Antigen detection and apoptosis in Mongolian gerbil’s kidney experimentally intraperitoneally infected by swine hepatitis E virus

We examined the effect of hepatitis E virus (HEV) on the renal tissue pathogenesis, morphological damages and related molecular mechanisms following swine HEV suspension intraperitoneally inoculation in Mongolian gerbils. The microscopic and ultramicroscopic analyses of kidney tissue structure were carried out at different points after inoculation of HEV. The immunohistochemistry, real-time PCR and Western blot were performed to explore the molecular mechanisms associated with HEV presence in the renal tissues. Real-time PCR revealed that the copies of HEV RNA in the kidney were detected at 7 dpi, and peaked at 14 dpi at a concentration was 7.18 logs g−1, with detection of HEV ORF2 antigen by immunohistochemistry. Hematoxylin and eosin (HE) staining showed pathological lesions including glomerular atrophy, degeneration, edema and necrosis of renal tubular epithelial cells and Mallory and Sirius red staining indicated the presence of collagen fibers and fibrosis in kidney tissues of inoculated gerbils. Ultrastructural studies of basal membrane of renal tubules demonstrated the rough and uneven with mitochondria swelling and vacuolation in the tissues of HEV inoculated animals. Similarly, significantly higher number of (TUNEL)-positive cells were seen in renal tubule tissues compared to control group. Moreover, immuno histochemical results indicated that significant increase expression of the B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), FAS and Caspase-3 in HEV inoculated Mongolian gerbils at each time points. Relative mRNA expression by real-time PCR revealed a significantly higher (P < 0.05) mRNA level of BAX, Bcl-2 and caspase-3 transcription in HEV inoculated Mongolian gerbils. Our results demonstrates that activation of mitochondria and Caspase-3 protease might be induced the apoptosis which subsequently cause the necrosis and cell death of renal epithelial cells during acute phase of HEV infection in HEV inoculated Mongolian gerbils.