Development of a new, simple, rapid ultra-high-performance liquid chromatography (UHPLC) method for the quantification of 2-phenoxyethanol in vaccines for human use.

A new, simple and rapid method for the quantitative determination of the antimicrobial preservative 2-phenoxyethanol, based on reverse phase ultra-high-performance liquid chromatography has been developed. The validation was performed according the ICH Q2 guideline "Validation of Analytical Procedures". The desired chromatographic separation was achieved on a Waters Symmetry C18 (150 × 4.6 mm, 5 µm) column using an isocratic elution, with detection at 270 nm wavelength. The mobile phase consisted of acetonitrile/water (55:45, v/v), pumped at a flow rate of 1 mL/min. The calibration curve and the analytical procedure are linear (r2 = 0.999) from the concentration of 0.07 mg/mL to 1.1 mg/mL. The percent relative standard deviation for intra- and inter-day precision was <1%. The recovery of 2-phenoxyethanol in vaccines ranged between 96.5 and 100.60%. The limits of detection and quantitation were 1.3 × 10-4 and 2.7 × 10-4 mg/mL, respectively. The method was found to be robust by changing the column working temperature, the percentage of acetonitrile of the mobile phase and the flow rate. The validated method can be successfully and reliably used to quantify as well as to exclude presence of 2-phenoxyethanol preservative in marketed vaccines.

Anti-polysaccharide and anti-diphtheria protective antibodies after 13-valent pneumococcal conjugate vaccination in rheumatoid arthritis patients under immunosuppressive therapy.

Immunogenicity of 13-valent pneumococcal polysaccharide (PnPS) conjugate vaccine (PCV13) was evaluated in 38 rheumatoid arthritis patients under immunosuppressive treatment and 20 healthy controls (HC). Antibodies to all PnPS and diphtheria-toxin analogue conjugate protein were measured pre- (T0), 1 (T1), 6 (T2), 12 (T3) months post-immunization. Patients and HC had similar response to individual PnPS. Mean antibody levels to all PnPS but one doubled at T1 compared with T0, with T3 persistence for only 8-7/13 PnPS. Baseline antibody levels was inversely associated with the rate of responders at T1 (T1/T0≥2) to 11/13 PnPS. Few subjects reached protective IgG levels against some serotypes frequently isolated in Italian patients with invasive pneumococcal disease. Antibody response was not influenced by therapy, except the one to PS7F, which was reduced by tumor necrosis factor-α-inhibitors. Vaccination increased also anti-diphtheria IgG. Despite this study substantially confirmed the PCV13 immunogenicity in immunocompromised patients, it also revealed some limitations.

Adherence and invasive properties of Corynebacterium diphtheriae strains correlates with the predicted membrane-associated and secreted proteome.

BACKGROUND: Non-toxigenic Corynebacterium diphtheriae strains are emerging as a major cause of severe pharyngitis and tonsillitis as well as invasive diseases such as endocarditis, septic arthritis, splenic abscesses and osteomyelitis. C. diphtheriae strains have been reported to vary in their ability to adhere and invade different cell lines. To identify the genetic basis of variation in the degrees of pathogenicity, we sequenced the genomes of four strains of C. diphtheriae (ISS 3319, ISS 4060, ISS 4746 and ISS 4749) that are well characterised in terms of their ability to adhere and invade mammalian cells. RESULTS: Comparative analyses of 20 C. diphtheriae genome sequences, including 16 publicly available genomes, revealed a pan-genome comprising 3,989 protein coding sequences that include 1,625 core genes and 2,364 accessory genes. Most of the genomic variation between these strains relates to uncharacterised genes encoding hypothetical proteins or transposases. Further analyses of protein sequences using an array of bioinformatic tools predicted most of the accessory proteome to be located in the cytoplasm. The membrane-associated and secreted proteins are generally involved in adhesion and virulence characteristics. The genes encoding membrane-associated proteins, especially the number and organisation of the pilus gene clusters (spa) including the number of genes encoding surface proteins with LPXTG motifs differed between different strains. Other variations were among the genes encoding extracellular proteins, especially substrate binding proteins of different functional classes of ABC transport systems and 'non-classical' secreted proteins. CONCLUSIONS: The structure and organisation of the spa gene clusters correlates with differences in the ability of C. diphtheriae strains to adhere and invade the host cells. Furthermore, differences in the number of genes encoding membrane-associated proteins, e.g., additional proteins with LPXTG motifs could also result in variation in the adhesive properties between different strains. The variation in the secreted proteome may be associated with the degree of pathogenesis. While the role of the 'non-classical' secretome in virulence remains unclear, differences in the substrate binding proteins of various ABC transport systems and cytoplasmic proteins potentially suggest strain variation in nutritional requirements or a differential ability to utilize various carbon sources.

