Vi Antibody Research Articles

Detecting Residual Chronic Salmonella Typhi Carriers on the Road to Typhoid Elimination in Santiago, Chile, 2017-2019.

In Santiago, Chile, where typhoid had been hyperendemic (1977-1991), we investigated whether residual chronic carriers could be detected among household contacts of non-travel-related typhoid cases occurring during 2017-2019. Culture-confirmed cases were classified as autochthonous (domestically acquired) versus travel/immigration related. Household contacts of cases had stool cultures and serum Vi antibody measurements to detect chronic Salmonella Typhi carriers. Whole genome sequences of acute cases and their epidemiologically linked chronic carrier isolates were compared. Five of 16 autochthonous typhoid cases (31.3%) were linked to 4 chronic carriers in case households; 2 cases (onsets 23 months apart) were linked to the same carrier. Carriers were women aged 69-79 years with gallbladder dysfunction and Typhi fecal excretion; 3 had highly elevated serum anti-Vi titers. Genomic analyses revealed close identity (≤11 core genome single-nucleotide polymorphism [SNP] differences) between case and epidemiologically linked carrier isolates; all were genotypes prevalent in 1980s Santiago. A cluster of 4 additional autochthonous cases unlinked to a carrier was identified based on genomic identity (0-1 SNPs). Travel/immigration isolate genotypes were typical for the countries of travel/immigration. Although autochthonous typhoid cases in Santiago are currently rare, 5 of 16 such cases (31.3%) were linked to elderly chronic carriers identified among household contacts of cases.

Aging and the Impact of Solar Ultraviolet Radiation on the Expression of Type I and Type VI Collagen

Both endogenous and exogenous factors cause skin aging. This study aimed to compare the differential expressions of collagen type I (COL I) and collagen type VI (COL VI) in skins with biological aging and photoaging. In order to comprehend the impact of solar radiation in the dermis and the expression of COL I and COL VI, we studied the expression and their detection in healthy skin and in skin that had been characterized by aging. The hematoxylin and eosin staining protocol was performed in tissue paraffin blocks and they were then stained immunohistochemically with rabbit monoclonal anti-COL I and anti-COL VI antibodies. A total of 201 slides were studied with an Olympus BX 41 microscope, and the expressions of COL I and COL VI in the dermis were scored on a scale of 1 to 5, and then positively and statistically analyzed with IBM SPSS Statistics software. The results show that solar elastosis changes the structure of the skin’s collagen and solar elastosis was observed in the skin tissues with photoaging without appearing to be affected by its appearance in relation to age. Solar radiation divides the collagen fibers more rapidly than normal biological aging and replaces the collagen fibers of the skin. COL I and COL VI are expressed differently along the dermis of healthy skin tissue and the skin tissue subject to photoaging.

A typhoid fever protein capsular matrix vaccine candidate formulated with Advax-CpG adjuvant induces a robust and durable anti-typhoid Vi polysaccharide antibody response in mice, rabbits and nonhuman primates

Typhax is an investigational typhoid fever vaccine candidate that is comprised of Vi polysaccharide from Salmonella enterica serovar typhi (S. Typhi) non-covalently entrapped in a glutaraldehyde catalyzed, cross-linked α-poly-L-lysine and CRM197 protein matrix. A previous Phase 1 trial of an aluminum phosphate adjuvanted Typhax formulation showed it induced Vi IgG after a single dose but that subsequent doses failed to further boost Vi IgG levels. The current study asked whether Advax-CpG adjuvant might instead be able to overcome polysaccharide-induced immune inhibition and improve Typhax immunogenicity. Advax-CpG adjuvanted Typhax elicited high and sustained Vi IgG responses in mice, rabbits and non-human primates (NHP) with levels being boosted by repeated immunization. High Vi antibody responses were lost in CD4 + T cell depleted mice confirming that despite the lack of conjugation of the polysaccharide to the carrier protein, Typhax nevertheless acts in a T cell dependent manner, explaining its ability to induce long-term B cell memory responses to Vi capable of being boosted. In NHP, Advax-CpG adjuvanted Typhax induced up to 100-fold higher Vi IgG levels than the commercial Typhim Vi polysaccharide vaccine. Typhax induced high and sustained serum bactericidal activity against S. Typhi and stimulated robust Vi IgG responses even in animals previously primed with a pure polysaccharide vaccine. Hence Advax-CpG adjuvanted Typhax vaccine is a highly promising candidate to provide robust and durable protection against typhoid fever.

