Background and Objectives: Persistent exposure to airborne fine dust (FD) particles contributing to air pollution has been linked to various human health issues, including respiratory inflammation, allergies, and skin diseases. We aimed to identify potential seaweed anti-inflammatory bioactive reagents and determine their effects on systemic inflammatory responses induced by FD particles. Materials and Methods: While exploring anti-inflammatory bioactive reagents, we purified compounds with potential anti-inflammatory effects from the seaweed extracts of Ecklonia cava, Ecklonia stolonifera, and Codium fragile. Structural analyses of the purified compounds siphonaxanthin (Sx), fucoxanthin (Fx), dieckol (Dk), and phlorofucofuroeckol-A (PFF-A) were performed using NMR and LC-MS/MS. Results: Notably, these compounds, especially PFF-A, showed significant protective effects against FD-induced inflammatory responses in RAW 264.7 cells without cytotoxicity. Further investigation of inflammatory-associated signaling demonstrated that PFF-A inhibited IL-1β expression by modulating the NF-κB/MAPK signal pathway in FD-induced RAW 264.7 cells. Additionally, gene profiling revealed the early activation of various signature genes involved in the production of inflammatory cytokines and chemokines using gene profiling. Treatment with PFF-A markedly reduced the expression levels of pro-inflammatory and apoptosis-related genes and even elevated the Bmp gene families. Conclusions: These results suggested that PFF-A is a potential natural therapeutic candidate for managing FD-induced inflammatory response.

African swine fever virus (ASFV) research commonly relies on primary porcine alveolar macrophages (PAMs), whose limited availability and variability hinder standardized virus isolation and propagation. This study aimed to establish a continuous cell line highly susceptible to genotype II ASFV and characterize phenotypic and genomic changes during serial passage. Thirty COS-1-derived clones were screened after infection with Korea/Pig/PAJU1/2019 using quantitative real-time polymerase chain reaction, immunofluorescence, and hemadsorption assays. Selected clones underwent serial passage, and viruses from passages 5 and 10 in the most susceptible clone were analyzed by whole-genome sequencing. K-C4 supported stable ASFV replication, with a mean viral genome level of 8.80 ± 0.55 log₁₀ copies/mL, compared with 7.38 ± 0.90 log₁₀ copies/mL in PAMs. Productive infection was confirmed by p72-specific immunofluorescence. The parental and passage 1 viruses retained hemadsorption, whereas the passage 5 virus lacked detectable hemadsorption despite continued replication, and hemadsorption reappeared by passage 10. Whole-genome analysis identified passage-associated deletions of differing extent within EP402R, encoding the hemadsorption-associated CD2-like viral protein (CD2v), which corresponded with the hemadsorption phenotype at each passage. These findings establish K-C4 as a highly permissive platform for genotype II ASFV propagation and characterization while emphasizing the need to monitor phenotypic and genomic stability during serial passage.