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M9640704.TXT
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1996-03-04
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Document 0704
DOCN M9640704
TI Pathogenicity of Theileria parva is influenced by the host cell type
infected by the parasite.
DT 9604
AU Morrison WI; MacHugh ND; Lalor PA; Institute for Animal Health, Compton,
United Kingdom.
SO Infect Immun. 1996 Feb;64(2):557-62. Unique Identifier : AIDSLINE
MED/96145079
AB Theileria parva has been shown to infect and transform B cells and T
cells at similar frequencies in vitro. However, the majority of
parasitized cells in the tissues of infected cattle are alpha/beta T
cells. The aim of this study was to determine whether the cell type
infected with T. parva influenced the pathogenicity of the parasite. The
initial approach, which involved inoculation of cattle with autologous
cloned cell lines of different phenotypes, failed to resolve the issue,
because of prolonged period of culture required to clone and
characterize the cell lines resulted in attenuation of the cells. As an
alternative approach, cattle were inoculated with purified populations
of autologous cells that had been incubated in vitro with T. parva
sporozoites for 48 h. As few as 3 x 10(4) peripheral blood mononuclear
cells (PBMC) treated in this way were found to produce severe clinical
reactions with high levels of parasitosis. Infections of similar
severity were produced with purified populations of CD2+, CD4+, and CD8+
T cells. By contrast, infected B cells gave rise to mild self-limiting
infections even when administered at a 10-fold-higher dose. In animals
that received infected CD4+ or CD8+ T cells, the parasitized cells in
the lymph nodes on day 11 of infection were all within the CD4+ and CD8+
populations, respectively, indicating that there had been minimal
transfer of the parasite between cell types. Phenotypic analyses of
cultures of PBMC infected in vitro with saturating concentrations of
sporozoites revealed that parasitized B cells were abundant in the
cultures after 1 week but were subsequently overgrown by T cells. The
results of these experiments indicate that the cell type infected by T.
parva influences the pathogenicity of the parasite.
DE Animal B-Lymphocytes/PARASITOLOGY Cattle Cell Line CD4-Positive
T-Lymphocytes/PARASITOLOGY CD8-Positive T-Lymphocytes/PARASITOLOGY
Lymphocytes/*PARASITOLOGY Male Theileria parva/*PATHOGENICITY
Theileriasis/*IMMUNOLOGY JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).