Calibration and commutability assessment of the 1st International Standard for Diphtheria Antitoxin Human.

The 1st International Standard for Diphtheria Antitoxin Human (coded 10/262) was established by the World Health Organization Expert Committee on Biological Standardization in 2012. This paper describes the production, characterization and calibration of the new standard which is intended for use in the standardization of assays used to measure diphtheria antibody responses in human serum. The new standard was calibrated in terms of the International Standard for Diphtheria Antitoxin Equine in an international collaborative study. A total of 8 participants from 8 different countries performed in vivo and/or in vitro toxin neutralization tests and returned data that was used to assign units to the proposed new standard. The new standard has a diphtheria antitoxin potency of 2 IU/ampoule and is predicted to be stable. A follow up study was performed to assess commutability of the new standard. The follow up study was an existing external quality assessment, modified to include the new standard. Results obtained suggest that the new standard is commutable, showing comparable behaviour to native human serum samples in the majority of the assays compared, and is therefore suitable for use as a reference preparation in assays used to measure the level of anti-diphtheria antibodies in human serum.

Live biotherapeutic products and their regulatory framework in Italy and Europe.

In Italy and Europe, live microorganisms-containing products meant to be used by vulnerable or sick people for preventing or curing a disease are defined as live biotherapeutic products and are regulated as biological drugs. As such, they must undergo extensive quality, safety and efficacy testing and evaluation before receiving a marketing authorization. This review describes the regulatory framework of live biotherapeutic products with special focus on the European Pharmacopoeia monograph 3053 that set mandatory requirements for this kind of medicines, including verification of the number of live microorganisms and absence of certain contamination indicator microorganisms. The other product categories that may contain live microorganisms are also described, with brief references to the overlaps possibly occurring between the different categories.

Optimization of the monocyte activation test for evaluating pyrogenicity of tick-borne encephalitis virus vaccine

Pyrogen content is a key quality feature that must be checked in all injectable products, including vaccines. Four tests are currently available in the European Pharmacopoeia to monitor pyrogen/endotoxin presence: the rabbit pyrogen test (RPT), the bacterial endotoxin test, the recombinant factor C test, and the monocyte activation test (MAT). Here, we explored the possibility to replace the RPT with the MAT in the quality control of a vaccine against tick-borne encephalitis virus (TBEV). The testing was carried out using cryopreserved peripheral blood mononuclear cells as cell source. IL-6 release was selected as readout for the detection of both endotoxin and non-endotoxin contaminants. MAT applicability for pyrogen testing of the TBEV vaccine was assessed through preparatory tests and resulted in the establishment of a very sensitive assay (limit of detection (LOD) = 0.04 EU/mL; sensitivity = 0.1 EU/mL). Both quantitative Method A and semiquantitative Method B were used for data analysis. Our studies revealed that for a vaccine without intrinsic pyrogenicity, such as that against TBEV, sensitivity (the lowest endotoxin value of the standard curve) should be used instead of LOD to define a stable maximum valid dilution of the product. In conclusion, we describe the challenges of MAT implementation for anti-TBEV vaccine following the current Ph. Eur. chapter 2.6.30 and propose a re-evaluation of the validity criteria of Methods A and B in order to set a semi-quantitative or limit test suitable for those products for which a reference lot comparison analysis is not applicable or favorable.

Tetanus-diphtheria vaccination in adults: the long-term persistence of antibodies is not dependent on polyclonal B-cell activation and the defective response to diphtheria toxoid re-vaccination is associated to HLADRB1∗01.

