Identification and characterization of a novel secreted antigen 1 of Babesia microti and evaluation of its potential use in enzyme-linked immunosorbent assay and immunochromatographic test.
Here, we identified a novel secreted antigen designated as Babesia microti secreted antigen 1 (BmSA1) by immunoscreening a B. microti cDNA expression library using the sera from hamsters immunized with plasma, putatively containing secreted antigens, from B. microti-infected hamsters. Antibodies raised in mice immunized with recombinant BmSA1 (rBmSA1) recognized a native 33-kDa parasite protein. An enzyme-linked immunosorbent assay (ELISA) of rBmSA1 detected specific antibodies as early as 6 and 4 days post-infection in sera from a hamster experimentally infected with B. microti Gray strain (US type) and a mouse experimentally infected with B. microti Munich strain (rodent isolate), respectively. Moreover, a rapid immunochromatographic test (ICT) using rBmSA1 detected specific antibodies in a hamster experimentally infected with B. microti from day 6 to at least day 270 post-infection, which was quite consistent with the results of the ELISA. In addition, analysis of the sera involved in the first case of human babesiosis in Japan (Kobe type) showed that specific antibodies were detectable in the patient and the positive donor by ELISA using rBmSA1, and the ICT result was identical to the ELISA data. Taken together, these results indicated that BmSA1 could be a promising and universal target for developing both ELISA and ICT for the serodiagnosis of human babesiosis and for an epidemiological survey of its rodent reservoir.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
Yuzi
Y
Luo
Honglin
H
Jia
M Alaa
MA
Terkawi
Youn-Kyoung
YK
Goo
Suguru
S
Kawano
Hideo
H
Ooka
Yan
Y
Li
Longzheng
L
Yu
Shinuo
S
Cao
Junya
J
Yamagishi
Kozo
K
Fujisaki
Yoshifumi
Y
Nishikawa
Atsuko
A
Saito-Ito
Ikuo
I
Igarashi
Xuenan
X
Xuan
D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan / Q000235:genetics*; D041001:Babesia microti / Q000276:immunology*; D001404:Babesiosis / Q000175:diagnosis* / Q000469:parasitology; D015153:Blotting, Western; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D004926:Escherichia coli / Q000378:metabolism; D005260:Female; D015723:Gene Library; D006801:Humans; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D011817:Rabbits
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan