Although veterinary CNPV recombinant vaccines exist, recent attention has focussed on its use in human medicine with several human vaccines using this expression system undergoing clinical trials. The vaccines typically use the CNPV ALVAC strain, which is highly attenuated. The use of this strain has been involved in the expression of several key pathogen and tumour associated antigens. These include (but are not limited to) those found in rabies virus, hepatitis B and hepatitis C, leukaemia virus, HIV and cancers; such as melanoma and colorectal cancers.