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Published on: July 24, 2016
Differential expression of the immediate-early 2 and 3 proteins in developing mouse brains infected with murine
M Ishiwata1, S Baba, M Kawashima
1Department of Pathology, Hamamatsu University School of Medicine, Hamamatsu, Japan.
Abstract:
Murine cytomegalovirus (MCMV) immediate-early (IE) 2 protein has been reported to be dispensable for growth and latency in mice. Therefore, its role in viral pathogenesis and tissue tropism is not known. Here we prepared specific antibodies to the IE2 and IE3 proteins by using fusion proteins expressed in Escherichia coli as antigens. Immunostaining of MCMV-infected cultured fibroblasts revealed IE2 protein to be expressed diffusely in the nucleoplasm similar to the IE1 protein. In contrast, expression of the IE3 protein, 88 kDa, exhibited a punctate pattern in the nucleus in the early phase of infection then diminished. In the brain of neonatal mice infected with MCMV, both IE2 and IE3 proteins were detected immunohistochemically in the cells of the ventricular walls early in infection. When the infection was prolonged, the IE2 protein was expressed in neurons of the cortex and hippocampus, while the IE3 protein was preferentially expressed in glial cells in the early phase of infection, and its levels declined during the infection. These results suggest that the IE2 protein may play a role in persistent infection in neurons, whereas the IE3 protein, expressed preferentially in glial cells, may play the main role in acute infection.
Insights
Murine cytomegalovirus immediate-early 2 (IE2) protein is found in neurons during persistent infection. The IE3 protein is mainly in glial cells during acute infection, suggesting distinct roles in viral pathogenesis.
Area of Science:
- Virology
- Immunology
- Neuroscience
Background:
- Murine cytomegalovirus (MCMV) immediate-early (IE) 2 protein's role in pathogenesis and tissue tropism is unknown.
- Previous studies indicated IE2 protein is dispensable for MCMV growth and latency in mice.
Purpose of the Study:
- To investigate the roles of MCMV IE2 and IE3 proteins in viral pathogenesis and tissue tropism.
- To characterize the expression patterns of IE2 and IE3 proteins during MCMV infection in vitro and in vivo.
Main Methods:
- Generation of specific antibodies against MCMV IE2 and IE3 proteins using E. coli expressed fusion proteins.
- Immunohistochemical staining of MCMV-infected cultured fibroblasts and neonatal mouse brains.
- Analysis of IE2 and IE3 protein expression patterns in different cell types and during different infection phases.
Main Results:
- IE2 protein showed diffuse nucleoplasmic expression in fibroblasts, similar to IE1.
- IE3 protein exhibited punctate nuclear expression in early infection, diminishing over time.
- In neonatal mouse brains, IE2 was detected in neurons during prolonged infection, while IE3 was preferentially in glial cells during acute infection.
Conclusions:
- IE2 protein may contribute to persistent MCMV infection in neurons.
- IE3 protein, predominantly expressed in glial cells, likely plays a significant role in acute MCMV infection.
