Both CP15 and CP25 are left as trails behind gliding sporozoites of Cryptosporidium parvum (Apicomplexa).

Sporozoites of Cryptosporidium parvum were examined after gliding upon glass microscope slides using monoclonal antibodies to the 15 and 25 kDa surface molecules and immunogold-silver enhancement. Both antibodies bound to surface antigen deposited as trials behind parasites, suggesting that both surface molecules are involved in substrate attachment.