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.

[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.

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.

[Sero-epidemiological study of cowdriosis in Moorish zebu cattle from Senegal]

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.

Comparison of the serological responses to Moraxella catarrhalis immunoglobulin D-binding outer membrane protein and the ubiquitous surface proteins A1 and A2

Moraxella catarrhalis immunoglobulin D-binding protein (MID) is a complex antigen with unique immunoglobulin D (IgD)-binding, adhesion, and hemagglutination properties. Previous studies have shown that antibodies raised against MID764-913 in rabbits inhibited M. catarrhalis adhesion to human alveolar epithelial cells, and immunization with MID764-913 resulted in an increased pulmonary clearance in a murine model. Strong immune responses against MID have also consistently been shown in humans. Here, the MID-specified IgG responses were compared to those of ubiquitous surface proteins A1 and A2 (UspA1/A2) using a series of recombinant fragments that spanned all three proteins. Sera were obtained from young children, aged 6 months to 1 year (n=8) and 2 to 3 years (n=15), and healthy adults (n=16). Acute- and convalescent-phase sera from chronic obstructive pulmonary disease (COPD) patients with M. catarrhalis infective exacerbations (n=23) were also analyzed. Young children, who are at risk of M. catarrhalis infection, had low levels of anti-MID and anti-UspA1/A2 antibodies. Healthy adults and the majority of COPD patients (16/23) had high levels of antibodies directed against, among others, the adhesive domain of MID and the fibronectin- and C3-binding domains of UspA1/A2. Among eight COPD patients in whom a rise in antibody levels could be detected, these functional domains were also the main regions targeted by the antibodies. In addition, human IgG directed against MID was bactericidal and anti-MID antibodies were additive to antibodies targeting UspA1/A2. Hence, the functional domains in these three antigens may have significant potential in a future vaccine against M. catarrhalis.

Evaluation of a western blot method for the detection of Yersinia antibodies: evidence of serological cross-reactivity between Yersinia outer membrane proteins and Borrelia burgdorferi

Yersinia enterocolitica and Yersinia pseudotuberculosis have been identified as causative organisms of reactive arthritis in humans. We evaluated a Western blot assay which uses Yersinia outer membrane proteins as antigens for the detection of Yersinia antibodies as a replacement for the complement fixation (CF) assay. Clinical agreement, sensitivity, and specificity were determined by testing 19 positive and 21 negative serum samples by the CF assay, Western blot assay, and enzyme-linked immunosorbent assay (ELISA). The CF assay and ELISA were compared to the Western blot assay, which was the reference method used in this study. Sera with antibodies that could potentially cross-react with Yersinia were also tested by the Western blot assay. The agreement, sensitivity, and specificity of the CF method were 61%, 26%, and 95%, respectively; and those for the ELISA were 89%, 95%, and 82%, respectively. The prevalences of Yersinia antibodies in 50 healthy donors were 6% for immunoglobulin G (IgG), 2% for IgA, and 2% for IgM. Sera positive for Bartonella henselae, Brucella, Chlamydia pneumoniae, and Rickettsia rickettsii antibodies showed cross-reactivity by the Western blot assay. The highest cross-reactivity was observed with Borrelia burgdorferi; 5 of 11 (45%) specimens were cross-reactive by the IgM-specific assay. Overall, the Western blot assay performs acceptably and is more sensitive than the CF assay, warranting replacement of the CF assay in the laboratory. Due to the evidence of cross-reactivity, particularly with B. burgdorferi, which can cause an oligoarthritis similar to reactive arthritis, the diagnosis of reactive arthritis should be based on clinical findings and complete serologic analysis of the potential causative infectious pathogens.

Evaluation of PCR-based assay for diagnosis of spotted fever group rickettsiosis in human serum samples

A nested PCR assay was developed for the detection of spotted fever group (SFG) rickettsiae in serum samples. The assay was based on specific primers derived from the rickettsial outer membrane protein B gene (rompB) of Rickettsia conorii. An SFG rickettsia-specific signal is obtained from R. akari, R. japonica, R. sibirica, and R. conorii. Other bacterial species tested did not generate any signal, attesting to the specificity of the assay. As few as seven copies of the rompB gene of R. conorii could be detected in 200 microl of serum sample. The assay was evaluated with a panel of sera obtained from patients with acute-phase febrile disease tested by immunofluorescent antibody assay (IFA). The SFG rickettsia-specific DNA fragment was detected in 71 out of 100 sera, which were proven to have immunoglobulin M antibodies against SFG rickettsial antigen by IFA. The results were further confirmed by restriction fragment length polymorphism and sequencing analysis of the DNA fragments. The results indicated that this PCR assay is suitable for the diagnosis of spotted fever group rickettsiosis in Korea.

