Influenza A virus (IAV) is an important zoonotic pathogen that can cause disease in animals such as poultry and pigs, and it can cause infection and even death in humans, posing a serious threat to public health. IAV is an enveloped virus that relies on host cell metabolic systems, especially lipid metabolism systems, to complete its life cycle in host cells. On the other side, host cells regulate their metabolic processes to prevent IAV replication and maintain their normal physiological functions. This review summarizes the roles of fatty acid, cholesterol, phospholipid and glycolipid metabolism in IAV infection, proposes future research challenges, and looks forward to the prospective application of lipid metabolism modification to limit IAV infection, which will provide new directions for the development of anti-influenza drugs.

The H9N2 avian influenza virus (AIV) is currently widespread worldwide, posing a severe threat to the poultry industry and public health. Reassortment is an important way for influenza viruses to adapt to a new host. In 2007, the PB2 gene of H9N2 AIV in China was reassorted, and the DK1-like lineage replaced the F/98-like lineage, forming a dominant genotype of G57. This genotype and its reassortants (such as H7N9, H10N8 and H5N6) showed higher mammalian adaptation, and caused increased human infections. However, the adaptive mechanisms of the DK1-like lineage PB2 gene remain unclear. Here, we confirmed that the PB2 lineage of the H9N2 AIV currently prevalent in China still belongs to the DK1-like lineage and, compared with the previously predominant F/98-like lineage, the DK1-like lineage PB2 gene significantly enhances H9N2 AIV to mammalian adaptation. Through transcriptomic analysis and qRT–PCR and western blot experiments, we identified a host factor, sphingosine kinase 1 (SphK1), that is closely related to viral replication. SphK1 inhibits the replication of DK1-like PB2 gene H9N2 AIV, but the ability of SphK1 protein to bind DK1-like PB2 protein is weaker than that of F/98-like PB2 protein, which may contribute to H9N2 AIV containing the DK1-like PB2 gene to escape the inhibitory effect of host factor SphK1 for efficient infection. This study broadens our understanding of the adaptive evolution of H9N2 AIV and highlights the necessity to pay close attention to the AIV that contains the adaptive PB2 protein in animals and humans.

Due to their facile synthesis and friendly functionalization, gold nanoparticles (AuNPs) have been applied in all kinds of biosensors. More importantly, these biosensors, with the combination of AuNPs and immunoassay, are expected to be used for the detection of different compounds with low concentrations in complex samples. In this study, a AuNPs-labeled antibody immunoprobe was prepared and combined with a fluorescence-quenching principle and a background fluorescence-quenching immunochromatographic assay (bFQICA), achieving rapid on-site detection. By using a portable fluorescence immunoquantitative analyzer and a QR code with a built-in standard curve, the rapid quantitative determination for nitrofurazone metabolite of semicarbazide (SEM) in animal-derived foods was realized. The limits of detection (LODs) for bFQICA in egg, chicken, fish, and shrimp were 0.09, 0.10, 0.12, and 0.15 μg kg⁻¹ for SEM, respectively, with the linear range of 0.08–0.41 μg L⁻¹, the recoveries ranging from 73.5% to 109.2%, and the coefficient of variation <15%, only taking 13 min for the SEM detection. The analysis of animal-derived foods by bFQICA complied with that of liquid chromatography-tandem mass spectrometry (LC-MS/MS).