The gp135 of caprine arthritis encephalitis virus affords greater sensitivity than the p28 in immunodiffusion serology.

The 135,000 mw glycoprotein (gp135) and the 28,000 mw internal protein (p28) of caprine arthritis encephalitis virus are major viral constituents in precipitin lines formed between crude antigen preparations and sera from infected goats. In testing 307 goat and sheep sera, 118 samples were positive in a gp135 assay and only 82 were positive in a p28 assay. However, some goat sera were found which reacted only with the p28 and therefore testing for antibody against both proteins may be necessary to identify a maximum number of virus infected goats by immunodiffusion.