Assessing the Role of Host Immunity in Mycobacterial Infection Using a Zebrafish Model

Take anesthetized wild-type zebrafish and immunocompromised zebrafish that lack lymphocytes.

Place each fish ventral side up into a slit carved in a moist sponge to maintain viability.

Inject Mycobacterium marinum into the abdominal cavity to establish a systemic infection that models human tuberculosis.

After injection, transfer the fish into fresh tank water for recovery and monitor them.

In the wild-type fish, an inflammatory response forms a granuloma composed of bacteria, infected macrophages, and lymphocytes. The granuloma contains the bacteria, preventing their spread.

Lymphocytes secrete cytokines that reinforce the antimicrobial function of macrophages, enabling bacterial killing.

In the immunocompromised fish, the granuloma lacks lymphocytes. As a result, macrophages remain partially activated, allowing the bacteria to survive, replicate, and spread, resulting in fish mortality.

Generate a survival graph. The high mortality in immunocompromised fish highlights the role of lymphocytes in controlling infection.

First, pipette a 5 microliter droplet of the diluted bacterial solution onto a piece of paraffin film. Then, pull the droplet into a 30-gauge insulin needle.

Use a five to ei