The tick protective antigen, 4D8, is a conserved protein involved in modulation of tick blood ingestion and reproduction.

The gene that encodes the tick protective antigen, 4D8, was cloned from 10 species belonging to 6 genera, and the nucleotide and amino acid sequences were analyzed. 4D8 nucleotide and protein sequences were conserved among these tick species with identity/similarity between 65-98 and 60-98%, respectively. The function of 4D8 was characterized by RNA interference (RNAi) in five tick species. After the ticks were allowed to feed, degeneration of gut, salivary glands and reproductive tissues was observed, and tick survival, weight and oviposition were significantly reduced. 4D8 RNAi effected >90% reduction in oviposition in all tick species tested. Because of the critical role that 4D8 plays during tick feeding and oviposition, which ultimately results in the reduction of tick progeny, we proposed the generic name "subolesin" (Latin, suboles: offspring, progeny) for tick 4D8 proteins and subA for the subolesin-encoding gene.