JC Polyomavirus Infection Reveals Delayed Progression of the Infectious Cycle in Normal Human Astrocytes

Abstract

Animal models are crucial in advancing biomedical research and defining the pathogenesis of human disease. Unfortunately, not all diseases can be easily modeled in a nonhuman host or such models are cost prohibitive to generate, including models for the human-specific virus JC polyomavirus (JCPyV). JCPyV infects most of the population but can cause a rare, fatal disease, progressive multifocal leukoencephalopathy (PML). There have been considerable advancements in understanding the molecular mechanisms of JCPyV infection, but this has mostly been limited to immortalized cell culture models. In contrast, PML pathogenesis research has been greatly hindered because of the lack of an animal model. We have further characterized JCPyV infection in primary human astrocytes to better define the infectious process in a primary cell type. Albeit a cell culture model, primary astrocytes may better recapitulate human disease, are easier to maintain than other primary cells, and are less expensive than using an animal model.

The MAPK/ERK Pathway and the Role of DUSP1 in JCPyV Infection of Primary Astrocytes

“…The maintenance and description of normal human astrocytes (NHAs) (passage 1 [P1]) were previously reported [ 32 ]. Briefly, NHAs were cultured in astrocyte growth medium and supplemented with SingleQuots supplements and 1% penicillin–streptomycin (P–S).…”

“…Specifically, the most widely used cell model of JCPyV infection is SVG-A cells (referred herein as SVGAs), immortalized human fetal glial cells, mostly composed of astrocytes, that constitutively express SV40 Large T antigen (T Ag) to increase viral replication [ 29 , 30 , 31 ]. Our laboratory recently characterized JCPyV infection in primary normal human astrocytes (NHAs) as a tool to understand the infectious cycle [ 32 , 33 ]. When JCPyV infection in NHAs was compared to SVGAs, it was discovered that JCPyV infection was delayed in primary astrocytes, mostly due to the inadequate production of JCPyV Large T Ag compared to levels of this viral protein in cells immortalized with SV40 Large T Ag [ 32 ].…”

“…Our laboratory recently characterized JCPyV infection in primary normal human astrocytes (NHAs) as a tool to understand the infectious cycle [ 32 , 33 ]. When JCPyV infection in NHAs was compared to SVGAs, it was discovered that JCPyV infection was delayed in primary astrocytes, mostly due to the inadequate production of JCPyV Large T Ag compared to levels of this viral protein in cells immortalized with SV40 Large T Ag [ 32 ]. This research corroborated the observations of Kondo et.…”

“…in a chimeric mouse model; astrocytes were readily infected, but expressed low levels of the late viral gene product VP1 [ 5 , 33 , 34 , 35 ]. Further, we demonstrated that the immortalization of NHAs with SV40 Large T Ag, termed NHA-Ts, restored levels of VP1 expression comparable to JCPyV infection in SVGAs [ 32 ]. These results illustrate that expression of SV40 T Ag greatly contributed to the delayed progression in JCPyV infection observed in NHAs when compared to SVGAs [ 32 ].…”

“…Further, we demonstrated that the immortalization of NHAs with SV40 Large T Ag, termed NHA-Ts, restored levels of VP1 expression comparable to JCPyV infection in SVGAs [ 32 ]. These results illustrate that expression of SV40 T Ag greatly contributed to the delayed progression in JCPyV infection observed in NHAs when compared to SVGAs [ 32 ]. However, expression of SV40 Large T Ag to immortalize cells and enhance JCPyV replication may also dysregulate the cell cycle and activate cellular signaling pathways, confounding results in immortalized cell types [ 36 , 37 ].…”