Persistence of Antibody After a Vi-Tetanus Toxoid Conjugate Vaccine and Effect of Boosting With a Plain Polysaccharide Vaccine on Vi Antibody and Antigen-Specific B Cells

BackgroundSalmonella enterica serovar Typhi is estimated to cause 9 to 13 million cases of typhoid fever annually. Typhoid conjugate vaccines represent a promising prophylactic measure to prevent disease, but there are few data assessing persistence of immunity. The effect of a Vi polysaccharide booster vaccine in individuals previously vaccinated with the Vi-tetanus toxoid typhoid conjugate vaccine has not been assessed previously.MethodsThirty five healthy adult volunteers received a single dose of the Vi conjugate vaccine (Vi-TT) and 37 received a single dose of Vi polysaccharide vaccine (Vi-PS) prior to oral challenge with live S. Typhi bacteria as part of a randomised controlled, phase 2b study. In addition to data previously published showing persistence of Vi IgG and IgA antibodies for 7 months after Vi vaccination, titres were measured at intervals until 13 months post-vaccination. Ten participants who received Vi-TT (both challenged and unchallenged) were re-vaccinated with Vi-PS at an interval of 19-23 months post-prime. Anti-Vi IgG and IgA titres, and Vi-specific antibody secreting cells and memory B cells were measured at seven days and one month post-boost.FindingsVi IgG and IgA antibody titres remained significantly elevated above baseline levels 13 months after priming with Vi-TT, with a 4-fold rise retained in 90% and 88% of recipients (Vi IgG and IgA, respectively). Anti-Vi IgG and IgA antibody titres were found to persist at higher levels in participants who received a single dose of Vi-TT than in those who received Vi-PS. No significant boost in Vi-antibody titre was observed in response to oral challenge with S. Typhi bacteria, one month after vaccination. Following a Vi-PS booster vaccination in those previously vaccinated with Vi-TT, anti-Vi IgG and IgA titres were significantly elevated, with similar titres observed at one month post-boost compared with one month after primary vaccination. The frequency of Vi-specific IgA antibody secreting cells increased significantly 7 days post-boost compared with pre-boost. No memory B cell response was observed following Vi-PS booster vaccination.InterpretationStrong persistence of anti-Vi IgG and IgA following Vi-TT vaccination suggests that the conjugate vaccine may offer durable protection, supporting its use in endemic settings.

Roles of Salmonella typhi and Salmonella paratyphi in Gallbladder Cancer Development.

Background:Typhoid (Salmonella typhi and paratyphi) carriers and gall bladder cancer (GBC) are endemic in northern India. Results of previous studies about association of typhoid carriers with GBC are inconsistent. We studied antibodies against Salmonella typhi and paratyphi in serum samples of patients with GBC. Methods:We performed modified Widal test for antibodies against Salmonella typhi (Vi and O) and Salmonella paratyphi (AO and BO) antigens in patients with GBC (n=100), xanthogranulomatous cholecystitis (XGC, n=24), chronic cholecystitis (CC, n=200) and healthy controls (HC, n=200). Results: Serum antibodies against Salmonella were more frequently positive in GBC (22%) and XGC (29%), particularly in males in age ≥50 years (GBC: 47% and XGC: 50%) vs. HC (0) (P<0.01). Vi antibody was more common in GBC (13%, OR:9.8) and XGC (8%, OR:5.9) than HC (2%). O antibody was more common in GBC (8%, OR: 8.6) and XGC (8%, OR: 9.0) than HC (1%). O antibody was also more common in males with GBC (12%) than CC (1%) and HC (1%) (P=0.02 and P<0.001, respectively). AO (6%) and BO (4%) antibodies were detected in GBC, particularly in males, than HC (0), (P<0.01). Salmonella antibodies were more frequent in GBC with GS than those without GS (50% vs. 20%, OR=3.94, P=0.01). Conclusions: Salmonella carrier state was more common in GBC and XGC, particularly in elderly males than HC. The Vi antibody was more common in GBC and XGC than HC. Salmonella infection was more common in GBC with GS than those without GS.

