It has been suggested that parasite substrate production (altering cell membranes and facilitating viral infection), changes in local microbiota (by modulating the cervical microenvironment, thereby promoting the exploitation of vaginal substrates and improving pathogen virulence) and cysteine protease production that can degrade antibodies) can all alter a host’s immune response, as such biological interactions could modulate parasite-virus coexistence29,31. Here, CTSB is linked to viral infectious disease.