Seroprevalence of Bordetella pertussis antibodies in mothers and their newborn infants

BACKGROUND: Pertussis is a highly communicable, vaccine-preventable respiratory disease. Although the largest number of reported cases is among young infants, the most rapidly increasing incidence in the USA is in adolescents and young adults. Importantly, adult family members are the likely major reservoir, infecting susceptible infants before completion of childhood vaccination. We studied maternal-neonatal paired blood samples for the presence of pertussis-related antibodies to assess level of immunity and passive transplacental antibody passage. METHODS. Unselected maternal-neonatal cord blood samples were collected from 101 term deliveries in a single urban uninsured/underinsured hospital setting. Sera were analyzed for anti-pertussis toxin (PT), filamentous hemagglutinin (FHA) and pertactin (PRN) IgG antibodies by enzyme-linked immunosorbent assay (ELISA). Antibody titers were calculated using reference line methodology. Antibody values were log-transformed to establish geometric mean titers (GMT) for analysis. Student's t-test, Mann-Whitney, Pearson correlation and chi square were used for statistical comparisons as appropriate. RESULTS. Mean (SD) maternal age, gestational age and birth weight were 26.8 (6.8) years, 38.9 (1.4) weeks and 3239 (501) g, respectively. Detectable maternal levels of anti-PT, FHA and PRN were found in 34.7%, 95.0% and 80.2%, respectively. Maternal GMT (SD) for PT, FHA and PRN were 4.4 (2.6), 26.6 (3.1) and 12.3 (2.9), respectively. There was no significant relationship between PT, FHA or PRN detection or antibody GMT and maternal age. Maternal anti-PT, FHA and PRN were highly correlated with neonatal cord blood values. CONCLUSION: Despite previous childhood immunization, a large number of parous women have low or undetectable pertussis-related antibody levels, suggesting susceptibility to infection. Even with efficient transplacental passage of these antibodies, neonates similarly have limited measurable protection as detected by cord blood sampling. These data support the need for adolescent or adult vaccination against Bordetella pertussis. Healthcare providers and their clients should be aware of the risk for infant infection via family member transmission.

Bacterial peptidoglycan-associated lipoprotein: a naturally occurring toll-like receptor 2 agonist that is shed into serum and has synergy with lipopolysaccharide

Sepsis is initiated by interactions between microbial products and host inflammatory cells. Toll-like receptors (TLRs) are central innate immune mediators of sepsis that recognize different components of microorganisms. Peptidoglycan-associated lipoprotein (PAL) is a ubiquitous gram-negative bacterial outer-membrane protein that is shed by bacteria into the circulation of septic animals. We explored the inflammatory effects of purified PAL and of a naturally occurring form of PAL that is shed into serum. PAL is released into human serum by Escherichia coli bacteria in a form that induces cytokine production by macrophages and is tightly associated with lipopolysaccharide (LPS). PAL activates inflammation through TLR2. PAL and LPS synergistically activate macrophages. These data suggest that PAL may play an important role in the pathogenesis of sepsis and imply that physiologically relevant PAL and LPS are shed into serum and act in concert to initiate inflammation in sepsis.

The Emerging PathogenMoraxella catarrhalisInteracts with Complement Inhibitor C4b Binding Protein through Ubiquitous Surface Proteins A1 and A2

Moraxella catarrhalis ubiquitous surface protein A2 (UspA2) mediates resistance to the bactericidal activity of normal human serum. In this study, an interaction between the complement fluid phase regulator of the classical pathway, C4b binding protein (C4BP), and M. catarrhalis mutants lacking UspA1 and/or UspA2 was analyzed by flow cytometry and a RIA. Two clinical isolates of M. catarrhalis expressed UspA2 at a higher density than UspA1. The UspA1 mutants showed a decreased C4BP binding (37.6% reduction), whereas the UspA2-deficient Moraxella mutants displayed a strongly reduced (94.6%) C4BP binding compared with the wild type. In addition, experiments with recombinantly expressed UspA1(50-770) and UspA2(30-539) showed that C4BP (range, 1-1000 nM) bound to the two proteins in a dose-dependent manner. The equilibrium constants (K(D)) for the UspA1(50-770) and UspA2(30-539) interactions with a single subunit of C4BP were 13 microM and 1.1 microM, respectively. The main isoform of C4BP contains seven identical alpha-chains and one beta-chain linked together with disulfide bridges, and the alpha-chains contain eight complement control protein (CCP) modules. The UspA1 and A2 bound to the alpha-chain of C4BP, and experiments with C4BP lacking CCP2, CCP5, or CCP7 showed that these three CCPs were important for the Usp binding. Importantly, C4BP bound to the surface of M. catarrhalis retained its cofactor activity as determined by analysis of C4b degradation. Taken together, M. catarrhalis interferes with the classical complement activation pathway by binding C4BP to UspA1 and UspA2.

