A-B binds specifically to neurons and blocks protein synthesis to kill the nerve cells. A'-B' binds specifically to intestinal epithelial cells and blocks Na2 uptake to cause diarrhea. What would injection of a hybrid toxin, A'-B, into an animal do to its muscle cells

it will have no effects.

Explanation:

A'-B' will produce no effects because the receptor sites to which the hybrid A-B' is specific to is lacking in muscles cells, only present in epithelial cells .Therefore the hybrid  A-B' will not be able to bind and this will  not affect  influx of  sodium ions  for depolarization.

Generally, A-B toxins are protein complexes, produced by bacteria which are pathogenic to the host. The A-represent separate components, while the B represent another components.Thus the two-components proteins, interacts to produce negative effect in the host.The A -components represent the active form, while the B-components represent the binding site.

In this present scenario, the binding site  in the muscles cells specific  for the A-B'to bind to is missing, therefore the toxin produces no effects and no change in internal functions of the muscle cells.