Antibodies in sera of the AWBE- or ADJ-immunized mice did not inhibit the alkaline phosphatase (AP), phosphodiesterase-5 (PDE-5), or acetylcholinesterase (AChE) activities present in AWBE; however, after infection, a non-significant and partial inhibition of the AP and PDE-5 activities was observed with the AWBE-immunized sera as compared to control group sera; minor effects were registered on the AChE (not shown). This evidence concerns the gene PDE5A and infection.