Vi polysaccharide and conjugated vaccines afford similar early, IgM or IgG-independent control of infection but boosting with conjugated Vi vaccines sustains the efficacy of immune responses

Introduction

Vaccination with Vi capsular polysaccharide (Vi-PS) or protein-Vi typhoid conjugate vaccine (TCV) can protect adults against Salmonella Typhi infections. TCVs offer better protection than Vi-PS in infants and may offer better protection in adults. Potential reasons for why TCV may be superior in adults are not fully understood.

Methods and results

Here, we immunized wild-type (WT) mice and mice deficient in IgG or IgM with Vi-PS or TCVs (Vi conjugated to tetanus toxoid or CRM197) for up to seven months, with and without subsequent challenge with Vi-expressing Salmonella Typhimurium. Unexpectedly, IgM or IgG alone were similarly able to reduce bacterial burdens in tissues, and this was observed in response to conjugated or unconjugated Vi vaccines and was independent of antibody being of high affinity. Only in the longer-term after immunization (>5 months) were differences observed in tissue bacterial burdens of mice immunized with Vi-PS or TCV. These differences related to the maintenance of antibody responses at higher levels in mice boosted with TCV, with the rate of fall in IgG titres induced to Vi-PS being greater than for TCV.

Discussion

Therefore, Vi-specific IgM or IgG are independently capable of protecting from infection and any superior protection from vaccination with TCV in adults may relate to responses being able to persist better rather than from differences in the antibody isotypes induced. These findings suggest that enhancing our understanding of how responses to vaccines are maintained may inform on how to maximize protection afforded by conjugate vaccines against encapsulated pathogens such as S. Typhi.

The influence of conjugation variables on the design and immunogenicity of a glycoconjugate vaccine against Salmonella Typhi

In recent years there have been major efforts to develop glycoconjugate vaccines based on the Vi polysaccharide that will protect against Salmonella enterica Typhi infections, particularly typhoid fever, which remains a major public health concern in low-income countries. The design of glycoconjugate vaccines influences the immune responses they elicit. Here we systematically test the response in mice to Vi glycoconjugates that differ in Vi chain length (full-length and fragmented), carrier protein, conjugation chemistry, saccharide to protein ratio and size. We show that the length of Vi chains, but not the ultimate size of the conjugate, has an impact on the anti-Vi IgG immune response induced. Full-length Vi conjugates, independent of the carrier protein, induce peak IgG responses rapidly after just one immunization, and secondary immunization does not enhance the magnitude of these responses. Fragmented Vi linked to CRM₁₉₇ and diphtheria toxoid, but not to tetanus toxoid, gives lower anti-Vi antibody responses after the first immunization than full-length Vi conjugates, but antibody titres are similar to those induced by full-length Vi conjugates following a second dose. The chemistry to conjugate Vi to the carrier protein, the linker used, and the saccharide to protein ratio do not significantly alter the response. We conclude that Vi length and carrier protein are the variables that influence the anti-Vi IgG response to immunization the most, while other parameters are of lesser importance.

Efficient immunization of rhesus macaques with an HCV candidate vaccine by heterologous priming-boosting with novel adenoviral vectors based on different serotypes

Efficient vaccination against viral agents requires a strong T-cell-mediated immune response to clear viral-infected cells. Optimal vaccination can be achieved by administration of recombinant viral vectors encoding phatogen antigens. Adenoviral vectors have attracted considerable attention as potential viral vectors for genetic vaccination owing to their favorable safety profile and potent transduction efficiency following intramuscular injection. However, the neutralizing antibody response against adenoviral capsid proteins following adenoviral vectors injection limits the success of vaccination protocols based on multiple administrations of the same adenoviral serotype. In this work, we describe efficient immunization of rhesus macaques, the preferred model for preclinical assessment, with an HCV candidate vaccine by heterologous priming-boosting with adenoviral vectors based on different serotypes. The induced responses are broad and show significant cross-strain reactivity. Boosting can be delayed for over 2 years after priming, indicating that there is long-term maintenance of resting memory cells.

An evaluation of root canal treatment in patients who have received irradiation to the mandible and maxilla

OBJECTIVE

The purpose of this study was to evaluate the success and failure of root canal treatment performed in areas of previous irradiation and to examine any cases of osteoradionecrosis associated with such treatment.

STUDY DESIGN

A retrospective analysis was done on 22 teeth that had root canal treatment after radiation therapy. Strict radiographic and clinical criteria were used to determine success and failure.

RESULTS

There was a mean follow-up period of 19 months. Of 22 cases, 20 (91%) were considered successful. Both failures occurred with a diagnosis of pulpal necrosis. There were no occurrences of osteoradionecrosis.

CONCLUSIONS

Our study showed that root canal treatment in previously irradiated patients may be successful. In addition, treatment approaches, as well as the criteria for success and failure, should be the same for irradiated patients as for those who have not received radiation treatment.

BMS-192548, a tetracyclic binding inhibitor of neuropeptide Y receptors, from Aspergillus niger WB2346. I. Taxonomy, fermentation, isolation and biological activity

During the screening of microbial fermentation extracts for their ability to inhibit the binding of 125I-peptid YY (PYY) to the neuropeptide Y (NPY) receptor using the scintillation proximity assay (SPA), BMS-192548 was isolated from the extract of Aspergillus niger WB2346 by bioassay-guided fractionation. BMS-192548 showed the inhibitory activity against 125I-PYY binding to SK-N-MC and SMS-KAN cells, which express NPY1 and NPY2 receptors, respectively, with IC50 values of 24 microM in Y1 and 27 microM in Y2 receptor binding. BMS-192548 demonstrated weak cytotoxicity against murine tumor cell line M-109 with an IC50 value of 240 microM.

Transmolar pin and magnetic carrier for midfacial reconstruction: a clinical report

With previous prosthetic restorations of bilateral maxillary resections, tissue erosion and bleeding on the cephalic parts of the cavity have been caused by movement and pressure from the prosthesis. Retention of a prosthesis is a major determinant in its successful use. Physical and psychologic stresses are common when one is unable to use a prosthesis comfortably. The use of a musculocutaneous flap and an obturator prosthesis had provided near-immediate reconstruction of a massive midfacial defect. This method of reconstruction resulted in soft tissue replacement for appearance and functional rehabilitation of the upper lip while maintaining sound oncologic principles.

Comparison of the binding and functional actions of angiotensin agonists in clone 9 cells: additional evidence for angiotensin II receptor heterogeneity

The effects of the angiotensin-II (AII) agonists and antagonists on both 125I-SARILE binding and phosphoinositol (PI) accumulation in clone 9 cells were examined. Clone 9 cells, which are derived from rat liver, have been shown to respond to AII agonists with an increase in PI accumulation which is inhibitable by Sar1,Ile8-AII (SARILE) and DUP-753 but not PD-123319, suggesting that they possess the AT1 subtype of AII receptor. The present results confirmed these properties. The order of potency of AII agonists was AII > AIII > AI. Clone 9 cells also possessed binding sites for 125I-SARILE. The majority of these were AT1 type receptors, although a small number of AT2 receptors may also have been present. The order of potency of AII agonists in inhibiting 125I-SARILE binding was AII >> AIII = AI. The difference in rank order of potency between the functional and binding assay was due to AIII being much less potent in the binding assay than the functional assay. Since the potency of AIII relative to AII was lower than that at either AT1 or AT2 subtypes of AII receptor, these data suggest that an additional subtype, with selectively low affinity for AIII, exists.