title: A tightly regulated surface protein of Borrelia burgdorferi is not essential to the mouse-tick infectious cycle.
abstract: Borrelia burgdorferi synthesizes a variety of differentially regulated outer surface lipoproteins in the tick vector and in vertebrate hosts. Among these is OspD, a protein that is highly induced in vitro by conditions that mimic the tick environment. Using genetically engineered strains in which ospD is deleted, we demonstrate that this protein is not required for B. burgdorferi survival and infectivity in either the mouse or the tick. However, examination of both transcript levels and protein expression indicates that OspD expression is limited to a discrete window of time during B. burgdorferi replication within the tick. This time frame corresponds to tick detachment from the host following feeding, and expression of OspD continues during tick digestion of the blood meal but is low or undetectable after the tick has molted. The high level of OspD production correlates to the highest cell densities that B. burgdorferi is known to reach in vivo. Although OspD is nonessential to the infectious cycle of B. burgdorferi, the tight regulation of expression suggests a beneficial contribution of OspD to the spirochete during bacterial replication within the tick midgut.
authors.affiliation: Rocky Mountain Laboratories, NIAID, NIH, 903 South 4th St., Hamilton, MT 59840, USA. pestewart@niaid.nih.gov
authors.forename: Philip E
authors.initials: PE
authors.lastname: Stewart
authors.forename: Aaron
authors.initials: A
authors.lastname: Bestor
authors.forename: Jonah N
authors.initials: JN
authors.lastname: Cullen
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Rosa
mesh_terms: D000818:Animals; D000843:Ankle Joint / Q000382:microbiology; D000907:Antibodies, Bacterial / Q000097:blood; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology*; D015153:Blotting, Western; D025065:Borrelia burgdorferi / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D004423:Ear / Q000382:microbiology; D041981:Gastrointestinal Tract / Q000382:microbiology; D017353:Gene Deletion; D020869:Gene Expression Profiling; D008193:Lyme Disease / Q000382:microbiology; D051379:Mice; D016254:Mutagenesis, Insertional; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D013987:Ticks / Q000382:microbiology*; D013997:Time Factors; D001743:Urinary Bladder / Q000382:microbiology; D010566:Virulence Factors, Bordetella / Q000235:genetics / Q000378:metabolism*
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D010566:Virulence Factors, Bordetella; C077524:outer surface protein D, Borrelia burgdorferi