity in mice.
abstract: Brucella spp. are facultative intracellular pathogens that have the ability to survive and multiply in professional and non-professional phagocytes, and cause abortion in domestic animals and undulant fever in humans. The mechanism and factors of virulence are not fully understood. Nicotinamidase/pyrazinamidase mutant (pncA mutant) of Brucella abortus failed to replicate in HeLa cells, and showed a lower rate of intracellular replication than that of wild-type strain in macrophages. Addition of nicotinic acid, but not nicotinamide, into medium supported intracellular replication of pncA mutant in HeLa cells and macrophages. The pncA mutant was not co-localizing with either late endosomes or lysosomes. The B. abortus virB4 mutant was completely cleared from the spleens of mice after 4 weeks, while the pncA mutant showed a 1.5-log reduction of the number of bacteria isolated from spleens after 10 weeks. Although pncA mutant showed reduced virulence in mice and defective intracellular replication, its ability to confer protection against the virulent B. abortus strain 544 was fully retained. These results suggest that PncA does not contribute to intracellular trafficking of B. abortus, but contributes to utilization of nutrients required for intracellular growth. Our results indicate that detailed characterizations of the pncA mutant may help the improvement of currently available live vaccines.
authors.affiliation: Department of Applied Veterinary Science, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro-shi, Hokkaido 080-8555, Japan.
authors.forename: Suk
authors.initials: S
authors.lastname: Kim
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kurokawa
authors.forename: Kenta
authors.initials: K
authors.lastname: Watanabe
authors.forename: Sou-Ichi
authors.initials: S
authors.lastname: Makino
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Shirahata
authors.forename: Masahisa
authors.initials: M
authors.lastname: Watarai
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines; D001483:Base Sequence; D002003:Brucella abortus / Q000201:enzymology* / Q000254:growth & development / Q000472:pathogenicity* / Q000502:physiology; D002455:Cell Division; D017931:DNA Primers; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D009535:Nicotinamidase / Q000378:metabolism*; D016133:Polymerase Chain Reaction
chemical_list: D001428:Bacterial Vaccines; D017931:DNA Primers; D009535:Nicotinamidase