Transfusion-acquired, autochthonous human babesiosis in Japan: isolation of Babesia microti-like parasites with hu-RBC-SCID mice.
We have isolated piroplasms from a patient who developed the first case of human babesiosis in Japan by using NOD/shi-scid mice whose circulating erythrocytes (RBCs) had been replaced with human RBCs (hu-RBC-SCID mice). Following inoculation of the patient's blood specimen into hu-RBC-SCID mice, parasites proliferated within the human RBCs in the mice, resulting in a high level of parasitemia. Parasite DNA was prepared from blood samples of the patient and the mice, and the nuclear small-subunit rRNA gene (rDNA) was amplified and sequenced. Both DNA samples gave rise to identical sequences which showed the highest degree of homology (99.2%) with the Babesia microti rDNA. Because the patient had received a blood transfusion before the onset of babesiosis, we investigated the eight donors who were involved. Their archived blood samples were analyzed for specific antibody and parasite DNA; only a single donor was found to be positive by both tests, and the parasite rDNA sequence from the donor coincided with that derived from the patient. The donor's serum exhibited a high antibody titer against the isolate from the patient, whereas it exhibited only a weak cross-reaction against B. microti strains isolated in the United States. We conclude that the first Japanese babesiosis case occurred due to a blood transfusion and that the etiological agent is an indigenous Japanese parasite which may be a geographical variant of B. microti. Our results also demonstrated the usefulness of hu-RBC-SCID mice for isolation of parasites from humans and for maintenance of the parasite infectivity for human RBCs.
Saito-Ito
A
A
Department of Medical Zoology, Kobe 650-0017, School of Veterinary Medicine, Rakuno-gakuen University, Ebetsu 069-8501, Japan.
Tsuji
M
M
Wei
Q
Q
He
S
S
Matsui
T
T
Kohsaki
M
M
Arai
S
S
Kamiyama
T
T
Hioki
K
K
Ishihara
C
C
D000818:Animals; D001403:Babesia / Q000145:classification / Q000302:isolation & purification*; D001404:Babesiosis / Q000175:diagnosis*; D004912:Erythrocytes / Q000469:parasitology*; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000737:chemistry; D065227:Transfusion Reaction
D012335:RNA, Ribosomal