Table of Contents

Volume 2, Issue 3

  May/June 2006

  Pages 89 - 143

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 Issue Catalogue (MARC XML)

RESEARCH PAPERS

Open Access Article

Preclinical Laboratory Evaluation of a Bivalent Staphylococcus aureus Saccharide: Exotoxin A Protein Conjugate Vaccine

Mei M. Ho, Barbara Bolgiano, Angela Martino, Satnam K. Kairo and Michael J. Corbel
Pages 89 - 98
Abstract | PDF

A bivalent, unadjuvanted conjugate vaccine composed of Staphylococcus aureus capsular polysaccharides type 5 and 8 (T5 and T8 PS) conjugated to a novel carrier protein, the mutant non-toxic recombinant Pseudomonas aeruginosa exotoxin A (rEPA), has been the subject of recent clinical trials. A programme of preclinical laboratory evaluation was carried out in support of the clinical trials conducted by the National Vaccine Evaluation Consortium. This involved physical chemical characterisation and limited assessment of toxicity and immunogenicity. The carrier protein showed good stability and its conformation was essentially maintained when conjugated. The T5- and T8-rEPA conjugates were of a size range (1-3 x 10⁶ g/mol) consistent with polysaccharide conjugates. Fluorescence spectroscopy and molecular sizing showed good batch-to-batch consistency. Although all batches of final fill preparations elicited positive immune responses in the mouse model with three schedule doses of 0.25 mg of each T5/ 8 conjugate per dose, the mouse serum IgG response to T8 PS varied from batch to batch. Storage temperature at 37?C or below or with repetitive temperature fluctuations did not significantly affect the IgG responses to T5 or T8 PS. Storage at 56?C, however, diminished the mouse serum IgG response to T5 PS. The conformation of the conjugated protein and size of the conjugates correlated well with mouse immunogenicity in the thermal stability samples; significant unfolding of the protein and downshifts in molecular size of the conjugate were only observed when stored at 56?C. The relatively high stability of the novel carrier protein when conjugated to large polysaccharides makes this an attractive candidate carrier protein for other conjugate vaccines. When assayed for serum IgG concentration, the bivalent T5/ 8 conjugate was found to evoke an IgG response well over the threshold value of 10 mg/ml anti-T5 and -T8 IgG established for the ELISA immunogenicity assay.

Open Access Article

Determinants of Pneumococcal Vaccinationi among Patients with Chronic Obstructive Pulomonary Disease in Spain

Maria C Ariñez-Fernandez, Pilar Carrasco-Garrido, Marta Garcia-Carballo, Valentin Hernandez-Barrera, Ángel Gil de Miguel and Rodrigo Jiménez-García
Pages 99 - 104
Abstract | PDF

Background. Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality in adults. Pneumococcal vaccination is recommended to persons suffering COPD. This study aimed at describing pneumococcal vaccination coverages in patients with COPD and analyzing the factors associated with such vaccination.
Methods. This was designed as a descriptive study conducted in the primary-care setting. Each of the 2422 medical practitioners included in the study had to enroll five COPD patients. As the dependent variable, we took the answer to the question, “Have you ever been given a pneumococcal vaccine shot at some time in your life?”. As independent variables, we analyzed sociodemographic, health-status and lifestyle variables, along with history of influenza vaccination.
Results. A total of 10,711 patients were enrolled and, 32.5% (95% CI 31.6-33.4) of participants reported receiving pneumococcal vaccination. Female gender, higher age and more advanced COPD stage were the variables associated with a higher likelihood of being vaccinated. History of influenza vaccination in the most recent campaign was also associated with pneumococcal vaccination. Conclusion. Pneumococcal vaccination coverages among Spanish COPD patients are low and strategies to improve them must be implemented as a matter of urgency.

Open Access Article

Generalized Cutaneous Reactions to the Anthrax Vaccine: Preliminary Results of Anthrax Vaccine-Specific Cell Mediated Immunity and Cytokine Profiles

Amy L. Parker, Ronald W. England, Steven A. Nguyen, Bonnie A. Whisman and Larry L. Hagan
Pages 105 - 109
Abstract | PDF

Over two years, the Vaccine Adverse Event Reporting System reported that 0.042% of all anthrax vaccine (Biothrax, Bioport Corporation) doses administered were associated with cutaneous reactions, half of which were eczematous. This case series attempts to immunologically detail this eczematous reaction in four patients by measuring anthrax vaccine-specific cell mediated immunity (ASCMI), profiling TH1 and TH2 cytokine response to the anthrax vaccine in vitro, and analyzing of skin biopsy specimens. Results demonstrated that 1) ASCMI was variable and likely unrelated to this reaction; 2) a lack of TH1 cytokine response to anthrax vaccine may be associated with an increased risk of this eczematous reaction; and 3) skin biopsy findings were non-specific but supportive of a clinical diagnosis of eczema. Future studies with more patients may yield data to further characterize the ASCMI response and cytokine profiles among patients with this type of reaction.

