Sensitivity and specificity of recombinant proteins in Toxocara spp. for serodiagnosis in humans: Differences in adult and child populations

Abstract

Toxocariasis is a neglected zoonosis that affects children and adults. Recombinant proteins have been widely investigated for diagnosis, achieving high sensitivity and specificity in an overall population; however, little is known about age as a factor in its application. This study aims to investigate the diagnostic potential of Toxocara canis TES-30 and TES-120 recombinant proteins in humans, differentiating between its performance in children and adults. Serum samples collected from children and adults seropositive to Toxocara spp. were tested with indirect ELISA using T. canis TES-30 and TES-120 recombinant proteins produced in Escherichia coli. While rTES-30 sensitivity was not affected by age (81.8% in children and 87% in adults), rTES-120 sensitivity severely decreased in children to only 63.6%, down from 95.7% in adults. Furthermore, the sensitivity of rTES-30 increased to 97.8% after Western blotting confirmation. High specificity (>94%) against other geohelminths was reported for both recombinant proteins. Our study favors the use of rTES-30 with total IgG as the primary antibody in an indirect ELISA assay as a tool for epidemiological human studies.

Evaluation of Toxocara canis Glycosylated TES Produced in Pichia pastoris for Immunodiagnosis of Human Toxocariasis

“…To verify the sensitivity and specificity of recombinant antigens produced by P. pastoris, we used the same tools recommended for the diagnosis of T. canis (ELISA and Western Blotting) [2]. While specificity was close to 100% against seropositive samples from Table 2 parasites, the sensitivity of the recombinant proteins (56%~69%) was not as high as proteins produced in E. coli (80~93%), as reported by Mohamad and coauthors [3] and our previous results (75.6-84.4%) [11]. It is important to emphasize that the same ELISA protocol and serum panel was used for both the E. coli and P. pastoris proteins.…”

“…In the other hand, recombinant TES proteins in E. coli have been assayed previously by our group and we showed a high specificity (92.5-95%) and sensitivity (75.6-84.4%) [11], however E. coli expression presented a cytoplasmic protein expression that was insoluble, while P. pastoris have the advantage of secreting the target protein to cell exterior, being soluble [3,6,12,13]. As E. coli insoluble protein could have sensitivity issues due to denaturing requirements to solubilize it; expressing in yeast could be a valid alternative to avoid protein refolding.…”

“…In Figure 2, we show the bands of rTES-30 and rTES-120, as well as their deglycosylated product being recognized by a patient's antibody. As a positive control, we used a previously-studied rTES-120 produced in E. coli [11]. In Table 2, we verified the specificity of the proteins against other parasites.…”

“…It is important to emphasis that both P. pastoris products are the same to a previously published study with E. coli, changing only the expression system, primers details of each product are available on Santos and coauthors study [11].…”

The State of the Humoral Link of Immunity in Children with Toxocariasis

“…Токсокароз людини широко поширений і зазвичай не має чітко вираженої симптоматики. Майже 14% населення Сполучених Штатів Америки вражені токсокарозом [6]. У жителів сільської місцевості, у тропічних та слаборозвинених країнах даний показник значно зростає, інколи до 90% [7].…”