Anti-microbial immunomodulation

A method of modulating an immune system in a vertebrate host for the prophylactic [or therapeutic]treatment of infection by a first microbial pathogen in a target tissue, the method comprising:

• administering to the vertebrate host an effective amount of an antigenic formulation comprising antigenic determinants specific for a second heterologous microbial pathogen, wherein:
• the antigenic determinants are selected from the group consisting of whole cells or cell wall extracts;
• the first microbial pathogen is a microbial lung pathogen that is not a Klebsiella pneumonia, Streptococcus pneumonia, Pseudomonas aeruginosa or a viral lung pathogen, and the second heterologous microbial pathogen is a Klebsiella pneumonia, and the target tissue is the lung;
• and,
• wherein the administering comprises administering successive doses of the formulation at a dosage interval of at least one hour, so that two or more doses are administered over a period from 2 days to 1 month, over a dosage duration of at least one week.