Background: Viral infection of SARS-Cov-2 causes severe pathogenesis due to vasculitis and Kawasaki disease-like symptoms. We have demonstrated the efficacy of a drug seed VasSF, a recombinant single-chain Fv of IgG, using vasculitis model SCG/Kj mice. However, it is a problem using the SCG/Kj mice as they have low reproductive performance due to disease symptoms. Objective: To improve the performance, we tested if the VasSF treatment could increase the pup production in SCG/ Kj mice. Methods: SCG/Kj female mice (n=7) were treated with VasSF. After the treatment, the females were caged with SCG/Kj males. Pup production of the females was compared with that of females without VasSF treatment (n=19). The effect of VasSF on the females was also assayed by the urinary protein and occult blood scores. Results: VasSF increased the number of deliveries in SCG/Kj females, but not the litter size or pregnancy rate. The increase in the number of litters was slightly related to low urinary protein score, but not to urinary occult blood score. Conclusions: VasSF treatment increased the number of pup deliveries per female in SCG/Kj mice, maybe due to the suppression of vasculitis/nephritis progression. With efficient reproduction by VasSF, further use of SCG/Kj mice can be expected in vasculitis/nephritis research.
