IMMUNE-RESPONSE AND PERSISTENCE OF THE PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS IN INFECTED-PIGS AND FARM UNITS
IMMUNE-RESPONSE AND PERSISTENCE OF THE PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME VIRUS IN INFECTED-PIGS AND FARM UNITS
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DOI：
10.1136/vr.134.22.567
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发表时间：
1994-05-28
影响因子：
2.2
通讯作者：
TORRISON, J
中科院分区：
文献类型：
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作者：
ALBINA, E;MADEC, F;TORRISON, J
在实验和自然感染的猪中测定了对猪繁殖与呼吸综合征（PRRS）病毒的血清抗体反应的动力学和病毒感染后的持续性。在一项实验研究中，四头无特定病原体（SPF）母猪在妊娠90天时感染PRRS病毒的法国株，并从出生起监测其仔猪（试验仔猪）29周。在一窝仔猪中，在仔猪摄入初乳之前不存在针对PRRS病毒的抗体。出生后4天，这些仔猪的血清中存在被动抗体，但当在少数猪中观察到临床体征时，这些抗体在3周内（断奶前）消失。在第二窝仔猪中，大部分仔猪在4周龄之前没有可检测到的抗体，并且在其生命的第二周期间观察到临床体征。到8周时，在所有猪中检测到抗体，并且它们持续到29周时观察停止。两组3只SPF猪在4周龄时与试验仔猪直接接触，一组5只SPF猪在13周龄时与试验仔猪间接接触。前两组显示临床症状和血清转化，但第三组没有。在22周龄时，使两只试验仔猪经受运动应激并给予外源性皮质类固醇，之后接触的SPF猪出现临床体征并发生血清转化。在三个农场进行了为期六个月的流行病学调查，观察到类似的血清学特征。断奶后不久未发生血清转化的猪出现临床症状，并在5个月后发生血清转化。在研究期间，在农场疾病发作后不久血清转化的许多猪中，PRRS病毒抗体降低至不可检测的水平。得出的结论是，PRRS病毒可以持续在农场延长的时间后，首次感染。
The kinetics of the serum antibody response to porcine reproductive and respiratory syndrome (PRRS) virus and the persistence of the virus after infection were determined in experimentally and naturally infected pigs. In an experimental study, four specific pathogen free (SPF) sows were infected with a French strain of PRRS virus at 90 days of gestation, and their piglets (the test piglets) were monitored for 29 weeks from birth. In one litter, antibodies against PRRS virus were absent before the piglets had ingested colostrum. Four days after birth, passive antibodies were present in the serum of these piglets, but they had disappeared by three weeks (just before weaning) when clinical signs were observed in a minority of the pigs. In a second litter, most of the piglets had no detectable antibodies until they were four weeks old, and clinical signs were observed during their second week of life. By eight weeks, antibodies were detected in all the pigs, and they persisted until observations ceased at 29 weeks. Two groups of three SPF pigs were placed in direct contact with the test piglets when they were four weeks old and a group of five SPF pigs was placed in indirect contact when they were 13 weeks old. The first two groups showed clinical signs and seroconverted but the third group did not. At 22 weeks old, two of the test piglets were subjected to movement stress and were given exogenous corticosteroids, after which the in-contact SPF pigs developed clinical signs and seroconverted. An epidemiological survey was carried out on three farms for six months, when similar serological profiles were observed. Pigs that did not seroconvert shortly after weaning developed clinical signs and seroconverted five months later. Antibodies to PRRS virus diminished to undetectable levels within the study period in a number of the pigs which had seroconverted soon after the onset of disease on the farm. It is concluded that the PRRS virus can persist on farms for extended periods after an initial infection.