Glycoconjugate vaccines: classic and novel approaches.

Glycoconjugate vaccines, obtained by carbohydrates covalently bound to protein carriers, have contributed to fight diseases such as meningitidis, pneumonia and typhoid fever. Despite new technologies such as RNA and adenovirus based vaccine have now reached the market, these approaches are unable to target carbohydrates which are key virulence factors.This issue intends to provide an overview on relevant directions where the field is evolving and serve as starting point to increase interest in this exciting and fundamental part of vaccinology.

First isolation and characterization of Brucella suis from yak.

Brucella spp., facultative intracellular pathogens that can persistently colonize animal host cells and cause zoonosis, affect public health and safety. A Brucella strain was isolated from yak in Qinghai Province. To detect whether this isolate could cause an outbreak of brucellosis and to reveal its genetic characteristics, several typing and whole-genome sequencing methods were applied to identify its species and genetic characteristics. Phylogenetic analysis based on MLVA and whole-genome sequencing revealed the genetic characteristics of the isolated strain. The results showed that the isolated strain is a B. suis biovar 1 smooth strain, and this isolate was named B. suis QH05. The results of comparative genomics and MLVA showed that B. suis QH05 is not a vaccine strain. Comparison with other B. suis strains isolated from humans and animals indicated that B. suis QH05 may be linked to specific animal and human sources. In conclusion, B. suis QH05 does not belong to the Brucella epidemic species in China, and as the first isolation of B. suis from yak, this strain expands the host range of B. suis.

A review on strategies for decreasing E. coli O157:H7 risk in animals.

Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is a food-borne pathogen that younger children are most prone to this microorganism. Hemolytic Uremic Syndrome (HUS) caused by EHEC, leads to the destruction of red blood cells and kidney failure. The virulence of E.coli O157:H7 is attributed to fimbriae, that facilitate colonization of bacteria within the colon and verotoxins (VT) or Shiga toxins (Stx) that are released into the blood. Although, in most cases, the infection is self-limitedin young children and aged population, it may cause HUS. Therefore, several investigations are performed in order to offer effective therapies and vaccines, which can prevent and treat the infection in appropriate time. As the pathogenesis of this infection is complicated, a multi-targeted strategy is required. Since cattle are the most important reservoir of EHEC and the root of contamination, reducing E. coli O157:H7 at the farm level should decrease the risk of human illness. Several vaccine approaches have been employed with different proper outcomes in animal models, including recombinant proteins (virulence factors such as; Stx1/2, intimin, EspA, fusion proteins of A and B Stx subunits), avirulent ghost cells of EHEC O157:H7, live attenuated bacteria expressing recombinant proteins, recombinant fimbrial proteins. In addition to protein-based vaccines, DNA vaccines have provided proper prevention in the laboratory animal model. This review paper summarizes the previous studies, current status and future perspective of different immunization strategies for eradicating Enterohemorrhagic Escherichia coli O157:H7.

Effects of different vaccine combinations against Mycoplasma gallisepticum on the internal egg and eggshell characteristics of commercial layer chickens 1,2,3.

Live F-strain Mycoplasma gallisepticum (FMG) vaccines are presently being used to help control field-strain MG outbreaks. However, they may exert some adverse effects on egg production. Live strains of MG of lesser virulence as well as killed vaccines have little or no effect on egg production, but afford lower levels of protection. This has led to research investigating their use in combination with a subsequent overlay vaccination of FMG given later in the production cycle. In the present study, 2 trials were conducted to investigate the effects of prelay vaccinations of live and killed MG vaccines or their combination, in conjunction with an FMG vaccine overlay after peak production, on the egg characteristics of commercial layers. The following vaccination treatments were administered at 10 wk of age (woa): 1) unvaccinated (Control), 2) MG-Bacterin (MGBac) vaccine, 3) ts-11 strain MG (ts11MG) vaccine, and 4) MGBac and ts11MG combination (MGBac + ts11MG). At 45 woa, half of the birds were overlaid with an FMG vaccine. In each trial, internal egg and eggshell parameters including egg weight (EW), Haugh unit score (HU), eggshell breaking strength (EBS), percentage yolk weight (PYW), percentage albumen weight (PAW), percentage eggshell weight (PSW), eggshell weight per unit surface area (SWUSA), percentage yolk moisture (PYM), and percent total lipids (PYL) were determined at various time periods between 21 and 52 woa. At 28 woa, SWUSA was lower in the ts11MG and MGBac + ts11MG groups compared to the Control group. Conversely, at 43 woa, SWUSA was higher in the ts11MG than in the MGBac group. Between 23 and 43 woa, PYL was higher in the MGBac and ts11MG groups in comparison to the Control group. In conclusion, vaccination with MGBac alone or in combination with ts11MG at 10 woa with or without an FMG vaccine overlay at 45 woa does not adversely affect the internal egg or eggshell quality of commercial layers throughout lay.

