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Morphologic features, structure, and adherence to bovine turbinate cells of three haemophilus somnus variants
Abstract:
Three colony variants (translucent, small opaque, and large opaque) of Haemophilus somnus recovered during infection studies of chicken embryos were examined using electron microscopy. Ruthenium red-strained H somnus preparations revealed no capsule in any variants. Pili were not seen on phosphotungstate-negative stained preparations. The translucent variant was thin-walled and had an irregular, pleomorphic rod shape. The small opaque variant had a thicker cell wall and an even rod shape. The large opaque variant had the thickest, most rigid wall of the 3, with uniform rod morphologic features. When each of the 3 variants was allowed to contact bovine epithelial turbinate cells, the translucent and small opaque were significantly (P less than 0.01) more adherent than was the large opaque variant.
Insights
Three variants of Haemophilus somnus were studied. The translucent and small opaque variants showed greater adherence to bovine cells than the large opaque variant, despite no observed capsule or pili.
Area of Science:
- Microbiology
- Veterinary Science
- Cell Biology
Background:
- Haemophilus somnus is a significant pathogen in livestock.
- Understanding bacterial variants is crucial for infection control.
- Previous research has not fully characterized H. somnus variants' adherence properties.
Purpose of the Study:
- To characterize three colony variants of Haemophilus somnus.
- To compare the adherence of these variants to bovine epithelial cells.
Main Methods:
- Electron microscopy was used to examine bacterial morphology.
- Ruthenium red staining assessed capsule presence.
- Phosphotungstate staining identified pili.
- Adherence assays were performed with bovine epithelial turbinate cells.
Main Results:
- No capsule or pili were detected in any H. somnus variant.
- The translucent variant was thin-walled and pleomorphic.
- The small opaque variant had a thicker wall and even rod shape.
- The large opaque variant possessed the thickest, most rigid wall.
- Translucent and small opaque variants demonstrated significantly higher adherence to bovine cells compared to the large opaque variant.
Conclusions:
- Bacterial cell wall thickness and morphology correlate with adherence.
- H. somnus variants exhibit differential adherence capabilities.
- These findings contribute to understanding H. somnus pathogenesis and host interactions.