Human hepatitis viruses are still being discovered and there is much to be understood about the ones that are already known. In comparison, little time and money has been spent on non-human viruses. To Think That Xenotransplants Are Safe. First of all, zoonotic transmission of farm animal viruses to humans IS known. Pigs are reservoirs and are the most important amplifying animal for Japanese B virus.
Swine are susceptible to swine influenza virus.
A hybrid of swine influenza virus and that of birds is thought to have been the cause of the deadly 1918 human influenza pandemic. No human BLV infection has ever been found. Paradoxically, BLV virus grows very well on certain human cell cultures in the laboratory. Contact between farmers and their cattle is certainly close enough to have given at least one opportunity for natural infection. The supply of human organs for transplantation is insufficient to meet the demand.