الفهرس 
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Abstract
Trichinella spiralis is the main species that is incriminated in human trichinosis. Man acquires the infection through accidental ingestion of infective viable larvae in raw or improperly cooked meat. The ingested larvae pass through three sequential phases: the enteral phase, parenteral phase, and encysting phase. The disease is usually manifested with non-specific presentations that lead to late or even misdiagnosis especially, in a non-endemic area.
Diagnosis of human trichinosis is mainly based on the combination of exposure history, clinical, laboratory, and epidemiological aspects. Direct parasitological diagnosis for the detection of trichina capsules is invasive and not sensitive especially in light infection, while serology for antibody detection is of low benefit in acute trichinosis as it does not discriminate between recent and past infection. Furthermore, there is a window period of 3–4 weeks between Trichinella infection and specific antibody positivity. The detection of Trichinella CAg can avoid the previous drawbacks by providing an early diagnosis. However, the sensitivity of detecting CAg in patients with clinical trichinosis is low due to the reduced levels of
T. spiralis CAg in serum samples. The application of NPs produces highly sensitive diagnostic assays due to their small size and large surface area making them biocompatible and highly stable.
The present work assessed the use of NCSB-ELISA for the diagnosis of experimental trichinosis through the detection of T. spiralis AW-CEA in serum compared to traditional sandwich ELISA. Fifty-seven male Swiss albino mice were enrolled in the study and were categorized into three groups as follows:
GI (Infected group) (36 mice infected with T. spiralis).
GII (Cross-reactivity group) (9 mice with other parasitic infections).
GIII (Negative control) (12 normal uninfected).
The following steps were done: Polyclonal antibodies (pAbs) were prepared against
T. spiralis adult worms’ crude extract-antigen (AW-CEA) in immunized rabbits. Chitosan-nanoparticles (CSNP) were prepared and loaded on anti- T. spiralis AW- CEA IgG- Abs and HRP conjugated IgG-Ab. Reactivity and specificity of pAbs were then assessed by indirect ELISA (titration) while standardization of pAbs was done by sandwich ELISA. Experimental animals were grouped and infected. Finally, detection of T. spiralis AW-CEA in serum samples of mice was tested by traditional sandwich ELISA and CSNP-based sandwich ELISA using the prepared pAbs.
The present study found that Anti-T. spiralis AW-CEA IgG-pAbs were prepared by immunization of rabbits using three intramuscular doses of prepared AW-CEA. An increasing antibody level started one week after the 1st dose. Three days after the 2nd booster dose, immune sera gave a high titer against AW-CEA with OD equal to
1.473. Traditional sandwich ELISA could not detect AW-CEA at 6, and 8 dpi. It started to detect the AW-CEA at 10 dpi with a sensitivity of 16.67% and a specificity of 100%, then increased gradually to reach optimum sensitivity at 16 dpi and a specificity of 90.91 %. Statistical analysis showed that there was a highly significant difference (p < 0.001) in the detection of AW-CEA in serum samples by traditional sandwich ELISA in GI versus each of GII and GIII at 16 dpi. Using NCSB-ELISA, AW-CEA was detected in serum samples at 8 dpi with recorded sensitivity of 50% and a specificity of 100%. There was a highly significant difference (p < 0.001) in the detection of AW-CEA by NCSB- ELISA (p< 0.001) in GI versus each of GII and GIII at 10, 12,14 and 16 dpi.
from the obtained results, we proved that NCSB-ELISA is a promising sensitive technique for early and specific diagnosis of acute trichinosis in an animal model. Thus, it can be used as a potential alternative to the standard ELISA to obtain confident results.