Porcine reproductive and respiratory syndrome virus (PRRSV) causes enormous economic losses to the global swine industry. Given the extensive viral diversity and the limited heterologous cross-protection of current vaccines, antiviral strategies with broad activity against diverse PRRSV strains are urgently needed. This study investigated the anti-PRRSV activity of tannic acid (TA), a plant-derived polyphenol. TA potently inhibited PRRSV replication in both MARC-145 cells (half-maximal inhibitory concentration [IC50] = 5.34 μM; selectivity index [SI] = 12.59) and primary porcine alveolar macrophages (IC50 = 4.22 μM; SI = 42.65) and exhibited broad activity against multiple lineages of PRRSV-2. Mode-of-action assays revealed that TA primarily exerts virucidal and post-entry inhibitory effects. RNA sequencing-based transcriptomic analysis of TA-treated, PRRSV-infected cells identified differentially expressed genes significantly enriched in the mitogen-activated protein kinase (MAPK), tumor necrosis factor (TNF), and interleukin-17 (IL-17) signaling pathways. Among five candidate genes selected for small interfering RNA (siRNA)-mediated functional validation, knockdown of TNF alpha-induced protein 3 (TNFAIP3, also known as A20) most significantly suppressed PRRSV replication. PRRSV infection markedly upregulated TNFAIP3 expression, and TA reversed this upregulation in a dose-dependent manner. TNFAIP3 silencing reduced viral RNA levels, nucleocapsid (N) protein expression, and infectious titers, with the most pronounced effect during early infection. Collectively, the findings identify TA as a potent anti-PRRSV polyphenol and reveal TNFAIP3 as a candidate proviral host factor that is upregulated during PRRSV infection, providing insights into virus-host interactions and potential targets for host-directed antiviral strategies.
Human G11P[25] rotaviruses reported to date have been porcine-like strains with relatively conserved Wa-like genomic backbones. A novel human G11P[25] strain, RVA/Human-wt/JPN/S22-592/2023/G11P[25] (short name, S22-592), was detected in stool from a 17-year-old boy hospitalized with severe gastroenteritis in Japan. In this study, we sequenced and characterized the whole genome of strain S22-592. Whole-genome analysis revealed a unique genotype constellation, G11-P[25]-I12-R2-C3-M3-A3-N2-T3-E1-H1. Phylogenetic analysis and sequence comparisons indicated that five of the 11 genomic segments (VP7, VP4, VP6, NSP4, and NSP5) are most similar to those of Korean porcine-like human G11P[25] CAU12-2-like strains, which possess the genotype constellation G11-P[25]-I12-R1-C1-M1-A1-N1-T1-E1-H1, representing an I12-containing Wa-like backbone. Of the remaining segments, VP1 and NSP1-NSP3 are most closely related to Chinese feline-like human G3P[9] 2020999/23582009-like strains, which have the genotype constellation G3-P[9]-I2-R2-C2-M2-A3-N2-T3-E3-H3, whereas VP2 and VP3 are most closely related to Thai/Japanese human G3P[9] B2682/To16-11-like strains, which have the genotype constellation G3-P[9]-I3-R3-C3-M3-A3-N3-T3-E3-H6. Together, these findings expand the known range of human G11P[25] rotaviruses beyond the relatively conserved porcine-like/Wa-like lineages described previously, and suggest that S22-592 represents a genomic mosaic assembled from segment groups with distinct porcine-, human-, and feline-associated evolutionary histories.
Dengue virus (DENV) remains a major global health problem, and experimentally tractable animal models are essential for investigating severe dengue pathogenesis and antiviral or vaccine strategies. However, whereas interferon receptor-deficient mouse models are used, the disease phenotype in C57BL/6N Ifnar1−/− Ifngr1−/− double-knockout (DKO) mice has not been sufficiently characterized. Here, we generated and characterized C57BL/6N-based DKO mice deficient in both type I and type II interferon receptors (Ifnar1−/− Ifngr1−/−). We first assessed susceptibility to DENV-2 NGC infection in wild-type, single-knockout, and DKO mice and found that combined Ifnar1 and Ifngr1 loss was required for rapid and severe disease. DENV-2 NGC-infected DKO mice exhibited marked weight loss, severe clinical manifestations, and 100% mortality. We then performed phenotypic screening using selected DENV serotype 1–4 strains under strain-specific inoculation conditions. This revealed strain- and condition-dependent differences in disease outcomes, and DENV-2 NGC was selected for further characterization based on the rapid lethal disease observed under the conditions used. Detailed characterization of DENV-2 NGC infection demonstrated progressive viral RNA accumulation in multiple organs, including the liver, brain, spleen, and large intestine, and infectious virus was detected in selected peripheral tissues. Histopathological analyses revealed multi-organ tissue alterations with inflammatory changes and vascular abnormalities, and Evans blue extravasation assays demonstrated increased vascular permeability in infected tissues. Collectively, these findings establish a C57BL/6N-based Ifnar1−/− Ifngr1−/− mouse platform for studying DENV-2 NGC-induced severe disease phenotypes and provide a practical framework for future mechanistic and preclinical studies on antiviral or vaccine strategies.
The Mayaro virus (MAYV) is an arbovirus belonging to the Togaviridae family, genus Alphavirus. MAYV causes several sporadic outbreaks, affecting regions of the Americas. There are no specific antivirals for treating the disease. Therefore, studies are increasingly needed to discover effective antivirals against these neglected viruses. Thus, our study investigates the antiviral potential in vitro of a natural hydroxynaphthoquinone (QHM0001 - lapachol) and its synthetic derivatives (QHM0011, 0020 and 0110) against CMV-MAYV-nanoluc. We observed that the compounds QHM0001, 0011, 0020 and 0110 interfered with the post-entry stages (2 h.p.i.) of the CMV-MAYV-nanoluc, suggesting an effect on the viral genome replication stage. QHM0001, 0011 and 0020 showed high percentages of inhibition in late stages (4, 6 and 8 h.p.i.) of CMV-MAYV-nanoluc replication cycle. Thus, our study highlights the potential of the tested hydroxynaphthoquinones as promising candidates for new broad-spectrum antivirals.
