Complement expression in common carp (Cyprinus carpio L.) during infection with Ichthyophthirius multifiliis

Area of Science:

• Immunology
• Aquatic Animal Health
• Molecular Biology

Background:

• Ichthyophthirius multifiliis (white spot disease) is a major ectoparasite affecting carp health.
• The complement system plays a crucial role in innate immunity against parasitic infections.
• Understanding the complement response in carp is vital for disease management.

Purpose of the Study:

• To develop a real-time PCR assay for analyzing the complement response in carp infected with I. multifiliis.
• To investigate the expression patterns of key complement genes across different tissues and time points post-infection.

Main Methods:

• Designed specific primers for carp complement genes (C1r/s, C3, C4, C5, factor I, Bf/C2-A, MBL, MASP).
• Analyzed gene expression using real-time PCR on RNA from carp skin, liver, and blood.
• Samples were collected at 3, 12, 24, 36, and 48 hours post-infection (pi).

Main Results:

• Significant up-regulation of factor B/C2-A (Bf/C2-A) in skin, blood, and liver at later time points (24-48 h pi).
• Intermediate down-regulation of MBL-associated serine protease (MASP) in skin and liver.
• Complement factor C3 showed significant up-regulation in the liver at 24 h pi.

Conclusions:

• Carp complement gene expression is significantly stimulated by I. multifiliis infection.
• Early and dramatic up-regulation of Bf/C2-A suggests its role as an acute-phase reactant in carp skin.
• Fish skin is an important extra-hepatic site for complement molecule expression and regulation; leukocytes also contribute.