Comparison of the Efficiency of Biological Transmission of Anaplasma marginale (Rickettsiales: Anaplasmataceae) by Dermacentor andersoni Stiles (Acari: Ixodidae) with Mechanical Transmission by the Horse Fly, Tabanus fuscicostatus Hine (Diptera: Muscidae)

SUMMARY Anaplasmosis, a tick-borne cattle disease caused by the rickettsia Anaplasma marginale, is endemic in tropical and subtropical areas of the world. The disease causes considerable economic loss to both the dairy and beef industries worldwide. Analyses of 16S rRNA, groESL, and surface proteins have resulted in the recent reclassification of the order Rickettsiales. The genus Anaplasma, of which A. marginale is the type species, now also includes A. bovis, A. platys, and A. phagocytophilum, which were previously known as Ehrlichia bovis, E. platys, and the E. phagocytophila group (which causes human granulocytic ehrlichiosis), respectively. Live and killed vaccines have been used for control of anaplasmosis, and both types of vaccines have advantages and disadvantages. These vaccines have been effective in preventing clinical anaplasmosis in cattle but have not blocked A. marginale infection. Thus, persistently infected cattle serve as a reservoir of infective blood for both mechanical transmission and infection of ticks. Advances in biochemical, immunologic, and molecular technologies during the last decade have been applied to research of A. marginale and related organisms. The recent development of a cell culture system for A. marginale provides a potential source of antigen for the development of improved killed and live vaccines, and the availability of cell culture-derived antigen would eliminate the use of cattle in vaccine production. Increased knowledge of A. marginale antigen repertoires and an improved understanding of bovine cellular and humoral immune responses to A. marginale, combined with the new technologies, should contribute to the development of more effective vaccines for control and prevention of anaplasmosis.

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Developmental Studies of Anaplasma marginale (Rickettsiales: Anaplasmataceae) in Male Dermacentor andersoni (Acari: Ixodidae) Infected as Adults by Using Nonradioactive In Situ Hybridization and Microscopy

Journal of Medical Entomology ◽

10.1093/jmedent/33.6.911 ◽

1996 ◽

Vol 33 (6) ◽

pp. 911-920 ◽

Cited By ~ 28

Author(s):

Nie-Lin Ge ◽

Katherine M. Kocan ◽

Edmour F. Blouin ◽

George L. Murphy

Keyword(s):

In Situ Hybridization ◽

Anaplasma Marginale ◽

Developmental Studies ◽

Dermacentor Andersoni ◽

Nonradioactive In Situ Hybridization

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Anaplasma marginale Actively Modulates Vacuolar Maturation during Intracellular Infection of Its Tick Vector, Dermacentor andersoni

Applied and Environmental Microbiology ◽

10.1128/aem.01030-16 ◽

2016 ◽

Vol 82 (15) ◽

pp. 4715-4731 ◽

Cited By ~ 4

Author(s):

Forgivemore Magunda ◽

Chelsea Wright Thompson ◽

David A. Schneider ◽

Susan M. Noh

Keyword(s):

Protein Synthesis ◽

Bacterial Pathogens ◽

Cathepsin L ◽

Anaplasma Marginale ◽

Transmission Efficiency ◽

Recycling Endosome ◽

Dermacentor Andersoni ◽

Content Type ◽

Tick Vector ◽

Tick Midgut

ABSTRACTTick-borne transmission of bacterial pathogens in the orderRickettsialesis responsible for diverse infectious diseases, many of them severe, in humans and animals. Transmission dynamics differ among these pathogens and are reflected in the pathogen-vector interaction.Anaplasma marginalehas been shown to establish and maintain infectivity withinDermacentorspp. for weeks to months while escaping the complex network of vacuolar peptidases that are responsible for digestion of the tick blood meal. How this prolonged maintenance of infectivity in a potentially hostile environment is achieved has been unknown. Using the natural vectorDermacentor andersoni, we demonstrated thatA. marginale-infected tick vacuoles (AmVs) concurrently recruit markers of the early endosome (Rab5), recycling endosome (Rab4 and Rab11), and late endosome (Rab7), are maintained near neutral pH, do not fuse with lysosomes, exclude the protease cathepsin L, and engage the endoplasmic reticulum and Golgi apparatus for up to 21 days postinfection. Maintenance of this safe vacuolar niche requires activeA. marginaleprotein synthesis; in its absence, the AmVs mature into acidic, protease-active phagolysosomes. Identification of this bacterially directed modeling of the tick midgut endosome provides a mechanistic basis for examination of the differences in transmission efficiency observed amongA. marginalestrains and among vector populations.IMPORTANCETicks transmit a variety of intracellular bacterial pathogens that cause significant diseases in humans and animals. For successful transmission, these bacterial pathogens must first gain entry into the tick midgut digestive cells, avoid digestion, and establish a replicative niche without harming the tick vector. Little is known about how this replicative niche is established and maintained. Using the ruminant pathogenA. marginaleand its natural tick vector,D. andersoni, this study characterized the features of theA. marginaleniche in the tick midgut and demonstrates thatA. marginaleprotein synthesis is required for the maintenance of this niche. This work opens a new line of inquiry about the pathogen effectors and their targets within the tick that mediate tick-pathogen interactions and ultimately serve as the determinants of pathogen success.

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