Infection with the bacterium Campylobacter jejuni is a leading cause of severe bacterial gastroenteritis. C. jejuni produces an outer membrane adhesion protein known as CadF, which allows the bacteria to attach to epithelial cells lining the ileum. This attachment triggers cellular damage, resulting in the effacement (destruction) of microvilli on these epithelial cells.
Explain why the loss of microvilli reduces the absorption of digested nutrients, and why this leads to a reduction in water absorption, causing watery diarrhoea.
Not all infants infected with C. jejuni exhibit severe symptoms. Researchers monitored the concentration of anti-CadF antibodies in three cohorts of infants:
The table below shows the mean concentration of anti-CadF antibodies (in arbitrary units) at different points during their clinical monitoring:
| Cohort | Day 0 (Admission) | Day 3 | Day 6 | Discharge |
|---|---|---|---|---|
| Cohort X (Infected, mild symptoms) | 2.10 | 3.40 | 4.10 | 3.80 |
| Cohort Y (Infected, severe diarrhoea) | 0.80 | 0.60 | 0.75 | 0.90 |
| Cohort Z (Healthy controls) | 1.10 | 1.15 | 1.10 | 1.10 |
Scientists propose administering monoclonal anti-CadF antibodies as a form of passive immunity treatment.
Using the table, suggest how this passive immunity treatment would prevent severe clinical symptoms and state, with a reason, which cohort of infants should be targeted for this antibody treatment.
To be effective, this monoclonal antibody treatment must be injected. If the anti-CadF antibody were administered orally, it would be digested and rendered inactive.
Describe the biological processes by which this antibody would be chemically digested.