Laboratory diagnosis of two scrub typhus outbreaks at Camp Fuji, Japan in 2000 and 2001 by enzyme-linked immunosorbent assay, rapid flow assay, and Western blot assay using outer membrane 56-kD recombinant proteins

Two scrub typhus outbreaks occurred among U.S. Marines training at Camp Fuji, Japan, between October 25 and November 3, 2000 and October 17 and November 30, 2001. Nine cases in approximately 800 Marines in 2000 and eight cases in approximately 900 Marines in 2001 (approximate attack rates = 1.1% and 0.9%, respectively) reported with signs and symptoms of fever, rash, headache, lymphadenopathy, myalgia, and eschar. Serologies and rapid response to doxycycline treatment indicated they had scrub typhus. Sixty-four convalescent serum samples (18 suspected cases and 46 negative controls) from U.S. Marines training at Camp Fuji during the outbreaks were assessed by enzyme-linked immunosorbent assay (ELISA), rapid flow assay (RFA), and Western blot assay for evidence of infection with Orientia tsutsugamushi, the causative agent of scrub typhus. All but one suspected case had serologic evidence of scrub typhus and all 46 control sera were non-reactive to O. tsutsugamushi antigens. The recombinant 56-kD antigen (r56) from the Karp, Kato and Gilliam strains of O. tsutsugamushi in an ELISA format provided better results than Karp r56 alone (ELISA and RFA) or whole cell antigen preparation from Karp, Kato and Gilliam (ELISA).

Study and treatment of post Lyme disease (STOP-LD): a randomized double masked clinical trial

OBJECTIVE

To determine whether post Lyme syndrome (PLS) is antibiotic responsive.

METHODS

The authors conducted a single-center randomized double-masked placebo-controlled trial on 55 patients with Lyme disease with persistent severe fatigue at least 6 or more months after antibiotic therapy. Patients were randomly assigned to receive 28 days of IV ceftriaxone or placebo. The primary clinical outcomes were improvement in fatigue, defined by a change of 0.7 points or more on an 11-item fatigue questionnaire, and improvement in cognitive function (mental speed), defined by a change of 25% or more on a test of reaction time. The primary laboratory outcome was an experimental measure of CSF infection, outer surface protein A (OspA). Outcome data were collected at the 6-month visit.

RESULTS

Patients assigned to ceftriaxone showed improvement in disabling fatigue compared to the placebo group (rate ratio, 3.5; 95% CI, 1.50 to 8.03; p = 0.001). No beneficial treatment effect was observed for cognitive function or the laboratory measure of persistent infection. Four patients, three of whom were on placebo, had adverse events associated with treatment, which required hospitalization.

CONCLUSIONS

Ceftriaxone therapy in patients with PLS with severe fatigue was associated with an improvement in fatigue but not with cognitive function or an experimental laboratory measure of infection in this study. Because fatigue (a nonspecific symptom) was the only outcome that improved and because treatment was associated with adverse events, this study does not support the use of additional antibiotic therapy with parenteral ceftriaxone in post-treatment, persistently fatigued patients with PLS.

Outer membrane protein A (OmpA), peptidoglycan-associated lipoprotein (PAL), and murein lipoprotein (MLP) are released in experimental Gram-negative sepsis

We previously showed that Escherichia coli bacteria incubated in normal human serum release complexes that contain three conserved Gram-negative bacterial outer membrane proteins (OMPs) and LPS. We have identified the OMPs as outer membrane protein A (OmpA), peptidoglycan-associated lipoprotein (PAL), and murein lipoprotein (MLP). These OMPs are conserved among enteric Gram-negative bacteria and are bound by IgG in antisera raised to heat-killed rough bacteria such as E. coli J5 (J5 IgG). The present experiments were performed to further analyze the release of these OMPs in a rat wound infection model of sepsis. Plasma was collected from thermally injured rats with E. coli O18 sepsis and filtered. LPS was affinity-purified from plasma filtrates using monoclonal antibody specific for the O-polysaccharide side chain of E. coli O18 LPS. Plasma filtrates were also incubated with J5 IgG conjugated to magnetic beads. Affinity-purified samples were analyzed for the OMPs by immunoblotting. OmpA, PAL, and MLP were released into septic rat blood in complexes with LPS. PAL was consistently present in samples affinity-purified using J5 IgG. The results indicate that OmpA, PAL, and MLP are released and circulate in experimental Gram-negative sepsis and suggest that a proportion of released OMPs are tightly associated with LPS.

