Rossow K D
South Dakota Animal Disease Research and Diagnostic Laboratory, South Dakota State University, Brookings 57007-1396, USA.
Vet Pathol. 1998 Jan;35(1):1-20. doi: 10.1177/030098589803500101.
In 1987, porcine reproductive and respiratory syndrome (PRRS) was recognized in the USA as a new disease of swine causing late-term reproductive failure and severe pneumonia in neonatal pigs. The syndrome is caused by an RNA virus referred to as PRRS virus (PRRSV), which is classified in the family Arteriviridae. Swine macrophages are the only indigenous cell type known to support PRRSV replication. Direct contact between infected and naive pigs is the predominant route of PRRSV transmission. Exposure of a mucosal surface to PRRSV leads to virus replication in regional macrophages, a prolonged viremia and systemic distribution of virus to other macrophage populations. Reproductive failure induced by PRRSV infection in late-gestation sows is characterized by premature farrowing of stillborn, partially autolyzed, and mummified fetuses. Pneumonia caused by PRRSV infection is more severe in young pigs compared to adults and may be complicated by concurrent bacterial infections. Gross lung lesions associated with PRRSV infection vary from none to diffuse consolidation. In addition, multiple lymph nodes may be markedly enlarged. Microscopically, PRRSV-pneumonia is characterized by multifocal, interstitial thickening by macrophages and necrotic cell debris in alveoli. Other less common microscopic lesions of PRRSV infection include myocarditis, vasculitis, encephalitis, and lymphoid hypertrophy and hyperplasia. In acute or subacute PRRSV infections, serum and lung are the best specimens for diagnosis. Persistent PRRSV infections can be produced by transplacental or intranasal infection. Persistent PRRSV infections are an important factor for virus survival and transmission within a swine herd and will complicate control programs.
1987年，猪繁殖与呼吸综合征（PRRS）在美国被确认为一种猪的新疾病，可导致妊娠后期母猪繁殖失败以及新生仔猪严重肺炎。该综合征由一种被称为猪繁殖与呼吸综合征病毒（PRRSV）的RNA病毒引起，PRRSV属于动脉炎病毒科。猪巨噬细胞是已知唯一支持PRRSV复制的天然细胞类型。感染猪与未感染猪之间的直接接触是PRRSV传播的主要途径。PRRSV暴露于黏膜表面会导致区域巨噬细胞中的病毒复制、长时间的病毒血症以及病毒向其他巨噬细胞群体的全身扩散。妊娠后期母猪感染PRRSV所致的繁殖失败表现为早产死胎、部分自溶胎和木乃伊胎。与成年猪相比，PRRSV感染引起的肺炎在幼猪中更为严重，且可能并发细菌感染。与PRRSV感染相关的肺部肉眼病变从无到弥漫性实变不等。此外，多个淋巴结可能会明显肿大。在显微镜下，PRRSV肺炎的特征是多灶性、由巨噬细胞引起的间质增厚以及肺泡内的坏死细胞碎片。PRRSV感染的其他较不常见的显微镜下病变包括心肌炎、血管炎、脑炎以及淋巴样肥大和增生。在急性或亚急性PRRSV感染中，血清和肺是诊断的最佳标本。经胎盘或鼻内感染可导致持续性PRRSV感染。持续性PRRSV感染是病毒在猪群中存活和传播的重要因素，会使防控计划复杂化。
