Laboratory of Cell Biology and Virology, Institute of Molecular Biology of NAS RA, 0014 Yerevan, Armenia.
Laboratory of Molecular and Cellular Immunology, Institute of Molecular Biology NAS RA, 0014 Yerevan, Armenia.
Front Biosci (Landmark Ed). 2024 Apr 23;29(4):164. doi: 10.31083/j.fbl2904164.
The African swine fever (ASF) virus (ASFV) and ASF-like viral sequences were identified in human samples and sewage as well as in different water environments. Pigs regularly experience infections by the ASFV. The considerable stability of the virus in the environment suggests that there is ongoing and long-term contact between humans and the ASFV. However, humans exhibit resistance to the ASFV, and the decisive factor in developing infection in the body is most likely the reaction of target macrophages to the virus. Therefore, this study aimed to characterize the responses of human macrophages to the virus and explore the distinct features of the viral replication cycle within human macrophages.
The ASFV Armenia/07 strain was used in all experiments. In this study, quantitative real-time polymerase chain reaction (qRT-PCR) was used to determine the ASFV gene expression; flow cytometry analysis was performed to evaluate the effects of the inactive and active ASFV (inASFV and aASFV) treatments on the phenotype of THP-1-derived macrophages (Mφ0) and inflammatory markers. Moreover, other methods such as cell viability and apoptosis assays, staining techniques, phagocytosis assay, lysosome-associated membrane protein (LAMP-1) cytometry, and cytokine detection were used during experiments.
Our findings showed that the virus initiated replication by entering human macrophages. Subsequently, the virus shed its capsid and initiated the transcription of numerous viral genes, and at least some of these genes executed their functions. In THP-1-derived macrophages (Mφ0), the ASFV implemented several functions to suppress cell activity, although the timing of their implementation was slower compared with virus-sensitive porcine alveolar macrophages (PAMs). Additionally, the virus could not complete the entire replication cycle in human Mφ0, as indicated by the absence of viral factories and a decrease in infectious titers of the virus with each subsequent passage. Overall, the infection of Mφ0 with the ASFV caused significant alterations in their phenotype and functions, such as increased TLR2, TLR3, CD80, CD36, CD163, CXCR2, and surface LAMP-1 expression. Increased production of the tumor necrosis factor (TNF) and interleukin (IL)-10 and decreased production of interferon (IFN)-α were also observed. Taken together, the virus enters human THP-1-derived macrophages, starts transcription, and causes immunological responses by target cells but cannot complete the replicative cycle.
These findings suggest that there may be molecular limitations within human macrophages that at least partially restrict the complete replication of the ASFV. Understanding the factors that hinder viral replication in Mφ0 can provide valuable insights into the host-virus interactions and the mechanisms underlying the resistance of human macrophages to the ASFV.
非洲猪瘟病毒（ASFV）和类 ASF 病毒序列已在人体样本、污水以及不同的水环境中被发现。猪经常受到 ASFV 的感染。病毒在环境中的稳定性表明，人类与 ASFV 之间存在持续且长期的接触。然而，人类对 ASFV 具有抵抗力，决定机体感染的关键因素很可能是靶巨噬细胞对病毒的反应。因此，本研究旨在描述人类巨噬细胞对病毒的反应，并探讨病毒在人类巨噬细胞内复制周期的独特特征。
本研究使用 ASFV 亚美尼亚/07 株。在所有实验中，均采用实时定量聚合酶链反应（qRT-PCR）来确定 ASFV 基因的表达；采用流式细胞术分析评估失活 ASFV（inASFV）和活性 ASFV（aASFV）处理对 THP-1 衍生巨噬细胞（Mφ0）表型和炎症标志物的影响。此外，在实验过程中还使用了细胞活力和凋亡测定、染色技术、吞噬作用测定、溶酶体相关膜蛋白（LAMP-1）细胞术和细胞因子检测等其他方法。
我们的研究结果表明，病毒通过进入人类巨噬细胞启动复制。随后，病毒脱去衣壳并启动大量病毒基因的转录，其中至少部分基因执行其功能。在 THP-1 衍生的巨噬细胞（Mφ0）中，尽管病毒实施其功能的时间较慢，但 ASFV 实施了几种抑制细胞活性的功能，而与病毒敏感的猪肺泡巨噬细胞（PAMs）相比。此外，由于每个后续传代的病毒滴度降低，病毒不能在人 Mφ0 中完成整个复制周期。总之，ASFV 感染 Mφ0 会导致其表型和功能发生重大变化，例如 TLR2、TLR3、CD80、CD36、CD163、CXCR2 和表面 LAMP-1 的表达增加。还观察到肿瘤坏死因子（TNF）和白细胞介素（IL）-10 的产生增加，干扰素（IFN）-α的产生减少。
这些发现表明，人 THP-1 衍生的巨噬细胞内可能存在分子限制，这些限制至少部分限制了 ASFV 的完全复制。了解阻碍 Mφ0 中病毒复制的因素可以深入了解宿主-病毒相互作用以及人类巨噬细胞抵抗 ASFV 的机制。
