Outer surface protein E (OspE) mediates Borrelia burgdorferi sensu stricto strain-specific complement evasion in the eastern fence lizard, Sceloporus undulatus.

In North America, Lyme disease is primarily caused by the spirochetal bacterium Borrelia burgdorferi sensu stricto (Bb), which is transmitted between multiple vertebrate hosts and ixodid ticks, and is a model commonly used to study host-pathogen interactions. While Bb is consistently observed in its mammalian and avian reservoirs, the bacterium is rarely isolated from North American reptiles. Two closely related lizard species, the eastern fence lizard (Sceloporus undulatus) and the western fence lizard (Sceloporus occidentalis), are examples of reptiles parasitized by Ixodes ticks. Vertebrates are known to generate complement as an innate defense mechanism, which can be activated before Bb disseminate to distal tissues. Complement from western fence lizards has proven lethal against one Bb strain, implying the role of complement in making those lizards unable to serve as hosts to Bb. However, Bb DNA is occasionally identified in distal tissues of field-collected eastern fence lizards, suggesting some Bb strains may overcome complement-mediated clearance in these lizards. These findings raise questions regarding the role of complement and its impact on Bb interactions with North American lizards. In this study, we found Bb seropositivity in a small population of wild-caught eastern fence lizards and observed Bb strain-specific survivability in lizard sera. We also found that a Bb outer surface protein, OspE, from Bb strains viable in sera, promotes lizard serum survivability and binds to a complement inhibitor, factor H, from eastern fence lizards. Our data thus identify bacterial and host determinants of eastern fence lizard complement evasion, providing insights into the role of complement influencing Bb interactions with North American lizards.

Proteome array of antibody responses to Chlamydia trachomatis infection in nonhuman primates.

AIMS: Nonhuman primates have been used to investigate pathogenic mechanisms and evaluate immune responses following Chlamydia trachomatis inoculation. This study aimed to systemically profile antibody responses to C. trachomatis infection in nonhuman primates. MATERIALS AND METHODS: Sera were obtained from 4 pig-tailed and 8 long-tailed macaques which were intravaginally or ocularly infected with live C. trachomatis organisms, and analyzed by C. trachomatis proteome array of antigens. KEY FINDINGS: The sera from 12 macaques recognized total 172 C. trachomatis antigens. While 84 antigens were recognized by pig-tailed macaques intravaginally infected with serovar D strain, 125 antigens were recognized by long-tailed macaques ocularly infected with serovar A, and 37 antigens were recognized by both. Ocular inoculation with virulent A2497 strain induced antibodies to more antigens. Among the antigens uniquely recognized by A2497 strain infected macaques, outer membrane complex B antigen (OmcB) induced robust antibody response. Although macaques infected by less virulent A/HAR-13 strain failed to develop antibodies to OmcB, reinfection by A2497 strain induced high levels of antibodies to OmcB. SIGNIFICANCE: Proteome array has revealed a correlation of chlamydial infection invasiveness with chlamydial antigen immunogenicity, and identified antibody responses to OmcB potentially as biomarkers for invasive infection with C. trachomatis.

PerioVax3, a key antigenic determinant with immunoprotective potential against periodontal pathogen.

