HEMAGGLUTINATION WITH PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS

Porcine reproductive and respiratory syndrome (PRRS) virus grown on MA RC-145 cell cultures was tested for hemagglutination (HA) with erythro cytes from a variety of species at 4 degrees C, room temperature and 3 7 degrees C. HA was observed at all temperatures with mouse erythrocyt es but not with cattle, sheep, goat, horse, swine, guinea pig, mongoli an gerbil, goose and chicken erythrocytes. The HA activity was enhance d by treatment of virus materials with Tween 80 followed by treatment with ether. The HA titer and HA pattern of virus materials treated wit h Tween 80 and ether (TE) were 4- to 8-fold higher and more clear than those of the virus materials without TE treatment. The optimum condit ions consisted in pretreatment of virus material with Tween 80 at a fi nal concentration of 0.06-0.125% (v/v) for 15-60 min followed by treat ment with ether at a concentration of 50% (v/v) for 5-15 min in ice ba th with continuous shaking. The curve of active virus production in in tra- and extracellular virus samples resembled that of HA production a lthough it rose somewhat earlier in intracellular virus samples. The H A reaction was inhibited by specific antiserum. HI antibody titers of individual pig sera showed a significant positive correlation with the ir neutralizing antibody titers.