SummaryThe tprK gene sequence of Treponema pallidum subspecies pallidum ( T. pallidum ) is heterogeneous within and among isolates. Heterogeneity in the tprK open reading frame is localized in seven discrete variable (V) regions, and variability results from apparent base changes, insertions or deletions. The TprK V regions are the focus of anti-TprK antibodies arising during infection. To test our hypothesis that V region sequences change during infection and passage, we developed a clonal isolate from the Chicago strain of T. pallidum and confirmed V region diversification during passage of this isolate. We describe the sequence anatomy of the seven V regions of tprK and the identification of putative donor sites for new V region sequences, and we propose a model for generation of new V regions by segmental gene conversion. These findings suggest that antigenic variation of TprK occurs in T. pallidum and may be important in immune evasion and persistence.

Aims Epigenetic regulators, including microRNAs(miRNAs), are implicated in type 2 diabetes, but evidence linking circulating miRNAs in pregnancy and risk of gestational diabetes(GDM) is sparse. Potential modifiers, including pre-pregnancy overweight/obesity and offspring sex, are unexamined. We hypothesized that circulating levels of early-mid-pregnancy(range 7-23 weeks of gestation) candidate miRNAs are related to subsequent development of GDM. We also hypothesized that miRNA-GDM associations might vary by pre-pregnancy body-mass index(ppBMI) or offspring sex. Methods In a case-control analysis(36 GDM cases/80 controls) from the Omega study, a prospective cohort study of pregnancy complications, we measured early–mid-pregnancy plasma levels of 10 miRNAs chosen for potential roles in pregnancy course and complications(miR-126-3p, -155-5p, -21-3p, -146b-5p, -210-3p, -222-3p, -223-3p, -517-5p, -518a-3p, and 29a-3p) using qRT-PCR. Logistic regression models adjusted for gestational age at blood draw (GA) were fit to compare circulating miRNAs between cases and controls. We repeated analyses among overweight/obese(ppBMI≥25kg/m2) or lean(ppBMI<25kg/m2) women, and women with male or female offspring separately. Results Mean age was 34.3 years(cases) and 32.9 years(controls). GA-adjusted miR-155-5p(β=0.260/p=0.028) and - 21-3p(β=0.316/p=0.005) levels were positively associated with GDM. MiR-146b-5p(β=0.266/p=0.068) and miR-517-5p(β=0.196/p=0.074) were borderline. Associations of miR-21-3p and miR-210-3p with GDM were observed among overweight/obese but not lean women. Associations of six miRNAs(miR-155-5p, -21-3p, - 146b-5p, -223-3p, -517-5p, and -29a-3p) with GDM were present only among women carrying male fetuses(all p<0.05). Conclusions Circulating early–mid-pregnancy miRNAs are associated with GDM, particularly among women who are overweight/obese pre-pregnancy or pregnant with male offspring. This area has potential to clarify mechanisms underlying GDM pathogenesis and identify at-risk mothers earlier in pregnancy.

Treponema pallidum includes three subspecies of antigenically highly related treponemes. These organisms cause clinically distinct diseases and cannot be distinguished by any existing test. In this report, genetic signatures are identified in two tpr genes which, in combination with the previously published signature in the 5 flanking region of the tpp15 gene, can differentiate the T. pallidum subspecies, as well as a simian treponeme.

ObjectiveInsulin resistance (IR), a reduced physiological response of peripheral tissues to the action of insulin, is one of the major causes of type 2 diabetes. We sought to evaluate the relationship between serum C-reactive protein (CRP), a marker of systemic inflammation, and prevalence of IR among Peruvian adults.MethodsThis population based study of 1,525 individuals (569 men and 956 women; mean age 39 years old) was conducted among residents in Lima and Callao, Peru. Fasting plasma glucose, insulin, and CRP concentrations were measured using standard approaches. Insulin resistance was assessed using the homeostasis model (HOMA-IR). Categories of CRP were defined by the following tertiles: <0.81 mg/l, 0.81-2.53 mg/l, and >2.53 mg/l. Logistic regression procedures were employed to estimate odds ratios (OR) and 95% confidence intervals (CI).ResultsElevated CRP were significantly associated with increased mean fasting insulin and mean HOMA-IR concentrations (p < 0.001). Women with CRP concentration >2.53 mg/l (upper tertile) had a 2.18-fold increased risk of IR (OR = 2.18 95% CI 1.51-3.16) as compared with those in the lowest tertile (<0.81 mg/l). Among men, those in the upper tertile had a 2.54-fold increased risk of IR (OR = 2.54 95% CI 1.54-4.20) as compared with those in the lowest tertile.ConclusionOur observations among Peruvians suggest that chronic systemic inflammation, as evidenced by elevated CRP, may be of etiologic importance in insulin resistance and diabetes.

Variation in the expression of the different Tpr proteins in the syphilis spirochete, Treponema pallidum subsp. pallidum, may have important implications in its ability to evade host immune detection and cause persistent infection. In the present study we examined the pattern of antibody responsiveness to different Tpr members during infection with three isolates of T. pallidum. There was variability in the specificities and temporal patterns of reactivity of the antibodies elicited against the individual Tpr proteins, suggesting that isolates may express different repertoires of Tpr proteins during infection.

