猪圆环病毒2型(PCV2)与几种经济上重要的疾病有关,这些疾病被描述为PCV2相关疾病(PCVAD)。PCV2在淋巴母细胞中复制,并且PCV2颗粒被单核细胞吸收而没有有效复制或完全降解。糖胺聚糖(GAG)已被证明是PCV2结合和进入T淋巴细胞和连续细胞系的重要受体。这项研究的目的是确定来自原代猪单核细胞中不同疾病爆发的六种PCV2毒株之间的病毒摄取和结果是否存在差异:Stoon-1010(PCV2a;PMWS),1121(PCV2a;流产),1147(PCV2b;PDNS),09V448(PCV2d-1;淋巴组织中具有高病毒载量的PCVAD[PCVADhigh]),DE222-13(PCV2d-2;PCVADhigh),和19V245(PCV2d-2;PCVADhigh)。PCV2在外周血单核细胞中的摄取在PCV2菌株之间是不同的。对于Stoon-1010、DE222-13和19V245,在单核细胞中发现大量PCV2颗粒,而对于1121、1147和09V448,发现少量PCV2颗粒。竞争,去除细胞表面的GAG,证明了硫酸软骨素(CS)和硫酸皮肤素(DS)在PCV2进入单核细胞中的重要作用。暴露在PCV2衣壳表面的带正电荷/负电荷的氨基酸的图谱显示,它们的数量和分布可能对衣壳与GAG的结合产生影响,内化为单核细胞。根据PCV2衣壳上正电荷氨基酸的分布,假设有磷酸根,并进一步证明,作为介导病毒附着的有效候选者,和内在化,单核细胞。IMPORTANCEPCV2在世界上几乎每个养猪场都存在,并且与大量疾病(PCV2相关疾病[PCVAD])有关。造成严重的经济损失。尽管疫苗接种已成功应用于该领域,关于PCV2感染的发病机制仍有许多未解决的问题。本文报道了外周血单核细胞对各种PCV2株的摄取差异,并揭示了Pietrain猪单核细胞强病毒摄取能力的机制。我们进一步证明:(i)GAG介导单核细胞对PCV2颗粒的摄取,(ii)衣壳外表面上带正电荷的三翼风车状氨基酸模式正在激活PCV2的摄取,和(iii)磷聚糖是PCV2内化的潜在候选物之一。这些结果为PCVAD的机制提供了新的见解,并有助于更好地理解PCV2的进化。这可能导致抗性猪的发展。
Porcine circovirus type 2 (PCV2) is associated with several economically important diseases that are described as PCV2-associated diseases (PCVADs). PCV2 is replicating in lymphoblasts, and PCV2 particles are taken up by monocytes without effective replication or complete degradation. Glycosaminoglycans (GAGs) have been demonstrated to be important receptors for PCV2 binding and entry in T-lymphocytes and continuous cell lines. The objective of this study was to determine whether differences exist in viral uptake and outcome among six PCV2 strains from different disease outbreaks in primary porcine monocytes: Stoon-1010 (PCV2a; PMWS), 1121 (PCV2a; abortion), 1147 (PCV2b; PDNS), 09V448 (PCV2d-1; PCVAD with high viral load in lymphoid tissues [PCVADhigh]), DE222-13 (PCV2d-2; PCVADhigh), and 19V245 (PCV2d-2; PCVADhigh). The uptake of PCV2 in peripheral blood monocytes was different among the PCV2 strains. A large number of PCV2 particles were found in the monocytes for Stoon-1010, DE222-13, and 19V245, while a low number was found for 1121, 1147, and 09V448. Competition with, and removal of GAGs on the cell surface, demonstrated an important role of chondroitin sulfate (CS) and dermatan sulfate (DS) in PCV2 entry into monocytes. The mapping of positively/negatively charged amino acids exposed on the surface of PCV2 capsids revealed that their number and distribution could have an impact on the binding of the capsids to GAGs, and the internalization into monocytes. Based on the distribution of positively charged amino acids on PCV2 capsids,
phosphacan was hypothesized, and further demonstrated, as an effective candidate to mediate virus attachment to, and internalization in, monocytes. IMPORTANCE PCV2 is present on almost every pig farm in the world and is associated with a high number of diseases (PCV2-associated diseases [PCVADs]). It causes severe economic losses. Although vaccination is successfully applied in the field, there are still a lot of unanswered questions on the pathogenesis of PCV2 infections. This article reports on the uptake difference of various PCV2 strains by peripheral blood monocytes, and reveals the mechanism of the strong viral uptake ability of monocytes of Piétrain pigs. We further demonstrated that: (i) GAGs mediate the uptake of PCV2 particles by monocytes, (ii) positively charged three-wings-windmill-like amino acid patterns on the capsid outer surface are activating PCV2 uptake, and (iii)
phosphacan is one of the potential candidates for PCV2 internalization. These results provide new insights into the mechanisms involved in PCVAD and contribute to a better understanding of PCV2 evolution. This may lead to the development of resistant pigs.