猫カリシウイルスに対するマウス―猫キメラ抗体
の作製と安全性

梅橋操子^1，2）†　　　今村　孝^1）　　　秋山俊介^1）　　　時吉幸男^1）

（2001年8月13日受付・2002年1月28日受理）

要　　　　　約 　 　猫に対し安全で，かつ，特異性が均一で比較的容易に大量の抗体を得ることができるというモノクローナル抗体の特性を兼ね備えたウイルス治療用抗体を得るため，マウス―猫キメラ抗体（キメラ抗体）の作製を試みた．猫免疫グロブリンの定常領域遺伝子と抗猫カリシウイルス（FCV）モノクローナル抗体産生細胞から単離した可変領域遺伝子を用いて，抗FCVキメラ抗体（F1D7）産生細胞を作製した．F1D7産生細胞を培養して得られたキメラ抗体の10mg/kgまたは50mg/kgをSPF猫の皮下に6回反復投与し，安全性を検討した．対照のマウス抗体を投与した猫では，流涙や痙攣，血圧および脈拍数の低下が認められたが，キメラ抗体を投与した猫では異常は認められなかった．以上の成績より，猫に対して異種蛋白であるマウス抗体の抗体定常領域を同種の猫抗体定常領域に変換することにより，猫におけるアナフィラキシー惹起性を回避できることが確認された． ―キーワード：アナフィラキシー反応，猫，猫カリシウイルス，マウス―猫キメラ抗体，安全性． --------------------　日獣会誌　55，293〜297（2002） Development and Safety of a Mouse-Cat Chimeric Antibody against the Feline Calicivirus Misako UMEHASHI＊†, Takashi IMAMURA, Shunsuke AKIYAMA and Sachio TOKIYOSHI ＊The Chemo-Sero-Therapeutic Research Institute, Kyokushi, Kikuchi, Kumamoto Prefecture 869-1298, Japan SUMMARY   To obtain a safe antibody for the treatment of cats infected with the feline calicivirus (FCV), we tried to develop an anti-FCV mouse-cat chimeric antibody with the features of monoclonal antibodies, which are homogeneous in specificity and, once established, attainable in large quantities with relative ease. To make the mouse-cat chimeric light- and heavy-chain genes, we cloned variable region light-chain and heavy-chain (VL and VH) genes from mouse hybridoma cells producing anti-FCV neutralizing mouse monoclonal antibodies. Then the VL genes were connected with the constant region of light-chain genes and the VH genes with the constant region of heavy-chain genes of feline immunoglobulin. With chimeric light- and heavy-chain genes constructed in this way, we developed a stable, transformed cell that constantly produces anti-FCV neutralizing mouse-cat chimeric antibodies (F1D7). In order to confirm the safety of F1D7 in cats, we conducted repeated administrative experiments with specific pathogen-free cats. These cats were given 6 subcutaneous administrations of either 10 mg/kg or 50 mg/kg of F1D7 or of the anti-human IgM mouse monoclonal antibody (mouse-MoAb). The animals' body conditions, blood pressure, and heart rate were monitored. Animals to which 50 mg/kg of the mouse-MoAb was administered demonstrated such anaphylactic reactions as lachrymal cramping, lowered blood pressure, and decreased heart rate. No animals to which F1D7 was administered, however, demonstrated any abnormalities at all. These results suggest that substitution of the constant region of heterologous mouse immunoglobulin for homologous feline immunoglobulin decreases anaphylactic reactions in cats. ―Key words : anaphylactic reactions, cat, feline calicivirus, mouse-cat chimeric antibody, safety. †　Correspondence to : Misako UMEHASHI (Ginkyo College of Medical Science) 1-6-2 Okubo, Kumamoto 860-0083, Japan　　TEL 096-344-7611 FAX 096-344-7614 --------------------　　J. Jpn. Vet. Med. Assoc., 55, 293〜297 (2002)