Enzyme-linked immunosorbent assay for detection of feline herpesvirus 1 IgG in serum, aqueous humor, and cerebrospinal fluid

Feline herpesvirus 1 (FHV) is an important cause of feline ocular and respiratory disease, but the role the virus plays in central nervous system disease of cats has not been explored. The study described here was performed to validate an indirect enzyme-linked immunosorbent assay (ELISA) to detect FHV-specific IgG antibodies for use in feline epidemiologic, ocular, and central nervous system disease studies. The indirect IgG ELISA was applied to serum, aqueous humor, and cerebrospinal fluid from cats. Serum FHV IgG ELISA results were compared with those of serum neutralization in client-owned cats and laboratory-housed cats following vaccination. Of the 100 client-owned cats tested by ELISA, 97 had detectable FHV IgG; 95 had titers >32. The FHV IgG ELISA was more sensitive than serum neutralization and could be used with aqueous humor and cerebrospinal fluid. Cats with inflammatory central nervous system or ocular diseases had significant leakage of serum proteins into aqueous humor and cerebrospinal fluid, necessitating use of cutoff values derived from serum when these fluids were assessed.