Persistent Bordetella bronchiseptica pneumonia in an immunocompetent infant and genetic comparison of clinical isolates with kennel cough vaccine strains.

An infant who experienced recurrent episodes of respiratory failure received a diagnosis of pertussis on the basis of immunofluorescence testing, but culture revealed macrolide-resistant Bordetella bronchiseptica. Genetic analysis demonstrated that the child was not infected with a kennel cough vaccine strain, although the family's dog had recently been vaccinated. The infection cleared with imipenem therapy.

Immunization update.

Although the development and licensure of new vaccines over the last 2 years has generated a lot of excitement as well as debate, there is a lot more to come. Not discussed in this article. licensure of another long-awaited vaccine albeit for use in adults was that for herpes zoster. The second HPV and rotavirus vaccines are awaiting approval in the US. Next in line are the vaccines both prophylactic as well as therapeutic against HIV. Topics of debate over the new vaccines include discussions amongst practices as to the affordability and cost of the new vaccines as well as the ethical debate amongst lawmakers and the general public regarding the rights and wrongs of compulsory vaccination against HPV. Another ongoing discussion is regarding the availability of approved vaccines. Shortages have been seen with several of the childhood vaccines including heptavalent pneumococcal conjugate vaccine, tetravalent meningococcal conjugate vaccine, hepatitis A vaccine, as well as the ongoing saga with influenza vaccines. Across the globe while the struggle against polio continues, there is encouraging news regarding the reduction in measles-related deaths, particularly in Africa. The last few years have indeed been landmark years in infectious disease research as the search continues for better and safer vaccines globally.

Vaccination coverage in a cohort of HIV-infected patients receiving care at an AIDS outpatient clinic in Espírito Santo, Brazil.

This cross-sectional study assessed the immunization status of human immune deficiency virus (HIV)-infected patients receiving care at an outpatient clinic in Brazil. The sociodemographic characteristics, CD4 count and HIV viral load of 281 out of 612 adult outpatients were analyzed. A total of 331 patients were excluded because of no availability of vaccination cards. Chi-square or Fisher's exact test were used. Immunization coverage was higher for diphtheria/tetanus (59.79%) and hepatitis B (56.7%), and lowest for hepatitis A (6.8%) and for meningococcal group C (6%). Only 11.74% of the patients had received the influenza virus vaccine yearly since their HIV-infection diagnosis. No vaccination against influenza (p<0.034) or hepatitis B (p<0.029) were associated with CD4 counts <500cells/mL; no vaccination against flu or pneumococcus were associated with detectable HIV viral load (p<0.049 and p<0.002, respectively). Immunization coverage is still very low among HIV-infected adults in this setting despite recommendations and high infection-related mortality.

Compulsory and recommended vaccination in Italy: evaluation of coverage and non-compliance between 1998-2002 in Northern Italy.

