LOW PATHOGENICITY PRRS LIVE VIRUS VACCINES AND METHODS OF PREPARATION THEREOF

摘要

Vaccine comprising a virus having the designation ATCC VR2509 is claimed. Also claimed are: (1) an isolated and purified North American porcine reproductive and respiratory syndrome (PRRS) virus (PRRSV) strain where the strain has the designation ATCC VR2509, and (2) an isolated and purified PRRSV strain, wherein the strain gives plaques having an average dia. of 2 mm when the plaques are obtd. by a method comprising: (a) inoculating an aliquot of cells with the strain, where the cells have the designation ATCC VR2509, where the aliquot is obtd. from a confluent monolayer of the cells maintained in Eagle's min. essential medium (MEM) supplemented with 3% fetal calf serum and 0.15% sodium carbonate, where the aliquot includes 1-2/*105 cells/ml of MEM, (b) incubating the aliquot at 37 deg C for 60 mins, (c) removing the inoculum from the aliquot, (d) washing the aliquot with MEM, (e) resuspending the aliquot in 5 ml of 2X MEM and 1.6% boiled Noble agar supplemented with 250 ~mg of diethylaminoethyl (DEAE)- dextran, (f) plating the aliquot and (g) further incubating the aliquot at 37 deg C for 5 days in CO2 incubator to give the plaques.