MAPT and infection: However, in the case of P. aeruginosa strain ExoY+, it is established that the ExoY exoenzyme is a promiscuous cyclase that also generates cGMP, cUMP, and cCMP, in addition to cAMP following infection.15,16 As such, it is likely that additional secondary messenger systems are activated following infection resulting in the generation of cytotoxic forms of oligomeric tau.