A LONG-TERM STUDY OF GOATS NATURALLY INFECTED WITH CAPRINE ARTHRITIS-ENCEPHALITIS VIRUS

The caprine arthritis-encephalitis virus (CAEV) is a big problem in da iry goat industry. Little is known about its characteristics in natura lly infected goat herds. The aims of this study were: 1) to study how antibody expression, measured by agar gel immunodiffusion test (AGIDT) , varied over time in naturally infected seropositive goats, 2) to obs erve clinical signs in seropositive adult goats and 3) to follow seroc onversion and gamma globulin concentration in goat kids artificially r eared on cow milk replacement product only, compared to kids reared on untreated goat milk. The antibody expression pattern to the viral pro teins gp135 and p28 varied in the individual goat and intermittent neg ative reactions were seen in 19 adult animals followed for 30-91 weeks . Four seropositive goats developed clinical symptoms with difficultie s to move. However, no correlation between clinical signs and antibody expression pattern was seen. During the first 27 weeks of age no kid in the milk replacement reared group (N=4) seroconverted, but 5 of the 7 kids fed goat milk occasionally showed a positive antibody reaction . The gamma globulin concentration was significantly higher in the goa t milk fed group until the kids had become more than 19 weeks old. The results show that a great variation of the antibody pattern in indivi dual goats occur, and there-fore the AGIDT is only reliable as a herd screening test. Frequent sampling is necessary to get reliable informa tion about spreading of the CAEV in a naturally infected goat herd. Re moving kids from their dams immediately after birth combined with segr egation and artificial rearing protected them from CAEV infection. How ever their gamma globulin concentration was initially low.