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Posts Tagged ‘virus’

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 researchers determined the animals died of malignant catarrhal fever because they had been kept near flocks of sheep, which routinely carry a disease called ovine herpes virus 2. Researchers 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.

James Butler photo courtesy of Flickr. Click photo to view his photostream.

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, lead 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 associated with 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 related to skin cells.

Researchers 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.

Taus, N.S., Schneider, D.A., Oaks, J.L., Yan, H.,Gailbreath, K.L., Knowles, D.P., Li, H., Sheep (Ovis aries) airway epithelial cells support ovine herpesvirus 2 lytic replication in vivo, Veterinary Microbiology (2008),doi:10.1016/j.vetmic.2010.03.013

If it’s swine flu, why do people get it?

Illustration of avian flu on a human cell.

The event we hope never happens: a human cell (lower right) becomes infected with both an avian influenza virus (purple core, upper right) and a human influenza virus (orange core, upper center). Inside the cell, the viruses can mingle, producing new viral particles (purple and orange core, upper left) capable of spreading easily from person to person and as deadly as the original avian strain. Illustration from Russell Kightley Media.

With swine flu so much in the news these days, it’s a good time to look back at a story Washington State Magazine ran in August of 2007 (“Contagion! Emerging diseases: Unraveling the mystery“). Washington State University has one of the best teams of researchers in the world devoted to the study of diseases that can pass from their usual animal hosts to humans, such as Salmonella and E. coli. Our story delved into what changes a  virus or bacterium has to go through before it can infect people, why pigs are so often a way station for “bugs” that eventually infect people, why these diseases seem to occur in bursts, and why some outbreaks become full-blown epidemics.