Division of Viral Disease and Epidemiology, National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
Division of Pathology and Pathophysiology, National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
J Vet Med Sci. 2020 Jul 10;82(7):935-942. doi: 10.1292/jvms.20-0122. Epub 2020 May 22.
The objective of the present study was to evaluate the cross-protective immunity between type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) isolates in growing pigs. Japanese type 1 PRRSV, first isolated from a pig with respiratory disorders in a farm in 2009, exhibits unique genetic characteristics. The pathogenicity of a Japanese standard strain of type 2 PRRSV, EDRD1, in pigs immunized by the type 1 PRRSV isolate, Jpn EU 4-37 was determined by evaluating clinical signs, viremia, antibody response, and pathological lesions. Similarly, we evaluated the pathogenicity of Jpn EU 4-37 in pigs immunized by EDRD1 and compared the cross-protective immunity between these isolates. The EDRD1 challenge after Jpn EU 4-37 inoculation reduced viral clearance and shedding in pigs, compared to those treated with the EDRD1 single infection. On the other hand, the pathogenicity of Jpn EU 4-37 after EDRD1 infection did not differ significantly compared to non-immunized pigs treated with Jpn EU 4-37. Therefore, exposure to Jpn EU 4-37 could not induce enough immunity to reduce the viremia against subsequent infection by type 2 PRRSV. However, the immunity induced by Jpn EU 4-37 infection may play a role in reducing viremia caused by type 2 PRRSV. Moreover, the immunity induced by the EDRD1 and other genetically related viruses, which are broadly distributed in Japan, may not contribute to cross-protection against Jpn EU 4-37 as an emerging virus.
本研究旨在评估生长猪中 1 型和 2 型猪繁殖与呼吸综合征病毒（PRRSV）分离株之间的交叉保护免疫。2009 年，从日本一家农场的呼吸系统疾病猪中首次分离到日本 1 型 PRRSV，其具有独特的遗传特征。用 1 型 PRRSV 分离株 Jpn EU 4-37 免疫的猪的日本标准 2 型 PRRSV 株 EDRD1 的致病性，通过评估临床症状、病毒血症、抗体反应和病理损伤来确定。同样，我们评估了 Jpn EU 4-37 在 EDRD1 免疫的猪中的致病性，并比较了这些分离株之间的交叉保护免疫。与单独用 EDRD1 感染处理的猪相比，Jpn EU 4-37 接种后 EDRD1 挑战降低了猪的病毒清除和脱落。另一方面，与未免疫的 Jpn EU 4-37 处理的猪相比，Jpn EU 4-37 感染后 EDRD1 的致病性没有显著差异。因此，暴露于 Jpn EU 4-37 不能诱导足够的免疫力来降低对随后感染 2 型 PRRSV 的病毒血症。然而，Jpn EU 4-37 感染诱导的免疫可能在降低由 2 型 PRRSV 引起的病毒血症方面发挥作用。此外，由 EDRD1 和其他在日本广泛分布的遗传相关病毒诱导的免疫可能不会对作为新兴病毒的 Jpn EU 4-37 提供交叉保护。
