The role of GRA8 antigen-derived synthetic peptides in serotyping of toxoplasma gondii

Abstract

Toxoplasma gondii is an obligate intracellular parasite, capable of infecting humans and other warm-blooded animals. It is typically associated with the adequately named infection, toxoplasmosis.The aim of the present work was to develop serotyping by selecting different synthetic GRA8 C-terminal polymorphic peptides with 64 human serum samples (of known strain types) to determine the peptides’ ability to differentiate strain types of T. gondii (I, II, III and atypical).Serotyping is a typing method consisting of an immunoenzymatic assay (enzyme-linked immunosorbent assay [ELISA]) using synthetic polymorphic peptides derived from Toxoplasma gondii antigens.Sera samples were processed through indirect ELISA and the colour product formed measured by absorbance at 415 nm. Data obtained was processed in a Receiver Operating Characteristic (ROC) curve to determine the sensibility and specificity of each peptide.Of the four GRA8II peptides used (217, 221, 246 and 258), only GRA8II 221 proved to have some ability to differentiate strains of type II from non-type II with an 85,8% probability of doing so. However, with such poor results for the remaining three peptides (all three with a probability of successfully distinguish between different strains types under 60%), GRA8 may not be an ideal peptide to be used for serotyping.

Date of Award	22 May 2017
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	José Manuel Correia da Costa (Supervisor) & Susana Costa (Co-Supervisor)