Santa's Little Helper Academy. However, his new crime-fighting job makes him jaded and one day at home he bites Bart. The Simpsons must therefore send the dog away to live with officer Lou. However, he gets to return after saving Bart from a toxic smoke cloud at school and then leaving the police force. In "How Munched is That Birdie in the Window?" (season 22, 2010), after Santa's Little Helper devours a pigeon with a broken leg that Bart was nursing, Bart gets mad at the dog and is unable to forgive him. The Simpsons therefore give him away to an ostrich farm.
Helper dependent virus and capsid encoding DNA, plus helper DNA. Every cell that is successfully transfected with all three DNA fragments will produce the necessary proteins to produce infective viruses. These viruses will only have transgenic DNA encapsidated and therefore once they've infected a patient's cell, they will not be capable of reproducing. Helper dependent viruses can also occur in nature without being "gutted". The term satellite virus has been given to a large group of viruses that all require the presence of another virus to replicate. Many of these are plant viruses, but animal viruses can be seen in the case of