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Production of species-specific murine monoclonal antibodies against Cryptococcus neoformans which recognize a
A J Hamilton1, M A Bartholomew, J Figueroa
1Department of Clinical Sciences, Guy's Hospital, London, United Kingdom.
Abstract:
Three monoclonal antibodies (MAbs), designated 7C5, 7C9, and 5G8, against a cytoplasmic antigen of Cryptococcus neoformans were produced. MAbs 7C5 and 7C9 recognize culture filtrate antigen (exoantigen) of both encapsulated and nonencapsulated isolates of this pathogen, which suggests that they do not recognize capsular polysaccharide material. This is supported by immunofluorescence data which show reactivity of all 3 MAbs to cytoplasm and cell membranes only. MAb 7C9 also recognized C. neoformans var. gattii antigens but no other fungal pathogens tested in an enzyme-linked immunosorbent assay, while 7C5 and 5G8 recognized antigens of the cross-reactive pathogen Trichosporon beigelii but did not recognize either C. neoformans var. gattii isolates or any other fungal antigens. By Western blot (immunoblot), 7C9 detected antigen at 110 to 120, 65 to 70, 45 to 50, and 36 to 38 kDa; in addition to the latter band, the other two MAbs recognized a band at approximately 30 kDa. All three MAbs were of the immunoglobulin G1 subclass. The two MAbs which are capable of reacting with noncapsular culture supernatant antigen have possible uses in serodiagnosis, particularly in AIDS patients infected with C. neoformans, since in this group the present latex agglutination test has some limitations.
Insights
New monoclonal antibodies (MAbs) target Cryptococcus neoformans cytoplasm. These antibodies show promise for improved serodiagnosis in AIDS patients, overcoming limitations of current tests.
Area of Science:
- Immunology
- Mycology
- Infectious Diseases
Background:
- Cryptococcus neoformans is an opportunistic fungal pathogen causing cryptococcosis, particularly in immunocompromised individuals like those with AIDS.
- Current diagnostic methods, such as latex agglutination, have limitations in detecting C. neoformans, especially in certain patient groups.
Purpose of the Study:
- To produce and characterize monoclonal antibodies (MAbs) against cytoplasmic antigens of Cryptococcus neoformans.
- To evaluate the specificity and potential diagnostic utility of these MAbs.
Main Methods:
- Production of three monoclonal antibodies (7C5, 7C9, 5G8) against a cytoplasmic antigen of C. neoformans.
- Immunofluorescence assays to determine antibody reactivity with cellular components.
- Enzyme-linked immunosorbent assays (ELISA) and Western blot (immunoblot) to assess antigen recognition and specificity against various fungal pathogens.
Main Results:
- MAbs 7C5 and 7C9 recognize non-capsular exoantigens of C. neoformans, indicating reactivity with cytoplasmic and cell membrane components.
- MAb 7C9 showed specificity for C. neoformans var. gattii, while MAbs 7C5 and 5G8 cross-reacted with Trichosporon beigelii.
- Western blot analysis identified distinct antigen bands recognized by each MAb, with molecular weights ranging from 30 kDa to 120 kDa.
Conclusions:
- The developed MAbs, particularly 7C5 and 7C9, recognize non-capsular antigens of C. neoformans.
- These MAbs hold potential for improving the serodiagnosis of cryptococcosis, especially in AIDS patients where conventional tests may be less effective.