Development of a mouse-feline chimeric antibody against feline tumor necrosis factor-alpha

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Feline infectious peritonitis (FIP) is a fatal inflammatory disease caused by FIP virus infection. Feline tumor necrosis factor (fTNF)-alpha is closely involved in the aggravation of FIP pathology. We previously described the preparation of neutralizing mouse anti-fTNF-alpha monoclonal antibody (mAb 2–4) and clarified its role in the clinical condition of cats with FIP using in vitro systems. However, administration of mouse mAb 2–4 to cat may lead to a production of feline anti-mouse antibodies. In the present study, we prepared a mouse-feline chimeric mAb (chimeric mAb 2–4) by fusing the variable region of mouse mAb 2–4 to the constant region of feline antibody. The chimeric mAb 2–4 was confirmed to have fTNF-alpha neutralization activity. Purified mouse mAb 2–4 and chimeric mAb 2–4 were repeatedly administered to cats, and the changes in the ability to induce feline anti-mouse antibody response were investigated. In the serum of cats treated with mouse mAb 2–4, feline anti-mouse antibody production was induced, and the fTNF-alpha neutralization effect of mouse mAb 2–4 was reduced. In contrast, in cats treated with chimeric mAb 2–4, the feline anti-mouse antibody response was decreased compared to that of mouse mAb 2–4-treated cats.