A novel 57-kDa merozoite protein of Babesia gibsoni is a prospective antigen for diagnosis and serosurvey of canine babesiosis by enzyme-linked immunosorbent assay.
We isolated a novel single copy gene encoding a 57-kDa merozoite protein of Babesia gibsoni (BgP57). The nucleotide sequence of the cDNA was 2387 bp with an open reading frame (ORF) of 1644 bp encoding a 57-kDa predicted polypeptide having 547 amino acid residues. The recombinant BgP57 (rBgP57) without a predicted signal peptide was expressed in Escherichia coli as a soluble glutathione S-transferase (GST) fusion protein. Western blotting showed that the corresponding native protein was 57-kDa, consistent with molecular weight of predicted mature polypeptide. An indirect enzyme-linked immunosorbent assay (ELISA) using the rBgP57 detected specific antibodies in the sequential sera from a dog experimentally infected with B. gibsoni. Moreover, the antigen did not cross-react with antibodies to B. canis sub-species and closely related apicomplexan parasites indicating that the rBgP57 was a specific antigen for B. gibsoni antibodies. The diagnostic performance of ELISA based on rBgP57 using 107 sera from B. gibsoni-naturally infected dogs was the same as the previously identified rBgP32 but performed better than the previously studied rBgP50. Although, seminested PCR detected higher proportions (82%) of positive samples than the ELISAs, the Mcnemar's chi-square test showed that there was no significant difference in relative effectiveness of rBgP57-ELISA and seminested PCR (chi(2)=2.70; P=0.1003) in identifying positive samples. The rBgP57-ELISA when used in combination with rBgP32-ELISA and rBgP50-ELISA appeared to improve sensitivity of the rBgP57-ELISA for detection of B. gibsoni antibodies. Overall, the rBgP57-ELISA and seminested PCR when used in combination, could improve epidemiological surveys and clinical diagnosis of B. gibsoni infection.
Aboge
Gabriel Oluga
GO
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
Jia
Honglin
H
Terkawi
Mohamad Alaa
MA
Goo
Younkyoung
Y
Kuriki
Ken
K
Nishikawa
Yoshifumi
Y
Igarashi
Ikuo
I
Suzuki
Hiroshi
H
Xuan
Xuenan
X
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000097:blood* / Q000235:genetics / Q000378:metabolism; D001403:Babesia / Q000235:genetics / Q000378:metabolism*; D001404:Babesiosis / Q000175:diagnosis / Q000453:epidemiology / Q000662:veterinary*; D001483:Base Sequence; D003001:Cloning, Molecular; D004283:Dog Diseases / Q000175:diagnosis* / Q000453:epidemiology; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D052940:Merozoites / Q000378:metabolism; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000737:chemistry; D012680:Sensitivity and Specificity
D000953:Antigens, Protozoan; D015800:Protozoan Proteins