Nano-gold based ELISA versus traditional ELISA for early detection of Trichinella spiralis crude excretory antigen in experimentally infected mice

Document Type : Original Article

Authors

Medical Parasitology Department, Faculty of Medicine, Menoufia University, Menoufia, Egypt

Abstract

Background: The main disadvantage of ELISA in diagnosis of trichinosis is the false-negative result
especially during early infections. Nanoparticle-based immunoassays were developed for serodiagnosis
of several parasitic diseases.
Objective: Comparison of nano-gold based ELISA (NGB-ELISA) to the traditional sandwich ELISA for
the early detection of T. spiralis crude excretory antigen (CEA) in serum and fecal samples of T. spiralisexperimentally
infected mice.
Material and Methods: In the present study, 180 mice were distributed in three groups. In GI (T. spiralisinfected
group) 108 mice were infected. Infection was confirmed by the presence of encysted T. spiralis
larvae in excised muscle specimens on the 28th day post-infection (dpi). For microscopic examination by
direct smear and MIFC methods and detection of T. spiralis CEA, stool samples were collected on the 2nd,
4th, 6th, 8th, and 10th dpi; then mice were sacrificed, and blood samples were collected on the 2nd, 4th, 6th, 8th,
10th, 12th, 14th, 21st, and 28th dpi. The study included two control groups; GII (specificity group) included 18
mice infected with Cryptosporidium spp., T. gondii, and S. mansoni (6 mice each) for testing cross-reactivity.
Stool and serum samples were collected on the day of sacrifice (30th dpi for Cryptosporidium, 60th dpi for
T. gondii and S. mansoni). The GIII (sensitivity control group) included 54 non-infected mice. Mice were
subjected to stool and blood samples collection, and sacrification as described in T. spiralis-infected group.
Results: While microscopic examination of direct smear proved negative for detection of T. spiralis
diagnostic stages, MIFC technique showed diagnostic larvae and adult worms in only 5% of mice sacrificed
on the 6th dpi. For T. spiralis CEA detection, the difference between NGB-ELISA and traditional ELISA was
not significant in fecal samples. In contrast, NGB-ELISA showed significantly higher number of positive
serum samples than traditional ELISA, detecting the infection earlier (2nd versus 10th dpi) with a diagnostic
accuracy of 92.78% compared to 67.78%.
Conclusion: The NGB-ELISA for detection of T. spiralis CEA in serum samples was superior to the
traditional ELISA as it revealed a significantly higher number of positive cases. It verified the infection
earlier and was more sensitive until the 14th dpi with a specificity of 100%. Regarding coproantigens, no
significant differences were noticed between either ELISAs.

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