Cellular and humoral immune responses to tetanus-diphtheria vaccine (Td) were assessed in human leukocyte antigen (HLA)-typed Italian military personnel who received multiple concomitant vaccines. Td-specific antibodies and T-lymphocytes were measured in individuals with one (group-1) and more than one (group-2) Td boosters. A third group (group-3), who received several vaccines, but not Td, was studied to verify the hypothesis of the polyclonal B-cell activation as mechanism for antibody persistence. The antibody response to Td toxoids was higher in group-1, who showed lower baseline antibody levels, than in group-2 subjects. The antibody response to tetanus was higher than to diphtheria toxoid in both groups. No correlation between antibody and cellular response, and no interference in the response to Td by co-administration of different vaccines were observed. HLA-DRB1∗01 allele was detected at significant higher frequency in subjects unable to double the baseline anti-diphtheria antibody levels after the vaccination. Anti-tetanus and diphtheria antibodies half-lives were assessed and the long-lasting persistence above the threshold for protection (0.1 IU/ml) was estimated in over 65 and 20 years, respectively. No significant increase of anti-diphtheria antibodies was observed in consequence of polyclonal B-cell activation. This study emphasizes the duration of Td vaccination-induced seroprotection, suggesting that re-vaccination should probably be performed at intervals longer than 10 years. No reciprocal interference by concomitantly administered vaccines has been observed. HLA-DRB1∗01 allele was significantly associated with anti-diphtheria defective response. Finally, this study does not confirm that anti-diphtheria antibody levels are maintained by polyclonal B-cell activation. Clinical trial registry: The study was registered with NCT01807780.

Experimental model of infection with non-toxigenic strains of Corynebacterium diphtheriae and development of septic arthritis.

Corynebacterium diphtheriae is a well-known cause of localized respiratory tract infections. However, this micro-organism can also be associated with invasive infections, such as endocarditis, septic arthritis and osteomyelitis. Invasive infections are often caused by non-toxigenic strains. To set up an in vivo experimental model of C. diphtheriae infection, mice were infected intravenously with different doses (ranging from 1 x 10(7) to 5 x 10(8) bacteria per mouse) of three non-toxigenic strains, namely ISS-4749, ISS-4746 and ISS-3319. Similar mortality rates were observed with the three strains, with an LD50 ranging from 9 x 10(7) to 1.2 x 10(8). All strains were arthritogenic, although to different extents. ISS-4749 and ISS-4746 infection resulted in a maximum of 60 and 50 %, respectively, of animals with articular lesions, while in the ISS-3319-infected group only 25 % were positive. There were differences in systemic and joint cytokine production in the three experimental groups. ISS-4749- and ISS-4746-infected mice exhibited higher local levels of interleukin (IL)-6 and IL-1beta than ISS-3319-infected animals. At systemic levels, ISS-3319 was able to induce early and sustained production of interferon-gamma (IFN-gamma), but not IL-6. Conversely, infection with the other strains resulted in high IL-6, but not IFN-gamma, production. In conclusion, an experimental model of C. diphtheriae infection was set up, with development of septic arthritis. This model could be useful in studies on the pathogenicity and characterization of virulence factors other than toxin production.

Association of group A streptococcal emm types with virulence traits and macrolide-resistance genes is independent of the source of isolation.

Streptococcus pyogenes (group A streptococci; GAS) recovered from paediatric pharyngitis (101 isolates) and asymptomatic children (79 isolates) in the same geographical area and period, as well as isolates collected during an enhanced national surveillance programme for GAS invasive diseases (79 isolates), were screened for the incidence of the streptococcal pyrogenic exotoxin (spe) genes speA and speC, as well as the macrolide-resistance genes erm(B), erm(A) subclass erm(TR) and mef(A), and typed by emm sequencing. The speA gene was detected with comparable incidence among throat isolates (13.9 % of asymptomatic children and 16.8 % of pharyngitis isolates) and in 25 % of invasive cases; in contrast, speC incidence was, surprisingly, higher in paediatric populations (55.4 % in pharyngitis isolates and 65.8 % in asymptomatic children) than in invasive isolates (30 %; P < 0.0001). Macrolide resistance was detected in 26.6, 38.0 and 37.6 % of strains belonging to invasive, asymptomatic and pharyngitis populations, respectively. The different incidences of exotoxin and antibiotic-resistance genes among populations did not appear to have an intrinsic clinical significance, but may reflect the propensity of these traits to be associated with certain emm types independent of the source from which the strains were isolated. Further investigations with larger emm-type populations are warranted to confirm this.