Release of gram-negative outer-membrane proteins into human serum and septic rat blood and their interactions with immunoglobulin in antiserum to Escherichia coli J5

Prior studies indicate that 3 bacterial outer-membrane proteins (OMPs) are released into serum associated with lipopolysaccharide (LPS) and are bound by IgG in antiserum to Escherichia coli J5 (anti-J5 IgG). The present studies analyzed the interaction of the OMPs with anti-J5 IgG and evaluated their release in an infected burn model of gram-negative sepsis. Affinity purification studies were performed on filtrates of bacteria incubated in human serum and plasma from rats with sepsis by use of O chain-specific anti-LPS IgG and anti-J5 IgG. All 3 OMPs were captured from septic rat blood by anti-LPS IgG. Release of OMPs into serum was highest for immature bacterial cultures and was increased by antibiotics in vitro and in vivo. Anti-J5 IgG selectively captured an 18-kDa OMP released into serum and into plasma from septic rats. The results raise the possibility that anti-J5 IgG may, in part, protect via anti-OMP antibodies.

[Homeostasis of small molecules originating from microbes and its role in microbial relations with the host]

It is suggested that disorders at the low molecular levels--at the level of small molecules originating from microbes (SMOM) underlie nonspecific pyoinflammatory diseases and decompensation of SMOM homeostatic disorders in the human blood plays a certain role in the complex multifactorial pathogenesis of sepsis. The blood from 16 donors showed fatty acids (hydroxy acids, branched, short-chain, unsaturated, cyclopropanic acids), aldehydes, alcohols, and phenylcarbolic compounds which are not produced by mammalian cells and which are structural components or microbial metabolites. That from 59 patients with various diseases (peritonitis, endocarditis, urinary tract infection, etc.) displayed a reduction or a complete disappearance of only small molecules which are as part of the endogenous microflora and, concomitantly, a 100-fold increase or more in other molecules, and the emergence of new SMOM lacking in the donor blood. The findings yield a concept that there is the homeostasis of small molecules originating from microbes, whose severe disorders (SMOM homeostatic decompensation) are likely to be a first link in the genesis of a systemic inflammatory response, in the development of septic shock and multiorgan failure.

Characterization of VspB of Borrelia turicatae, a major outer membrane protein expressed in blood and tissues of mice

Serotypes A and B of the relapsing fever spirochete Borrelia turicatae produce different disease manifestations in infected mice. Whereas serotype B causes more severe arthritis and reaches higher densities in the blood of mice than serotype A, serotype A invades the central nervous system earlier than serotype B during infection. These differences between serotypes A and B in mice are associated with the expression of different surface proteins, VspA and VspB, respectively, in the culture medium. To determine whether these proteins, in particular, VspB, are also expressed in vivo, scid mice infected with B. turicatae were studied. The expression of VspB by spirochetes in the blood was demonstrated in Coomassie blue-stained polyacrylamide gels and Western blots with a specific monoclonal antibody. Indirect immunofluorescence and immunoperoxidase studies confirmed the expression of VspB in the blood and also demonstrated VspB expression in the joints and heart. The gene for VspB was next identified and cloned by using partial amino acid sequencing, reverse transcriptase PCR, and a specific monoclonal antibody. The vspB gene encodes a protein of 216 amino acids that is 68% identical to VspA of B. turicatae and 44 to 56% identical to representative Vsp and OspC lipoproteins of other Borrelia spp. The processed VspB protein was distinguished from 26 other Vsp and OspC proteins by a high predicted isoelectric point at 9.39. The promoter region for vspB was similar to the promoter region for the vsp33 gene of Borrelia hermsii and for the ospC gene of Borrelia burgdorferi, two genes known to be environmentally regulated. These studies established that the virulence-associated VspB protein is expressed by spirochetes in the mouse and that VspB is a novel member of the Vsp-OspC family of proteins.

Strain- and growth condition-dependent variability in outer membrane protein expression by Bordetella bronchiseptica isolates from dogs

OBJECTIVE

To characterize strain-dependent and growth condition-dependent variability in outer membrane protein (OMP) expression of Bordetella bronchiseptica isolates from dogs and evaluate the systemic immune response to OMP of B bronchiseptica among infected dogs.

SAMPLE POPULATION

8 strains of B bronchiseptica isolated from dogs, including a historic reference strain, 2 commercially available vaccine strains, and 5 field strains, and serum samples collected from 3 specific-pathogen-free (SPF) dogs before and 1 month after infection with B bronchiseptica.

PROCEDURE

OMP were isolated from cultures in the late exponential phase of growth and compared among strains and, within strains, among growth conditions by means of polyacrylamide gel electrophoresis and immunoblotting. Serum samples were probed with OMP from 1 of the field strains.

