Santa's Little Helper their old pet. Bart eventually gives Santa's Little Helper away instead of Laddie when repo men take back everything he fraudulently purchased. Feeling guilty about this disloyalty and bored with his too perfect new dog, Bart tries to get him back. When he finally finds him, Santa's Little Helper is serving as a seeing-eye dog for a blind man, but eventually decides to return to the family. In "Stop or My Dog Will Shoot" (season 18, 2007), Santa's Little Helper becomes a local hero after finding a lost Homer, and the Simpsons decide to enroll him in the Animal Police
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