Chimeric Protein Designed by Genome-Scale Immunoinformatics Enhances Serodiagnosis of Bovine Neosporosis

Abstract

Neosporosis has become a concern since it is associated with abortion in cattle. Currently, in situ diagnosis is determined through anamnesis, evaluation of the history, and perception of the clinical signs of the herd. There is no practical and noninvasive test adapted to a large number of samples, which represents a gap for the use of new approaches that provide information about infections and the risks of herds. Here, we performed a search in the Neospora caninum genome by linear B-cell epitopes using immunoinformatic tools aiming to develop a chimeric protein with high potential to bind specifically to antibodies from infected cattle samples. An enzyme-linked immunosorbent assay with the new chimeric antigen was developed and tested with sera from natural field N. caninum-infected bovines. The cross-reactivity of the new antigen was also evaluated using sera from bovines infected by other abortive pathogens, including Trypanosoma vivax, Leptospira sp., Mycobacterium bovis, and Brucella abortus, and enzootic bovine leucosis caused by bovine leukemia virus, as well as with samples of animals infected with Toxoplasma gondii. The assay using the chimeric protein showed 96.6% ± 3.4% of sensitivity in comparison to healthy animal sera. Meanwhile, in relation to false-positive results provided by cross-reactivity with others pathogens, the specificity value was 97.0% ± 2.9%. In conclusion, immunoinformatic tools provide an efficient platform to build an accurate protein to diagnose bovine neosporosis based on serum samples.

Comparative Evaluation of Four Potent Neospora caninum Diagnostic Antigens Using Immunochromatographic Assay for Detection of Specific Antibody in Cattle

“…The diagnostic potentials of NcSAG1, NcGRA7, NcGRA6, and NLA have been reported using various immunodiagnostic approaches [9,12]. Recently, an efficient serodiagnostic approach based on the ELISA from chimeric antigens has been introduced to the field of Neospora control [26]. However, in the current study we attempted to develop potent ICTs by comparing various antigens, recombinant NcSAG1, rNcGRA7, rNcGRA6, in addition to native Neospora lysate antigen.…”

“…or Leptospira spp. (26). Regarding NcGRA6, NcGRA7, and NLA-based ICTs, in addition to crossreactivity issues, further studies are required for better assessment using a higher number of control samples from different animal species and stages of N. caninum infection.…”