The Seroprevalence of Functional Anti-Shigellosis Antibodies at KEMRI Wellcome Trust Research Programme (KWTRP)

The seroprevalence of functional anti-shigellosis antibodies within the Kenyan population

• Shigella is the leading cause of diarrhoea in children under 5 years. It causes a high burden of disease in low-and-middle-income countries (LMICs), where 70% of all cases occur [1]. Different Shigella species cause shigellosis; however, S. flexneri (serotypes 1b, 2a, 3a and 6) and S. sonnei are most prevalent in LMICs
• Natural exposure to Shigella induces serum serotype-specific antibody responses, which are associated with protection from repeated exposure. Serum IgG antibodies to different antigens, particularly the O-antigen on the lipopolysaccharide (LPS), are considered good markers of protection
• Antibodies may prevent shigella within the host by binding to and blocking bacterial growth. However, antibodies are able to function through an array of other fc-mediated functions that recruit immune cells and complement, affecting anti-shigellosis activity
• These fc-dependent functions are known to correlate with protection from disease within controlled human infection studies
• However, the seroprevalence and specific targets of functional anti-shigella antibodies within the Kenyan population are unknown
• We will use an age-stratified sample set to profile Shigella-specific serum bactericidal antibody (SBA), opsonophagocytic killing antibody (OPKA) activity, antibodependent respiratory burst and complement fixation. In addition, antigen-specific Fc-dependent antibody levels to LPS and virulence proteins IpaB, IpaC, IpaD, IpaH, and VirG will be assessed.