Experimental inoculation of late term pregnant sows with a field isolate of porcine reproductive and respiratory syndrome vaccine-derived virus.
The use of a live attenuated porcine reproductive and respiratory syndrome virus (PRRSV) vaccine in piglets has been associated with reproductive disorders in non-vaccinated sows. Vaccine-derived virus (VDV) has been isolated from foetuses, stillborn pigs, and dead piglets, indicating that the live vaccine spread from vaccinated piglets to non-vaccinated sows, and that the virus might be implicated in the severe reproductive problems observed. In the present study, one such VDV isolate was used to experimentally infect pregnant sows in the last trimester. The chosen isolate, which had more than 99.6% identity to the attenuated vaccine virus, originated from the lungs of a stillborn pig from a swine herd with a sudden high level of stillborn pigs and increased piglet mortality in the nursing period. Intranasal inoculation of sows with the virus isolate resulted in congenital infection, foetal death, and preweaning pig mortality. As such, the present study showed that vaccine-derived PRRSV can cause disease in swine consistent with PRRS.
Nielsen
J
J
Danish Veterinary Institute for Virus Research, Lindholm, DK-4771 Kalvehave, Denmark. jn@vetvirus.dk
Bøtner
A
A
Bille-Hansen
V
V
Oleksiewicz
M B
MB
Storgaard
T
T
D000818:Animals; D004279:DNA, Viral / Q000032:analysis; D005260:Female; D005313:Fetal Death / Q000209:etiology / Q000662:veterinary; D008168:Lung / Q000196:embryology / Q000473:pathology / Q000821:virology; D019318:Porcine Reproductive and Respiratory Syndrome / Q000209:etiology* / Q000517:prevention & control; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology / Q000302:isolation & purification / Q000472:pathogenicity*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000209:etiology / Q000662:veterinary*; D012098:Reproduction; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D013552:Swine; D014611:Vaccination / Q000009:adverse effects / Q000662:veterinary*; D014613:Vaccines, Attenuated / Q000009:adverse effects; D014765:Viral Vaccines / Q000009:adverse effects*; D014774:Virulence
D004279:DNA, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines