Establishment of an Experimental Procedure for Preparing Trial Serum Samples for the Specific Serodiagnosis of Toxocara Canis for External Quality Assessment Schemes
Vu Quang Huy1, 2, 3, *, Tran Diep Tuan1, Tran Phu Manh Sieu1, 4, Le Van Chuong1, 2, Huynh Thi Diem Phuc3, Bui Quang Sang3, Nguyen Nhat Giang5
External quality assessment (EQA) provides evidence of reliable, accurate and precise results for customers using the diagnostic test for Toxocara canis.
To establish a procedure for producing standard Toxocara canis serum samples for serodiagnostic testing in EQA.
The collected serum samples thought to contain anti-Toxocara canis antibodies were screened by ELISA and confirmed by Western blotting. These samples were found to be negative for other helminth antibodies, anti-HIV-1 and -2 antibodies, anti-HCV antibodies, and antibodies to HBs antigen. The sera were divided, processed by both freeze-drying and freezing methods, and then stored. The stability and homogeneity of the samples were evaluated after 7 days, 1 month, 3 months and 6 months, respectively. An F-test and a T-test were applied to evaluate their homogeneity and stability.
Among the eleven samples confirmed positive by ELISA, ten of them were confirmed through Western blotting by positive reaction with 5 specific Toxocara canis bands. Two lots of trial standard sera containing specific anti-Toxocara canis antibodies were successfully produced. Lot DK had a concentration of 31.012 ± 1.14 NovaTec Units (NTU), and Lot DL had a concentration of 27.184 ± 0.994 NTU. After storage at -80°C, the samples prepared by the freeze-drying method were stable for at least 3 months, and the samples prepared by the freezing method were stable for 6 months (p>0.05). Samples produced by both methods were stable for 7 days at 30°C (p>0.05).
Specific serodiagnosis samples of anti-Toxocara canis antibodies for EQA could be produced that possessed homogeneity and stability lasting for 3 months and 6 months by the freeze-drying and freezing methods, respectively. At 30°C, the samples produced by both methods were stable for 7 days, suitable for delivery to remote laboratories.
* Address correspondence to this author at the Vu Quang Huy, HCMC University of Medicine and Pharmacy, 131 Nguyen Chi Thanh Street, District 5, Ho Chi Minh City, Vietnam; Tel: (+84) 913586389; Email: firstname.lastname@example.org.