Development of new antibody formats for optimization of lateral flow test against Shiga toxin for its use in surveillance and foodborne outbreaks

• Grant number: 23/10094-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: March 01, 2024
• End date: February 29, 2028
• Field of knowledge: Health Sciences - Collective Health - Public Health
• Principal Investigator: Daniela Luz Hessel da Cunha
• Grantee: Bruna de Sousa Melo
• Host Institution: Instituto Butantan. Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

Among the diarrheagenic Escherichia colipathotypes, Shiga toxin-producing E. coli (STEC), and its enterohemorrhagic subgroup (EHEC), stand out for their potential to cause serious diseases, such as hemorrhagic colitis, which affects up to 90% of infected patients, and hemolytic uremic syndrome, which occurs in 5 to 15% of individuals. Such complications occur due to the production of its main virulence factor, the Shiga toxin (Stx). This toxin has two types, Stx1 and Stx2, in addition to their variants. Routine diagnosis of STEC today is still based on isolation of the bacteria from feces in MacConkey Sorbitol (SMAC) selective medium, detection of Stx from fecal filtrates by molecular methods, or by commercial kits. However, these tests have disadvantages, such as selectivity only for the serogroup O157:H7 or their high cost. Also, the occurrence of this bacteria in the cattle herd and the fact that outbreaks are endemic in Argentina, makes surveillance for these pathogens necessary. Previous work validated an immunochromatographic test with 94% and 92% sensitivity and 99% and 98% specificity for Stx1 and Stx2, respectively. However, this test used polyclonal antibodies produced in rabbits and monoclonal antibodies from hybridomas, which make it a more expensive and limited test in terms of production. This project aim to develop new formats of antibodies against Shiga toxins, such as VhH and IgY, to improve and optimize the immunochromatographic test developed, with the objective of offering it to the market for diagnosis and surveillance of STEC.