Researchers from the Technical University of Munich (TUM) have found a method to efficiently study molecular mechanisms of disease resistance or biomedical issues in farm animals. Genetically engineering animals offered researchers detailed insights into the molecular basis of health and disease.
Researchers are now able to introduce specific gene mutations into the desired organ or even correct existing genes without making new animal models for each target gene. This reduces the number of animals needed for research.
Using the CRISPR/Cas9 [it’s a tool to rewrite DNA information] method, genes can be inactivated or specifically modified easily. The technique consists of two components.
The gRNA (guide RNA) is a short sequence that binds specifically to the DNA segment of the gene that is to be modified. The Cas9 nuclease, the actual “gene scissors”, binds to the gRNA and cuts the respective section of the target DNA. This cut activates repair mechanisms that can inactivate gene functions or incorporate specific mutations.
Benjamin Schusser, Professor of Reproductive Biotechnology at the TUM, explains “The generated animals provide the gene scissors, the Cas9 protein, right along with them. So all we have to do is to introduce the guide RNAs to get animals which have specific genetic characteristics.”
“The initial generation of these animals took about 3 years. Cas9 can now be used at all stages of animal development since every cell in the body permanently possesses the Cas9 protein. We have been successfully able to utilize this method in chicken embryos as well as in living pigs.”
researchers found that the engineered pigs and chickens possess the Cas9 nuclease in all organs. This is particularly useful in biomedical and agricultural research.
Pigs are used as disease models for humans because their anatomy and physiology are much more similar to humans in comparison to mice (currently a common disease model). Thus, a modified pig may help to better understand the mechanism of carcinogenesis in humans. Potential new treatments for humans can also be tested in animal models.
“Cas9-equipped animals make it possible, for example, to specifically inactivate tumor-relevant genes and to simulate cancer development.”
Cas9 pigs and chickens allow researchers to test which genes might be involved in the formation of traits, such as — disease resistance, directly in the animal.
Prof. Schusser said, “The mechanism of the CRISPR/Cas9 system may also be useful for combating infections using DNA viruses. Initial cell culture experiments showed that this already works for the avian herpes virus.”