Petri Sheep

In the winter of 2003, a large herd of bison in an Idaho feedlot was cut in half when a disease outbreak swept through, killing 825 animals.

Two years ago, 19 cattle, most owned by FFA students, died after being shown in Washington's Puyallup State Fair.

In both instances, Washington State University scientists determined the animals died of cancerous catarrhal fever because they had been kept near flocks of sheep, which routinely carry a disease called ovine herpes virus 2. Scientists have known of the disease for decades, but have repeatedly been frustrated in their attempts to grow it in a lab-a major step in developing a vaccine.

So they use the next best thing to a Petri dish: sheep.

USDA and WSU researchers, writing in an upcoming issue of the journal Veterinary Microbiology, say they have propagated the virus in sheep and for the first time identified specific cells where it can replicate. Their discovery opens the door for growing these cells and the virus in a laboratory setting, where they can then begin developing vaccines.

Naomi Taus, main author and veterinary medical officer for the Pullman unit of the USDA's Agricultural Research Service, says she and her colleagues collected secretions from sheep-snot, actually-and aerosolized it to expose other sheep. They then took tissue samples from the sheep and searched for infections by looking for fluorescent markers designed to bind with proteins linked to the virus and certain cell types.

It turns out the virus is entering the sheep at the deepest levels of the lungs in what's called a type II alveolar epithelial cell-a cell correlation to skin cells.

Scientists now hope to culture and manipulate these cells in a laboratory setting-a real Petri dish-to develop a vaccine that can be used by the bison industry.


Posted by: Kelly    Source