RESULTS

Strain-dependent variability in OMP profiles and growth condition-dependent and strain-dependent variability in expression of filamentous hemagglutinin (FHA) and pertactin was found, along with heterogeneity of the pertactin proteins produced by these B bronchiseptica strains. All 3 SPF dogs seroconverted to proteins with estimated molecular masses of 200 and 66 kDa, suggesting that FHA and pertactin were involved in the immunologic response of these dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that there is growth condition and strain variability in expression of OMP, FHA, and pertactin proteins produced by B bronchiseptica. This information could be useful in the improvement of vaccines for prevention of bordetellosis in dogs.

Correlation of immunity in experimental syphilis with serum-mediated aggregation of Treponema pallidum rare outer membrane proteins

We have previously shown by freeze-fracture electron microscopy that serum from infection-immune syphilitic rabbits aggregates the low-density membrane-spanning Treponema pallidum rare outer membrane proteins (TROMPs). The purpose of this study was to determine if a relationship could be demonstrated between acquired immunity in experimental rabbit syphilis, serum complement-dependent treponemicidal antibody, and antibody directed against TROMPs as measured by the aggregation of TROMP particles. Three groups of T. pallidum-infected rabbits were treated curatively with penicillin at 9 days, 30 days, and 6 months postinfection to generate various degrees of immunity to challenge reinfection. Sera from rabbits completely susceptible to localized and disseminated reinfection possessed a low titer of treponemicidal antibody (</=1:1 in killing >/=50% of a treponemal suspension) and showed a correspondingly low level of TROMP aggregation (16.5% of the total number of outer membrane particles counted) similar to normal serum controls (13. 4%); the number of particles within these aggregates never exceeded three. Sera from partially immune rabbits, which were susceptible to local reinfection but had no evidence of dissemination, showed an increase in the titer of treponemicidal antibody (1:16) compared to the completely susceptible group (</=1:1). Although no significant increase was observed in the total number of TROMP particles aggregated (18.9%) compared to the number in controls (13.4%), approximately 15% of these aggregates did exhibit a significant increase in the number of particles per aggregate (4 to 5 particles) compared to controls (</=3 particles), indicating a measurable increase in anti-TROMP antibody. Finally, sera from rabbits completely immune to both local and disseminated reinfection possessed both high titers of treponemicidal antibody (1:128) and significant aggregation of TROMP (88.6%); approximately 50% of these aggregates contained four to six particles. The results indicate that complete immunity in experimental rabbit syphilis correlates with antibody that kills T. pallidum and aggregates TROMPs, suggesting that TROMPs are molecules which contribute to the development of acquired immunity.

[The clinico-pathogenetic significance of the outer membrane proteins determined by the invasiveness plasmid in Flexner's shigellosis]

S. flexneri 2a outer membrane proteins of 38, 43, 62 and 78 kD, determined by the 140 mD invasiveness plasmid, serving as antigens and specific rabbit sera serving as antibodies were used for diagnosing S. flexneri infection in the enzyme immunoassay. The examination of 96 patients and 20 healthy donors showed the possibility of the detection of S. flexneri 2a protein invasins and antibodies to them at different periods of the disease. During the severe course of shigellosis a higher level of protein invasins in the blood serum of patients was established in comparison with that observed during the medium severe course. An elevated level of protein invasins in the blood serum was accompanied by a lower content of specific antibodies to them, which was probably due to the immunosuppressive action of the invasiveness plasmid, established in earlier experiments.

Humoral immune response to membrane components of Chlamydia trachomatis and expression of human 60 kDa heat shock protein in follicular fluid of in-vitro fertilization patients

Recent evidence suggests that Chlamydia trachomatis can persist in the female upper genital tract in an unculturable state. Since unsuspected C. trachomatis infection has been associated with adverse in-vitro fertilization (IVF) outcome we sought to detect further evidence of C. trachomatis in the genital tracts of women undergoing IVF. The prevalence and distribution of antibodies to the major structural proteins of C. trachomatis in paired follicular fluid and sera of women undergoing IVF were examined. Sera and follicular fluid samples from 149 women were assayed for immunoglobulin (Ig)G and IgA antibodies to two C. trachomatis antigens, the major outer membrane protein (MOMP) and a recombinant lipopolysaccharide (rLPS) fragment. Additionally, the expression of human 60 kDa heat shock protein (hsp 60) in follicular fluid was determined. All cervical and follicular fluid samples were negative for C. trachomatis by polymerase chain reaction, ligase chain reaction and DNA probe. Sera from 60% of the subjects were positive for antichlamydial rLPS IgG; 36% were positive for anti-MOMP IgG. Similarly, rLPS-directed and MOMP-directed IgA were detected in sera of 34 and 14% of the subjects respectively. IgG antibodies to MOMP and rLPS were detected in 42 and 41% of the follicular fluid examined respectively. Anti-MOMP IgA was identified in 8.7% of the follicular fluid while 27.5% were positive for anti-rLPS IgA. Human hsp 60 expression was documented in 11.6% of the follicular fluid tested. IgA antibodies to both MOMP (P = 0.03) and rLPS (P = 0.02) in follicular fluid were associated with a failure to become pregnant after embryo transfer. IgG antibodies in sera and follicular fluid and IgA antibodies in sera were unrelated to IVF outcome. Similarly only anti-MOMP IgA (P = 0.02) and anti-rLPS IgA (P = 0.04) in follicular fluid were correlated with human hsp 60 expression in follicular fluid. The unique association between IgA antibodies to two chlamydial antigens in follicular fluid and both hsp 60 expression and IVF failure provides further support for the possibility that a persistent upper genital tract chlamydial infection contributes to IVF failure in some women.

