Hepatitis E virus (HEV) infection can induce infertility and miscarriage in pregnant women and infect neonates through vertical transmission. However, the mechanism of infertility and vertical transmission remains unclear. In the present study, we evaluated the replication of HEV in the ovary and structural and molecular changes induced by HEV after intraperitoneal injection of HEV in rabbits. Positive- and negative-strand HEV RNA was detected in the ovaries at 28 and 49 days post-infection. Positive HEV open reading frames 2 and 3 signals were observed in the ovaries by immunohistochemistry staining. Histopathological changes of ovarian tissues were observed, including scattered cell necrosis and lymphocyte infiltration. The ratio of normal follicles decreased, whereas the ratio of atresia follicles increased in the HEV RNA-positive ovaries compared to the control group by counting the number of follicles at all levels. In addition, TUNEL results showed that apoptosis in follicle cells and oocytes was promoted by HEV infection. These results suggest that the ovary is one of the replication sites of HEV and that the expression of HEV RNA and antigen in ovarian tissue caused structural and molecular changes that promoted germ cell apoptosis. HEV can infect and replicate in the ovum at different stages, which is a novel mechanism for HEV vertical transmission.

Giant pandas are the flagship species in world conservation. Due to bamboo being the primary food source for giant pandas, dental wear is common owing to the extreme toughness of the bamboo fiber. Even though research on tooth enamel wear in humans and domestic animals is well-established, research on tooth enamel wear in giant pandas is scarce. The purpose of this study is to evaluate tooth enamel wear resistance in giant pandas to provide a basis for a better understanding of their evolutionary process. From microscopic and macroscopic perspectives, the abrasion resistance of dental enamel in giant pandas is compared with that of herbivorous cattle and carnivorous dogs in this study. This involves the use of micro-scratch and frictional wear tests. The results show that the boundary between the enamel prism and the enamel prism stroma is well-defined in panda and canine teeth, while bovine tooth enamel appears denser. Under constant load, the tribological properties of giant panda enamel are similar to those of canines and significantly different from those of bovines. Test results show that the depth of micro scratches in giant panda and canine enamel was greater than in cattle, with greater elastic recovery occurring in dogs. Scratch morphology indicates that the enamel substantive damage critical value is greater in pandas than in both dogs and cattle. The analysis suggests that giant panda enamel consists of a neatly arranged special structure that may disperse extrusion stress and absorb impact energy through a series of inelastic deformation mechanisms to cope with the wear caused by eating bamboo. In this study, the excellent wear resistance of giant panda's tooth enamel is verified by wear tests. A possible theoretical explanation of how the special structure of giant panda tooth enamel may improve its wear resistance is provided. This provides a direction for subsequent theoretical and experimental studies on giant panda tooth enamel and its biomaterials.