Collagen VI (CVI) antibodies regulate macrophages differentiation through FcgammaRIIb signal transduction pathway

We previously reported that monoclonal antibody against collagen VI (CVI mAb) regressing atherosclerotic plaque through inducing the shift of macrophage differentiation, namely from M1 to M2, and ensuing the macrophages engulf the plaque lipids and transfer the lipids to HDL through restoring lipid transfer protein ABCA1 expression. Here we report the cellular signal transduction on the CVI mAb inhibition of oxLDL‐induced M1 differentiation. Using purified human CD14+ cells, we find that oxLDL induces M1 differentiation is JNK and ERK MAPKs dependent. And CVI mAb inhibits M1, while activates M2 differentiation, though oxLDL also activates M2 differentiation in some way, but the M1/M2 ratio are significantly reversed by CVI mAb. The molecular mechanism behind these is that CVI mAb activates macrophage FcgammaRIIb and its downstream SHIP and Dok phosphatases, and inhibits Syk and Ras signal transduction pathway, which are MAPKs upstream kinases, so that CVI mAb inhibits ERK, JNK, and p38 MAPKs activation, and ensuing M1 differentiation. Thus, we found the signal transduction pathway of CVI mAb inhibition of oxLDL‐induced M1 differentiation: CVI mAb→FcgammaRIIb→SHIP→Dok→Syk and Ras→ERK and JNK MAPKs→M1. These results might give a new clue on control the lipids‐induced inflammatory reaction on the large blood vessel and therapeutic method to prevent atherosclerosis.Support or Funding InformationThis work was supported by the National Natural Science Foundation of China (grants 81772074, 81974045), the Natural Science Foundation of Guangdong, China (grant 2012B050600002), the Guangdong Province Talent Recruitment Foundation and the Guangdong Innovative Research Team Program (No. 201001Y0104675344), Project of Guangzhou city scientific plan (201804020002).

Evaluation of Polysaccharide Typhim Vi Antibody Response as a predictor of Humoral Immunodeficiency in Haematological Malignancies

An increasing healthcare challenge in the management of haematological malignancy (HM) is secondary immunodeficiency. From January 2019, the EMA included the evaluation of specific antibody (Ab) responses to better select patients for immunoglobulin replacement therapy (IgRT). We evaluated Ab responses to pneumococcal and Salmonella typhi pure polysaccharide immunization in a cohort of 42 HM patients and 24 healthy-controls. Pre-post specific Ab concentrations were measured by ELISA at 4 weeks. Globally, significantly lower Typhim Vi (TV) seroprevalence (9%) compared to 23-valent pneumococcal polysaccharide vaccine (PPV) (76%) (p <0.001) was observed. TV non responders (88%) were higher than PPV non responders (62%) (p <0.0001) and correlated better to infectious history. By ROC analysis, pre-post 5-fold TV increase was the best cut-off to discriminate HM with recurrent infections and controls (sensitivity 91%, specificity 100%). Despite the small sample cohort, our results suggest that specific anti-S typhi Ab response is a useful complementary assay in the diagnosis and management decision of SID to HM.

S.Typhi derived OmpC peptide conjugated with Vi-polysaccharide evokes better immune response than free Vi-polysaccharide in mice