BACKGROUND: Since vaccinations are an effective prevention tool for maintaining the health of society, the monitoring of immunization coverage allows us to identify areas where disease outbreaks are likely to occur, and possibly assist us in predicting future outbreaks. The aim of this study is the investigation of the coverage achieved for compulsory (diphtheria, tetanus, polio, hepatitis B,) and recommended (pertussis, Haemophilus influenzae, measles-mumps-rubella) vaccinations between 1998 and 2002 in the municipality of Bologna and the identification of the subjects not complying with compulsory and recommended vaccinations. METHODS: The statistics regarding vaccinal coverage were elaborated from the data supplied by the Bologna vaccinal registration system (1998-2000) and the IPV4 program (2001-2002). To calculate the coverage for compulsory vaccinations and cases of non-compliance reference was made to the protocol drawn up by the Emilia Romagna Regional Administration. The reasons for non-compliance were divided into various categories RESULTS: In Bologna the levels of immunization for the four compulsory vaccinations are satisfactory: over 95% children completed the vaccinal cycle, receiving the booster for anti-polio foreseen in their 3rd year and for anti-diphtheria, tetanus, pertussis at 6 years. The frequency of subjects with total non-compliance (i.e. those who have not begun any compulsory vaccinations by the age of one year) is generally higher in Bologna than in the region, with a slight increase in 2002 (2.52% and 1.06% in the city and the region respectively). The frequency of the anti-measles vaccination is higher than that of mumps and rubella, which means that the single vaccine, as opposed to the combined MMR (measles-mumps-rubella) was still being used in the period in question. The most common reason for non compliance is objection of parents and is probably due to reduction of certain diseases or anxiety about the possible risks. CONCLUSION: In Bologna the frequency of children aged 12 and 24 months who have achieved compulsory vaccination varied, in 2002, between 95% and 98%. As regards recommended vaccinations the percentage of coverage against Haemophilus influenzae is 93.3%, while the levels for measles, mumps and pertussis range from 84% to approx. 92%. Although these percentages are higher if compared to those obtained by other Italian regions, every effort should be made to strengthen the aspects that lead to a successful vaccinal strategy.

Vibrio cholerae O139 Bengal: odyssey of a fortuitous variant.

Vibrio cholerae O139, the new serogroup associated with epidemic cholera, came into being in the second half of the year 1992 in an explosive fashion and was responsible for several outbreaks in India and other neighbouring countries. This was an unprecedented event in the history of cholera and the genesis of the O139 serogroup was, at that time, thought to be the beginning of the next or the eighth pandemic of cholera. However, with the passage of time, the O1 serogroup of the El Tor biotype again reappeared and displaced the O139 serogroup on the Indian subcontinent, and there was a feeling among cholera workers that the appearance of this new serogroup may have been a one-time event. The resurgence of the O139 serogroup in September 1996 in Calcutta and the coexistence of both the O1 and O139 serogroups in much of the cholera endemic areas in India and elsewhere, suggested that the O139 serogroup has come to stay and is a permanent entity to contend with in the coming years. During the past 10 years, intensive work on all aspects of the O139 serogroup was carried out by cholera researchers around the world. The salient findings on this serogroup over the past 10 years pertinent to its prevalence, clinico-epidemiological features, virulence-associated genes, rapid screening and identification, molecular epidemiology, and vaccine developments have been highlighted.

Immunization of children with sickle cell disease with Haemophilus influenzae type b polysaccharide vaccine.

There are limited data concerning safety and immunogenicity of Haemophilus influenzae type b polysaccharide vaccine in children with sickle cell disease. Ninety-eight patients with sickle cell disease (65 with SS phenotype, 23 with SC phenotype, and 10 with S beta-thalassemia) 1.5 to 20 years of age were given 25 micrograms of vaccine subcutaneously. The vaccine was well tolerated; mild side effects were observed in 6 of 98 (6.1%) children. In addition, one patient with a recent vasoocclusive crisis was hospitalized because of fever and vasoocclusive crisis 8 hours after vaccination. Prevaccination anticapsular antibody concentrations (by radioimmunoassay) were less than 0.15 microgram/mL in 7 of 11 children 18 to 24 months of age (geometric mean 0.17 microgram/mL), in 10 of 25 children 2 to 5 years of age (geometric mean 0.36 microgram/mL), and in 3 of 50 patients 6 to 20 years of age (geometric mean 1.03 microgram/mL). Inadequate response (1- to 2-month postvaccination antibody level less than 1 microgram/mL) was found in 3 of 5 children 18 to 24 months of age (geometric mean 1.74 microgram/mL), in 8 of 21 children 2 to 5 years of age (geometric mean 2.20 micrograms/mL), and in 2 of 49 patients 6 to 20 years of age (geometric mean 18.03 micrograms/mL). Six months after vaccination, greater than 1 microgram/mL of antibody was present in the 2 children 6 to 20 years of age with inadequate response but not in the 7 children 2 to 5 years of age with inadequate response.(ABSTRACT TRUNCATED AT 250 WORDS)

The immune response against Francisella tularensis live vaccine strain in Lps(n) and Lps(d) mice.

