Jw. Thomford et al., CULTIVATION AND PHYLOGENETIC CHARACTERIZATION OF A NEWLY RECOGNIZED HUMAN PATHOGENIC PROTOZOAN, The Journal of infectious diseases, 169(5), 1994, pp. 1050-1056
An intraerythrocytic protozoan (WA1) recently isolated from a patient
in Washington State was shown to be morphologically identical to Babes
ia microti but biologically and genetically distinct. Continuous growt
h of WA1 was established in stationary erythrocyte cultures. Hybridiza
tion of a chemiluminescent Babesia-specific DNA probe to Southern blot
s of restriction enzyme-digested genomic DNA showed that WA1 could be
distinguished from other Babesia species that were antigenically cross
-reactive (Babesia gibsoni and babesial parasites from desert bighorn
sheep, Ovis canadensis nelsoni) or known to infect humans (B. microti,
Babesia divergens, and Babesia equi), or both. A 1436-bp portion of t
he nuclear small subunit rRNA gene of WA1 was sequenced and analyzed.
Genetic distance analysis showed that WA1 is most closely related to t
he canine pathogen B. gibsoni and lies within a phylogenetic cluster w
ith Theileria species and B. equi. The methodology described will be u
seful for improved diagnosis and identification of human protozoal pat
hogens.