Aim We investigated association of maternal retinol binding protein 4 (RBP4) with risk of gestational diabetes (GDM). Methods GDM cases (N=173) and controls (N=187) were selected from among participants of a cohort study of risk factors of pregnancy complications. Early pregnancy (16 weeks on average) serum RBP4 concentration was measured using an ELISA-based immunoassay. Logistic regression was used to estimate unadjusted and adjusted odds ratios (ORs/aORs) and 95% confidence intervals (95%CI). Results Mean serum RBP4 was significantly higher among GDM cases compared with controls (47.1 vs. 41.1 μg/ml, respectively; p-value<0.05). Participants in the highest quartile for serum RBP4 had a 1.89-fold higher risk of GDM compared with participants in the lowest quartile (95%CI: 1.05-3.43). However, this relationship did not reach statistical significance after adjustment for confounders (aOR: 1.54; 95%CI: 0.82-2.90). Women who were ≥35 years old and who had high RBP4 (≥38.3 μg/ml, the median) had a 2.31-fold higher risk of GDM compared with women who were < 35 years old and had low RBP4 (<38.3 μg/ml) (aOR: 2.31; 95%CI: 1.26-4.23; p-value for interaction=0.021). Conclusion Overall, there is modest evidence of a positive association of early pregnancy elevated RBP4 concentration with increased GDM risk, particularly among women with advanced age.

The tpr gene family of Treponema pallidum subsp. pallidum, the causative agent of syphilis, has recently become the focus of intensive investigation. TprF and TprI sequences are highly conserved among different isolates and are the targets of strong humoral and cellular immune responses of the host, and immunization with a recombinant peptide from the amino terminus of these antigens has been shown to alter significantly lesion development following homologous challenge. This indicates that these antigens are expressed during infection and strongly suggests a key functionality. tprF and tprI are located immediately downstream of the tprG and tprJ genes, respectively, separated by very short intergenic spacers (55 nucleotides for G-F and 56 nucleotides for J-I). Preliminary analysis using gene-specific primers failed to amplify tprJ in the Sea 81-4 isolate. In this study, sequence and transcriptional analysis of these loci showed a similar gene organization in the Nichols and Sea 81-4 strains, a complex pattern of transcription, and the presence of G homopolymeric repeats of variable lengths upstream of the tprF, tprI, tprG, and tprJ transcriptional start sites. However, distinctive features were also identified in the Sea 81-4 isolate, including a tprG-like open reading frame in the tprJ locus, a frameshift and a premature termination in the tprG coding sequence, a longer tprG-tprF intergenic spacer, and absence of cotranscription of the tprG-tprF genes.

Treponema paraluiscuniculi, the etiologic agent of rabbit venereal syphilis, is morphologically indistinguishable from Treponema pallidum subsp. pallidum (T. pallidum), the human syphilis treponeme, and induces similar immune responses and histopathologic changes in the infected host. Because of their high degree of relatedness, comparative studies are likely to identify genetic determinants that contribute to pathogenesis or virulence in human syphilis. The tpr (Treponema pallidum repeat) genes are believed to code for potential virulence factors. In this study, we identified 10 tpr homologs in Treponema paraluiscuniculi Cuniculi A strain and determined their sequence architecture. Half of this group of paralogous genes were predicted to be nonfunctional due to the presence of frameshifts and premature stop codons. Furthermore, the immune response against the T. paraluiscuniculi Tpr homologs in long-term-infected rabbits was studied by enzymelinked immunosorbent assay and lymphocyte proliferation assay, showing that TprK is the only target of the antibody and T-cell responses during experimental infection and emphasizing the importance of this putative virulence factor in venereal treponematosis.The spirochetes are a small but diverse family of bacteria and show a wide range of host specificities. Examples of these are the easily cultivated free-living organisms (Spirochaeta spp.), commensal treponemes of the termite gut, the human and animal pathogens in the genera Borrelia, Leptospira, and Brachyspira, and the cultivable and noncultivatable treponemes of humans and animals. Of the five noncultivatable pathogenic treponemes, Treponema paraluiscuniculi naturally infects rabbits but is thought not to be infectious for humans (14). In contrast, the three subspecies of Treponema pallidum naturally infect humans but can also experimentally infect rabbits and other mammals. Treponema carateum naturally infects humans but is unable to multiply in rabbits or other nonprimates (28).Treponema paraluiscuniculi is the etiologic agent of rabbit venereal syphilis. It was identified in 1913, only 8 years after Treponema pallidum subsp. pallidum (T. pallidum hereafter), the etiologic agent of human venereal syphilis, was discovered (3, 25). By dark-field microscopy, immunoassay, and electron microscopy, T. paraluiscuniculi and the other pathogenic treponemes are morphologically indistinguishable (17) and appear to induce similar immune responses and histopathologic changes. Furthermore, T. paraluiscuniculi-infected rabbits develop antibodies that can be detected with both treponemal and nontreponemal standard tests for syphilis (11,12). Immunoblotting tests show only subtle differences between the specificities of T. paraluiscuniculi and T. pallidum antisera for T. pallidum antigens (2, 26). Despite this apparently high level of relatedness, the pathogenic treponemes have different host specificities and cause clinically distinct diseases. Infections with all these treponemal species are chronic, and while homologous immunity...