PARENTERAL ADMINISTRATION OF FVRCP VACCINES
INDUCES ANTIBODIES AGAINST FELINE RENAL TISSUES.

MR Lappin, WA Jensen, R Chandrashekar, and SD Kinney. From
the Department of Clinical Sciences (Lappin), Colorado State
University, Fort Collins, CO and the Heska Corporation, Fort Collins
CO (Jensen, Chandrashekar, and Kinney).

  Chronic renal failure is a common cause of death in cats.
Lymphocytic/plasmacytic interstitial nephritis is common histopathologically,
suggesting immune-mediated reactions may play a role. Feline herpesvirus 1,
calicivirus, and panleukopenia virus for use in feline vaccines (FVRCP) are
commonly grown in Crandall-Reese Feline Kidney (CRFK) cells. As a
consequence, commercially available FVRCP vaccines contain CRFK proteins.
The objectives of this study were to determine whether cats inoculated with
FVRCP vaccines develop antibodies against CRFK cell extracts and if so, to
determine if these antibodies reacted with extracts of feline renal tissue (FRT).

  Fourteen age-matched, mixed-sex, unvaccinated kittens were divided into seven
pairs. To each pair of kittens, one of the following was administered: 10µg of
CRFK protein SQ; 50µg of CRFK protein SQ; 50µg of CRFK protein plus an
aluminum adjuvant SQ; a FVRCP vaccine for intranasal administration, or one of
three FVRCP vaccines for SQ administration. The concentration of CRFK protein
used was comparable to the range detected in the vaccines. Kittens receiving
CRFK proteins were inoculated every two to four weeks for a total of eight times
during the study period and kittens receiving vaccines were inoculated every three
weeks for three inoculations. Serum samples were collected prior to inoculation
and six months later. ELISAs to detect feline antibodies that bind to CRFK cell
extracts or FRT extracts were optimized. All sera were assayed in both ELISAs
and absorbance values calculated. An individual cat was considered positive for
antibodies against either CRFK cell extracts or FRT extracts if the mean
absorbance value of duplicate post-inoculation wells was greater than the mean
plus three standard deviations of the 14 pre-inoculation sample absorbance values.

  None of the cats was positive for antibodies against CRFK or FRT extracts prior
to inoculation. All six kittens inoculated with CRFK proteins were positive for
anti-CRFK antibodies in the post-inoculation sample; five of these six kittens were
positive for anti-FRT antibodies. Neither cat inoculated with the intranasal FVRCP
vaccine was positive for anti-CRFK or anti-FRT antibodies post-inoculation. Of
the cats inoculated with FVRCP vaccines SQ, five of six and four of six were
positive for anti-CRFK antibodies or anti-FRT antibodies in the post-inoculation
sample, respectively.

  Administration of FVRCP vaccines SQ to cats can induce antibody responses to
CRFK proteins and feline renal tissues. Further research will be needed to define
the role of these autoantibodies in the development of chronic renal failure in cats.
Systolic BP (mmHg)

EFFICACY OF GIARDIA VACCINATION FOR TREATMENT
OF GIARDIASIS IN CATS. 

John E. Stein, Michael R. Lappin.
Department of Clinical Sciences, Colorado State University, Fort
Collins, Colorado.

  Recently, Giardia vaccines for use with dogs and cats have been shown to lessen
clinical signs of giardiasis and greatly lessen cyst shedding on challenge when used
as a preventative. Treatment of giardiasis with currently available drugs may be
ineffective and some drugs have significant side-effects. Use of Giardia
vaccination as an immunotherapy led to cessation of diarrhea and cyst shedding in
seven naturally-infected dogs. This study was undertaken in order to assess the
efficacy of Giardia vaccination as a treatment of giardiasis in experimentally-infected
cats.

  Sixteen young adult, FeLV and FIV naïve, mixed sex cats were used. The cats
were shown to be microscopically negative for Giardia cysts in feces after zinc
sulfate centrifugation and a commercially available immunofluorescent antibody
assay (IFA; Meridian Diagnostics, Cincinnati, OH) three times prior to infection.
The cats were housed individually in SPF facilities to avoid cross-infection. On
day 0, an equal number of Giardia cysts of a strain initially isolated from a human
were administered to all cats via an oral-gastric tube under brief sedation. On
weeks four, six, and 10, eight randomly selected cats were administered Giardia
vaccine (Fel-O-Vax® Giardia, Fort Dodge Animal Health, Overland Park, KS)
subcutaneously. For each of 28 weeks post-infection (PI), three fecal samples per
cat were examined for Giardia cysts. By use of IFA, cyst numbers were counted
and a score from 0 to 4 assigned. Results from the vaccinated and unvaccinated
cats were compared by logistic regression.

  All cats were shedding cysts by the end of week 2. Diarrhea was rarely detected
and when occurred was mild and transient. By week 28, five of eight vaccinated
cats and seven of eight control cats maintained patent Giardia infections.
Magnitude of infection based on the number of positive samples and number of
cysts per sample decreased progressively in both groups over time. There was no
statistically significant difference between groups over time (p value = 0.3173).
Administration of three Giardia vaccinations was ineffective for elimination of
this strain of Giardia from cats. Since clinical signs were minimal in both groups
of cats, it could not be determined whether vaccination lessened clinical disease.

Whether Giardia vaccination is an effective treatment for giardiasis in naturally-infected
cats remains to be determined.

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