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Neutralization of Chlamydia psittaci with monoclonal antibodies
S Ando1, I Takashima, N Hashimoto
1Department of Veterinary Public Health, Faculty of Veterinary Medicine, Hokkaido University, Japan.
Abstract:
Neutralization of Chlamydia (C.) psittaci avian strain P-1041 was examined in vitro using monoclonal antibodies (MAbs). Of the 10 MAbs used, 6 were found to exhibit neutralizing capability. These include 3 against major outer membrane protein (MOMP), 1 against lipopolysaccharide (LPS) and 2 against other protein molecules [90 kilodalton (kDa) and 90/50 kDa]. Most neutralizing MAbs were dependent on complement for efficient neutralization, while a strain-specific MAb (2B5) against the 90 kDa protein displayed a different requirement for complement and neutralized the infectivity of the P-1041 at high concentrations without complement. By competitive inhibition enzyme-linked immunosorbent assay (competitive inhibition ELISA), all 3 neutralizing anti-MOMP MAbs were demonstrated to recognize different epitopes found in very close proximity to each other on the outer membrane.
Insights
Six of ten monoclonal antibodies (MAbs) neutralized Chlamydia psittaci avian strain P-1041 in vitro. Most MAbs required complement, but one strain-specific MAb against a 90 kDa protein neutralized without it.
Area of Science:
- * Immunology
- * Microbiology
- * Veterinary Medicine
Background:
- * Chlamydia psittaci is an avian pathogen causing significant disease in poultry and psittacine birds.
- * Understanding the mechanisms of antibody-mediated neutralization is crucial for developing effective vaccines and treatments.
- * Monoclonal antibodies (MAbs) offer a targeted approach to investigate pathogen-specific immune responses.
Purpose of the Study:
- * To evaluate the in vitro neutralizing activity of MAbs against the avian Chlamydia psittaci strain P-1041.
- * To identify the specific targets (antigens) of neutralizing MAbs on the C. psittaci outer membrane.
- * To characterize the role of complement in MAb-mediated neutralization.
Main Methods:
- * In vitro neutralization assays using ten MAbs against C. psittaci avian strain P-1041.
- * Identification of MAb targets including major outer membrane protein (MOMP), lipopolysaccharide (LPS), and other proteins (90 kDa, 90/50 kDa).
- * Competitive inhibition enzyme-linked immunosorbent assay (ELISA) to map MAb epitopes on MOMP.
Main Results:
- * Six out of ten MAbs demonstrated neutralizing capability against C. psittaci P-1041.
- * Neutralizing MAbs targeted MOMP (3 MAbs), LPS (1 MAb), and other proteins (2 MAbs).
- * Most neutralizing MAbs required complement, but a strain-specific MAb (2B5) against a 90 kDa protein neutralized infectivity without complement at high concentrations.
- * Competitive inhibition ELISA revealed that the three anti-MOMP MAbs bind to distinct, closely located epitopes on the outer membrane.
Conclusions:
- * Monoclonal antibodies targeting various C. psittaci antigens, particularly MOMP, can effectively neutralize the avian strain P-1041 in vitro.
- * Complement plays a significant role in MAb-mediated neutralization, although strain-specific antibodies may bypass this requirement.
- * The identification of distinct neutralizing epitopes on MOMP provides valuable insights for subunit vaccine development against Chlamydia psittaci.