Treponema (T.) denticola is one of the key etiological agents in the development of periodontitis. The major outer sheath protein (Msp) of T. denticola has been shown to mediate pathogenesis and to facilitate adhesion of T. denticola to mucosal surfaces. This study aimed to find short polypeptides in the amino acid sequence of Msp which may be immunogenic and might elicit protective antisera against T. denticola. The complete msp sequence was divided into six fragments and the corresponding genes were cloned and expressed. Antisera against the polypeptides were raised in rabbits and fragment 3 (F3), hereinafter called PerioVax3 was the most potent fragment of the Msp in terms of yielding high titer antiserum. An adhesion assay was done to examine the inhibitory effects of antisera on the attachment of T. denticola to human gingival fibroblasts (HGFs) and human fibronectin. Antiserum against PerioVax3 significantly inhibited attachment of T. denticola to the substratum. Also, antiserum against PerioVax3 inhibited detachment of HGFs upon T. denticola exposure. To begin examining the clinical relevance of this work, blood samples from 12 sever periodontitis patients were collected and the sera were used in western blotting against the recombinant polypeptides. Periodontitis patient antisera exclusively detected PerioVax3 in western blotting. The data suggest that PerioVax3 carries epitopes that may trigger humoral immunity against T. denticola, which may protect against its adhesion functions. The complexity of periodontitis suggests that PerioVax3 may be considered for testing as a component of an experimental multivalent periodontal vaccine in further preclinical and clinical studies.

In silico analysis and recombinant expression of BamA protein as a universal vaccine against Escherichia coli in mice.

Colibacillosis, caused by pathogenic Escherichia coli, is a common disease in animals and human worldwide with extensive losses in breeding industry and with millions of people death annually. There is thus an urgent need for the development of universal vaccines against colibacillosis. In this study, the BamA protein was analyzed in silico for sequence homology, physicochemical properties, allergenic prediction, and epitopes prediction. The BamA protein (containing 286 amino acids) clusters in E. coli were retrieved in UniProtKB database, in which 81.7 % sequences were identical (Uniref entry A7ZHR7), and sequences with 94.82 % identity were above 93.4 %. Moreover, BamA was highly conserved among Salmonella and Shigella and has no allergenicity to mice and human. The epitopes of BamA were located principally in periplasm and extracellular domain. Surf_Ag_VNR domain (at position 448-810 aa) of BamA was expressed, purified, and then used for immunization of mice. Titers of the rBamA sera were 1:736,000 and 1:152,000 against rBamA and E. coli and over 1:27,000 against Salmonella and Shigella. Opsonophagocytosis result revealed that the rBamA sera strengthened the phagocytic activity of neutrophils against E. coli. The survival rate of mice vaccinated with rBamA and PBS was 80 and 20 %, respectively. These data indicated that BamA could serve as a promising universal vaccine candidate for the development of a protective subunit vaccine against bacterial infection. Thus, the above protocol would provide more feasible technical clues and choices for available control of pathogenic E. coli, Salmonella, and Shigella.

Epidemiology and emm types of invasive group A streptococcal infections in Finland, 2008-2013.

Invasive Streptococcus pyogenes (group A streptococcus, GAS) infections are a major global cause of morbidity and mortality. We analysed the surveillance data on invasive GAS and the microbiological characteristics of corresponding isolates to assess the incidence and emm type distribution of invasive GAS infections in Finland. Cases defined as patients with isolations of blood and cerebrospinal fluid S. pyogenes are mandatorily notified to the National Infectious Disease Registry and sent to the national reference laboratory for emm typing. Antimicrobial data were collected through the network including all clinical microbiology laboratories. Pulsed-field gel electrophoresis (PFGE) analysis was performed to assess clonality. In total, 1165 cases of invasive GAS were reported in Finland during 2008-2013; the median age was 52 years (range, 0-100) and 54% were male. The overall day 7 case fatality rate was 5.1% (59 cases). The average annual incidence was 3.6 cases per 100,000 population. A total of 1122 invasive GAS isolates (96%) were analysed by emm typing; 72 different emm types were identified, of which emm28 (297 isolates, 26%), emm89 (193 isolates, 12%) and emm1 (132 isolates, 12%) were the most common types. During 2008-2013, an increase of erythromycin resistance (1.9% to 8.7%) and clindamycin (0.9% to 9.2%) was observed. This resistance increase was in parallel with the introduction of a novel clone emm33 into Finland. The overall incidence of invasive GAS infections remained stable over the study period in Finland. We identified clonal spread of macrolide-resistant invasive emm33 GAS type, highlighting the importance of molecular surveillance.

