Monoclonal antibody directed against Neospora caninum tachyzoite carbohydrate epitope reacts specifically with apical complex-associated sialylated beta tubulin

Srinivasan, Sangeetha; Baszler, Timothy; Vonlaufen, Nathalie; Leepin, Angela; Sanderson, Sanya J; Wastling, Jonathan M; Hemphill, Andrew (2006). Monoclonal antibody directed against Neospora caninum tachyzoite carbohydrate epitope reacts specifically with apical complex-associated sialylated beta tubulin. Journal of parasitology, 92(6), pp. 1235-43. Lawrence, Kans.: American Society of Parasitologists 10.1645/GE-889R.1

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Monoclonal antibodies (mabs) were generated against whole sonicated Neospora caninum tachyzoites as immunogen. Initial ELISA screening of the reactivity of hybridoma culture supernatants using the same antigen and antigen treated with sodium periodate prior to antibody binding resulted in the identification of 8 supernatants with reactivity against putative carbohydrate epitopes. Following immunoblotting, mab6D12 (IgG1), binding a 52/48-kDa doublet, and mab6C6 (IgM), binding a 190/180-kDa doublet, were selected for further studies. Immunofluorescence of tachyzoite-infected cultures localized the corresponding epitopes not to the surface, but to interior epitopes at the apical part of N. caninum tachyzoites. During in vitro tachyzoite to bradyzoite stage conversion, mab6C6 labeling translocated toward the cyst periphery, while for mab6D12 no changes in localization were noted. Upon extraction of tachyzoites with the nonionic detergent Triton-X-100, the 52-kDa band recognized by mab6D12 was present exclusively in the insoluble, cytoskeletal fraction of both N. caninum and Toxoplasma gondii tachyzoites. Tandem mass spectrometry analysis identified this protein as N. caninum beta tubulin. The 48-kDa band labeled by mab6D12 was a Vero cell protein contamination. The protein(s) reacting with mab6C6 could not be conclusively identified by mass spectrometry. Immunofluorescence consistently failed to label T. gondii tachyzoites, indicating that beta tubulin in T. gondii and N. caninum could be differentially modified or that the reactive epitope in T. gondii is masked. Immunogold TEM of isolated apical cytoskeletal preparations and dual immunofluorescence with antibody to tubulin confirmed that mab6D12 binds to the anterior part of apical complex-associated microtubules. The sodium periodate sensitivity of the beta tubulin associated epitope was confirmed by immunoblotting and ELISA, and treatment of N. caninum cytoskeletal proteins with sialidase prior to mab6D12 labeling resulted in a profound loss of antibody binding, suggesting that mab6D12 reacts with sialylated beta tubulin.

Item Type:

Journal Article (Original Article)


05 Veterinary Medicine > Department of Infectious Diseases and Pathobiology (DIP) > Institute of Parasitology

UniBE Contributor:

Vonlaufen, Nathalie Françoise F.; Leepin, Angela and Hemphill, Andrew




American Society of Parasitologists




Factscience Import

Date Deposited:

04 Oct 2013 14:45

Last Modified:

04 May 2014 23:13

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URI: (FactScience: 886)

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