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- Author or Editor: M. A. Toivio-Kinnucan x
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Summary
A panel of monoclonal antibodies (MAb) developed against Mycoplasma gallisepticum strain PG31 was used to probe the antigenic profiles of 5 recognized strains (PG31, R, S6, F, A5969) and 6 field isolates of M gallisepticum. Monoclonal antibody G9 predominantly recognized antigens at apparent molecular mass positions of 90 to 98 kDA. The MAb reacted with all strains and isolates, but the molecular mass position of the antigens varied among some mycoplasmas. Monoclonal antibody G12 reacted with all strains and isolates of M gallisepticum and had an identical banding pattern. However, MAb G10 and G11 reacted selectively only with a limited number of strains and/or isolates. Surface distribution of the MAb-recognized antigens was revealed by immunoelectron microscopy.
Partial physicochemical characterization of MAb G9-recognized antigens identified glycopeptide characteristics. Monoclonal antibody G9 reacted with surface antigens and, hence, participated in agglutination of M gallisepticum. However, the degree of agglutination varied among the various strains and isolates, indicating a quantitative or conformational limitation or an alteration in the anomeric expression of the epitopes. Antigenic variation in M gallisepticum may be mediated by immunologic selective pressures, or a proclivity for habit niche in the host.
Summary
Ultrastructure of the interactions of host cell mitochondria with developing Toxoplasma gondii tissue cysts was examined in cultured cells, using transmission electron microscopy of infected cells and rhodamine 123 (a mitochondria-specific vital fluorescent dye) staining of isolated tissue cysts. Structurally mature T gondii tissue cysts were observed as early as 2 days after inoculation of cultured cells. During development of T gondii, host cell mitochondria were observed surrounding the parasitophorous vacuole membrane. Mitochondria became flat and elongated in the vicinity of the parasitophorous vacuole membrane. These mitochondria were also closely associated with T gondii tissue cysts. Incubation of tissue cysts from cultured cells and tissue cysts from mouse brains with rhodamine 123 revealed fluorescence of the tissue cyst wall in living specimens. Incubation of tissue cysts with 10 µM rotenone caused diminished fluorescence of the tissue cyst walls, and 100 µM rotenone caused complete inhibition. Mouse RBC, and tissue cysts fixed in 100% methanol did not fluoresce after exposure to rhodamine. Tissue cysts in 9 isolates of T gondii from mouse brains were examined, using rhodamine 123, and the tissue cyst walls of all isolates fluoresced, indicating no isolate effects. Our results indicate that host cell mitochondria may be closely associated with the tissue cysts of T gondii in cell cultures and in mice.
Abstract
Objective
To characterize the canine melanoma antigen recognized by the murine monoclonal antibody IBF9 as to its cellular location, molecular size, protein and glycogen contents, and distribution in cell lines.
Sample Population
7 cultured canine melanoma cell lines.
Procedure
Molecular characteristics of the antigen were determined by western blotting, enzymatic digestion studies, and tunicamycin inhibition studies. Distribution of the antigen in the cultured melanoma cell lines was determined by flow cytometry.
Results
The antigen consists of 2 proteins with molecular mass of 89 and 85 kd. Tunicamycin and enzymatic digestion studies indicated that these proteins contained little glycosylation. Immunogold and immunofluorescence studies localized the antigen to the cell surface. Antigen expression was consistent within each cell line, with > 90% of the cells positive for all cell lines except 1 (80%). Percentage of positive cells and relative intensity of immunostaining were constant throughout all phases of the cell cycle.
Conclusions
The antigen identified by MAB IBF9 is a well-conserved and highly expressed cell surface protein present during all phases of the cell cycle in all malignant canine melanoma cell lines examined.
Clinical Relevance
Because of consistency in expression, the antigen may have potential for use in dogs for melanoma immunodiagnostics and immunotherapy. (Am J Vet Res 1997;58:46–52)
SUMMARY
The ultrastructure of tachyzoites of 3 isolates of Neospora caninum from dogs was examined, using transmission electron microscopy of infected cultured cells. Ultrastructure of the 3 isolates was similar. Tachyzoites had a pellicle, 22 subpellicular microtubules, a conoid, anterior and posterior polar rings, 8 to 12 electron-dense rhoptries, numerous micronemes, a single vesicular nucleus, tubular mitochondria, Golgi complexes, ribosomes, endoplasmic reticula, an inactive micropore, electron-dense bodies, lipid bodies, and amylopectin bodies. Most tachyzoites were located adjacent to the host cell nucleus in a parasitophorous vacuole that contained numerous intravacuolar tubules. Tachyzoites divided by endodyogeny. Neospora caninum tissue cysts were not seen. Comparison of N caninum with Toxoplasma gondii tachyzoites indicated that the 2 species can be differentiated on the basis of structure and numbers of rhoptries and numbers and location of micronemes and electron-dense bodies.