Identification of immunogenic proteins of the bacterium Acinetobacter baumannii using a proteomic approach.

PURPOSE: Acinetobacter baumannii is an important opportunistic pathogen that causes pneumoniae, urinary tract infections, and/or septicemia in immunocompromised patients. This pathogen is frequently associated with nosocomial outbreaks worldwide and has become particularly problematic because of its prevalence and resistance patterns to several antibiotics. In the present study, we used an immunoproteome-based approach to identify immunogenic proteins located on the surface of A. baumannii for the development of a possible immunotherapy against this devastating bacterial infection. EXPERIMENTAL DESIGN: Sera from patients with A. baumannii infections (n = 50) and from a control group of healthy individuals (n = 3) were analyzed for reactivity against A. baumannii outer membrane proteins (OMPs) using Western blot analysis. To identify potential immunogenic proteins in A. baumannii, OMPs were separated by 2DE, and reactive sera from infected patients were randomly selected and divided into two different pools, each containing 15 sera. Finally, MALDI-TOF/TOF mass spectrometric analysis was employed to identify the corresponding proteins. RESULTS: This analysis identified six immunoreactive proteins: OmpA, Omp34kDa, OprC, OprB-like, OXA-23, and ferric siderophore receptor protein. Notably, these proteins are highly abundant on the bacterial surface and involved in virulence, antibiotic resistance, and growth. CONCLUSIONS AND CLINICAL RELEVANCE: Our results support the notion that the proteins identified in the present immunoproteome study could serve as antigen candidates for the development of vaccines and passive immunotherapies against A. baumannii infections.

Bactericidal antibody response against P6, protein D, and OMP26 of nontypeable Haemophilus influenzae after acute otitis media in otitis-prone children.

The bactericidal antibody response to three nontypeable Haemophilus influenzae (NTHi) outer membrane proteins (D, P6, and OMP26) was studied in 24 otitis-prone children (aged 7-28 months) after an acute otitis media (AOM) caused by NTHi. The study was carried out to understand the contribution of antigen-specific bactericidal antibody responses in the class of children who are most vulnerable to recurrent otitis media infections. Levels of protein D (P = 0.005) and P6 (P = 0.026) but not OMP26 antibodies were higher in bactericidal sera compared with nonbactericidal sera. For five (24%) and 16 (76%) of 21 bactericidal sera tested, removal of anti-protein D and P6 antibody, respectively, resulted in a two- to fourfold drop in bactericidal antibody. Antibodies to OMP26 did not make any contribution to the overall bactericidal activity in any serum samples. Eleven of 21 sera (52%) had bactericidal activity against a heterologous NTHi (86-028 NP) strain but the titers were significantly lower (P < 0.05) as compared to the homologous strains. Future studies of protein D, P6, OMP26, and other potential NTHi vaccine antigens should include studies of bactericidal antibody in children who are otitis prone as a possible correlate of protection.

Circulating bacterial membrane vesicles cause sepsis in rats.

Gram-negative bacteria remain the leading cause of sepsis, a disease that is consistently in the top 10 causes of death internationally. Curing bacteremia alone does not necessarily end the disease process as other factors may cause inflammatory damage. Bacterial outer membrane vesicles (OMVs) are naturally produced blebs from the outer membrane of gram-negative bacteria, which contain various proteins and lipopolysaccharide (LPS). We hypothesize that these vesicles initiate an inflammatory response independent of the parent bacteria. Outer membrane vesicles were isolated from cultures of Escherichia coli, and the concentration of LPS in the OMVs was measured. Adult male Sprague-Dawley rats were separated into five treatment groups: OMV, 2xOMV, LPS, lactated Ringer's, and sham. Our findings show that infused OMVs elicit physiological, histological, and molecular changes in rats that are consistent with sepsis. Hyperdynamic changes in heart rates and mean arterial pressures are observed as well as the elevation of the proinflammatory cytokines tumor necrosis factor α and interleukin 6. Downstream events such as the recruitment of neutrophils into tissues due to the presentation of vascular adhesion molecules also occur in OMV-treated animals. Although soluble LPS elicits stronger responses than did OMVs, responses to the latter consistently exceeded those associated with lactated Ringer's infusion. These results indicate OMVs, independent of the parent bacteria, do initiate an inflammatory response; however, further studies are required to better characterize the temporal biomolecular interactions involved.

