Researchers have discovered that cows genetically engineered with a mouse gene called SP110 produce immune cells that are very effective at slowing down the growth of the bacterium Mycobacterium bovis (the cause of bovine tuberculosis.) Furthermore, such genetically modified cows appear less susceptible to developing the deadly symptoms of tuberculosis.
The outcome of the research has been published in the journal PNAS. The research is titled “TALE nickase-mediated SP110 knockin endows cattle with increased resistance to tuberculosis.”
This genetic experiment is considered to be the one of the first creations of transgenic cattle a “transgenic” animal using a novel genome-editing tool called transcription activator-like effector nuclease (TALEN) (this is an advanced means of genetic engineering.) The study was carried by researchers from Northwest A&F University located in Shaanxi, China.
With the study, The Scientist reports, scientists inserted the mouse nuclear body protein gene SP110 into the genome of fetal Friesan cow cells. The cells were then used as starting donors for embryos. Through this process, the research group created 23 cattle. Of these 23 cows, 13 calves survived past six months.
The selected gene was chosen due to its immunity to M. tuberculosis. The gene affects the growth of the bacterium in immune cells. The gene also and triggers infected cells to undergo faster and earlier cell death, than would occur with a natural infection.
Following the breeding, the researchers proceeded to test the 13 surviving cattle at a special farm. When immune cells cultured from the cows were exposed to M. bovis the bacteria grew at only half the rate that they did in cells in standard cattle. Furthwrmore, the infected transgenic cells underwent more rapid cell death.
The researchers observed similar patterns in live cows. These cows were either directly infected with the pathogenic bacteria or they were cows kept in the same holding pen as infected animals.
The transgenic animals that were exposed to the bacterium were found to have fewer bacterial cells and had fewer disease-caused internal lesions conpared with control animals. Of the nine transgenic cows exposed to infected cattle, six failed to contract tuberculosis while the remaining three had lesser symptoms than all nine of the non-transgenic controls.
Another interesting observation was that the modified gene was passed on to a new generation. Here the gene in the new offspring continued to confer the same immunity benefits.
