Objective: Smallpox is a severe infectious disease caused by the smallpox virus, and the death rate is as high as 30% within 15–20 days post infection.
Methods: We prepared and tested pepsin-digested F(ab’)2 fragments of serum IgGs from horses.
Results: Transmission electron microscopy showed that the purified virus conformed to the morphology of VVTT. The titer was above 1.0 × 107 PFU/mL. The purity quotient of purified antigen is more than 90% by HPLC. After purification and cutting, and the yield of the purified product F(ab')2 was about 1.3%, the purity of F(ab')2 was more than 90%, and the neutralizing antibody titer was over 1:3200. F(ab')2 fragments have a good preventive and therapeutic effect in mice at antibody dosages of 5.2 mg/mL and 2.6 mg/mL. Compared with the model group, the viral loads of the drug-treated mice were all suppressed to varying degrees, with the higher dose groups (5.2 and 2.6 mg/mL) showing a 2-3 folds reduction in viral loads.
Conclusion: The process for producing equine immunoglobulin F(ab')2 against VVTT was established. The prepared horse anti-smallpox immunoglobulin product has a good neutralizing antibody effect on VVTT. The highly purified preparation should be a potential candidate for smallpox treatment.