Abstract: The present invention relates to: Dirofilaria and Brugia thioredoxin peroxidase type-2 (TPx-2) proteins; Dirofilaria and Brugia TPx-2 nucleic acid molecules, including those that encode such TPx-2 proteins; antibodies raised against such TPx-2 proteins; and compounds that inhibit Dirofilaria and Brugia TPx-2 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 helminths.