最近,NADC34样猪繁殖与呼吸综合征病毒(PRRSV)的出现,导致猪群大量流产,在中国引起了极大的关注。在这项研究中,PRRSV变异株,PRRSV/CN/FJGD01/2021,从NADC30样之间的重组演变而来,像NADC34一样,2021年在福建省分离到JXA1类病毒,并对其在仔猪中的致病性进行了检测。动物实验表明,PRRSV/CN/FJGD01/2021感染可诱发100%的发病率,并引起较高的病毒血症,持续高烧(连续14天>40°C),显著的体重减轻,与仔猪的NADC30样FJZ03菌株和NADC34样FJ0908菌株相比,严重的组织病理学肺损害。PRRSV/CN/FJGD01/2021株的致病性高于FJZ03和FJ0908株,但在仔猪中的致病性低于中国高致病性(HP)-PRRSV。此外,IngelvacPRRS修饰活疫苗(MLV)在仔猪中提供针对异源PRRSV/CN/FJGD01/2021的不完全交叉保护。我们的发现有助于了解NADC34样PRRSV在中国的流行现状。重要性NADC34样PRRSV的致病性在毒力方面具有广泛的差异。重要的是,NADC34类PRRSV自2017年在中国首次出现以来,已经与当地菌株进行了复杂的重组。然而,重组NADC34样病毒的致病性很少在猪中进行实验评估.在这项研究中,一种新的PRRSV株,PRRSV/CN/FJGD01/2021是从2021年在中国经历高流产率(20%)时期的母猪中分离出来的。值得注意的是,系统发育和重组分析表明,PRRSV/CN/FJGD01/2021是来自NADC30-,NADC34-,和类似JXA1的分离株。PRRSV/CN/FJGD01/2021被证明会导致更高的病毒载量,持续发烧,显著的体重减轻,中度呼吸临床体征,和仔猪严重的肺组织病理学病变。PRRSV/CN/FJGD01/2021对仔猪的致病性高于NADC30样FJZ03和NADC34样FJ0908,但低于中国HP-PRRSV。这些数据表明PRRSV/CN/FJGD01/2021对仔猪具有中等毒力。此外,IngelvacPRRSMLV可以部分提供针对仔猪PRRSV/CN/FJGD01/2021挑战的保护功效。
Recently, the emergence of a NADC34-like porcine reproductive and respiratory syndrome virus (PRRSV), which causes a large number of abortions in swine herds, has raised great concern in China. In this study, a PRRSV variant strain, PRRSV/CN/FJGD01/2021, evolved from recombination between NADC30-like, NADC34-like, and JXA1-like viruses was isolated in Fujian province in 2021, and its pathogenicity in piglets was examined. Animal experiments demonstrated that PRRSV/CN/FJGD01/2021 infection could induce 100% morbidity and cause higher viremia, a persistently higher fever (>40°C for 14 consecutive days), significant weight loss, and severe histopathological lung lesions compared to the NADC30-like FJZ03 strain and NADC34-like FJ0908 strain in piglets. The PRRSV/CN/FJGD01/2021 strain displayed higher pathogenicity than the FJZ03 and FJ0908 strains, but lower pathogenicity than the Chinese highly pathogenic (HP)-PRRSVs in piglets. Moreover, the Ingelvac PRRS modified live vaccine (MLV) provides incomplete cross-protection against heterologous PRRSV/CN/FJGD01/2021 in piglets. Our findings contribute to the understanding of the current epidemic situation of NADC34-like PRRSV in China. IMPORTANCE The pathogenicity of NADC34-like PRRSV has broad variations in virulence. Importantly, NADC34-like PRRSV has undergone complex recombination with local strains since it first emerged in 2017 in China. However, the pathogenicity of the recombinant NADC34-like virus was rarely experimentally evaluated in pigs. In this study, a novel PRRSV strain, PRRSV/CN/FJGD01/2021, was isolated from sows enduring a high-abortion-rate (20%) period in China in 2021. Notably, phylogenetic and recombination analyses revealed that PRRSV/CN/FJGD01/2021 is a recombinant virus from NADC30-, NADC34-, and JXA1-like isolates. PRRSV/CN/FJGD01/2021 was shown to cause higher virus load, persistent fever, significant weight loss, moderate respiratory clinical signs, and severe histopathological lung lesions in piglets. PRRSV/CN/FJGD01/2021 exhibited higher pathogenicity than NADC30-like FJZ03 and NADC34-like FJ0908, but lower than Chinese HP-PRRSVs for piglets. These data indicated that PRRSV/CN/FJGD01/2021 has intermediate virulence for piglets. Furthermore, the Ingelvac PRRS MLV could partly provide protective efficacy against PRRSV/CN/FJGD01/2021 challenge in piglets.