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Experimental rabies in skunks: immunofluorescence light and electron microscopic studies
Abstract:
Striped skunks (Mephitis mephitis) were inoculated into the abductor digiti quinti muscle with street rabies virus isolated from salivary glands of rabid skunks. Using the immunofluorescence technique, antigen was detected in muscle cells at the inoculation site before it was detected in the central nervous system. Neurons and their processes in nearly all regions of the brain, spinal cord, cerebrospinal ganglia, and peripheral nerves contained antigen in terminal stages of the disease. Electron microscopically, matrix (viral nucleocapsid), virions, and anomalous viral products were mainly in neuronal perikarya and dendrites, and less often in myelinated axons. Matrices, virions, and crystalloid structures were in muscle fibers at the inoculation site. Viral budding occurred on endoplasmic reticulum, neurotubules, and neuronal plasma membrane. In the brain and dorsal horn of the spinal cord, virus budded from the postsynaptic and adjacent dendritic or perikaryal plasma membrane. There was simultaneous esotropic uptake of these particles by adjacent axon terminals. The results strongly suggest that direct transneuronal transfer of virus from perikarya and dendrites to adjacent axon terminals is a mechanism in dissemination of rabies in the central nervous system of striped skunks. Variation in the length of the incubation period may be due partly to replication or virus in myocytes at the inoculation site and subsequent transfer to peripheral nerves.
Insights
Rabies virus infects skunk muscle cells before reaching the brain. Direct transfer between neurons likely spreads rabies in the central nervous system, influencing incubation periods.
Area of Science:
- Veterinary Virology
- Neuroscience
- Pathology
Background:
- Rabies is a fatal viral disease transmitted by infected animals.
- The transmission routes and cellular mechanisms of rabies virus in striped skunks (Mephitis mephitis) are not fully understood.
- Understanding viral dissemination is crucial for disease control and prevention.
Purpose of the Study:
- To investigate the early sites of rabies virus replication and dissemination in striped skunks.
- To elucidate the cellular mechanisms of rabies virus spread within the central nervous system (CNS) and peripheral nerves.
- To explore the role of muscle cells and neuronal transfer in rabies pathogenesis.
Main Methods:
- Inoculation of striped skunks with street rabies virus in the abductor digiti quinti muscle.
- Detection of viral antigen using immunofluorescence and electron microscopy.
- Examination of viral distribution in muscle, CNS, and peripheral nerve tissues.
Main Results:
- Rabies virus antigen was detected in muscle cells at the inoculation site prior to CNS detection.
- Viral antigen was widespread in neurons throughout the brain, spinal cord, and peripheral nerves in terminal stages.
- Electron microscopy revealed viral particles and replication within neuronal perikarya, dendrites, and muscle fibers.
- Viral budding occurred on various cellular membranes, including neuronal plasma membranes and endoplasmic reticulum.
- Evidence suggests direct transneuronal transfer of virus between adjacent neurons in the CNS.
Conclusions:
- Rabies virus replicates in skunk muscle cells, potentially influencing incubation period.
- Direct transneuronal transfer is a significant mechanism for rabies virus dissemination within the skunk CNS.
- The findings provide insights into rabies pathogenesis and spread in wildlife reservoirs.