tailieunhanh - Báo cáo khoa học: "Assessment of Replication and Virulence of Attenuated Pseudorabies Virus in Swine"

Tuyển tập các báo cáo nghiên cứu khoa học quốc tế về bệnh thú y đề tài: Assessment of Replication and Virulence of Attenuated Pseudorabies Virus in Swine | J. Vet. Sci. 2002 3 2 61-66 JOURNAL OF Veterinary Science Assessment of Replication and Virulence of Attenuated Pseudorabies Virus in Swine T. J. Newbya D. P. Carterb . Yoonc M. W. Jackwoodd and P. A. Hawkinse aAnimal Health Group Pfizer Inc Lincoln Nebraska USA Weterinary Resources Inc. Ames Iowa USA Department of Veterinary Diagnostic and Production Animal Medicine College of Veterinary Medicine University of Iowa Ames Iowa USA Department of Avian Medicine College of Veterinary Medicine University of Georgia Athens Georgia USA eAnimal Health Group Pfizer Inc New York New York USA Received Jan. 16 2002 Accepted Mar. 29 2002 ABSTRACT A nonclinical study was conducted to characterize the replication behavior of a modified live gE-deleted pseudorabies virus PRV MS 1 in swine and potential for reversion to virulence after anim al passages. Tw o to 3 week-old weaned pigs negative for PRV were m aintained in isolation and ch allen ge d by intranasal instillation. For the first passage 6 pigs were given 1 mL of PRV MS 1 TCID50 mL and 2 were necropsied at 3 4 and 5 days post-inoculation PI . Brain and second ary lym phoid tissues were collected homogenized and the supernatants individually pooled for virus isolation and PRV w as recovered from each sample. No clinical signs of PRV infection were observed but each pig had a nasal swab suspect or positive for PRV. For the second passage 5 pigs were given 1 m L of the homogenate of mixed tissues from 1 animal in the previous passage PRV at TCID50 m L . At 5 days PI all pigs w ere necropsied and PRV w as not recovered from their tissu e homogenates or nasal sw abs and no clinical signs were observed. During a second attem p t at a second passage tissue homogenates from all pigs in the first passage PRV at approxim ately TCID 50 m L were pooled and used to inoculate 15 pigs with 2 mL for 3 consecutive days. Ten pigs w ere m onitored for clinic al signs and seroconversion th rou gh 21 days PI and 5 pigs .