Association of the FcγRIIB-nt645+25A/G polymorphism with the expression level of the FcγRIIb receptor, the antibody response to Porphyromonas gingivalis and the severity of periodontitis.

BACKGROUND AND OBJECTIVE: Human FcγRIIb is an immunoglobulin G (IgG) receptor that inhibits the activation of B lymphocytes through cross-linking with the B-cell receptor via immune complexes. This function acts as a negative regulator of antibody production. Our previous studies have demonstrated the gene polymorphisms in FcγRIIb to be associated with periodontitis. In this study, we presented a polymorphism--FcγRIIB-nt645+25A/G (rs2125685)--in intron 4 and analyzed its functional relevance to periodontitis. We examined whether the FcγRIIB-nt645+25A/G polymorphism is associated with periodontal parameters, the IgG response to the periodontopathic bacterium Porphyromonas gingivalis and/or the expression level of FcγRIIb on peripheral B lymphocytes. MATERIAL AND METHODS: Thirty-two patients with chronic periodontitis were genotyped with nested PCR and by direct sequencing of genome DNA. The levels of serum IgG and of specific IgG subclasses for P. gingivalis sonicate and for the recombinant 40-kDa outer membrane protein (OMP) were determined. The expression levels of FcγRIIb on peripheral B lymphocytes from 19 healthy donors were measured by flow cytometry. RESULTS: Patients with the FcγRIIB-nt645+25AA genotype showed significantly higher mean clinical attachment levels compared to patients with the FcγRIIB-nt645+25GG genotype (p = 0.003) and a significantly lower IgG response to P. gingivalis sonicate and to the 40-kDa OMP. The expression levels of FcγRIIb protein on the cell surface in peripheral B lymphocytes were higher in healthy donors with the FcγRIIB-nt645+25AA genotype than in those with the FcγRIIB-nt645+25GG genotype (p = 0.03). CONCLUSION: The higher expression levels of FcγRIIb in subjects with the FcγRIIB-nt645+25AA genotype may induce a lower level of production of IgG against P. gingivalis and therefore more severe periodontitis.

Analysis of the cross-reactivity of various 56 kDa recombinant protein antigens with serum samples collected after Orientia tsutsugamushi infection by ELISA.

Orientia tsutsugamushi, the etiologic agent of scrub typhus, has a highly expressed and immunodominant 56-kD outer membrane protein. This protein is one of the leading candidates for diagnosis and vaccine development for scrub typhus. Previous studies using recombinant 56-kD protein (r56s) derived from Karp strain (Kpr56) in a mouse model have shown good homologous protection but only moderate to poor heterologous protection. We evaluated the cross-reactivity of recombinant 56-kD proteins from Karp, Kato, Gilliam, TA763, and three chimeric 56-kD proteins. Not all r56s are equally reactive with strain-specific serum samples. These data provide a first glance of how reactive these r56s are toward the antiserum of different strains and which r56 exhibits the broadest reactivity. A formulation of this combination has the potential to provide broad protection against the heterologous challenge and to be used in a highly sensitive diagnostic assay.

[The laboratory diagnostic of pancreatitis of Yersinia etiology].

