This study aimed to develop an immunochromatographic test strip model based on magnetic fluorescence nanomaterials in order to make up for the shortcoming of lateral flow immunoassay and provide technical support for the development of more sensitive rapid immunological assays. Using deoxynivalenol (DON) as the target, carboxyl-modified superparamagnetic particles were prepared by the solvothermal method. The magnetic particles, green fluorescent protein and anti-DON monoclonal antibody were coupled by the carbodiimide method to prepare magnetic fluorescent antibody probe. A magnetic fluorescence immunochromatographic test strip was established with DON-bovine serum albumin (BSA) as the test line. Meanwhile, a colloidal gold immunochromatographic test strip was established with colloidal goldlabeled anti-DON monoclonal antibody as the probe and DON-BSA as the test line. The magnetic fluorescence antibody probe exhibited good magnetic and fluorescent properties and antibody reactivity. The regression equation of the magnetic fluorescence immunochromatographic test strip was y = -0.562x + 0.921, R² = 0.990. The half maximal inhibitory concentration (IC₅₀) was 5.611 ng/mL, and the detection limit was 1.089 ng/mL. The sensitivity of the colloidal gold immunochromatographic test strip was 500 ng/mL with naked eyes, the regression equation was y = -0.543x + 1.485, R² = 0.991, the IC₅₀ was 65.16 ng/mL, and the detection limit was 11.94 ng/mL. The sensitivity of the magnetic fluorescence immunochromatographic test strip was 10.96 folds higher than that of the colloidal gold immunochromatographic test strip. The magnetic fluorescence immunochromatographic test strip allowed simultaneous sample enrichment and fluorescence signal detection and was successfully used in the detection of DON with high sensitivity. This study may lay the foundation for the application of magnetic fluorescence nanoparticles in the field of immunochromatographic assay.

Porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped single-stranded positive sense RNA arterivirus. Infection by PRRSV results in porcine reproductive and respiratory syndrome (PRRS), characterized by abortions, stillbirths, weak-born piglets, and mummified fetuses in sows as well as respiratory diseases in pigs of all ages. PRRSV has caused tremendous economic losses to the global swine industry. Comprehensive investigation on PRRSV infection would be beneficial for the prevention and control of PRRS, and contribute to the high-quality development of the swine industry. Autophagy is a lysosome-dependent degradation and recycling process for abnormal proteins, damaged organelles, and invading pathogens. It comprises macroautophagy, microautophagy, and chaperone-mediated autophagy (CMA), among which macroautophagy has been most extensively investigated so far, and is classified as non-selective autophagy and selective autophagy. Autophagy plays crucial roles in maintaining cellular homeostasis, controlling the quality of organelles, and transporting intracellular materials. Furthermore, autophagy is involved in diverse diseases, such as neurodegenerative diseases, autoimmune diseases, and cancers. Moreover, autophagy is a potent defense response to eliminate invading viruses, while viruses have evolved multiple strategies to subvert the autophagic degradation or even exploit autophagy for their own benefits. This review systematically scrutinized recent research progress on the roles and mechanisms of autophagy involved in PRRSV infection, and elaborated that autophagy played a dual role during PRRSV infection. On the one hand, PRRSV non-structural and structural proteins triggered macroautophagy (including reticulophagy, mitophagy, aggrephagy, and lipophagy) and CMA via a variety of mechanisms; in turn, macroautophagy and CMA facilitated PRRSV infection by participation in viral replication, antagonism of apoptosis, and inhibition of host immunity. On the other hand, selective autophagy (eg., reticulophagy) and CMA suppressed PRRSV infection by degradation of viral non-structural proteins and activation of antiviral immune responses. This review actually deepend the understanding of PRRSV infection from the autophagy perspective. In addition, this review summarized and raised certain controversial or unsolved issues, which provided clues for future studies on the roles and mechanisms of autophagy involved in PRRSV infection; in the meantime, this review illustrated and supported potential targets against autophagy for developing antiviral interventions to restrain PRRS epidemics.

Porcine epidemic diarrhea virus (PEDV), an enteric coronavirus, is widely spread worldwide and causes huge economic losses. The effective measure to control the viral infection is to develop ideal vaccines. Here, the collagenase equivalent domain (COE) of PEDV was displayed on the surface of nanoparticles (NPs) in order to develop a newer, safer and more effective subunit vaccine against PEDV. The monomeric COE was displayed on the mi3 protein, which self-assembles into nanoparticles composed of 60 subunits, using the SpyTag/SpyCatcher system. The size, zeta potential, microstructure of the COE-mi3 virus-like particles (VLPs) were investigated. The COE-mi3 VLPs that possessed good security, stability and better retention can be more efficiently taken up by antigen-presenting cells (APCs) and help promote dendritic cells (DCs) maturation. Moreover, COE-mi3 VLPs could prominently improve specific antibody levels including neutralizing antibodies (NAbs), and serum IgG, mucosal IgA. Moreover, COE-mi3 VLPs elicited more activation of CD4⁺ and CD8⁺ T cells and production of IFN-γ and IL-4 cytokines. In particular, COE-mi3 VLPs is an effectual antigen-delivery platform to enhance germinal center (GC) B cell responses. This structure-based self-assembly of NP gives great potential to be developed as a new subunit vaccines attractive platform, and may also provide new ideas for the development of other enteric coronavirus vaccines.