Salmonella typhi is a causative organism for typhoid fever. Free Vi capsular polysaccharide (Vi) is licensed for use as vaccine for typhoid fever in individuals 2 years of age and older, which has limited memory response. There is dire need of protein or peptide as conjugate partner with Vi polysaccharide to improve shortcomings of Vi vaccine. Prediction of immunogenic peptide was deduced by program T sites. Carbodiimide mediated conjugation of Vi polysaccharide with OmpCp was performed utilizing ADH as linker. Immune response of Vi-conjugates along with control group was tested in mice. Ig and IgG antibodies against Vi polysaccharide was measured by ELISA. Two immunodominant regions (loop number 3a and 7) with high content of T-cell epitopes from OmpC was selected and synthesized. Vi poly/OmpCp ratios in Vi-conjugates were ~0.43–0.65. Vi polysaccharide alone elicited very low levels of Vi antibody without any booster effect. Vi-conjugate evoked 20-fold higher immune response compared to free Vi. Further, adequate levels of IgG antibodies were induced only by the Vi-conjugate suggesting that T-helper cells had been induced. Our data suggest that selected short peptide (OmpCp)as a carrier with Vi polysaccharide is assumed to be a promising molecule for candidate vaccine for typhoid fever.

Validation of quantitative salivary gland scintigraphy in relation to the American-European concensus criteria for Sjögren's syndrome.

The aim of this retrospective study was to evaluate the diagnostic value of semiquantitative parameters in salivary gland scintigraphy (SGS) in the diagnostic work-up of primary Sjögren's Syndrome (SS) using the American-European consensus criteria (AECC) as the gold standard. 99mTc-pertechnetate-SGS was performed in 110 patients with suspected primary SS. Uptake ratios (URs) and excretion fractions (EFs) for all parotid and submandibular salivary glands were calculated. Patients were divided into SS-positive, SS-negative, and SS-equivocal groups on the basis of the AECC criteria. SGS semiquantitative parameters were compared per group and cut-off values were defined. Ninety-six (87%) women and 14 (13%) men with a mean age of 51 years (range: 18-77 years) were included. All patients underwent SGS, labial biopsy, Schirmer's test, and antibody tests (anti-SS-A and anti-SS-B). Twenty-four patients were SS positive, 56 patients were SS negative, and 30 patients were SS-equivocal.UR of the parotid glands did not differ between SS-positive and SS-negative groups [mean (range): 3.4 (1.4-6.9) and 3.9 (2.2-6.5), respectively], whereas UR of the submandibular glands were significantly lower in SS-positive patients [mean (range): 2.7 (1.1-5.6) and 3.5 (2.3-5.3), respectively]. EF in both parotid and submandibular glands was significantly lower in SS-positive patients compared with SS-negative patients: parotid 24% (range: -4 to 53%) and 36% (range: 15-58%), respectively; submandibular 16% (range: -5 to 46%) and 29% (range: 9-49%), respectively.On the basis of a cut-off value of 2.0 for UR and 20% for EF, the sensitivity, specificity, positive predictive value, and negative predictive value were 0.67, 0.86, 86, and 67%, respectively. Of 30 SS-equivocal patients, 15 had a positive SGS, whereas the other 15 were SGS negative. In both, there was no correlation with the AECC criteria IV (histopathology) and VI (antibodies). In these cases, the SGS result was decisive. Quantitative SGS is a valuable tool in the diagnostic management of patients with suspected primary SS, especially in those in whom the nonscintigraphic AECC criteria are not conclusive. The straightforward quantitative analysis of SGS used in this study can be implemented in any nuclear medicine department.

Assessment of paediatric Hashimoto's thyroiditis using superb microvascular imaging

To evaluate the role of superb microvascular imaging along with greyscale and Doppler imaging for thyroid gland evaluation in Hashimoto's thyroiditis (HT) versus control subjects. The study included 33 healthy volunteers with normal ultrasound and laboratory findings and 70 patients with HT based on laboratory and sonographic findings who were undergoing follow-up and receiving medical treatment. HT patients were classified based on the modification of the scheme proposed by Sostre and Reyes that incorporates the extent of hypoechoic foci or patchy infiltration as grade A (foci involving <50% of the gland) and B (foci involving >50% of the gland). Thyroid volume, mean resistive indices, peak-systolic and end-diastolic velocities based on Doppler imaging, and vascularity index via superb microvascular imaging were obtained using a Canon Aplio 500 ultrasound device using a linear 10-14 MHz transducer. Patients with HT had significantly higher median thyroid volume and peak-systolic velocities (7.32 ml and 19 cm/s, respectively) compared to control subjects (4.62 ml and 16 cm/s, respectively). HT patients had significantly higher median vascularity index (VI; 13.5%) compared to control subjects (7.95%). A significant fair positive correlation with VI and anti-thyroglobulin antibody levels (r=0.356, p<0.05) and significant moderate positive correlation with VI and anti-thyroid peroxidase antibody levels (r=0.503, p<0.05) were found. In HT diagnosis, the optimal VI cut-off value was 10.58% with a sensitivity and specificity of 67.1% and 90%, respectively. Superb microvascular imaging appears to allow assessment of subtle vascularity changes in early HT stages that cannot be detected by Doppler parameters. This technique demonstrates excellent visualization of the microvascular structures and quantitative assessment based on a novel parameter such as VI.

