text: what are the disadvantages of using live intact animals or embyro in cultivatuing viruses?   good question.  just fyi, embryo is used to cultivate virusses because the environment can be easily controlled, unlike that of an animal.  embryo really don't have any disadvantages after you've discovered the method.  animals have several however.  he're a brief listing:  - immune system response time (from infection to plasma b cell action) - immune system strength (number of plasma b cells) - immune system aggression (number of antigens created by plasma b cells) - inconsistant host cells  control is the key.  embryo cultivation allows for this.  that's why it's used.