Experimental bovine trypanosomiasis. Changes in serum immunoglobulins, complement and complement components in...

Area of Science:

• Veterinary Immunology
• Parasitology
• Immunochemistry

Background:

• Trypanosoma congolense is a significant pathogen causing economic losses in livestock.
• Understanding the host immune response, particularly immunoglobulin and complement system alterations, is crucial for managing trypanosomiasis.

Purpose of the Study:

• To investigate the changes in immunoglobulin (IgG1, IgG2, IgM, IgA, IgE) and complement component levels in calves experimentally infected with T. congolense.
• To explore the relationship between parasite burden and the observed immunological changes.

Main Methods:

• Experimental infection of three calves with T. congolense.
• Quantification of serum IgG1, IgG2, IgM, IgA, and IgE levels.
• Measurement of total haemolytic complement and specific complement components (C1, C1q, C3, C8) and properdin.
• Correlation of immunological parameters with parasite counts.

Main Results:

• Serum IgG1 and IgG2 levels remained largely unchanged compared to normal animals.
• A significant increase in IgM was observed, correlating with parasite burden.
• Serum IgA and IgE levels were markedly decreased, also related to parasite load.
• Total haemolytic complement, C1, C1q, and C3 levels decreased.
• Properdin levels fluctuated with cyclical parasitemia.
• No significant change in C8 levels was detected.

Conclusions:

• T. congolense infection in calves induces specific alterations in immunoglobulin profiles, notably increased IgM and decreased IgA/IgE.
• Both classical and alternative complement pathways are activated during infection, but their terminal stages are not reached.
• These immune dysregulations likely contribute to the pathogenesis of bovine trypanosomiasis.