Primary humoral antibody response to Coxiella burnetii, the causative agent of Q fever.
Of 147 patients with acute Q fever diagnosed during a major outbreak in Birmingham, England, in early summer 1989, 41 provided sets of sera which allowed us to make a detailed analysis of the primary humoral immune response. Antibody titers specific for Coxiella burnetii were measured by the complement fixation test and by an immunoglobulin M (IgM)- and IgG-specific indirect immunofluorescence test. The relative avidity of specific IgGs was determined by the indirect immunofluorescence test with and without treatment of antigen-antibody complexes with 8 M urea. The IgG subclass responses after primary infection and their avidities were also determined for a limited number of paired serum specimens. Specific IgM titers persisted for more than 6 months in the majority of cases and were therefore not a sufficient criterion for the diagnosis of recent infection. However, for serial samples the antibody titer ratios (IgG/IgM) and the ratios (IgG titer with treatment/IgG titer without treatment) that indicated relative avidity changed significantly, depending on the time postinfection. Within the IgG class, the C. burnetii-specific antibody response over time was almost exclusively represented by subclass 1 molecules, which thus showed affinity maturation.
Guigno
D
D
Regional Virus Laboratory, Bristol, England.
Coupland
B
B
Smith
E G
EG
Farrell
I D
ID
Desselberger
U
U
Caul
E O
EO
D000907:Antibodies, Bacterial / Q000097:blood*; D003168:Complement Fixation Tests; D016997:Coxiella burnetii / Q000276:immunology*; D004196:Disease Outbreaks; D004739:England / Q000453:epidemiology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D011778:Q Fever / Q000453:epidemiology / Q000276:immunology*; D013997:Time Factors
D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D007075:Immunoglobulin M