The effectiveness of diagnostic techniques detecting pancreatitis of Yersinia etiology is discussed. The agglutination reaction and immune-enzyme assay have been applied to detect the outer membrane proteins antibodies of various classes coded by plasmid of Yersinia virulence pYV. The polymerase chain reaction technique was applied to detect sites of chromosomal genes coding the factors of Yersinia virulence--superantigen toxin YPM Y. pseudotuberculosis and protein of adhesion/invasion of Ail Y. enterocolitica. The application of the complex of specific techniques of laboratory examination of patients with acute pancreatitis and chronic pancreatitis with exacerbations permitted to confirm the Yersinia etiology of disease in 23.7% of cases. Then serologic techniques are the most informative in laboratory diagnostics.

Psoriasis--as an autoimmune disease caused by molecular mimicry.

Psoriasis is strongly associated with streptococcal throat infection, and patients have increased occurrence of such infections. Psoriatic lesional T cells are oligoclonal, and T cells recognizing determinants common to streptococcal M-protein and keratin have been detected in patients' blood. We propose that CD8(+) T cells in psoriatic epidermis respond mainly to such determinants, whereas CD4(+) T cells in the dermis preferentially recognize determinants on the streptococcal peptidoglycan that might itself act as an adjuvant. The streptococcal association might reflect the concurrence of superantigen production promoting skin-homing of tonsil T cells, M-protein mimicking keratin determinants, and adjuvant effects of the peptidoglycan. Accordingly, improvement of psoriasis after tonsillectomy should be associated with fewer T cells that recognize keratin and streptococcal determinants.

Identification of immunogenic antigen candidate for Chlamydophila pneumoniae diagnosis.

Chlamydophila pneumoniae is a Gram-negative intracellular obligate human pathogen and accounts for 5-10% of cases of community-acquired pneumonia. However, isolating and culturing this pathogen is difficult, so there have been several studies searching for new biomarkers for its diagnosis. In this study, we obtained immunogenic proteins of C. pneumoniae KNIH-1 for diagnosis using immunoproteomics. C. pneumoniae infection sera were selected for the highest index value of C. pneumoniae-specific IgG using microimmunofluorescence (MIF). The detected protein spots in common from C. pneumoniae infection sera using proteome analysis were identified as Omp11, type III secretion system ATPase, and PmpG by LC-MS/MS and MS databases. They were selected as candidate antigens. In addition, using in silico prediction we also identified proteins encoded by Omp11, PmpG and IncA as antigens. And then, IncA acts as an effector by a type III secretion system ATPase, as identified by mass spectrometry, and was selected as a candidate antigen. Thus, we predict proteins encoded by Omp11, the PmpG family and by IncA as candidate diagnostic immunogens.

Serological responses to microbial antigens in celiac disease patients during a gluten-free diet.

BACKGROUND: Immunoglobulin A (IgA) autoantibodies to tissue transglutaminase (tTG) are commonly used for screening and diagnosing of celiac disease (CD). Seroreactivity for anti-Saccharomyces cerevisiae antibody (ASCA) and bacterial antigens have also been detected in CD patients. The aim of this study was to examine prospectively serologic responses to microbial targets in adult CD patients at the time of diagnosis and during a gluten-free diet (GFD). Further, we wanted to evaluate whether these serologic specificities could provide new tools for the follow-up of CD patients. METHODS: Data on 55 adult biopsy-proven CD patients were available for follow-up study. Upper gastrointestinal endoscopy was performed on all patients. Sera from patients were tested for antibodies to tTG and ASCA and additionally analyzed with IgA enzyme-linked immunosorbent assays to Pseudomonas fluorescens-associated sequence, I2, and to a Bacteroides caccae TonB-linked outer membrane protein, OmpW. RESULTS: At the time of diagnosis, 91% of CD cases were positive for tTG and 49% for ASCA; positive seroreactivity to I2 was found in 86% and to OmpW in 60% of CD patients at the time of diagnosis. The frequency of seropositivity and serum levels of these antibodies decreased during GFD. Moreover, we found that the decline in the serum levels was significant in all of these markers (p < 0.005). Interestingly, we also found that serum levels of ASCA correlated with the grade of mucosal morphology (p = 0.021), as the ASCA serum levels declined in accordance with mucosal healing. CONCLUSIONS: Commensal enteric bacteria seem to play a role in the small intestinal mucosal damage in CD. This was proven by the serological responses to different microbial antigens shown in this study. Serum levels of ASCA, anti-I2, and anti-OmpW antibodies decreased significantly during GFD, indicating that these serologic markers are gluten dependent in CD patients. These specificities could provide new tools in the follow-up of CD patients.

