Immunodominant
proteins are variable in molecular and antigenic structure among different genospecies of Borrelia burgdorferi sensu lato. We have recently developed an immunoblot using five recombinant
antigens: the chromosomal-encoded B. burgdorferi
proteins p100, the
flagellin and an internal
flagellin fragment thereof, and the plasmid-encoded outersurface
proteins A (OspA) and C (
OspC). In the present study the same
antigens (derived from strain PKo, genospecies B. afzelii) were compared with the homologous
recombinant proteins from strain B31 (genospecies B. burgdorferi sensu stricto) and with OspA,
OspC and the internal
flagellin fragment from strain PBi (genospecies B. garinii). Patients with neuroborreliosis (n = 28) and patients with
acrodermatitis chronica atrophicans (n = 20) were investigated in the
IgG immunoblot; the
IgM immunoblot was performed only in patients with neuroborreliosis. There was a small increase in the detection rate of OspA-specific
IgG or
IgM antibodies using the different variants of recombinant OspA; however, OspA remained an insensitive
antigen for antibody detection in
Lyme borreliosis. The same was true to
OspC-specific
IgG antibodies. The sensitivity of
OspC, which is the immunodominant
antigen for
IgM antibody detection, could not be increased using recombinant
antigens derived from different strains. However, some sera which were negative in the recombinant immunoblot reacted with
OspC in the conventional immunoblot using B. burgdorferi whole cell lysate as
antigen. The most unexpected finding was the high degree of immunological heterogeneity of the internal
flagellin fragments:
IgG antibodies were detected in 18 of 48 patients using B31 fragments, in 25 of 48 using PKo fragments, in 23 of 48 using PBi fragments versus 33 of 48 when the three
recombinant proteins were combined. PKo-derived fragments were more sensitive for antibody detection in patients with
acrodermatitis chronica atrophicans, B31- and PBi-derived fragments for antibody detection in patients with neuroborreliosis. This is in agreement with the fact that isolates from patients with neuroborreliosis are predominantly belonging to the genospecies B. burgdorferi sensu stricto and B. garinii. For detection of
IgM antibodies in sera from patients with neuroborreliosis, recombinant internal fragments derived from strains B31 and PBi were more sensitive than the PKo-derived fragment. The best discrimination between neuroborreliosis sera and control sera was achieved when the
IgM blot was performed using recombinant internal
flagellin fragments derived from strains PKo and PBi and
OspC derived from B31 or PKo.