A search for cholera toxin (CT), toxin coregulated pilus (TCP), the regulatory element ToxR and other virulence factors in non-01/non-0139 Vibrio cholerae

Twenty-four selected non-O1/non-O139 Vibrio cholerae strains were examined for the presence of virulence associated genes like ctxA, tcpA, toxR and the repetitive sequence (RS element). Seventeen of these were isolated from diarrhoeal stool samples while the remaining seven were of local environmental origin. Nine and four respectively of these strains were positive for ctxA and tcpA by Multiplex PCR analysis. The majority (16 out of 18 tested) of the strains (including the four tcpA + strains) contained toxR sequences as determined by another PCR assay. The presence of RS element was demonstrable in ctxA+ strains only. Interestingly, three of these non-O1/non-O139 strains were shown to contain all the three virulence associated genes (ctxA, tcpA and toxR) as well as the RS element. Two of these belonged to serogroups 037 (V2) and 064 (CG15) while the third one (V315-1) was untypable. These three strains also produced cholera toxin, expressed toxin coregulated pilus (TCP) and/or TcpA related antigens when grown under appropriate culture conditions. Southern hybridization analysis of their chromosomal DNA fragments using DNA probes representing ctxA, zot, ace and RS element revealed that the strains V2 and CG15 contained, at least, two complete copies of the CTX genetic element, while the strain V315-1 had three or more copies of the same. Presence of the RS element in these strains led to tandem duplication of the CTX genetic element in the chromosome of V2 and V315-1, but not in CG15 where the copies were likely to be present at different loci. These results also indicate the presence of additional copies of incomplete "core region' with zot and ace genes, but not ctxA, in strains V2 and CG15. The significance of these results in terms of the pathogenic and epidemic potential of V. cholerae strains is discussed.

Antigens for serological diagnosis of ovine footrot

An antigen extracted from Dichelobacter nodosus with potassium thiocyanate (KSCN) is currently used in enzyme-linked immunosorbent assay (ELISA) for serological diagnosis of ovine footrot, but the test lacks specificity in mature sheep. Other antigens were therefore evaluated for use in this test. Structural components of the cell envelope of D. nodosus including outer membrane, cytoplasmic membrane, lipopolysaccharide and pilus and extracellular proteases were purified from cultured D. nodosus while recombinant membrane proteins, protease and pilus antigens were also evaluated. Many antigenic components of D. nodosus participated in reactions in ELISA that were not specific for infection with D. nodosus and apart from pilus, none of the antigens resulted in improved specificity of the ELISA. Using a positive-negative cut-off to yield sensitivity of 70%, ELISA using pili from cultured D. nodosus serogroup A had a specificity of 98.3% compared with 89.7% for the ELISA with KSCN-extract as antigen (P < 0.001). Recombinant pili morphogenetically expressed in Pseudomonas aeruginosa were unsuitable for use in ELISA due to copurification of Pseudomonas antigens to which apparently healthy sheep directed antibodies. The application of ELISA with D. nodosus pilus as antigen in footrot control programs is discussed.

Selection of Opa+ Neisseria gonorrhoeae by limited availability of normal human serum

Experimental infections of human male volunteers with Neisseria gonorrhoeae have provided valuable insights into the early stages of gonorrheal disease. Bacterial variants expressing outer membrane opacity (Opa) proteins appear to be selected from the inoculum during a period in which total recoverable numbers of bacteria decrease rapidly. This apparent survival advantage occurs simultaneously with the onset of an inflammatory response, characterized by local production of interleukin 6 (IL-6) and IL-8 and the appearance of leukocytes in urine. Since the inflammatory response may also result in the presence of serum factors on the mucosal surface, we investigated the possibility that killing in normal human serum (NHS) leads to the selection of Opa+ variants. We therefore studied killing of separate populations and mixtures of Opa- and Opa+ N. gonorrhoeae MS11mk in NHS. Expression of an Opa protein conferred a survival advantage upon the organism; i.e., the Opa+ variants were more serum resistant than their isogenic Opa- counterparts, resulting in a selection for Opa+ phenotypes when a mixture of Opa+ and Opa- gonococci (GC) was exposed to submaximal doses of NHS. This selection was observed in three different lipooligosaccharide (LOS) backgrounds, indicating that it was not due to a difference in LOS expression between Opa- and Opa+ phenotypes. Incubation in NHS of sialylated GC resulted in a similar selection for Opa+ variants. The presence of normal human urine during the serum killing assay had no effect on the selection phenomenon but drastically depleted NHS of bactericidal activity, which was found to be at least partly due to complement inhibition. The results suggest that serum killing may contribute to the transition from Opa- to Opa+ phenotypes during the early stages of infection of the male urethra.

