Evaluation of recombinant antigens in combination and single formula for diagnosis of feline toxoplasmosis

Abstract

Cats are the only definitive hosts of Toxoplasma gondii and constitute an essential source of infection to all warm blooded animals and humans. Diagnosis of T. gondii infection in cats is fundamental for proper management and control of infection in humans and animals. In the current study, we have evaluated the diagnostic performance of tachyzoite lysate antigen (TLA) and different T. gondii recombinant antigens including surface antigen 2 (SAG2), dense granule proteins 2, 6, 7, 15 (GRA2, GRA6, GRA7, GRA15) and microneme 10 protein (MIC10) in immunoglobulin G enzyme linked-immunosorbent assay (IgG ELISA) using cat serum samples, with reference to latex agglutination test (LAT). Remarkably, TLA showed better performance than other recombinant antigens in IgG ELISAs as compared to LAT, with concordance and Kappa values of 94.27% and 0.93, respectively. Furthermore, to improve the reactivity of the recombinant antigens, we have developed IgG ELISAs using different combinations with these recombinant antigens. Strikingly, a combination of SAG2 and GRAs has relatively similar performance as TLA evidenced by concordance and Kappa values of 94.27% and 0.81, respectively. The developed ELISA with a combination of recombinant antigens can be used as a promising diagnostic tool for routine testing of T. gondii infection and mass screening in cats. The major advantages of this assay are the high sensitivity and specificity, lower cost, safer production and easiness of standardization in various laboratories worldwide.

Serological and molecular rapid diagnostic tests for Toxoplasma infection in humans and animals

“…In the past two decades, several Toxoplasma recombinant antigens have been cloned and expressed in E. coli or yeast for use as diagnostic reagents for human and animal infections. They include antigens from the parasite surface (SAGs), matrix (MAGs), dense granule (GRAs), rhoptry (ROPs), and microneme (MICs) [43][44][45][46][47][48][49][50]. Four of the recombinant antigens (SAG1, SAG2, GRA3, and GRA6) expressed in E. coli have been used in an RDT to detect infection in cats.…”

Descriptive Comparison of ELISAs for the Detection of Toxoplasma gondii Antibodies in Animals: A Systematic Review

“…Out of 57 studies describing the evaluation of diagnostic performance of different ELISAs for the detection of T. gondii antibodies, the majority originated from Europe ( n = 21), followed by Asia ( n = 16), South America ( n = 9), North America ( n = 6), Africa ( n = 3) and Australia ( n = 2) ( Figure 2 ). Out of the 20 animal species covered, most of the studies (91%) focused on domesticated animals [ 33 , 37 , 46 , 47 , 48 , 49 , 50 ], but 7% were on zoo and wild animals [ 28 , 44 , 51 , 52 ], and one study targeted both domestic and wild animals [ 43 ]. Serum was the most widely used (89% of studies) sample for the detection of T. gondii -specific antibodies in animals, followed by meat juice/tissue fluid (7%) [ 37 , 45 , 53 , 54 ] and milk (4%) [ 55 , 56 ].…”

Development and evaluation of recombinant GRA8 protein for the serodiagnosis of Toxoplasma gondii infection in goats

“…Numerous GRA proteins, both single and combinations of proteins, have been applied for the serodetection of animal toxoplasmosis. In cats, a single GRA7 recombinant protein [27] and a mixture of recombinant GRA2, GRA6, GRA7, and GRA15 [28] were used to determine the prevalence of T. gondii infection in China and Japan, respectively. Moreover, recombinant GRA7 protein-based ELISA has been used in seroprevalence studies of farm animals in Egypt [29] and Thailand [30].…”