Classical swine fever virus infection suppresses claudin-1 expression to facilitate its replication in PK-15 cells.

Classical swine fever (CSF) is one of the most epidemic viral diseases in swine industry. The causative pathogen is CSF virus (CSFV), a small enveloped RNA virus of Flaviviridae family. Claudin-1 was reported to be involved in the infections of a number of viruses, including many from Flaviviridae family, but no studies have investigated the role of porcine claudin-1 during CSFV infection in PK-15 cells. In this study, on the one hand, we demonstrated that CSFV infection reduced the claudin-1 expression at both mRNA and protein levels; on the other hand, CSFV infection was enhanced after claudin-1 knockdown, but inhibited by claudin-1 overexpression in a dose-dependent manner. Furthermore, negative correlation was demonstrated between the claudin-1 expression and CSFV titer. In conclusion, claudin-1 might be a barrier for CSFV infection in PK-15 cells, while CSFV bypasses the barrier through lysosome mediated degradation of claudin-1, which could be repressed by bafilomycin A1. Although the elaborate mechanisms how claudin-1 plays its roles in CSFV infection require further investigations, this study may advance our understanding of the molecular host-pathogen interaction mechanisms underlying CSFV infection and suggests enhancement of porcine claudin-1 as a potential preventive or therapeutic strategy for CSF control.

[Organic mercury tolerance, absorption and transformation in Spartina plants].

Critical concentration of methylmercuric chloride (MeHgCl) in the nutrient solution to which Spartina plants are tolerant is 15 micromol/L, three times higher than that of tobacco plants. After being treated with methylmercuric chloride, total quantity of organic mercury within plants increased and that of nutrient solution decreased greatly so that total quantity of inorganic mercury rose. It is inferred that Spartina plants absorb organic mercury and partially transform organic into inorganic mercury, and then more inorganic mercury is accumulated in underground parts of plants. In addition, inorganic mercury derived from organic mercury moved to solution by diffusion and permeation. In this way, the features Spartina plants exhibit in mercury accumulation and transformation from organic to inorganic mercury are valuable for phytoremediation of environment pollution.