Diagnosis of leptospirosis by recombinant antigen based single serum dilution ELISA.

BACKGROUND & OBJECTIVES: Leptospirosis, a zoonosis with a worldwide distribution is an acute febrile illness caused by spirochaetes of the pathogenic Leptospira interrogans. Microscopic agglutination test (MAT), the reference method for diagnosis was successively done to evaluate the modified ELISA which was developed with the recombinant LipL32 antigen for the detection of anti-leptospiral antibodies in human serum samples. METHODS: The recombinant LipL32 antigen was developed from the serovar Pomona strain Pomona of the pathogenic L. interrogans species. The predicted titre at a single working dilution was plotted against the observed antiserum titre. Subsequently, predicted antibody activity titres were determined directly from the standard curve by solving the regression line equation. The relative sensitivity, specificity and accuracy of the single dilution ELISA for the detection of anti-leptospiral antibodies were determined in comparison to the MAT. RESULTS: A linear relationship was found between the predicted antibody titres at a single working dilution of 1:250 and the corresponding observed serum titres by the standard serial-dilution method. Regression analysis was used to determine a standard curve from which an equation was derived that allowed demonstration of the mentioned correlation. The equation was then used to convert the corrected absorbance readings of the single working dilution directly into the predicted ELISA antibody titres. A high level of sensitivity of 96 per cent and specificity of 91 per cent between ELISA and MAT titres was found. The kappa value was almost 1.0 indicating perfect agreement. INTERPRETATION & CONCLUSIONS: The r LipL32 ELISA was proved to be sensitive, specific and accurate as compared to the standard MAT and the test could be efficiently utilized as a screening test for a large number of human serum samples for the detection of leptospiral antibodies.

Outer membrane protein A expression in Escherichia coli K1 is required to prevent the maturation of myeloid dendritic cells and the induction of IL-10 and TGF-beta.

Dendritic cells (DCs) are professional APCs that direct both cellular and humoral immune responses. Escherichia coli K1 causes meningitis in neonates; however, the interactions between this pathogen and DCs have not been previously explored. In the present study, we observed that E. coli K1, expressing outer membrane protein A (OmpA), was able to enter, survive, and replicate inside DCs, whereas OmpA(-) E. coli was killed within a short period. Opsonization of OmpA(+) E. coli either with adult or cord serum did not affect its survival inside DCs. Exposure of DCs to live OmpA(+) E. coli K1 prevented DCs from progressing in their maturation process as indicated by failure to up-regulate costimulatory molecules, CD40, HLA-DR, and CD86. The distinct DC phenotype requires direct contact between live bacteria and DCs. The expression of costimulatory molecules was suppressed even after pretreatment of DCs with LPS or peptidoglycan. Furthermore, the suppressive effects of OmpA(+) E. coli on DCs were abrogated when the bacteria were incubated with anti-OmpA Ab. The inhibitory effect on DC maturation was associated with increased production of IL-10 as well as TGF-beta and decreased production of IL-6, TNF-alpha, IL-1beta, and IL-12p70 by DCs, a phenotype associated with tolerogenic DCs. These results suggest that the subversion of DC functions may be a novel strategy deployed by this pathogen to escape immune defense and persist in the infected host to reach a high degree of bacteremia, which is crucial for E. coli to cross the blood-brain barrier.

Significantly improved accuracy of diagnosis of early Lyme disease by peptide enzyme-linked immunosorbent assay based on the borreliacidal antibody epitope of Borrelia burgdorferi OspC.