Virulence properties of type VII Streptococcus agalactiae (group B streptococci) and immunochemical analysis of capsular type polysaccharide.

Strains of a new polysaccharide type of group B streptococci (GBS), type VII, have been isolated from human carriers and invasive infections. Some of these strains bear the protein antigen c or R, as do other GBS serotypes. The capsular type polysaccharide is sialylated and this residue is involved in the immunodeterminant structure. All type VII strains examined were virulent in CD-1 mice; the LD50 after intraperitoneal (i.p.) challenge was 4.57 (SD 0.12) x10(7) cfu for the reference strain and 5.49 (SD 1.5) x10(7) cfu for clinical isolates. A particular feature of this serotype was the ability to induce septic arthritis not only when injected intravenously (i.v.), but also when injected i.p. Rabbit antiserum against the capsular type VII polysaccharide exhibited opsonic activity in a phagocytosis assay and protective activity against infection.

Molecular epidemiology and characteristics of Corynebacterium diphtheriae and Corynebacterium ulcerans strains isolated in Italy during the 1990s.

Five cases of diphtheria were reported in Italy between January 1990 and June 2001. Three cases were confirmed microbiologically by the isolation of toxigenic Corynebacterium diphtheriae (two cases) and Corynebacterium ulcerans (one case). Over the same period, 11 cases of non-toxigenic C. diphtheriae infection were reported to the Italian Public Health Institute, from which the causative organism was isolated from a skin infection in one case and from the throat in the other ten. Seven of the throat isolates were associated with fever, severe pharyngitis and tonsillitis and were all biotype gravis. Because there are no standardized breakpoints, the antimicrobial sensitivities of C. diphtheriae were determined in accordance with the National Committee for Clinical Laboratory Standards guidelines for Streptococcus spp. other than Streptococcus pneumoniae. MICs for penicillin ranged between 0.125 and 0.250 mg l(-1) and 7 out of 11 strains had a minimal bactericidal concentration (MBC)/MIC ratio >or= 32. All strains were sensitive to clindamycin (MIC

Simple and rapid technique for monitoring the quality of meningococcal polysaccharides by high performance size-exclusion chromatography.

The molecular size of meningococcal polysaccharides is an important physico-chemical parameter which correlates with immunogenicity. This paper describes the experimental conditions for high-performance size-exclusion chromatography on a PL Aquagel-OH 60 column to follow changes in the size distribution and therefore in the distribution coefficient (K(D)) of the meningococcal polysaccharides of groups A, C, Y and W-135 used to formulate anti-Neisseria meningitidis vaccines. The experimental conditions were also found to be suitable for a rapid monitoring of the quality (no group A polysaccharide depolymerization) of the tetravalent meningococcal polysaccharide vaccine.

Tetanus in Italy 2001-2010: a continuing threat in older adults.

