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Abundant defective viral particles budding from microglia in the course of retroviral spongiform encephalopathy
1Institut f]ur Virologie und Immunbiologie, Universit]at W]urzburg, D-97078 W]urzburg, Germany.
Abstract:
A pathogenetic hallmark of retroviral neurodegeneration is the affinity of neurovirulent retroviruses for microglia cells, while degenerating neurons are excluded from retroviral infections. Microglia isolated ex vivo from rats peripherally infected with a neurovirulent retrovirus released abundant mature type C virions; however, infectivity associated with microglia was very low. In microglia, viral transcription was unaffected but envelope proteins were insufficiently cleaved into mature viral proteins and were not detected on the microglia cell surface. These microglia-specific defects in envelope protein translocation and processing not only may have prevented formation of infectious virus particles but also may have caused further cellular defects in microglia with the consequence of indirect neuronal damage. It is conceivable that similar events play a role in neuro-AIDS.
Insights
Neurovirulent retroviruses infect microglia but produce low-infectivity virions due to defective protein processing. This microglia defect may cause indirect neuronal damage, potentially relevant to neuro-AIDS.
Area of Science:
- Neurovirology
- Cellular and Molecular Neuroscience
- Immunology
Background:
- Retroviral neurodegeneration is characterized by neurovirulent retroviruses targeting microglia, sparing neurons.
- Microglia are key immune cells in the central nervous system, implicated in neuroinflammation and neurodegeneration.
Purpose of the Study:
- To investigate the mechanisms underlying low retroviral infectivity in microglia despite abundant virion release.
- To explore the role of microglia-specific viral processing defects in retroviral neurodegeneration and neuro-AIDS pathogenesis.
Main Methods:
- Isolation and ex vivo culture of microglia from rats peripherally infected with a neurovirulent retrovirus.
- Analysis of viral transcription, envelope protein cleavage, and cell surface detection in infected microglia.
Main Results:
- Microglia released abundant mature type C virions, but associated infectivity was very low.
- Viral transcription in microglia was normal, but envelope proteins were poorly cleaved and not detected on the cell surface.
- These defects suggest impaired formation of infectious viral particles and potential secondary cellular damage in microglia.
Conclusions:
- Microglia-specific defects in retroviral envelope protein processing hinder the production of infectious virions.
- These cellular defects may contribute to indirect neuronal damage, offering a potential mechanism for retroviral neurodegeneration.
- Similar pathogenetic mechanisms may be involved in the development of neuro-AIDS.