The role of the P28 multigene family in the pathogenesis of Ehrlichia chaffeensis infection.

<i>Ehrlichia chaffeensis</i> is a gram-negative obligate intracellular bacterium which parasitizes cells of the monocyte/macrophage lineage in mammals. <i>E. chaffeensis</i> possesses a unique cell wall that lacks LPS and the classical peptidoglycan found in other gram-negative bacteria. <i>Ehrlichia</i> reside inside unique membrane-bound vacuoles in the cytoplasm of host cells, known as morulae. <i>E. chaffeensis</i> is transmitted by lone star ticks, <i>Amblyomma americanum</i>, and is not transmitted transovarially, but is maintained in the environment by persistent infection of animal hosts. <i>E. chaffeensis</i> causes the emerging infectious disease, human monocytic ehrlichiosis (HME), a potentially fatal illness. Although easily treated with tetracycline, due to its obligate intracellular parasitism it is difficult to diagnose by routine clinical methods. <i>E. chaffeensis</i> expresses a 28 kDa outer membrane protein from a multigene family known as P28/OMP-1. Different alleles from this multigene family are expressed in different host cell types, but the role of this membrane protein remains unknown. Also, few host cell receptors, as well as host-pathogen protein interactions, have been identified for <i>E. chaffeensis</i>. Genetic manipulation of the family Anaplasmataceae has not been previously achieved, significantly hampering ehrlichial research. In this work, we describe a method for the transformation of the genus <i>Ehrlichia</i>, and apply this method to study the role of the P28 in ehrlichial pathogenesis by development of a knockout strain. Furthermore, we identify a novel host cell receptor implicated in ehrlichial binding and infection of host cells.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Grantor

The University of Texas Medical Branch

Year dc:date.issued

2006

Author dc:creator

• Scott Wesley Long

Advisor dc:contributor.advisor

• Dr. David H. Walker

Committee members dc:contributor.committeemember

• Dr. Xue-jie Yu
• Dr. Lawrence Stanberry
• Dr. Johnny Peterson
• Dr. Guy Palmer

• host-pathogen interactions
• genetic manipulation
• family Anaplasmataceae

Statement dc:rights

• Copyright © is held by the author. Presentation of this material on the TDL web site by The University of Texas Medical Branch at Galveston was made possible under a limited license grant from the author who has retained all copyrights in the works.

Language dc:language.iso

eng

Dc Identifier Other

etd-03292007-214452

OAI identifier oai:identifier

oai:utmb-ir.tdl.org:2152.3/71