Collagen Vi Antibody Induces Regression of Atherosclerosis by Activation of Monocytes/Macrophages Polarization and Lipid Efflux inApoE−/− Mice

Collagen Vi Antibody Induces Regression of Atherosclerosis by Activation of Monocytes/Macrophages Polarization and Lipid Efflux inApoE−/− Mice

Measurement of Typhi Vi antibodies can be used to assess adaptive immunity in patients with immunodeficiency.

SummaryVaccine‐specific antibody responses are essential in the diagnosis of antibody deficiencies. Responses to Pneumovax II are used to assess the response to polysaccharide antigens, but interpretation may be complicated. Typhim Vi®, a polysaccharide vaccine for Salmonella typhoid fever, may be an additional option for assessing humoral responses in patients suspected of having an immunodeficiency. Here we report a UK multi‐centre study describing the analytical and clinical performance of a Typhi Vi immunoglobulin (Ig)G enzyme‐linked immunosorbent assay (ELISA) calibrated to an affinity‐purified Typhi Vi IgG preparation. Intra‐ and interassay imprecision was low and the assay was linear, between 7·4 and 574 U/ml (slope = 0·99–1·00; R 2 > 0·99); 71% of blood donors had undetectable Typhi Vi IgG antibody concentrations. Of those with antibody concentrations > 7·4 U/ml, the concentration range was 7·7–167 U/ml. In antibody‐deficient patients receiving antibody replacement therapy the median Typhi Vi IgG antibody concentrations were < 25 U/ml. In vaccinated normal healthy volunteers, the median concentration post‐vaccination was 107 U/ml (range 31–542 U/ml). Eight of eight patients (100%) had post‐vaccination concentration increases of at least threefold and six of eight (75%) of at least 10‐fold. In an antibody‐deficient population (n = 23), only 30% had post‐vaccination concentration increases of at least threefold and 10% of at least 10‐fold. The antibody responses to Pneumovax II and Typhim Vi® correlated. We conclude that IgG responses to Typhim Vi® vaccination can be measured using the VaccZyme Salmonella typhi Vi IgG ELISA, and that measurement of these antibodies maybe a useful additional test to accompany Pneumovax II responses for the assessment of antibody deficiencies.

Is Salmonella enterica serovar Typhi associated with carcinoma gall bladder?

Introduction: Gallbladder carcinoma is a common hepatobiliary malignancy with poor prognosis. It is 3rd commonest malignancy in north India. Salmonella typhi is one of risk factor for gallbladder cancer. India is high endemic area for typhoid in the world. Various authors reported association between the two but without doing testing for typhoid carrier, association cannot be proven. Aim: The present study was designed to explore the association of the chronic typhoid carrier state and carcinoma gall bladder by detecting Salmonella typhi in specimens of gallbladder from patients with malignant and benign gallbladder diseases using a Nested PCR. Methods and material: In this prospective case control study, we have got 39 samples from Carcinoma Gall Bladder (GBC) patients as cases and 75 samples from benign Gall Bladder Diseases (GBD) patients as controls in two years duration. We have done Indirect haemagglutination test for typhoid carrier from five milliliters of blood which was collected from each patient before surgery. Nested PCR was done from gall bladder tissue, which was taken at operation, from both GBC and GBD patients. Result: Nested PCR showed 59% positivity for Salmonella typhi in the GBC and 56% in GBD, so association of Salmonella typhi with GBC was not statistically significant. Vi antibody was present 33% in GBC and 37% in GBD by IHA. It is also not statistically significant. Conclusion: A large number of sample size is require for proving association between carcinoma gall bladder and Salmonella typhi by using definite marker for Vi antibodies.

