Molecular cloning of ribosomal P protein in Toxoplasma gondii and the availability to detect antibody against recombinant protein in toxoplasmosis patients

Abstract

Among the panel of monoclonal antibodies (mAb) against Toxoplasma gondii , mAb of Tg621 (Tg621)clone blotted 38 kDa protein which localized in the cytoplasm of tachyzoites by immunofluorescence microscopy. Theprotein was not released into the parasitophorous vacuole during or after invasion. The cDNA fragment encoding theprotein was obtained by screening a T. gondiicDNA expression library with Tg621. The full length cDNA sequencewas completed with 5RACE as 1,592 bp, which contained open reading frame of 942 bp. The deduced amino acidsequence of Tg621 consisted of a polypeptide of 313 amino acids, with significant homology to ribosomal P proteins(RPP) of other organisms especially high to those of apicomplexan species. The expressed and purified TgRPP wasassayed in western blot with the sera of toxoplasmosis patients and normal sera, which resulted in the 74.0% ofpositive reactions in toxoplasmosis patients whereas 8.3% in normal group. Therefore, the antibody formation againstTgRPP in toxoplasmosis patients was regarded as specific for T. gondii infection and suggested a potential autoantibody.