Isolation, Cultivation and Characterization of a Poxvirus from some Horses in Kenya

Abstract

Two strains of pox virus isolated from naturally infected horses were adapted to the chorioallantoic membrane (CAM) of developing chick embryos and to tissue cultures of chicken fibroblasts and bovine calf kidney, bovine calf testis and bovine foetal skin.

Isolation of the virus was achieved in calf kidney monolayers. After that, it was adapted to grow in the other tissue cultures and the CAM. The virus acquired a haemagglutinating property after adaptation onto CAM and also became pathogenic for baby mice by the intraperitoneal route. Calves became infected by intradermal inoculation and chicks by the intrafollicular route.

The virus is sensitive to chloroform but resistant to ether. Both isolates show weak antigenic properties. Immune serum prepared against vaccinia and cowpox viruses respectively, neutralized the horse virus. The antisera also inhibited haemagglutination when this property was acquired by the virus after CAM adaptation. Precipitation lines were formed between vaccinia immune serum and the horse antigen.

These results suggest an immunological relationship between the horse virus and vaccinia and cowpox viruses.

The disease condition is discussed in comparison with horse pox and viral papular dermatitis.