Authentication of collagen VI antibodies

BackgroundCollagen VI is a ubiquitously-expressed macromolecule that forms unique microfibrillar assemblies in the extracellular matrix. Mutations in the COL6A1, COL6A2 and COL6A3 genes result in congenital muscular dystrophy, arguing that collagen is critical for skeletal muscle development and function. Antibodies against collagen VI are important clinical and diagnostic tools in muscular dystrophy. They are used to confirm genetic findings by detecting abnormalities in the distribution, organization and overall levels of collagen VI in cells and tissues isolated from patients.MethodsMany antibodies have been raised against tissue-purified collagen VI and individual collagen VI chains, however few have been properly validated for sensitivity and chain specificity. To address this deficiency, we compared the ability of 23 commercially-available antibodies to detect extracellular collagen VI by immunohistochemistry on frozen tissue sections. To determine chain specificity, immunoblot analyses were conducted on cell lysates isolated from cells transfected with cDNAs for each individual chain and cells expressing all three chains together.ResultsOur analyses identified 15 antibodies that recognized tissue collagen VI by immunohistochemistry at varying intensities and 20 that successfully detected collagen VI by immunoblotting. Three antibodies failed to recognize collagen VI by either method under the conditions tested. All chain-specific antibodies that worked by immunoblotting specifically recognized their correct chain, and no other chains.ConclusionsThis series of side-by-side comparisons reveal at least two antibodies specific for each chain that work well for immunohistochemistry on frozen sections. This validation study expands the repertoire of antibodies available for muscular dystrophy studies caused by defects in collagen VI.

Fifth Percentile Cutoff Values for Antipneumococcal Polysaccharide and Anti-Salmonella typhi Vi IgG Describe a Normal Polysaccharide Response.

Serotype-specific antibody responses to unconjugated pneumococcal polysaccharide vaccine (PPV) evaluated by a World Health Organization (WHO)-standardized enzyme-linked immunosorbent assay (ELISA) are the gold standard for diagnosis of specific polysaccharide antibody deficiency (SAD). The American Academy of Allergy, Asthma and Immunology (AAAAI) has proposed guidelines to interpret the PPV response measured by ELISA, but these are based on limited evidence. Additionally, ELISA is costly and labor-intensive. Measurement of antibody response to Salmonella typhi (S. typhi) Vi vaccine and serum allohemagglutinins (AHA) have been suggested as alternatives. However, there are no large cohort studies and cutoff values are lacking. To establish cutoff values for antipneumococcal polysaccharide antibody response, anti-S. typhi Vi antibody, and AHA. One hundred healthy subjects (10-55 years) were vaccinated with PPV and S. typhi Vi vaccine. Blood samples were obtained prior to and 3-4 weeks after vaccination. Polysaccharide responses to 3 serotypes were measured by WHO ELISA and to 12 serotypes by an in-house bead-based multiplex assay. Anti-S. typhi Vi IgG were measured with a commercial ELISA kit. AHA were measured by agglutination method. Applying AAAAI criteria, 30% of healthy subjects had a SAD. Using serotype-specific fifth percentile (p5) cutoff values for postvaccination IgG and fold increase pre- over postvaccination, only 4% of subjects had SAD. One-sided 95% prediction intervals for anti-S. typhi Vi postvaccination IgG (≥11.2 U/ml) and fold increase (≥2) were established. Eight percent had a response to S. typhi Vi vaccine below these cutoffs. AHA titer p5 cutoffs were ½ for anti-B and ¼ for anti-A. We establish reference cutoff values for interpretation of PPV response measured by bead-based assay, cutoff values for S. typhi Vi vaccine responses, and normal values for AHA. For the first time, the intraindividual consistency of all three methods is studied in a large cohort.

Salmonella enterica serovar Typhi and gallbladder cancer: a case-control study and meta-analysis.

