FELINE LEUKEMIA-VIRUS DETECTION BY ELISA AND PCR IN PERIPHERAL-BLOOD FROM 68 CATS WITH HIGH, MODERATE, OR LOW SUSPICION OF HAVING FELV-RELATED DISEASE

Clinicopathologic criteria were used to group 68 cats according to hig h, moderate, or low suspicion of having feline leukemia virus (FeLV)-r elated disease. Peripheral blood samples were tested for FeLV antigen by enzyme-linked immunosorbent assay (ELISA) and for FeLV DNA by polym erase chain reaction (PCR). There was no significant difference betwee n ELISA and PCR results in the 68 cats. In the high-suspicion group, 4 6% (11/24) of cytopenic cats were test positive (ELISA and PCR) and 87 % (13/15) with hemopoietic neoplasms were test-positive. Also within t he high suspicion group, test-positive cats were 2.5 times more likely to die within the 1 year follow-up period than were test-negative (EL ISA and PCR) cats. Among cats in the moderate-suspicion group, 15% (2/ 13) were test-positive, and none (0/16) of the cats in the low suspici on group was test positive. The relative risk of a positive test (ELIS A and PCR) in the high suspicion group was 3.7 times that for the mode rate-suspicion group and 22.8 times that for the low suspicion group. There was no significant difference in the relative risk of a positive test result between the moderate and low suspicion groups. The result s indicate that FeLV detection by PCR can be adapted for diagnostic pu rposes using peripheral blood samples, however, results do not differ significantly from FeLV ELISA results. Also, a proportion of cats with a high suspicion of having FeLV-related cytopenia and hemopoietic tum ors are negative for both circulating FeLV antigen and DNA. These cats may not have FeLV-related disease, or FeLV may exist in a disease-pro ducing but nonreplicating form ultimately detectable by PCR in tissues other than peripheral blood.