Objective—To characterize the antigen-specific
immune response to dietary proteins in cats and evaluate
whether there was a qualitative or quantitative
difference between the responses to dietary proteins
when those proteins were fed unprocessed or as part
of a canned diet.
Animals—14 healthy domestic shorthair cats.
Procedure—Cats were fed 2 dietary proteins (soy
and casein) either as unprocessed aqueous suspensions
or as part of canned diets for 21 days. Serum
IgG and IgA and salivary IgA were assayed by indirect
ELISA, and antigen-specific proliferation of mesenteric
lymph node-derived lymphocytes was determined.
Results—Robust serum IgG and IgA responses to
dietary proteins were elicited, irrespective of the form
in which they were fed. Salivary IgA responses to
unprocessed proteins were not detected. However, a
significant salivary IgA response to the protein isolated
from the canned casein diet was observed in cats
fed canned casein but not in those fed unprocessed
casein. Lymphocyte proliferation to the antigens was
slight, and there were no significant differences
Conclusions and Clinical Relevance—Results indicated
that cats develop robust serum IgG and IgA
responses to dietary proteins when fed as either
aqueous suspensions or as part of canned diets. For
certain proteins, there may be an increase and a qualitative
difference in the immunogenicity of canned
diets, compared with unprocessed proteins. Canned
diets may not be ideal for management of cats with
enteritis. (Am J Vet Res 2004;65:1427–1433)
Objective—To evaluate the effects of various concentrations of l-lysine on in vitro replication of feline herpesvirus 1 (FHV-1).
Sample—Cultures of Crandell-Rees feline kidney (CRFK) cells.
Procedures—CRFK cells were inoculated with FHV-1 and maintained in media with 20 combinations of l-arginine and l-lysine concentrations. Changes in cell viability were monitored by continuous measurement of electrical impedance of cultured cells and by observation of viral cytopathic effects. Viral load was determined by use of quantitative PCR assay in supernatants obtained from infected cultures at specified time points.
Results—Increases in l-lysine concentration had no effect on the kinetics of cell death in FHV-1-infected cultures. There was also no significant effect (r2 < 0.1) on viral DNA load for l-arginine concentrations ≥ 12 μg/mL There was a significant effect of increases in l-lysine concentration on viral DNA load in media supplemented with 6 μg of l-arginine/mL (mean ± SD slope, −4,641 ± 1,626 units; adjusted r2 = 0.45). However, the difference between the lowest (1 × 106.28 copies/μL) and highest (1 × 106.86 copies/μL) FHV-1 DNA load in these media was < 1 logarithm.
Conclusions and Clinical Relevance—The difference in FHV-1 DNA load was unlikely to be biologically important. Various l-lysine concentrations did not inhibit in vitro replication of FHV-1 at l-arginine concentrations sufficient to maintain cell growth. This conclusion was consistent with results of other studies in which investigators have not detected a consistently beneficial effect when l-lysine is administered to FHV-1-infected cats.