Infection with Enteropathogenic Escherichia coli (EPEC) can cause severe watery diarrhoea. EPEC bacteria produce proteins, such as intimin, which allow them to bind to epithelial cells lining the small intestine (ileum). This binding causes "attaching and effacing" lesions that lead to the loss of microvilli on these epithelial cells.
Explain why the loss of microvilli reduces the absorption of the products of digestion and why this reduces the absorption of water, resulting in diarrhoea.
Not all patients infected with EPEC develop severe diarrhoea. Scientists measured the concentration of anti-intimin antibodies in three groups of hospitalised infants:
The table below shows the mean anti-intimin antibody concentrations (in arbitrary units) at different stages of the hospital stay:
| Group | Day 0 (Admission) | Day 3 | Day 6 | Discharge |
|---|---|---|---|---|
| Group A (Infected, no severe diarrhoea) | 1.50 | 2.20 | 2.60 | 2.40 |
| Group B (Infected, with severe diarrhoea) | 0.90 | 0.70 | 0.85 | 0.95 |
| Group C (Uninfected controls) | 1.00 | 1.05 | 1.00 | 1.00 |
Scientists suggest that monoclonal anti-intimin antibodies could be administered to some infants as a form of passive immunity.
Use the table to suggest how this passive immunity would work and which infants should be offered this antibody treatment.
To be used as a passive immunity treatment, the anti-intimin antibody must be injected. If it were administered by mouth, it would be digested.
Describe how the antibody would be digested.