In Chile, where gallbladder cancer (GBC) rates are high and typhoid fever was endemic until the 1990s, we evaluated the association between Salmonella enterica serovar Typhi (S. Typhi) antibodies and GBC. We tested 39 GBC cases, 40 gallstone controls, and 39 population‐based controls for S. Typhi Vi antibodies and performed culture and quantitative polymerase chain reaction for the subset with bile, gallstone, tissue, and stool samples available. We calculated gender and education‐adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association with GBC. We also conducted a meta‐analysis of >1000 GBC cases by combining our results with previous studies. GBC cases were more likely to have high Vi antibody titer levels than combined controls (OR: 4.0, 95% CI: 0.9–18.3), although S. Typhi was not recovered from bile, gallstone, tissue, or stool samples. In our meta‐analysis, the summary relative risk was 4.6 (95% CI: 3.1–6.8, P heterogeneity=0.6) for anti‐Vi and 5.0 (95% CI: 2.7–9.3, P heterogeneity = 0.2) for bile or stool culture. Our results are consistent with the meta‐analysis. Despite differences in study methods (e.g., S. Typhi detection assay), most studies found a positive association between S. Typhi and GBC. However, the mechanism underlying this association requires further investigation

Collagen VI–NG2 axis in human tendon fibroblasts under conditions mimicking injury response

In response to injury, tendon fibroblasts are activated, migrate to the wound, and contribute to tissue repair by producing and organizing the extracellular matrix. Collagen VI is a microfibrillar collagen enriched in the pericellular matrix of tendon fibroblasts with a potential regulatory role in tendon repair mechanism. We investigated the molecular basis of the interaction between collagen VI and the cell membrane both in tissue sections and fibroblast cultures of human tendon, and analyzed the deposition of collagen VI during migration and myofibroblast trans-differentiation, two crucial events for tendon repair. Tendon fibroblast displayed a collagen VI microfibrillar network closely associated with the cell surface. Binding of collagen VI with the cell membrane was mediated by NG2 proteoglycan, as demonstrated by in vitro perturbation of collagen VI–NG2 interaction with a NG2-blocking antibody.Cultures subjected to wound healing scratch assay displayed collagen VI–NG2 complexes at the trailing edge of migrating cells, suggesting a potential role in cell migration. In fact, the addition of a NG2-blocking antibody led to an impairment of cell polarization and delay of wound closure. Similar results were obtained after in vitro perturbation of collagen VI extracellular assembly with the 3C4 anti-collagen VI antibody and in collagen VI-deficient tendon cultures of a Ullrich congenital muscular dystrophy patient carrying mutations in COL6A2 gene.Moreover, in vitro treatment with transforming growth factor β1 (TGFβ1) induced a dramatic reduction of NG2 expression, both at protein and mRNA transcript level, and the impairment of collagen VI association with the cell membrane. Instead, collagen VI was still detectable in the extracellular matrix in association with ED-A fibronectin and collagen I, which were strongly induced by TGFβ1 treatment.Our findings reveal a critical role of the NG2 proteoglycan for the binding of collagen VI to the surface of tendon fibroblasts. By interacting with NG2 proteoglycan and other extracellular matrix proteins, collagen VI regulates fibroblasts behavior and the assembly of tendon matrix, thereby playing a crucial role in tendon repair.

Differential Killing of Salmonella enterica Serovar Typhi by Antibodies Targeting Vi and Lipopolysaccharide O:9 Antigen.

