IMMUNOBLOT USING RECOMBINANT ANTIGENS DERIVED FROM DIFFERENT GENOSPECIES OF BORRELIA-BURGDORFERI SENSU-LATO

Immunodominant proteins are variable in molecular and antigenic struct ure among different genospecies of Borrelia burgdorferi sensu late. We have recently developed an immunoblot using five recombinant antigens : the chromesomal-encoded B. burgdorferi proteins p100, the flagellin and an internal flagellin fragment thereof, and the plasmid-encoded ou tersurface proteins A (OspA) and C (OspC). In the present study the sa me antigens (derived from strain PKo, genospecies B. afzelii) were com pared with the homologous recombinant proteins from strain B31 (genosp ecies B. burgdorferi sensu stricto) and with OspA, OspC and the intern al flagellin fragment from strain PBi (genospecies B. garinii). Patien ts with neuroborreliosis (n = 28) and patients with acrodermatitits ch ronica atrophicans (n = 20) were investigated in the IgG immunoblot; t he IgM immunoblot was performed only in patients with neuroborreliosis . There was a small increase in the detection rate of OspA-specific Ig G or IgM antibodies using the different variants of recombinant OspA; however, OspA remained an insensitive antigen for antibody detection i n 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 i mmunoblot using B. burgdorferi whole cell lysate as antigen. The most unexpected finding was the high degree of immunological heterogeneity of the internal flagellin fragments: IgC antibodies were detected in 1 8 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 recomb inant proteins were combined. PKo-derived fragments were more sensitiv e for antibody detection in patients with acrodermatitis chronica atro phicans, B31-and PBi-derived fragments for antibody detection in patie nts with neuroborreliosis. This is in agreement with the fact that iso lates from patients with neuroborreliosis are predominantly belonging to the genospecies B. burgdorferi sensu stricto and B. garinii. For de tection 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 I gM blot was performed using recombinant internal flagellin fragments d erived from strains PKo and PBi and OspC derived from B31 or PKo.