       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).

