P4HB and infection: However, due to the importance of PDI to A. phagocytophilum infection in vivo and since antibody against the Asp14113–124 PDI binding domain inhibits invasion of host cells as effectively as catalytically neutralizing PDI itself, vaccination to elicit a humoral immune response against this domain would be expected to noncytotoxically protect against granulocytic anaplasmosis by blocking the Asp14-PDI interaction and preventing the thiol-disulfide exchange that is key for infection.