title: Novel identification of Dermacentor variabilis Arp2/3 complex and its role in rickettsial infection of the arthropod vector.
abstract: Tick-borne spotted fever group (SFG) Rickettsia species must be able to infect both vertebrate and arthropod host cells. The host actin-related protein 2/3 (Arp2/3) complex is important in the invasion process and actin-based motility for several intracellular bacteria, including SFG Rickettsia in Drosophila and mammalian cells. To investigate the role of the tick Arp2/3 complex in tick-Rickettsia interactions, open reading frames of all subunits of the protein including Arp2, Arp3, ARPC1, ARPC2, ARPC3, ARPC4, and ARPC5 were identified from Dermacentor variabilis. Amino acid sequence analysis showed variation (ranging from 25-88%) in percent identity compared to the corresponding subunits of the complex from Drosophila melanogaster, Mus musculus, Homo sapiens, and Saccharomyces cerevisiae. Potential ATP binding sites were identified in D. variabilis (Dv) Arp2 and Arp3 subunits as well as five putative WD (Trp-Asp) motifs which were observed in DvARPC1. Transcriptional profiles of all subunits of the DvArp2/3 complex revealed greater mRNA expression in both Rickettsia-infected and -uninfected ovary compared to midgut and salivary glands. In response to R. montanensis infection of the tick ovary, the mRNA level of only DvARPC4 was significantly upregulated compared to uninfected tissues. Arp2/3 complex inhibition bioassays resulted in a decrease in the ability of R. montanensis to invade tick tissues with a significant difference in the tick ovary, indicating a role for the Arp2/3 complex in rickettsial invasion of tick cells. Characterization of tick-derived molecules associated with rickettsial infection is imperative in order to better comprehend the ecology of tick-borne rickettsial diseases.
authors.affiliation: Vector-borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America.
authors.forename: Natthida
authors.initials: N
authors.lastname: Petchampai
authors.affiliation: Vector-borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America.
authors.forename: Piyanate
authors.initials: P
authors.lastname: Sunyakumthorn
authors.affiliation: Vector-borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Guillotte
authors.affiliation: Vector-borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America.
authors.forename: Victoria I
authors.initials: VI
authors.lastname: Verhoeve
authors.affiliation: Vector-borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America.
authors.forename: Kaikhushroo H
authors.initials: KH
authors.lastname: Banajee
authors.affiliation: Vector-borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Kearney
authors.affiliation: Vector-borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America.
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Macaluso
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001179:Arthropod Vectors / Q000378:metabolism* / Q000382:microbiology*; D001665:Binding Sites; D003001:Cloning, Molecular; D003870:Dermacentor / Q000378:metabolism* / Q000382:microbiology*; D005260:Female; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012282:Rickettsia Infections / Q000378:metabolism* / Q000382:microbiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D021122:Protein Subunits; D012333:RNA, Messenger
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