Natural Infection with Rabies Virus: A Histopathological and Immunohistochemical Study of Human Brains

OBJECTIVES: Despite all the efforts and increased knowledge of rabies, the exact mechanisms of infection and mortality from the rabies virus are not well understood. To understand the mechanisms underlying the pathogenicity of rabies virus infection, it is crucial to study the tissue that the rabies virus naturally infects in humans. METHODS: Cerebellum brain tissue from 9 human post mortem cases from Iran, who had been infected with rabies virus, were examined histopathologically and immunohistochemically to evaluate the innate immune responses against the rabies virus. RESULTS: Histopathological examination revealed inflammation of the infected cerebellum and immunohistochemical analyses showed an increased immunoreactivity of heat shock protein 70, interleukin-6, interleukin-1, tumor necrosis factor-alpha, caspase-3, caspase-9, toll-like receptor3 and toll-like receptor4 in the infected brain tissue. CONCLUSION: These results indicated the involvement of innate immunity in rabies infected human brain tissue, which may aggravate the progression of this deadly disease.

Cell Death Mechanisms in Esophageal Squamous Cell Carcinoma Induced by Vesicular Stomatitis Virus Matrix Protein

OBJECTIVES: Vesicular stomatitis virus (VSV) is under development as an oncolytic virus due to its preferential replication in cancer cells and oncolytic activity, however the viral components responsible have not yet been determined. In this study the effects of VSV wild-type (wt) and M51R-mutant matrix proteins (M51R-mMP) on apoptosis, pyroptosis, necroptosis, and autophagy pathways, in an esophagus cancer cell line (KYSE-30) were investigated. METHODS: The KYSE-30 cells were transfected with pcDNA3.1 plasmids encoding wt or M51R-mMP, and apoptosis, pyroptosis, necroptosis, and autophagy were evaluated 48 and 72 hours after transfection. RESULTS: KYSE-30 cells transfected with VSV wt and M51R-mMPs significantly reduced cell viability to < 50% at 72 hours post-transfection. M51R-MP significantly increased the concentration of caspase-8 and caspase-9 at 48 and 72 hours post-transfection, respectively ( p < 0.05). In contrast, no significant changes were detected following transfection with the VSV wt plasmid. Moreover, VSV wt and M51R-mMP transfected cells did not change the expression of caspase-3. VSV wt and M51R-mMPs did not mMP change caspase-1 expression (a marker of pyroptosis) at 48 and 72 hours post-transfection. However, M51R-mMP and VSV wt transfected cells significantly increased RIP-1 (a marker of necroptosis) expression at 72 hours post-infection ( p < 0.05). Beclin-1, a biomarker of autophagy, was also induced by transfection with VSV wt or M51R-mMPs at 48 hours post-transfection. CONCLUSION: The results in this study indicated that VSV exerts oncolytic activity in KYSE-30 tumor cells through different cell death pathways, suggesting that M51R-mMP may potentially be used to enhance oncolysis.