Characterization of an immunoreactive protein from the agent of human granulocytic ehrlichiosis.
A gene that is homologous to the Ehrlichia chaffeensis groEL operon was recovered and characterized by broad-range PCR amplification of whole blood from patients with human granulocytic ehrlichiosis (HGE) and from infected HL60 cell cultures. Sequence analysis of an 820-bp DNA fragment recovered directly from human blood showed 76.5 and 76.3% identity with cognate sequences from E. chaffeensis and Cowdria ruminantium, respectively. Analysis of a 1.6-kb DNA fragment derived from an HGE agent-infected HL60 cell culture indicated a near-complete open reading frame that contained 75.6 and 75.2% sequence identity with the E. chaffeensis and C. ruminantium groEL sequences, respectively. Phylogenetic analysis of this fragment showed that the HGE agent-derived sequence was related to, but distinct from, the sequences of E. chaffeensis and C. ruminantium. Polyvalent antibody responses to a recombinant fusion protein based on the HGE agent groEL homolog were detected in three of three BALB/c mice that were infected by syringe inoculation with a Wisconsin strain of the HGE agent (WI-1) and nine of nine mice infected by Ixodes scapularis (Ixodes dammini) tick inoculation of an isolate from Nantucket Island, Mass. (NCH-1). No response was detected in mice infected with Borrelia burgdorferi or in control BALB/c mice. Further characterization of the sensitivity and specificity of immune responses to this protein will be facilitated by the use of recombinant fusion proteins or peptides based on the HGE agent-specific groEL homolog.
Kolbert
C P
CP
Department of Laboratory Medicine and Pathology, Mayo Foundation, Rochester, Minnesota 55905, USA.
Bruinsma
E S
ES
Abdulkarim
A S
AS
Hofmeister
E K
EK
Tompkins
R B
RB
Telford
S R
SR
Mitchell
P D
PD
Adams-Stich
J
J
Persing
D H
DH
D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D018834:Chaperonin 60 / Q000235:genetics; D018469:Ehrlichia chaffeensis / Q000235:genetics / Q000276:immunology*; D016873:Ehrlichiosis / Q000235:genetics / Q000276:immunology*; D005798:Genes, Bacterial; D018922:HL-60 Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016415:Sequence Alignment
D000942:Antigens, Bacterial; D018834:Chaperonin 60