Roles of the Maltese cross form in the development of parasitemia and protection against Babesia microti infection in mice.
Babesia microti, a hemoprotozoan parasite of rodents, is also important as a zoonotic agent of human babesiosis. The Maltese cross form, which consists of four masses in an erythrocyte, is characteristic of the developmental stage of B. microti. Monoclonal antibody (MAb) 2-1E, which specifically recognizes the Maltese cross form of B. microti, has been described previously. In the present study, we examined the roles of the Maltese cross form during the infectious course of B. microti in mice. The number of the Maltese cross form increased in the peripheral blood of infected mice prior to the peak of parasitemia. With confocal laser scanning microscopy, MAb 2-1E was found to be reactive with the ring form, with the parasites undergoing transformation to the Maltese cross form and subsequent division, and also with extracellular merozoites. Furthermore, the Maltese cross form-related antigen (MRA) gene was isolated from a B. microti cDNA library by immunoscreening with MAb 2-1E, and the nucleotide sequence was determined. Genomic analyses indicated that the MRA gene exists as a single-copy gene in B. microti. Immunization of mice with recombinant MRA induced significant protective immunity against B. microti infection. These findings indicate that the Maltese cross form plays important roles in both the development of parasitemia and the protective response against the infection.
Yokoyama
Naoaki
N
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
Bork
Sabine
S
Nishisaka
Mitsuhiro
M
Hirata
Haruyuki
H
Matsuo
Tomohide
T
Inoue
Noboru
N
Xuan
Xuenan
X
Suzuki
Hiroshi
H
Sugimoto
Chihiro
C
Igarashi
Ikuo
I
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D041001:Babesia microti / Q000254:growth & development* / Q000276:immunology*; D001404:Babesiosis / Q000469:parasitology / Q000517:prevention & control*; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D018512:Parasitemia / Q000469:parasitology / Q000517:prevention & control*; D016052:Protozoan Vaccines / Q000008:administration & dosage / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D017422:Sequence Analysis, DNA
D000911:Antibodies, Monoclonal; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; C470923:MRA protein, Babesia microti; D016052:Protozoan Vaccines; D011994:Recombinant Proteins