Santa's Little Helper backyard. In "Bart's Dog Gets an F" (season two, 1991), he manages to infuriate the entire family by destroying valued items in the home. As a result, Homer and Marge want to get rid of the dog, but Bart and Lisa convince them that he can be trained at an obedience school. Santa's Little Helper does not do well there as Bart is unwilling to use a choke chain suggested by the instructor. The night before the final exam, Bart and Santa's Little Helper play, thinking it will be their last few hours together. This bonding breaks down the communication
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