Molecular characterizations of three distinct Babesia gibsoni rhoptry-associated protein-1s (RAP-1s)

M. A. Terkawi, A. Amornthep, H. Ooka, G. Aboge, H. Jia, Y. K. Goo, B. Nelson, Junya Yamagishi, Y. Nishikawa, I. Igarashi, S. I. Kawazu, K. Fujisaki, X. Xuan

    Research output: Contribution to journalArticlepeer-review

    14 Citations (Scopus)


    Three cDNAs encoding rhoptry-associated protein 1 (RAP-1) homologues were found in the Babesia gibsoni EST database. Based on similarities to BgRAP-1a, which was identified previously by serological screening of a cDNA merozoite library, the two new genes were designated BgRAP-1b (337%) and BgRAP-1c (57%). Mice antiserum raised against each recombinant protein reacted specifically with B. gibsoni parasites as determined by Western blotting, which showed native molecular sizes of the BgRAP-1a (51 kDa), BgRAP-1b (53 kDa) and BgRAP-1c (47 kDa) consistent with predictable molecular weights. Immunofluoresence using these antibodies revealed localization of all BgRAP-1s within the matrix of merozoites; however, BgRAP-1a appeared to diverge from the other two when it was found secreted into the cytoplasm of infected erythrocytes. Apical localization of all 3 BgRAP-1s during the extracellular stage of the parasite combined with their ability to bind a canine erythrocyte membrane fraction was suggestive of a role for these proteins in erythrocyte attachment. Lastly, the ability of these recombinant proteins to be used as diagnostic reagents was tested by ELISA and the sensitivities of BgRAP-1a and BgRAP-1c were found increased through N-terminal truncation. Taken together, our data suggest divergent roles for the 3 BgRAP-1s in the merozoite stage of B. gibsoni.

    Original languageEnglish
    Pages (from-to)1147-1160
    Number of pages14
    Issue number10
    Publication statusPublished - 2009 Sep 1


    • Antigenicity
    • Babesia gibsoni
    • Rhoptry-associated protein

    ASJC Scopus subject areas

    • Parasitology
    • Animal Science and Zoology
    • Infectious Diseases


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