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.

Objectives: 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.