Related Experiment Videos
Electron microscopy of the suckling mouse cataract agent: a noncultivable animal pathogen possibly related to
Abstract:
The suckling mouse cataract agent (SMCA) is a filtrable (<220 nm), noncultivable agent isolated from ticks in Georgia in 1961. It grows to high titer in the eyes and brains of intracerebrally inoculated mice in which it induces cataract, uveitis, and chronic brain infection. SMCA in high titer may also be recovered from the tissues of embryonated hen eggs in which the infection is lethal within 4 to 9 days. Fine-structural studies of ultrathin sections of pellets obtained by ultracentrifugation of SMCA-infected egg allantoic fluids have revealed pleomorphic structures with morphological characteristics typical of mycoplasma. Similar organisms have been observed in egg allantoic fluids infected with an SMCA-related tick isolate, GT-48, but not in fluids from uninoculated control eggs. Mycoplasma-like entities were also observed in high concentration within retinal tissues of rats and mice studied at the time of maximal retinitis and uveitis after SMCA inoculation. Comparable tissues from normal mouse eyes were free of microorganisms. These fine-structural observations are in agreement with those reported by other investigators and suggest that SMCA-induced pathology is associated with an agent that resembles mycoplasma in size and morphology but differs from typical mycoplasma in its apparent non-cultivability on artificial media and its resistance to inactivation by broad-spectrum antibiotics.
Insights
The suckling mouse cataract agent (SMCA), a tick-borne pathogen, causes eye and brain infections in mice. Ultrastructural analysis reveals it resembles mycoplasma but is non-cultivable, suggesting a novel infectious agent.
Area of Science:
- Microbiology
- Ophthalmology
- Virology
Background:
- The suckling mouse cataract agent (SMCA) was isolated from ticks in 1961.
- SMCA induces cataract, uveitis, and chronic brain infections in mice.
- The agent is lethal to embryonated hen eggs within 4-9 days.
Purpose of the Study:
- To investigate the morphological characteristics of SMCA.
- To determine the nature of the agent causing SMCA-induced pathology.
- To compare SMCA with known microorganisms.
Main Methods:
- Fine-structural studies using ultrathin sections of ultracentrifuged SMCA-infected egg allantoic fluids.
- Electron microscopy of retinal tissues from infected and control mice and rats.
- Comparison of morphological findings with mycoplasma characteristics.
Main Results:
- Pleomorphic structures resembling mycoplasma were observed in SMCA-infected fluids and tissues.
- Mycoplasma-like entities were abundant in the retinas of infected animals.
- No microorganisms were found in control samples.
Conclusions:
- SMCA exhibits morphological characteristics similar to mycoplasma.
- The agent's non-cultivability and antibiotic resistance differentiate it from typical mycoplasma.
- SMCA-induced pathology is linked to this unique mycoplasma-like agent.