Genetic Engineering to Splice Cattle Disease

MANHATTAN, US - Traditional beef producers lose more than half a billion dollars a year to bovine respiratory disease complex. That's why finding innovative ways to combat it is at the top of Kansas State University researcher Shafiqul Chowdhury's to-do list.
calendar icon 3 April 2008
clock icon 3 minute read

Chowdhury, a professor of diagnostic medicine and pathobiology, has been tapped by the U.S. Department of Agriculture to build a better vaccine against bovine herpes virus-type 1. Bovine herpes is the initiator of bovine respiratory disease complex, which is made up of several viruses and subsequent infections that make cattle sick. The herpes virus directly causes bovine rhinotracheitis, which is part of the complex.

"The trick will be to disable the proteins without disabling the immune system's response."
Chowdhury, a professor of diagnostic medicine and pathobiology.

Afflicted cattle exhibit symptoms including rapid breathing, coughing, elevated temperature, lack of appetite, runny nose and eyes, and depression. The complex also can cause pregnant cows to abort.

"Bovine herpes virus-type 1 is typically where bovine disease complex starts," Chowdhury said. "It enters the animal and makes its way to the neuronal cell body where it's latent for life." But the herpes virus disarms the animal's immune system so that other opportunistic infections can take hold.

Chowdhury has studied how the virus gets into the body and past the immune system, as well as how it gets out of the neurons following reactivation from latency. He said that there are proteins enveloping the virus specifically designed to help the virus move within the neurons and evade the bovine immune system.

His current project targets two envelope glycoproteins - E and N - and a non-glycosylated envelope protein - Us9. Proteins E and Us9 promote transport within the neuron when the virus is reactivated, whereas glycoprotein N enables the virus to evade the immune system causing infection. Chowdhury will genetically modify these proteins to affect their ability to help the herpes virus spread and establish an infection.

"Being able to disable the virus in these ways will go a long way toward eradicating bovine respiratory disease complex," Chowdhury said. "And these three proteins show great promise. The trick will be to disable the proteins without disabling the immune system's response." Chowdhury has a $725,000 grant from the Department of Agriculture to study how best to genetically cripple these proteins, the end result being a new vaccine. He also is working with Fort Dodge Animal Health on vaccine development.

"There are some genetically engineered vaccines already out there. For example, glycoprotein E-deleted virus is the only vaccine allowed in European countries," Chowdhury said. "But the vaccine needs further improvement, especially with respect to immune response."

With the new vaccine, Chowdhury said he's also looking to build in a genetic marker so vaccinated animals can easily be distinguished from sick ones. That will also provide animals with better immunity. He said that developing a vaccine with these two properties would bring the U.S. beef industry one step closer to declaring the nation's meat disease-free.

Chowdhury is one of the more than 150 K-Staters who are active in the food safety and animal health arenas.

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