Use of a specific immunogenic region on the Cowdria ruminantium MAP1 protein in a serological assay

Currently available serological tests for cowdriosis (Cowdria ruminantium infection) in domestic ruminants are hampered by their low specificities because of cross-reactivity with Ehrlichia spp. The use of recombinant major antigenic protein (MAP1) of C. ruminantium for serodiagnosis was investigated. Overlapping fragments of the MAP1 protein were expressed in Escherichia coli and were reacted with sera from sheep infected with either C. ruminantium or Ehrlichia ovina. Two immunogenic regions on the MAP1 protein, designated MAP1-A and MAP1-B, were identified. MAP1-A was reactive with C. ruminantium antisera, E. ovina antisera, and three MAP1-specific monoclonal antibodies, whereas MAP1-B reacted only with C. ruminantium antisera. An indirect enzyme-linked immunosorbent assay (ELISA) based on MAP1-B was further developed and validated with sera from animals experimentally infected with C. ruminantium or several Ehrlichia spp. Antibodies raised in sheep, cattle, and goats against nine isolates of C. ruminantium reacted with MAP1-B. Cross-reactivity with MAP1-B was limited to Ehrlichia canis and Ehrlichia chaffeensis, two rickettsias which do not infect ruminants. Antibodies to Ehrlichia spp. which do infect ruminants (E. bovis, E. ovina, and E. phagocytophila) did not react with MAP1-B. Antibody titers to C. ruminantium in sera from experimentally infected cattle, goats, and sheep were detectable for 50 to 200 days postinfection. Further validation of the recombinant MAP1-B-based ELISA was done with sera obtained from sheep raised in heartwater-free areas in Zimbabwe and from several Caribbean islands. A total of 159 of 169 samples which were considered to be false positive by immunoblotting or indirect ELISA did not react with MAP1-B. In conclusion, recombinant MAP1-B may be a suitable antigen for a sensitive serological test for cowdriosis, with dramatically improved specificity.

Serologic studies of experimentally induced Salmonella choleraesuis var kunzendorf infection in pigs

Two indirect ELISA containing outer membrane protein (OMP) and lipopolysaccharide (LPS) antigens from a field isolate of Salmonella choleraesuis var kunzendorf were developed and evaluated in experimentally infected and uninfected control pigs. Experimentally induced infection with S choleraesuis was successfully established in 10 pigs by oral inoculation with 10(8) organisms, and 3 pigs died of clinical salmonellosis at postinoculation (PI) weeks 1, 2, and 4. Swab specimens from tonsils, nostrils, and rectum of pigs were obtained for culture, and sera were evaluated at weekly intervals for 9 weeks after inoculation. The ELISA containing OMP and LPS antigens with either anti-swine IgG or protein albumin-to-globulin ratio (antiglobulin) conjugates were standardized for serologic evaluation. All 4 ELISA (2 OMP and 2 LPS) detected seroconversion by PI week 3 and had sensitivities and specificities of 97.8 and 88.8, 100 and 100, 95.6 and 88.8, and 93.3 and 72.5%, at their ideal cutoff points (negative mean optical density +2 SD). There was excellent agreement between all 4 ELISA systems as determined by kappa values. Cultures of fecal, tonsil, and nasal swab specimens were positive for S choleraesuis until the fourth week of infection. Fecal swab specimens from 1 pig were positive for S choleraesuis until PI week 7. Persistent infection after antemortem culture results were negative was detected by all 4 ELISA, which indicated consistently high titers until the end of PI week 9.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of recombinant OspC from Borrelia burgdorferi for serodiagnosis of early Lyme disease