Highly specific borreliacidal antibodies are induced by infection with Borrelia burgdorferi, and the immunodominant response during early Lyme disease is specific for an epitope within the 7 amino acids nearest the C terminus of OspC. We evaluated the ability of an enzyme-linked immunosorbent assay (ELISA) based on a synthetic peptide (OspC7) that matched the region to detect the response and compared the sensitivity during early Lyme disease to that for an FDA-approved Western blot. When the optical density value was adjusted to 98% specificity based on the results from testing normal or uncharacterized sera (n = 236) or sera from patients with blood factors or illnesses that commonly produce antibodies that cross-react with B. burgdorferi antigens (n = 77), 115 (73%) of 157 sera from patients likely to have early Lyme disease were positive for immunoglobulin M (IgM) antibodies and 17 (11%) also had IgG antibodies. In addition, the IgM ELISA reactivities and the titers of antibodies detected by a flow cytometric borreliacidal antibody test correlated closely (r = 0.646). Moreover, the IgM ELISA was significantly more sensitive (P < 0.001) than the Western blot procedure. The findings therefore confirmed that the peptide IgM ELISA detected OspC borreliacidal antibodies and provided strong evidence that the test can eliminate the necessity for confirming early Lyme disease by a supplementary test such as Western blotting.

Serological reactivity and biochemical characterization of methylated and unmethylated forms of a recombinant protein fragment derived from outer membrane protein B of Rickettsia typhi.

Rickettsia typhi, an obligate intracellular bacterium that causes murine typhus, possesses a heavily methylated outer membrane protein B (OmpB) antigen. This immunodominant antigen is responsible for serological reactions and is capable of eliciting protective immune responses with a guinea pig model. Western blot analysis of partially digested OmpB with patient sera revealed that most of the reactive fragments are larger than 20 kDa. One of these fragments, which is located at the N terminus (amino acids 33 to 273), fragment A (At), has been expressed in Escherichia coli. The expressed protein (rAt) was purified by chromatography and properly refolded by sequential dialysis. The refolded rAt protein was recognized by at least 87% of the typhus group patient sera as determined by enzyme-linked immunosorbent assay (ELISA). However, the titers were lower than those obtained with OmpB of R. typhi. Since native OmpB is hypermethylated at lysine residues, we chemically methylated the lysine residues in rAt. The methylation was confirmed by amino acid composition analysis, and the methylation pattern of the methylated rAt (mrAt) protein was similar to that of native At from OmpB, as revealed by liquid chromatography-mass spectrometry analysis. Both rAt and mrAt were evaluated in an ELISA for their serological reactivity with patient sera. Among patient sera tested, 83% exhibited higher titers with mrAt than with rAt. These results suggest that rAt, with or without methylation, can potentially replace rickettsia-derived OmpB or whole-cell antigen for the diagnosis of R. typhi infection.

[Sero-epidemiological study of cowdriosis in Moorish zebu cattle from Senegal]. / Etude séro-épidémiologique de la cowdriose chez le zébu maure au Sénégal.

The seroprevalence against heartwater for maure zebus coming from Mali and Mauritania is analysed by indirect ELISA using the major antigenic protein number 1-B (MAP1-B). Sero-epidemiological results realized on maure zebu cattle give a good adequation between the abundance or absence of the vector tick in the two countries for 98% of prevalence in Mali (infected area) and 0% of prevalence in Mauritania (non infected area).

Borreliacidal OspC antibody response of canines with Lyme disease differs significantly from that of humans with Lyme disease.

Humans reliably produce high concentrations of borreliacidal OspC antibodies specific for the seven C-terminal amino acids shortly after infection with Borrelia burgdorferi. We show that dogs also produce OspC borreliacidal antibodies but that their frequencies, intensities, and antigenicities differ significantly. The findings therefore confirm a major difference between the borreliacidal antibody responses of humans and canines with Lyme disease.