The impact of Lps gene on the course of immune response against subcutaneous infection of mice with Francisella tularensis live vaccine strain was studied. Production and specificity of antibodies, cytotoxic responses of macrophages and NK-cells, spontaneous production ex vivo of cytokines IL-1 alpha, IL-2, IL-4, IL-6, IL-10, IFN-gamma, and TNF-alpha in spleen cell cultures in C3H/HeJ (Lps(d)) mice in comparison with C3H/HeN (Lps(n)) mice were tested. The value of LD(50) was significantly different in the two strains of mice (8.0 x 10(5) cfu for C3H/HeJ versus 4.61 x 10(3) cfu for C3H/HeJ mice after subcutaneous inoculation). The production of NO(2) is also impaired in C3H/HeJ mice in the early intervals after infection. Thus, the defective Lps gene of C3H/HeJ mice influences both the level of innate resistance of mice to F. tularensis live vaccine strain infection and the process of induction and regulation of immune response against this intracellular bacterial pathogen.

Evaluation of protein A and protein G as indicator system in an ELISA for detecting antibodies in mink to Pseudomonas aeruginosa.

A modified, indirect enzyme-linked immunosorbent assay (ELISA) was developed and applied in the detection of mink antibodies to Pseudomonas aeruginosa. In this assay, peroxidase conjugated protein A and protein G were evaluated as indicator systems for detecting antigen-antibody complexes. It was found that protein A has a strong affinity for mink immunoglobulins. In contrast, protein G showed no such affinity. The affinity of protein A for mink immunoglobulins was further demonstrated by immunoprecipitation assays.

Biological products; bacterial vaccines and toxoids; implementation of efficacy review. Final rule and final order.

The Food and Drug Administration (FDA) is amending the biologics regulations in response to the report and recommendations of the Panel on Review of Bacterial Vaccines and Toxoids with Standards of Potency (the Panel). The Panel reviewed the safety, efficacy, and labeling of bacterial vaccines and toxoids that have standards of potency, bacterial antitoxins, and immune globulins. On the basis of the Panel's findings and recommendations, FDA is classifying these products as Category I (safe, effective, and not misbranded), Category II (unsafe, ineffective, or misbranded), or Category IIIB (off the market pending completion of studies permitting a determination of effectiveness).

[Neisseria meningitidis and meningitis]. / Neisseria meningitidis et méningites.

Meningococcal meningitis epidemics can occur anywhere in the world. However this risk is particularly high during the dry season in the sub-Saharan zone of Africa known as the Lapeyssonnie meningitis belt. This area characterized by hyperendemicity that regularly gives rise to epidemics. Multilocus enzyme electrophoresis has made possible identification and monitoring of the progression of virulent clones of Neisseria meningitidis strains in the world. Monitoring is now possible by multilocus sequence typing and data bank on the Internet. Vaccination is a major prophylactic modality. The usefulness of plain group A plus C polysaccharide vaccines is limited because of poor effectiveness in young children who constitute the highest risk group. During epidemics, mass vaccination should be carried out as early as possible according to the state of alert defined for the area. More recent conjugate vaccines against group A and C, which are effective in young children and provide long-term protection by induction of immunologic memory, may allow routine vaccination in the future. Although clinical signs are often apparent, not all cases are diagnosed by clinical examination unless gravity is taken into account. Untreated the disease is always fatal. The only hope of survival is early institution of appropriate antimicrobial therapy (even prior to hospitalization). Several strains resistant to chloramphenicol have been reported and the number of strains with reduced sensitivity to penicillin is rising constantly. Although treatment remains feasible, the existence of resistant forms raises the need to monitor the sensitivity of meningococci using standardized of antibiograms.

[Polysaccharide subunit vaccines]. / Vaccins sous-unités polysaccharidiques.

The polysaccharide capsules of many germs (pneumococcus, meningococcus, Haemophilus b, salmonella, etc.) can induce synthesis of protective antibodies in man. The development of many vaccines has been based on this phenomenon. Unfortunately, the polysaccharide antigens cannot trigger an immune response before the age of 2 years. In addition, they do not induce an anamnestic response, as do protein antigens. Great progress has been made by conjugating these polysaccharide antigens with protein antigens (tetanus and diphtheria antigens in particular). The resulting novel antigen induces a thymus-dependent response in man, leading to immunogenicity from the first weeks of life, and to a higher and more durable antibody response. On subsequent administration, such conjugated vaccines provoke a booster effect. In practice, the anti-Haemophilus b conjugated vaccine has obtained spectacular results in prevention of meningitis, with an effectiveness close to 100%. Results of the first trials of conjugated anti-pneumococcal vaccines suggest that they may constitute an effective new means of combating the emerging pneumococcal strains resistant to penicillin.