Infection with Borrelia burgdorferi, the etiologic agent of Lyme disease, is associated with an early and dominant humoral response to the spirochete's 23-kDa outer surface protein C (OspC). We have cloned and expressed OspC as a fusion protein in Escherichia coli and have shown that patient serum samples react with it in an enzyme-linked immunosorbent assay (ELISA) (S. J. Padula, A. Sampieri, F. Dias, A. Szczepanski, and R. W. Ryan, Infect. Immun. 61:5097-5105, 1993). Now we have compared the detection of B. burgdorferi-specific immunoglobulin M antibodies in 74 individuals with culture-positive erythema migrans by a whole-cell ELISA, immunoblot, and the recombinant OspC (rOspC) ELISA. Seventy-six negative controls were also studied. With all of the tests, there was a statistically significant association between the duration of disease and the frequency of a positive result. With the rOspC ELISA, the predictive value of a positive test was 100% and the predictive value of a negative test was 74%. Similar results were obtained with the whole-cell ELISA and with the immunoblot using as the source of test antigen a strain of B. burgdorferi which expresses abundant levels of OspC. We conclude that the use of rOspC in an ELISA is a convenient, readily automated, and easily standardized test for the serodiagnosis of early Lyme disease.

Molecular analysis of the glpFKX regions of Escherichia coli and Shigella flexneri

We have identified a new gene, glpX, belonging to the glp regulon of Escherichia coli, located directly downstream of the glpK gene. The transcription of glpX is inducible with glycerol and sn-glycerol-3-phosphate and is constitutive in a glpR mutant. glpX is the third gene in the glpFKX operon. The function of GlpX remains unknown. GlpX has an apparent molecular weight of 40,000 on sodium dodecyl sulfate-polyacrylamide gels. In addition to determining the E. coli glpX sequence, we also sequenced the corresponding glpFKX region originating from Shigella flexneri, which after transfer into E. coli was instrumental in elucidating the function of glpF in glycerol transport (D. P. Richey and E. C. C. Lin, J. Bacteriol. 112:784-790, 1972). Sequencing of the glpFKX region of this hybrid strain revealed an amber mutation instead of the tryptophan 215 codon in glpF. The most striking difference between the E. coli and S. flexneri DNA was found directly behind glpK, where two repetitive (REP) sequences were present in S. flexneri, but not in the E. coli sequence. The presence or absence of these REP sequences had no effect on transport or on growth on glycerol. Not including the REP sequence-containing region, only 1.1% of a total of 2,167 bp sequenced was different in the two sequences. Comparison of the sequence with those in the EMBL data library revealed a 99% identity between the last third of glpX and the first part of a gene called mvrA. We show that the cloned mvrA gene (M. Morimyo, J. Bacteriol. 170:2136-2142, 1988) originated from the 88-min region of the Escherichia coli chromosome and not, as reported, from the 7-min region and that the gene product identified as MvrA is in fact encoded by a gene distal to glpX.

The interaction of naturally elaborated blebs from serum-susceptible and serum-resistant strains of Neisseria gonorrhoeae with normal human serum

We studied the interaction of normal human serum immunoglobulins with outer-membrane bleb antigens of Neisseria gonorrhoeae. Gonococcal 68,000 Dalton and Lip (H.8 antigen) outer-membrane proteins were recognized by normal human serum immunoglobulins in blebs from serum-resistant strains, but not in blebs from serum-susceptible strains. The addition of blebs from a serum-resistant strain to bactericidal assays resulted in significantly greater inhibition of serum killing than the addition of blebs from a serum-susceptible strain. Our results indicate that blebs from two serum-resistant gonococcal strains have an enhanced ability to bind and remove cell-targeted bactericidal factors, and that outer-membrane blebbing may contribute to serum resistance.

Characterization of naturally elaborated blebs from serum-susceptible and serum-resistant strains of Neisseria gonorrhoeae

Outer-membrane blebs from two serum-susceptible and two serum-resistant strains of Neisseria gonorrhoeae were characterized. In general, bleb surfaces resembled cell surfaces, but there were qualitative and quantitative protein differences in blebs released by serum-susceptible and serum-resistant strains. Relative to blebs from serum-resistant strains, blebs from serum-susceptible strains expressed reduced amounts of major outer-membrane proteins I and III, and little if any 68,000 Dalton outer-membrane protein.

[Studies on human porin. V. The expression of "porin31HL" in the plasmalemma is not by cell transformation]

In recent papers we proved "Porin 31HL" to be located on the surface of human, EBV-transformed B lymphocytes. Here we present proof of "Porin 31HL" in the plasmalemma of normal human blood lymphocytes. For this purpose B and T lymphocytes were isolated from human heparinized blood and examined by indirect immunofluorescence techniques using different monoclonal antibodies against purified "Porin 31HL" and some B and T cell markers, respectively. For comparison a number of established cell lines of different origin were employed. Hence it followed that normal B and T cells as well as transformed and leukemic cells express "Porin 31HL" in their membrane. No significant quantitative differences could be seen. Consequently, the location of "Porin 31HL" in the plasmalemma is not a product of transformation.