In genetic engineering of animals, retroviruses (disarmed) are used extensively as vectors. Retroviruses have the natural ability to integrate their genetic material into the host genome, making them ideal for delivering new genes into animal cells. The term "disarmed" refers to the modification of the virus so that it can no longer replicate or cause disease, ensuring safety during gene transfer.
Other vectors, such as E. coli and Ti plasmids, are primarily used for bacterial or plant genetic engineering, while Bacillus thuringiensis is mainly utilised for producing insecticidal proteins and not for gene delivery in animals. Hence, disarmed retroviruses are the preferred choice for animal genetic engineering.