Hello Everyone,
I've been discussing resistance ratios of healthy adult cats to Felv
with the vet that monitors my IBD list. She just sent this to me this
morning and knew you guys would be interested.
Nina
Lisa...this is a question that comes up quite frequently.
The natural resistance to FeLV infection in cats older than 4 to 6 months
is very well established among feline retrovirologist. While
susceptibility to FIV remains constant throughout life, that simply is not
the case with FeLV. While it is NOT impossible to infect an adult cat,
the inoculate of FeLV has to be really significant (or repeated) in order
to infect.
This has been shown in virtually all FeLV vaccine Challenge studies
involving adult cats. It is MOST difficult to assess efficacy of an FeLV
vaccine when using adults as controls...because they just don't get
infected. Schering Plough has turned this into a "3-year guarantee" for
their FeLV vaccine (a VERY reactive adjuvanted vaccine). This is a
'no-brainer'...obviously! Fact is, ALL FeLV vaccines look good in the
long run because of this natural resistance.
This phenomenon is apparently related to T-cell maturity in the individual
cat and the interaction of those lymphocytes with specific epitopes of
FeLV.
The updated Feline Vaccination Guidelines are being written now. This
material will be included to more clearly point out this phenomenon.
I do have a copy of the original paper...it goes back a number of years
now and was published in a virology journal...Richard Olsen (who developed
the first FeLV vaccine for Norden Laboratories) and Jennifer Royjko (sp?)
published the manuscript. I don't have that paper with me...but will try
to dig this out and send the ref if you're really interested in getting
into that.
RBFord
