Serological methods in the diagnosis of bluetongue

The viral antibodies in the serum of cattle, sheep and deer are not detectable in the ordinary direct CF test. We have shown that the so-called "non complement-fixing" viral antibodies in the serum of these animal species can be demonstrated by the MDCF test. The MDCF test, as well as the micro AGP test, are group reactive, with all BT isolates studied. However, it is possible with these tests to differentiate antigenically BT virus from EHD virus. The FAT was also useful in differentiating BT virus grown in TC cells from the EHD virus. In the PRN test, all the BT virus isolates studied cross reacted and although quantitative differences were frequently observed, no obvious antigenic classification was possible with the antiserums used in this work. Reactions between the BT viral isolates and the EHD virus were all within the limits of what is presently considered to be non-specific inhibition.