Diagnosis of a Rabbit Hemorrhagic Disease Virus 2 (RHDV2) and the Humoral Immune Protection Effect of VP60 Vaccine.

Rabbit hemorrhagic disease (RHD) is known as rabbit plague and hemorrhagic pneumonia. It is an acute, septic, and highly fatal infectious disease caused by the Lagovirus rabbit hemorrhagic disease virus (RHDV) in the family Caliciviridae that infects wild and domestic rabbits and hares (lagomorphs). At present, RHDV2 has caused huge economic losses to the commercial rabbit trade and led to a decline in the number of wild lagomorphs worldwide. We performed a necropsy and pathological observations on five dead rabbits on a rabbit farm in Tai'an, China. The results were highly similar to the clinical and pathological changes of typical RHD. RHDV2 strain was isolated and identified by RT-PCR, and partial gene sequencing and genetic evolution analysis were carried out. There were significant differences in genetic characteristics and antigenicity between RHDV2 and classical RHDV strain, and the vaccine prepared with the RHDV strain cannot effectively prevent rabbit infection with RHDV2. Therefore, we evaluated the protective efficacy of a novel rabbit hemorrhagic virus baculovirus vector inactivated vaccine (VP60) in clinical application by animal regression experiment. The result showed that VP60 could effectively induce humoral immunity in rabbits. The vaccine itself had no significant effect on the health status of rabbits. This study suggested that the clinical application of VP60 may provide new ideas for preventing the spread of RHD2.

Platycodon grandiflorus Polysaccharides Alleviate Cr(VI)-Induced Apoptosis in DF-1 Cells via ROS-Drp1 Signal Pathway.

Hexavalent chromium (Cr(VI)) is a widespread heavy metal that has been identified as a human carcinogen, and acute or chronic exposure to Cr(VI) can cause organ damage. Platycodon grandiflorus polysaccharide (PGPS) is a constituent extracted from the Chinese herb Platycodon grandiflorus, which has various pharmacological effects. Therefore, the author investigated the role of PGPSt in Cr(VI)-induced apoptosis in chicken embryo fibroblast cell lines (DF-1 cells). Firstly, this study infected DF-1 cells using Cr(VI) to set up a model for cytotoxicity and then added PGPSt. Then, the intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and apoptosis rate were evaluated. The results showed that PGPSt could inhibit Cr(VI)-induced mitochondrial damage and increase the apoptosis rate. For further exploration of the mechanism of regulation of PGPSt, the ROS-Drp1 pathway was investigated. The antioxidant N-acetyl-L-cysteine (NAC) and mitochondrial division inhibitor 1(Mdivi-1) were added, respectively. The results showed that the NAC and Mdivi-1 restored abnormal mitochondrial fission and cell apoptosis. Thus, PGPSt can alleviate Cr(VI)-induced apoptosis of DF-1 cells through the ROS-Drp1 signaling pathway, which may suggest new research ideas for developing new drugs to alleviate Cr(VI) toxicity.

Regulation of Parkin in Cr (VI)-induced mitophagy in chicken hepatocytes.

The large amount of heavy metal chromium emissions from industrial production, ore smelting and sewage treatment plants have made chromium one of the most widespread heavy metal pollutants, with Cr (VI) being the most toxic. In recent years, people have gradually recognized the great harm of heavy metal chromium pollution, but the research on its pathogenic mechanism is still not deep enough. In this study, we treated the Primary cells of chicken liver with Cr (VI) to establish a model of toxicity. The optimal treatment time and Cr (VI) concentration were screened using the CCK-8 test. The intracellular mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were measured qualitatively and quantitatively by laser confocal and flow cytometry, respectively. This result was confirmed by the fact that Cr (VI) could cause mitophagy by causing damage to mitochondria. Subsequently, this study used LMH cells to construct a Parkin silencing model to further investigate that Parkin exerts the function on the Cr (VI)-induced mitophagy in chicken hepatocytes. The results showed that the knockdown of Parkin effectively blocked p62 degradation and LC3 lipidation and that PINK1 expression was significantly inhibited in LMH cells, further suggesting that the knockdown of Parkin effectively inhibited mitophagy. Mitochondrial morphology, MMP, and ROS were observed using laser confocal. The results showed that Parkin knockdown resulted in mitochondrial fission and increased levels of reactive oxygen species, together with increased depolarization of the mitochondrial membrane potential. These changes led to increased mitochondrial damage. In conclusion, this study showed that Cr (VI) could cause the occurrence of mitophagy by damaging mitochondria, and Parkin played a crucial role in Cr (VI)-induced mitophagy in chicken hepatocytes.

Hydrogen-Rich Medium Regulates Cr(VI)-Induced ER Stress and Autophagy Signaling in DF-1 Cells.

Related studies have shown that chromium (Cr) is toxic to cells, and hydrogen can protect cells by regulating endoplasmic reticulum (ER) stress and autophagy. However, there are few reports on the protective effects of hydrogen on heavy metal-induced cell damage. The objective of this study was to investigate the protection of hydrogen-rich medium (HRM) on Cr(VI)-induced ER stress and autophagy in DF-1 cells. Therefore, HRM were pretreated for 30 min before Cr(VI) treatment, and detected the autophagy and ER stress-related indicators to determine the role of HRM. The results showed that HRM could reduce the cell damage caused by Cr(VI), and 3-methyladenine (3-MA) could protect cells by inhibiting over autophagy. HRM can reverse the changes of ER stress- and autophagy-related indexes caused by Cr(VI), and inhibit the excessive autophagy caused by Cr(VI). In conclusion, HRM can protect cells from damage induced by Cr(VI), and play a role by inhibiting ER stress-mediated autophagy.