Vaccination coverage in a cohort of HIV-infected patients receiving care at an AIDS outpatient clinic in Espírito Santo, Brazil

Abstract This cross-sectional study assessed the immunization status of human immune deficiency virus (HIV)-infected patients receiving care at an outpatient clinic in Brazil. The sociodemographic characteristics, CD4 count and HIV viral load of 281 out of 612 adult outpatients were analyzed. A total of 331 patients were excluded because of no availability of vaccination cards. Chi-square or Fisher's exact test were used. Immunization coverage was higher for diphtheria/tetanus (59.79%) and hepatitis B (56.7%), and lowest for hepatitis A (6.8%) and for meningococcal group C (6%). Only 11.74% of the patients had received the influenza virus vaccine yearly since their HIV-infection diagnosis. No vaccination against influenza (p < 0.034) or hepatitis B (p < 0.029) were associated with CD4 counts <500 cells/mL; no vaccination against flu or pneumococcus were associated with detectable HIV viral load (p < 0.049 and p < 0.002, respectively). Immunization coverage is still very low among HIV-infected adults in this setting despite recommendations and high infection-related mortality.

Molecular typing of Brucella melitensis endemic strains and differentiation from the vaccine strain Rev-1.

In the present study forty-four Greek endemic strains of Br. melitensis and three reference strains were genotyped by Multi locus Variable Number Tandem Repeat (ML-VNTR) analysis based on an eight-base pair tandem repeat sequence that was revealed in eight loci of Br. melitensis genome. The forty-four strains were discriminated from the vaccine strain Rev-1 by Restriction Fragment Length Polymorphism (RFLP) and Denaturant Gradient Gel Electrophoresis (DGGE). The ML-VNTR analysis revealed that endemic, reference and vaccine strains are genetically closely related, while most of the loci tested (1, 2, 4, 5 and 7) are highly polymorphic with Hunter-Gaston Genetic Diversity Index (HGDI) values in the range of 0.939 to 0.775. Analysis of ML-VNTRs loci stability through in vitro passages proved that loci 1 and 5 are non stable. Therefore, vaccine strain can be discriminated from endemic strains by allele's clusters of loci 2, 4, 6 and 7. RFLP and DGGE were also employed to analyse omp2 gene and reveled different patterns among Rev-1 and endemic strains. In RFLP, Rev-1 revealed three fragments (282, 238 and 44 bp), while endemic strains two fragments (238 and 44 bp). As for DGGE, the electrophoretic mobility of Rev-1 is different from the endemic strains due to heterologous binding of DNA chains of omp2a and omp2b gene. Overall, our data show clearly that it is feasible to genotype endemic strains of Br. melitensis and differentiate them from vaccine strain Rev-1 with ML-VNTR, RFLP and DGGE techniques. These tools can be used for conventional investigations in brucellosis outbreaks.

Immune response following vaccination against Salmonella Enteritidis using 2 commercial bacterins in laying hens.

The humoral and cell-mediated immune (CMI) response to 2 commercial killed Salmonella Enteritidis (SE) vaccines (Layermune and MBL SE4C) was evaluated in laying hens. Layers were distributed in 2 experimental groups. The first received a single immunization at 16 wk of age, while the second experimental group was immunized at 12 wk of age and again at 18 wk of age. Serum immunoglobulin (Ig)G antibodies were measured using a commercial SE ELISA kit and showed persistent levels from 3 to 32 and 34 wk post-vaccination. The vaccination protocol using 2 immunizations showed a higher seroconversion level than the single vaccination. However, our results for bacterial intracellular survival indicated that IgG titers were not linked with bacterial killing. Local IgA production was measured in the intestines and oviducts with an in-house SE whole cell antigen ELISA. Only the MBL SE4C vaccine elicited IgA antibody production when tested on intestine and oviduct mucosal secretions, 3-weeks post-vaccination in both immunization protocol groups. To evaluate the CMI response, the splenic T-cells and B-cells populations were analyzed using flow cytometry. The CD3/B-cell ratio decreased 3 wk after the second immunization in the twice vaccinated Layermune group due to an increase in B-cells.