Despite being a completely preventable disease, tetanus cases continue to occur in Italy and notification and hospitalization rates have been reported to be higher with respect to European and other industrialized countries. We examined statutory notification, hospitalization, mortality and seroprevalence data to describe tetanus epidemiology in Italy from 2001 to 2010. A total of 594 tetanus cases were notified, with an average annual incidence of 1.0/1,000,000 population. Most cases were unvaccinated or incompletely vaccinated. Eighty percent of cases occurred in subjects aged >64 years and a higher proportion of females with respect to males were reported in this age group. The annual number of hospital admissions was 1.4-1.7 times greater than the number of notifications in the same year. The mean annual number of reported deaths was 21. Seroprevalence data show progressively higher susceptibility levels with increasing age. Over 50% of persons aged 45-64 years and over two thirds of subjects ≥65 years had tetanus antibody levels <0.01 IU/ml. Results show that tetanus is a continuing problem in Italy and, as in other countries, most cases occur in older adults, especially elderly women. The observed differences in notification and hospitalization rates suggest underreporting by physicians. In recent years, Italy has accounted for most cases reported annually in the European Union (EU) but different case definitions are used. In Italy, a confirmed case is one that meets the clinical case definition while the EU case definition classifies confirmed cases as those with laboratory confirmation of disease. The incidence of clinical tetanus in Italy is ten-fold higher than in other industrialized countries, like Australia and Canada, likely due to higher susceptibility levels in Italy. In view of the low prevalence of tetanus antibodies in adults ≥45 years, strategies to improve vaccine uptake in this population group need to be implemented.

Identification and molecular discrimination of toxigenic and nontoxigenic diphtheria Corynebacterium strains by combined real-time polymerase chain reaction assays.

With the recognition of several diphtheria outbreaks and the emergence of nontoxigenic corynebacteria strains, there has been renewed interest in the development of laboratory diagnostic methods. Previously reported polymerase chain reaction (PCR) assays can have low diagnostic sensitivity or give species misidentifications among clinical isolates. The aim of the present study was the development of combined real-time PCR assays, based on the tox and rpoB genes, for the detection and differentiation of toxigenic and nontoxigenic corynebacteria. By the PCR tox assay, it was possible to perform the direct identification of DT tox gene of Corynebacterium diphtheriae and Corynebacterium ulcerans, while the PCR rpoB assay differentiated C. diphtheriae from C. ulcerans, irrespective of their toxigenic status. In addition, we detected the DT toxin of Corynebacterium pseudotuberculosis for the first time. These assays revealed high sensitivity, specificity, and reproducibility, and the availability of plasmid controls will facilitate further research into the diagnostics of diphtheria corynebacteria.

Improved specificity of a multiplex immunoassay for quantitation of anti-diphtheria toxin antibodies with the use of diphtheria toxoid.

A nonspecific binding of antibodies to diphtheria toxin, especially in adult serum samples, was observed in our diphtheria-tetanus-pertussis multiplex immunoassay (DTaP4 MIA). This can be significantly reduced by the use of diphtheria toxoid, achieving a good correlation with the Vero cell neutralization test and the toxin binding inhibition assay.

External quality assessment for the determination of diphtheria antitoxin in human serum.

Accurate determination of diphtheria toxin antibodies is of value in determining the rates of immunity within broad populations or the immune status of individuals who may be at risk of infection, by assessing responses to vaccination and immunization schedule efficacy. Here we report the results of an external quality assessment (EQA) study for diphtheria serology, performed within the dedicated surveillance network DIPNET. Twelve national laboratories from 11 European countries participated by testing a standard panel of 150 sera using their current routine method: Vero cell neutralization test (NT), double-antigen enzyme-linked immunosorbent assay (ELISA; DAE), dual double-antigen time-resolved fluorescence immunoassay (dDA-DELFIA), passive hemagglutination assay (PHA), toxin binding inhibition assay (ToBI), and in-house or commercial ELISAs. The objective of the study was not to identify the best assay, as the advantages and drawbacks of methods used were known, but to verify if laboratories using their routine method would have categorized (as negative, equivocal, or positive) a serum sample in the same way. The performance of each laboratory was determined by comparing its results on a quantitative and qualitative basis to NT results from a single reference laboratory, as this test is considered the in vitro "gold standard." The performance of laboratories using NT was generally very good, while the laboratories' performance using other in vitro methods was variable. Laboratories using ELISA and PHA performed less well than those using DAE, dDA-DELFIA, or ToBI. EQA is important for both laboratories that use in vitro nonstandardized methods and those that use commercial ELISA kits.

Isolation of Corynebacterium tuscaniae sp. nov. from blood cultures of a patient with endocarditis.

