What is the role of immunity in disease in animals?
Immunity is the internal protection of an organism from
infection with a pathogen. Therefore, immunity (which is typically
conferred by the immune system) has the role of protection against
disease in animals.
However, another aspect of immunity is innate or species-based
immunity. This is conferred by the genetics of the species and
protects the animal against pathogens that infect other species of
animals. For instance, cattle are not susceptible to PRRS virus
infection because PRRS is specific for pigs. This is not true of
all diseases, however - viruses such as rabies and foot and mouth
disease virus can infect multiple species.