Medical Genetics DNA 2 chromosome retrovirus ④)→ cell nucleu therapeutic DNA ) cell To reverse disease caused by genetic damage researchers isolate normal DNa and package it into a vector, a molecular delivery truck usually made from a disabled virus. Doctors then infect a target cell -usually from a tissue affected by the illness, such as liver or lung cells--with the vector. The vector unloads its DNA cargo, which then begins producing the missing protein and restores the cell to normalMedical Genetics To reverse disease caused by genetic damage, researchers isolate normal DNA and package it into a vector, a molecular delivery truck usually made from a disabled virus. Doctors then infect a target cell —usually from a tissue affected by the illness, such as liver or lung cells—with the vector. The vector unloads its DNA cargo, which then begins producing the missing protein and restores the cell to normal