A strain of an unknown coryneform bacterium was repeatedly isolated in pure culture from the blood of a patient affected by endocarditis. Comparative 16S rRNA gene sequence analysis revealed that this isolate represented a new subline within the genus Corynebacterium. This new taxon can be identified by the presence of corynomycolic acids and its enzymatic activities and fermentation of sugars. Acid production from glucose and maltose, pyrazinamidase and alkaline phoshatase activities, and hippurate hydrolysis were the most characteristic phenotypic features of the bacterium. On the basis of both phenotypic and phylogenetic evidence, it is proposed that this isolate be classified as a novel species, Corynebacterium tuscaniae sp. nov. The type strain, ISS-5309, has been deposited in the American Type Culture Collection (ATCC BAA-1141) and in the Culture Collection of the University of Göteborg (CCUG 51321).

Multiplex PCR assay for direct identification of group B streptococcal alpha-protein-like protein genes.

We developed a group B streptococcus multiplex PCR assay which allows, by direct analysis of the amplicon size, determination of the surface protein antigen genes of alpha-C protein, epsilon protein, Rib, Alp2, Alp3, and Alp4. The multiplex PCR assay offers a rapid and simple method of subtyping Streptococcus agalactiae based on surface protein genes.

Internalization of non-toxigenic Corynebacterium diphtheriae by cultured human respiratory epithelial cells.

Although infection by Corynebacterium diphtheriae is a model of extracellular mucosal pathogenesis, and diphtheria is one of the most worried diseases, this microorganism can be associated also with invasive infections such as endocarditis, septic arthritis, and osteomyelitis. Invasive infections are usually caused by non-toxigenic C. diphtheriae strains. Over the last years severe pharyngitis/tonsillitis associated with the isolation of non-toxigenic C. diphtheriae have been described. Penicillin treatment failure of these infections could only partially be explained by penicillin tolerance of the causing strain. Thus, we examined the in vitro ability of non-toxigenic C. diphtheriae throat clinical isolates to adhere to, and enter human respiratory epithelial cells. Trasmission and scanning electron microscopy demonstrated intracellular C. diphtheriae in laryngeal (HEp-2 cells) and pharyngeal (Detroit D562 cells) tissue culture. Live intracellular bacteria were detectable up to 48 h post-infection. Using a variety of compound that act on eukariotic cell structures, the internalization of C. diphtheriae seems to occur via a zipper-like mechanism. It is likely that internalization of C. diphtheriae can be involved in throat colonization contributing to bacterial eradication failure and asymptomatic carriage.

Immunogenicity of anti-Haemophilus influenzae type b CRM197 conjugate following mucosal vaccination with oligodeoxynucleotide containing immunostimulatory sequences as adjuvant.

Most vaccines are delivered by injection. Mucosal vaccination would increase compliance and decrease the risk of spread of infectious diseases due to a reduction of mucosal colonization and of contaminated syringes. However, most vaccines are unable to induce immune responses when administered mucosally, and require the use of strong adjuvant or effective delivery systems. Synthetic oligodeoxynucleotides (ODN) containing CpG immunostimulatory sequences (ISS) have been shown to act as potent adjuvants of type-1 immune responses also when mucosally co-administered with protein or peptide vaccines. We have shown that ISS can increase the anti-polysaccharide polyribosyl ribitol phosphate (PRP) antibody titres and anti-diphtheria toxin neutralizing antibody, if used as adjuvant of anti-Haemophilus influenzae type b (Hib) PRP vaccine conjugated with cross-reacting material (CRM) of diphtheria toxin in mice. Here, we show that ISS have the potential to increase host local and systemic antibody response against both the PRP and the protein component of a conjugated vaccine when mucosally administered in mice. Mucosal administration of Hib-CRM vaccine induced anti-PRP and neutralizing anti-diphtheria toxin antibodies of all the IgG subclasses, with a predominance of type-1 immune response-associated IgG2a and IgG3. At odds with systemic administration, the mucosal delivery of Hib-CRM induced anti-PRP and anti-diphtheria toxin mucosal IgA. These data envisage the feasibility of a mucosal vaccination with an already licensed Hib-CRM vaccine to achieve both an anti-H. influenzae and -diphtheria effective protection.