RtxA like protein contributes to infection of Francisella novicida in silkworm and human macrophage THP-1.
| Title: | RtxA like protein contributes to infection of Francisella novicida in silkworm and human macrophage THP-1. |
|---|---|
| Authors: | Saha, Shib Shankar1,2, Uda, Akihiko3, Watanabe, Kenta1, Shimizu, Takashi1, Watarai, Masahisa1 watarai@yamaguchi-u.ac.jp |
| Source: | Microbial Pathogenesis. Oct2018, Vol. 123, p74-81. 8p. |
| Subject Terms: | *FRANCISELLA novicida, *SILKWORMS, *MACROPHAGES, *TULAREMIA, *ZOONOSES |
| Abstract: | Abstract Tularemia is a zoonosis caused by CDC-declared Tier 1 threat agent Francisella tularensis. F. tularensis subsp. novicida (F. novicida) is virulent in mice but non-pathogenic in immunocompetent humans and serves as a potential surrogate organism. In a recent study, we established a silkworm (Bombyx mori) model of infection for F. novicida. Francisella secretes its virulence factors through various mechanisms that modify the intracellular environment to ensure its replication and survival. To identify new pathogenic factors, we focused on the type I secretory system (T1SS) of Francisella. In silico analysis revealed a RtxA (Repeats-in-toxin) like protein in the Francisella genome. The characteristics of RtxA like protein were investigated using mutant analysis. Firstly, the role of rtxA in silkworms was investigated by infecting them with F. novicida strains into the hemocoel. The rtxA mutant failed to kill the silkworms, whereas F. novicida wild-type (WT) strain killed silkworms within 3–7 days post infection. The arrested growth of the mutant strain in silkworms was observed using a whole-body CFU count assay. We also investigated the growth characteristics of the rtxA mutant in hemocytes, one of the primary multiplication sites of Francisella within silkworms. Interrupted growth of the rtxA mutant with significantly reduced cytotoxicity was observed in hemocytes via confocal microscopy. Next, we analyzed the effect of rtxA in human monocyte cell line THP-1. The mutant strain showed significantly decreased growth and reduced cytotoxicity compared with its parental strain in THP-1 cells. This study newly identified RtxA like protein of F. novicida as an important lethal pathogenic factor in silkworm and mammalian cells. Highlights • There is a RtxA like protein in Francisella novicida. • The deletion mutant of RtxA like protein failed to kill silkworm. • RtxA like protein contributes to intracellular growth in THP-1 cells. [ABSTRACT FROM AUTHOR] |
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| Items | – Name: Title Label: Title Group: Ti Data: RtxA like protein contributes to infection of Francisella novicida in silkworm and human macrophage THP-1. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Saha%2C+Shib+Shankar%22">Saha, Shib Shankar</searchLink><relatesTo>1,2</relatesTo><br /><searchLink fieldCode="AR" term="%22Uda%2C+Akihiko%22">Uda, Akihiko</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Watanabe%2C+Kenta%22">Watanabe, Kenta</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Shimizu%2C+Takashi%22">Shimizu, Takashi</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Watarai%2C+Masahisa%22">Watarai, Masahisa</searchLink><relatesTo>1</relatesTo><i> watarai@yamaguchi-u.ac.jp</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Microbial+Pathogenesis%22">Microbial Pathogenesis</searchLink>. Oct2018, Vol. 123, p74-81. 8p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22FRANCISELLA+novicida%22">FRANCISELLA novicida</searchLink><br />*<searchLink fieldCode="DE" term="%22SILKWORMS%22">SILKWORMS</searchLink><br />*<searchLink fieldCode="DE" term="%22MACROPHAGES%22">MACROPHAGES</searchLink><br />*<searchLink fieldCode="DE" term="%22TULAREMIA%22">TULAREMIA</searchLink><br />*<searchLink fieldCode="DE" term="%22ZOONOSES%22">ZOONOSES</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Abstract Tularemia is a zoonosis caused by CDC-declared Tier 1 threat agent Francisella tularensis. F. tularensis subsp. novicida (F. novicida) is virulent in mice but non-pathogenic in immunocompetent humans and serves as a potential surrogate organism. In a recent study, we established a silkworm (Bombyx mori) model of infection for F. novicida. Francisella secretes its virulence factors through various mechanisms that modify the intracellular environment to ensure its replication and survival. To identify new pathogenic factors, we focused on the type I secretory system (T1SS) of Francisella. In silico analysis revealed a RtxA (Repeats-in-toxin) like protein in the Francisella genome. The characteristics of RtxA like protein were investigated using mutant analysis. Firstly, the role of rtxA in silkworms was investigated by infecting them with F. novicida strains into the hemocoel. The rtxA mutant failed to kill the silkworms, whereas F. novicida wild-type (WT) strain killed silkworms within 3–7 days post infection. The arrested growth of the mutant strain in silkworms was observed using a whole-body CFU count assay. We also investigated the growth characteristics of the rtxA mutant in hemocytes, one of the primary multiplication sites of Francisella within silkworms. Interrupted growth of the rtxA mutant with significantly reduced cytotoxicity was observed in hemocytes via confocal microscopy. Next, we analyzed the effect of rtxA in human monocyte cell line THP-1. The mutant strain showed significantly decreased growth and reduced cytotoxicity compared with its parental strain in THP-1 cells. This study newly identified RtxA like protein of F. novicida as an important lethal pathogenic factor in silkworm and mammalian cells. Highlights • There is a RtxA like protein in Francisella novicida. • The deletion mutant of RtxA like protein failed to kill silkworm. • RtxA like protein contributes to intracellular growth in THP-1 cells. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Microbial Pathogenesis is the property of Academic Press Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.micpath.2018.06.046 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 8 StartPage: 74 Subjects: – SubjectFull: FRANCISELLA novicida Type: general – SubjectFull: SILKWORMS Type: general – SubjectFull: MACROPHAGES Type: general – SubjectFull: TULAREMIA Type: general – SubjectFull: ZOONOSES Type: general Titles: – TitleFull: RtxA like protein contributes to infection of Francisella novicida in silkworm and human macrophage THP-1. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Saha, Shib Shankar – PersonEntity: Name: NameFull: Uda, Akihiko – PersonEntity: Name: NameFull: Watanabe, Kenta – PersonEntity: Name: NameFull: Shimizu, Takashi – PersonEntity: Name: NameFull: Watarai, Masahisa IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 10 Text: Oct2018 Type: published Y: 2018 Identifiers: – Type: issn-print Value: 08824010 Numbering: – Type: volume Value: 123 Titles: – TitleFull: Microbial Pathogenesis Type: main |
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