Disease relevance of ospA

• A LightCycler-based PCR protocol was developed which targets the ospA gene for the identification and quantification of the different Borrelia burgdorferi sensu lato species in culture and in ticks, based on the use of a fluorescently labeled probe (HybProbe) and an internally labeled primer [1].
• Variation in the size of the ospA-containing linear plasmid, but not the linear chromosome, among the three Borrelia species associated with Lyme disease [2].
• The altered proteins were then analyzed by Western blot (immunoblot) with monoclonal antibodies which bind OspA on the surface of the intact B31 spirochete [3].
• Spirochete diversity in acrodermatitis chronica atrophicans lesions in a closely defined central European site was compared to that in the local vector population, in human erythema migrans lesions, and in cerebrospinal fluid by amplifying and sequencing a segment of the gene of outer surface protein A directly from sampled tissues [4].
• Only 1 patient each with erythema migrans, arthritis, or acrodermatitis had weak reactivity with outer surface protein A (OspA), and none responded to OspB [5].

High impact information on ospA

• B. burgdorferi M297, a mutant strain that lacks the plasmid that encodes OspA and OspB, also induced IL-10 gene transcription in PBMC, indicating that this phenomenon is not causally linked exclusively to OspA and its lipid moiety [6].
• All of the OspAs have a single conserved tryptophan at residue 216 or, in some cases, 217; however, the region of the protein flanking the tryptophan is hypervariable, as determined by a moving-window population analysis of ospA from 15 European and North American isolates of B. burgdorferi [3].
• The gene for the major outer surface protein A (OspA) from several clinically obtained strains of Borrelia burgdorferi, the cause of Lyme disease, has been cloned, sequenced, and expressed in Escherichia coli by using a T7-based expression system (J. J. Dunn, B. N. Lade, and A. G. Barbour, Protein Expr. Purif. 1:159-168, 1990) [3].
• The hypervariability of these solvent-exposed amino acid residues may contribute to the antigenic variation in OspA [3].
• Comparative sequence analysis suggested that serotype 5 OspA resulted from genetic recombination of serotype 4 and 6 ospA genes [7].

Biological context of ospA

• Accordance of ospA genotype 1 strains with B. burgdorferi sensu stricto and ospA genotype 2 strains with B. afzelii, as well as the ospA genotype strains 3-7 with B. garinii was confirmed by pulsed-field gel electrophoresis of MluI-digested genomic DNA [8].
• The open reading frames of all ospA genes consist of 819-825 nucleotides corresponding to proteins of approximately 30 kDa [8].
• One strain, JEM4, has a single ospA gene which is similar to European B. garinii strains PBr (sequence homology value: 94.1%) and T25 (91.2%) [9].
• Genetic diversity and the absence of regional differences of Borrelia garinii as demonstrated by ospA and ospB gene sequence analysis [10].
• The ospA-containing plasmid size of 50 kb in B. burgdorferi isolates is significantly smaller than the size of 55 kb in B. garinii isolates and 56 kb in group VS461 isolates [2].

Anatomical context of ospA

• Evaluation of an internally controlled real-time PCR targeting the ospA gene for detection of Borrelia burgdorferi sensu lato DNA in cerebrospinal fluid [11].
• Treatment-resistant Lyme arthritis, which may result from infection-induced autoimmunity, is associated with reactivity to a T cell epitope of outer-surface protein A (OspA(161-175)) of Borrelia burgdorferi sensu stricto (Bb) [12].

Associations of ospA with chemical compounds

• Since the reactive protein was extracted by the Triton X-114 phase partitioning method, the MAb recognized the common epitope present in OspA and OspB [13].

Other interactions of ospA

• Unfed adult Ixodes persulcatus ticks were collected from four locations of Nagano and Hokkaido in Japan. Infected Borrelia garinii were investigated by PCR-RFLP of the ospA and ospB gene sequences [10].

Analytical, diagnostic and therapeutic context of ospA

• This was also confirmed by ospA sequence analysis [14].
• The ospA sequences obtained in this study and previous published studies were compared with the results from OspA serotyping with monoclonal antibodies [8].
• In this study, we cloned and sequenced the genes encoding OspA and OspB from B. garinii strain FujiP2 (ribotype IV strain) isolated from I. persulcatus in Shizuoka, Japan. A sequence analysis revealed significant differences to the previously published sequences of ospA and ospB of B. burgdorferi sensu lato [15].
• Epitope-mapping studies using chemically cleaved OspA and a TrpE-OspA fusion have indicated that this hypervariable region is important for immune recognition [3].
• In this study, the reservoir role of Apodemus mice for B. garinii OspA serotype 4 was demonstrated by xenodiagnosis [16].

References