Ok let's begin...to start, let's stick with the term panleukopenia. The term feline distemper is actually very misleading. As far as I know the actual distemper virus has never been recorded in felines. The panleukopenia virus is actually a member of the parvoviridae family of viruses and belongs to the parvovirus genus, where as the distemper virus is a member of the paramyxoviridae family of viruses and belongs to the morbillivirus genus. When people speak of distemper in felines what they are actually referring to is Panleukopenia, a parvovirus, where as when people speak of distemper in canines they are referring to a morbillivirus.
Panleukopenia is a ssDNA (single stranded DNA) virus, where as distemper is a ssRNA (single stranded RNA) virus, therefore calling panleukopenia, feline distemper is quite misleading, since the replication of these two viruses is quite different.
If you are interested in learning more about the taxonomy of viruses, you can visit the International Committee on Taxonomy of Viruses, which lists viruses based on the Baltimore Classification system. The site is actually very informative and includes very detailed information on viruses such their gene sequence, which can be listed either in full or part. Here is a link to their website...
Now in regards to the actual Panleukopenia vaccine. It does in fact come in both a killed vaccine form and an MLV (modified live virus) form. Drug manufacturing companies such as Pfizer and Merial both sell the vaccine in a MLV form.
So now I need to figure out which form of the vaccine was given to Moki. If the vaccine was in fact in an MLV form, then nucleotide substitutions could have occured during the viruses replication, which in turn could lead to a new strain of the virus being created...
Here are a few interesting facts about Panleukopenia, (i'll have to explain their importance in regards to Moki's condition in another posting...):
1. Panleukopenia does not need a cell in order to survive in a host's system.
2. Panleukopenia does however need to find a rapidly dividing cell line such as the purkjie cell line found in the cerebellum of a developing fetus, in order for the virus to undergo replication. The reason the virus needs a rapidly dividing cell line in order to undergo replication has to do with the viruses capsid size which is so small that the viruses genome can only encode a few proteins. The virus thus depends on a host's cell in order to provide the missing proteins not encoded in the viruses own capsid, proteins such as a DNA polymerase which are only available during the S phase of a cell cycle.
3. "Cerebellar degeneration and myocardities may develop in kittens and puppies respectively, from virulent parvovirus or MLV vaccine virus infection."
To be continued...