Salmonella enterica serovar Typhi expresses a capsule of Vi polysaccharide, while most Salmonella serovars, including S. Enteritidis and S. Typhimurium, do not. Both S. Typhi and S. Enteritidis express the lipopolysaccharide O:9 antigen, yet there is little evidence of cross-protection from anti-O:9 antibodies. Vaccines based on Vi polysaccharide have efficacy against typhoid fever, indicating that antibodies against Vi confer protection. Here we investigate the role of Vi capsule and antibodies against Vi and O:9 in antibody-dependent complement- and phagocyte-mediated killing of Salmonella. Using isogenic Vi-expressing and non-Vi-expressing derivatives of S. Typhi and S. Typhimurium, we show that S. Typhi is inherently more sensitive to serum and blood than S. Typhimurium. Vi expression confers increased resistance to both complement- and phagocyte-mediated modalities of antibody-dependent killing in human blood. The Vi capsule is associated with reduced C3 and C5b-9 deposition, and decreased overall antibody binding to S. Typhi. However, purified human anti-Vi antibodies in the presence of complement are able to kill Vi-expressing Salmonella, while killing by anti-O:9 antibodies is inversely related to Vi expression. Human serum depleted of antibodies to antigens other than Vi retains the ability to kill Vi-expressing bacteria. Our findings support a protective role for Vi capsule in preventing complement and phagocyte killing of Salmonella that can be overcome by specific anti-Vi antibodies, but only to a limited extent by anti-O:9 antibodies.

A Japanese study to assess immunogenicity and safety of a typhoid Vi polysaccharide vaccine

BackgroundAlthough typhoid fever is rare in Japan, imported cases have been reported occasionally in travelers returning from endemic areas. To achieve licensing of a typhoid Vi polysaccharide vaccine (Typhim Vi®) and make it widely available in Japan, this study was conducted at the request of the Japanese Ministry of Health Labor and Welfare to assess the immunogenicity and safety of this vaccine when given as a single dose (the recommended schedule of administration) in a Japanese population. MethodsIn this multi-center, open-label, non-comparative, intervention study performed in Japan, 200 healthy volunteers (188 adults [≥18 years of age], 7 adolescents [12–17 years of age] and 5 children [2–11 years of age]) were administered Typhim Vi®. Immunogenicity was assessed 28 days after vaccinations using an ELISA method of anti-Vi antibody detection. A 4-fold increase in anti-Vi titer was considered as the threshold for seroconversion for anti-Vi antibodies. Safety was assessed up to 28 days following vaccination. ResultsOverall, 92.0% (95% confidence interval [CI]: 87.3–95.4%) of participants achieved seroconversion 28 days after a single dose of typhoid Vi polysaccharide vaccine. GMTs of Vi antibody titers increased from 6.6 (95% CI: 5.8–7.4) prior to vaccination to 157.3 (95% CI: 135.1–183.2) on Day 28 after vaccination. The geometric mean of individual anti-Vi antibody titer ratios (Day 28/Day 0) was 23.9 (95% CI: 20.3–28.3). There were no immediate adverse events and no adverse events led to the discontinuation of participants from the study. Across all age groups, pain and myalgia were the most frequently reported injection site and systemic reactions, respectively. Most of these reactions were mild in intensity and resolved within 7 days. ConclusionsA single dose of typhoid Vi polysaccharide vaccine, Typhim Vi®, demonstrated good safety and immunogenicity profile in a Japanese population.

Role of Gallstones in Typhoid Carriage in Egyptian Patients

Objectives: Salmonella typhi forms biofilm on the surface of gallstones promoting colonization and carrier state. The aims are to detect its frequency in chronic calcular cholecystitis patients, to find out their antibiotic resistance pattern, and also to examine biofilm on the surface of gallstones and detect its correlation to antibiotic susceptibility pattern. Materials and methods: The study group included 257 patients with chronic calcular cholecystitis. S. typhi was isolated from gall bladder specimens. Antibiotics susceptibility tests of the isolates were done. Biofilm on surface of gallstones were visualized using scanning electron microscopy. Virulence (Vi) antibodies against S. typhi were studied in sera of 257 healthy controls. Results: 10.9% of patients were chronic typhoid carriers compared to only 3.5% of the controls (OR= 3.37, p=0.002). Multidrug resistance was detected in 35.7% of isolates. S. typhi biofilms on the surface of the 21/28 (75%) gallstones were detected. Ninety percent of the strains that produced maximum amount of biofilm were multidrug-resistant. Conclusion: Chronic calcular cholecystitis patients are more prone to typhoid carriage due to biofilm formation of S. typhi on the surface of gallstones. J Microbiol Infect Dis 2012; 2(4): 142-149