Cloning and expression of the gene encoding the major surface protein 5 (MSP5) of Anaplasma phagocytophilum and potential application for serodiagnosis.
BACKGROUND
Anaplasma phagocytophilum (formerly known as the human granulocytic ehrlichia, Ehrlichia equi and Ehrlichia phagocytophila) is an obligate intracellular organism causing clinical disease in humans and various species of domestic animals.


OBJECTIVE
The objectives of this investigation were to sequence and clone the major surface protein 5 (MSP5) of A phagocytophilum and to evaluate the suitability of this antigen in the serologic diagnosis of anaplasmosis in humans and dogs.


METHODS
The msp5 gene of A phagocytophilum was sequenced, cloned, and expressed in Escherichia coli. The predicted amino acid sequence homology of the various MSP5/major antigenic protein 2 orthologs was compared among various Anaplasma and Ehrlichia species. Recombinant MSP5 of A phagocytophilum was used in an ELISA to detect antibodies in serum samples from humans and dogs infected with the organism.


RESULTS
Serum samples from 104 individuals previously diagnosed with A phagocytophilum infection, as well as samples from clinically healthy humans, were tested. In addition, multiple samples from 4 dogs experimentally infected with 2 different geographic isolates of A phagocytophilum and 5 dogs naturally infected with a Swiss isolate were tested using ELISA. Using this group of immunofluorescent antibody test-positive and immunofluorescent antibody test-negative samples, we found the overall agreement between assays to be >90%.


CONCLUSIONS
These results indicate that recombinant MSP5 has potential for use as a diagnostic test antigen to detect infection with A phagocytophilum in both dogs and humans. However, sequence similarities among orthologs of MSP5 in related species of anaplasma and ehrlichia suggest that cross-reactivity among these pathogens is likely if the entire peptide is used as a test antigen.
Alleman
A Rick
AR
College of Veterinary Medicine, University of Florida, Gainesville, FL, USA. allemanr@mail.vetmed.ufl.edu
Barbet
Anthony F
AF
Sorenson
Heather L
HL
Strik
Nicole I
NI
Wamsley
Heather L
HL
Wong
Susan J
SJ
Chandrashaker
Ramaswamy
R
Gaschen
Frédéric P
FP
Luckshander
Nicole
N
Bjöersdorff
Annelli
A
D000595:Amino Acid Sequence; D041081:Anaplasma phagocytophilum / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D004283:Dog Diseases / Q000175:diagnosis* / Q000382:microbiology*; D004285:Dogs; D016873:Ehrlichiosis / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D006801:Humans; D008969:Molecular Sequence Data; D013045:Species Specificity
D001425:Bacterial Outer Membrane Proteins; C111578:major surface protein 5, Anaplasma