The present invention relates to parasitic nematode transglutaminase proteins; to parasitic nematode transglutaminase nucleic acid molecules, including those that encode such transglutaminase proteins; to antibodies raised against such transglutaminase proteins; and to compounds that inhibit parasitic nematode transglutaminase activity. The present invention also includes methods to obtain such proteins, nucleic acid molecules, antibodies, and inhibitory compounds. Also included in the present invention are therapeutic compositions comprising such proteins, nucleic acid molecules, antibodies and/or inhibitory compounds as well as the use of such therapeutic compositions to protect animals from diseases caused by parasitic nematodes.