Comparative analysis of rapid agglutination latex test using single-chain antibody fragments (scFv) versus the gold standard Vero cell assay for Shiga toxin (Stx) detection

Author(s)

Shiga, E. A. ^[1] ; Guth, B. E. C. ^[2] ; Piazza, R. M. F. ^[1] ; Luz, D. ^{[1, 3]}

Affiliation

^[1] Inst Butantan, Lab Bacteriol, Av Vital Brazil 1500, BR-05503900 Sao Paulo, SP - Brazil

^[2] Univ Fed Sao Paulo, Dept Microbiol Imunol & Parasitol, Lab Microbiol, Sao Paulo - Brazil

^[3] Univ Fed Sao Paulo, Inst Ciencia & Tecnol, Lab Monoclonais, Rua Talim 330, Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: Journal of Microbiological Methods; v. 175, AUG 2020.
• Web of Science Citations: 0

Abstract

The latex agglutination test using single-chain antibody fragments (scFvStx1 and scFvStx2) coupled to latex particles, was compared with the gold standard Vero cell assay for Shiga toxin (Stx) detection, aiming to estimate the diagnosis potential of these scFv fragments in a rapid and straightforward test. The latex complexes identified the presence of the toxins up to a 1:8 dilution in the majority of the evaluated strains. Moreover, the Stx concentration was indirectly determined in Stx-producing Escherichia coli (STEC) strains, allowing detection limit inference. A Stx dilution curve was constructed, and the data was analyzed in a non-linear model by secondorder polynomial regression for prediction (p-value of 0.001 and a R-2 above 0.98 were considered for correlations). The detection limit was 30 ng/mL for Stx1 and 10 ng/mL for Stx2. The scFvStx1 and scFvStx2 coupled to latex nanoparticles provide a toxin assay with a competitive Stx detection limit, which has a low cost and short execution time. The diagnostic method proposed here, using, for the first time, recombinant antibody fragments, raises the possibility of developing a more affordable test to be used in the routine detection and surveillance of STEC infections. (AU)

• FAPESP's process: 15/17178-2 - OPTIMIZATION AND CHARACTERIZATION OF RECOMBINANT ANTIBODIES AND THEIR APPLICATION FOR DIAGNOSIS AND THERAPY OF SHIGA, HEAT-LABILE AND HEAT-STABLE ENTEROTOXINS
• Grantee: Roxane Maria Fontes Piazza
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/17006-2 - Shiga toxin-producing Escherichia coli (STEC) intoxication and colonization in Zebrafish model: An in vivo alternative for pathogenicity studies and therapeutic antibodies validation
• Grantee: Daniela Luz Hessel da Cunha
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/03160-9 - New strategies for recombinant antibodies generation against Stx1 and Stx2 toxins produced by Shiga toxin-producing E. coli
• Grantee: Daniela Luz Hessel da Cunha
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate