Protective murine monoclonal antibodies to Cryptococcus neoformans

Area of Science:

• Immunology
• Infectious Diseases
• Microbiology

Background:

• Cryptococcus neoformans is a fungal pathogen causing life-threatening meningoencephalitis.
• The capsular glucuronoxylomannan (GXM) is a key target for therapeutic antibodies.
• Murine monoclonal antibodies (MAbs) offer potential for passive immunotherapy against cryptococcosis.

Purpose of the Study:

• To evaluate the protective capacity of various murine monoclonal antibodies (MAbs) against Cryptococcus neoformans.
• To investigate the influence of epitope specificity and immunoglobulin isotype on MAb-mediated protection.
• To assess the therapeutic potential of MAbs in a murine model of lethal cryptococcosis.

Main Methods:

• Passive administration of MAbs (IgM, IgG3, IgG1, IgA) recognizing distinct C. neoformans capsular epitopes.
• Infection of A/J and BALB/c mice with a lethal dose of C. neoformans.
• Assessment of MAb efficacy by measuring prolonged survival in lethally infected mice.

Main Results:

• Three IgM MAbs targeting distinct epitopes prolonged survival to varying degrees.
• Significant differences in protective efficacy were observed among isotypes: IgA and IgG1 were most effective, followed by IgM, and then IgG3.
• MAbs derived from the same B-cell clone demonstrated isotype-dependent protective capacity.

Conclusions:

• Protective MAbs against the C. neoformans capsular polysaccharide have been identified.
• Both the specific epitope targeted and the antibody isotype are critical factors determining protective efficacy.
• These findings support the development of MAb-based therapies for cryptococcosis.