Biopsies - viral

ACEM

 ACEM
- members login -

Virological electron microscope methods

1) Faecal (stool) samples.

For electron microscope (EM) examination, viruses contained in faecal samples normally have to be concentrated and partially purified.

Samples of diarrhoea or stool are emulsified in saline and centrifuged at low speed to sediment large pieces of debris and most bacteria. The supernatant is then spun at high speed (high 'g') in an ultracentrifuge to sediment any viruses into a pellet at the bottom of the centrifuge tube.

The supernatant from this step is discarded and the pellet resuspended in a small volume of liquid. A drop of this resuspended pellet is placed on an EM specimen grid coated in a very thin layer of plastic, which supports any viruses in the sample. After being allowed to settle, excess fluid is blotted off, the grid washed in distilled water and the adherent viruses stained using a heavy metal salt solution (usually phosphotungstic acid).

The grid is then examined at high magnification (40,000 to 60,000 times) which allows recognition by the electron microscopist of characteristic virus symmetry and morphology.

 Click to view full image

Adenovirus. Thin section of a cell nucleus showing replicating Adenoviruses.
 
 

- help - - site map - - join ACEM - - disclaimer - - contact us - - members log-in - - top of page -