Toxoplasma gondii infects all warm-blooded animals including humans, causing serious public health problems and great economic loss in the animal husbandry. Commonly used serological tests for diagnosis of
toxoplasmosis involve preparation of whole Toxoplasma lysate
antigen (TLA) from tachyzoites. The production of this
antigen is associated with high costs and lengthy preparation and the possibility of staff
infection. There are also some difficulties in the standardization of such tests. One approach in order to improve the diagnosis of T. gondii
infection is to use recombinant chimeric
antigens in place of the TLA, which was confirmed by studies in the serodiagnosis of
toxoplasmosis in humans. In this paper, we assess, for the first time, the diagnostic utility of five T. gondii recombinant chimeric
antigens (MIC1-MAG1-SAG1S, SAG1L-MIC1-MAG1, SAG2-GRA1-ROP1S, SAG2-GRA1-ROP1L, and GRA1-GRA2-GRA6) in
immunoglobulin G (
IgG)
enzyme-linked
immunosorbent assays (
IgG ELISAs) with sera from three different groups of livestock animals (horses, pigs, and sheep). The reactivity of individual chimeric
antigens was analyzed in relation to the results obtained in
IgG ELISAs based on a mixture of three
antigens (M1: rSAG1+rMIC1+rMAG1, M2: rSAG2+rGRA1+rROP1, and M3: rGRA1+rGRA2+rGRA6) and referenced to TLA. All chimeric
antigens were characterized by high specificity (100%), and the sensitivity of the
IgG ELISAs based on chimeric
antigens was variable (between 28.4% and 100%) and mainly dependent on the animal species. The chimeric
antigens were generally more reactive than mixtures of three
antigens. The most effective for the diagnosis of
toxoplasmosis was SAG2-GRA1-ROP1L, which can detect specific
anti-T. gondii
antibodies in 100%, 93.8%, and 100% of positive serum samples from horses, pigs, and sheep, respectively. The present study shows that recombinant chimeric
antigens can be successfully used to diagnose T. gondii
infection in farm animals, and can replace the commonly used TLA.