Delayed seroconversion following naturally acquired caprine arthritis-encephalitis virus infection in goats

One hundred eight milking goats from a dairy that had been using a modified caprine arthritis-encephalitis virus (CAEV) eradication program were tested for CAEV antibodies by serologic methods and for proviral CAEV DNA by use of polymerase chain reaction (PCR) technology. All goats were free of clinical symptoms of CAEV infection. Twenty-seven of the 108 goats were considered seropositive, on the basis of ELISA results. Proviral CAEV DNA was detected, using PCR techniques, in mononuclear leukocytes in blood samples obtained from 25 of the these 27 seropositive goats. Twenty of the 81 seronegative goats also had positive PCR test results. Ten of these goats seroconverted by 8 months later, and virus was readily isolated from mononuclear leukocytes in venous blood samples after the goats had seroconverted. Virus was also isolated from mononuclear leukocytes in blood samples collected from 4 of 11 goats that were seronegative, but had positive PCR test results. These results indicated that seroconversion can be delayed for many months following natural infection with CAEV. Delayed seroconversion appears to be a feature of CAEV infection, which may have direct implications for CAEV eradication programs and epidemiologic studies that rely on serologic methods to detect infected goats.