The role of antibody in immunity against experimental naegleria meningoencephalitis ('amoebic meningitis').

Mice immunized with amoeba culture fluid (ACF) from axenically cultured Naegleria fowleri showed marked protection against a lethal amoeba challenge, a result consistent with previous observations from this laboratory. The nature of this acquired resistance is not known. The data presented show that the degree of protection conferred to mice by immunization is related to the levels of antinaegleria antibodies. These antibodies react with the surface of the amoeba. The data also show that serum (and the IgG serum fraction) from immunized mice confer protection to normal mice against a lethal N. fowleri challenge. Spleen cells from immunized animals were only capable of conferring protection to recipients, when the challenge time was delayed (10 days), at which time anti-naegleria antibodies appeared in the serum of the mice. The studies suggest that antibodies play an important role in the ACF-induced resistance to experimental naegleria meningoencephalitis.