No satisfactory explanation has so far been given for the persistence
in the body sometimes, of various microorganisms - bacteria, parasites
, fungi and viruses - in spite of their foreign antigens and a compete
nt immune system. It has been proposed as an explanation that these mi
croorganisms, in the course of evolution, have concealed their true an
tigens from the immune system. Free living microorganisms concealed th
eir true antigens when the heat of the sun, with the threat of dehydra
tion, induced the development in surviving mutants of a lipid coat to
reduce surface water losses. This coat enveloped the microorganisms, c
oncealing their true antigens. Viruses that cause chronic infections c
oncealed their true antigens beneath a viral envelope derived from hos
t cell. Exposing the true antigens on microorganisms and viruses with
suitable lipid solvents and re-introducing the microorganisms and viru
ses so treated into the host as a kind of vaccine, should provoke a ne
w immune response effective in eliminating the pathogens concerned fro
m the body and in preventing future infections. In this way, pathogens
could be used to treat and prevent certain infectious diseases. The a
bove procedure should have significant benefits for human and animal h
ealth.