Open Access Article

Bell’s Palsy and Parenteral Inactivated Influenza Vaccine

Julia Stowe, Nick Andrews, Lesley Wise and Elizabeth Miller
Pages 110 - 112
Abstract | PDF

Concern about a possible increased risk of Bell’s palsy after parenteral inactivated influenza vaccine was raised following the publication in 2004 of a Swiss study in which there was an increased risk following the nasal inactivated formulation of the vaccine. When data from passive reporting systems in the United States and the United Kingdom were examined there was some evidence of increased reporting following the parenteral vaccine. A large population based study using the General Practice Research Database (GPRD) was therefore performed to test the hypothesis that there was an increased risk of Bell’s palsy in the three months following parenteral inactivated influenza vaccine. The risk was also assessed for the same period following pneumococcal vaccine and was stratified into three age groups (<45, 45-64 and 65+ years). Relative incidence (RI) estimates were calculated using the self-controlled case-series method and showed no evidence of an increased risk in the three months following parenteral inactivated influenza vaccine RI 0.92 (95% confidence interval 0.78-1.08). There was also no evidence of an increased risk in any age group or following pneumococcal vaccine. A significant increase was seen on the day of vaccination (day 0) probably due to opportunistic recording of cases.

Open Access Article

Comparison of Rabbit and Mouse Models for Persistence Analysis of Plasmid-Based Vaccines

Vicky L. Leamy, Terrie Martin, Rohit Mahajan, Adrian Vilalta, Denis Rusalov, Jukka Hartikka, Vesselina Bozoukova, Keith D. Hall, Jane Morrow, Alain P. Rolland, David C. Kaslow and Peggy A. Lalor
Pages 113 - 118
Abstract | PDF

Experiments were conducted with a cationic lipid-formulated pDNA vaccine (VCL-AB01) to evaluate the models used to determine biodistribution, persistence and the potential for integration (into genomic DNA) of plasmid DNA-based vaccines. Mice were injected with a high-dose volume of 50 μL unilaterally containing ~2.42 × 10¹¹ plasmid copy numbers (PCN) or a low-dose volume of 20 μL bilaterally (~9.67 × 10¹⁰ PCN). Rabbits were injected bilaterally with a 0.5 mL (~1.37 × 10¹¹ PCN) volume. Injection site muscle tissue was harvested two days, one month, and two months postinjection for the low-dose murine and rabbit models and two days and two months postinjection for the high-dose murine model. Total DNA was extracted and analyzed by real-time quantitative PCR for sequences specific to the injected pDNA. The geometric mean PCN/μg of total DNA from the high and low dose models were compared to determine if injection volume impacts clearance and/or persistence. Results from these studies showed that PCN clearance over two months was similar in mice injected with 20 μL and rabbits injected with 0.5 mL, but PCN clearance was slower in mice injected with similar PCN in 50 μL (1.33 x 10¹³ PCN) compared to 20 μL (5.3 x 10¹² PCN),. Persistence at two months in the rabbit and low-dose murine models was comparable, with geometric mean of 5.22 × 10³ PCN/μg of total DNA for the low-dose volume murine model and 2.81 × 10³/μg DNA for the rabbit model. Interanimal variability in persistence was not impacted by dose volume.

Open Access Article

Confirmation of Immunogenic Consensus Sequence HIV-1 T-cell Epitopes in Bamako, Mali and Providence, Rhode Island

O.A. Koita, D. Dabitao, I. Mahamadou, M. Tall, S. Dao, A. Tounkara, H. Guiteye, C. Noumsi, O. Thiero, M. Kone, D. Rivera, J.A. McMurry, W. Martin and A.S. De Groot
Pages 119 - 128
Abstract | PDF

The design of epitope-driven vaccines for HIV has been significantly hampered by concerns about conservation of vaccine epitopes across clades of HIV. In previous work, we have described a computer-driven method for a cross-clade HIV vaccine comprised of overlapping, highly conserved helper T-cell epitopes or “immunogenic consensus sequence epitopes” (ICS epitopes). Here, we evaluated and compared the immunogenicity of 20 ICS HIV epitopes in ELISpot assays performed using peripheral blood monocytes (PBMC) from HIV-infected donors in Providence, Rhode Island, USA and in Bamako, Mali, West Africa. Each core 9-mer HIV sequence contained in a given consensus peptide was conserved in at least 105 to as many as 2,250 individual HIV-1 strains. Nineteen of the 20 ICS epitopes (95%) were confirmed in ELISpot assays using PBMC obtained from 13 healthy, HIV-1 infected subjects in Providence, and thirteen of the epitopes (65%) were confirmed in ELISpot assays using PBMC derived from 42 discarded blood units obtained at the Central Blood Bank in Bamako. Twelve of the epitopes were confirmed in ELISpot assays performed both in Providence and Bamako. These data confirm the utility of bioinformatics tools to select and design novel vaccines containing “immunogenic consensus sequence” T-cell epitopes for a globally relevant vaccine against HIV; a similar approach may also be useful for any pathogen that exhibits high variability (influenza, HCV, or variola for example). An HIV vaccine containing these immunogenic consensus sequences is currently under development.

Open Access Article

Prevalence of Pneumococcal Bacteremia Among Children < 36 Months of Age Presenting with Moderate Fever to Pediatric Emergency Rooms of the Metropolitan Region (Santiago), Chile

Rosanna M. Lagos, Alma E. Muñoz and Myron M. Levine
Pages 129 - 133
Abstract | PDF

Blood culture collection from outpatients < age 36 months with high fever (> 40º C, rectal) became a standard of ambulatory care in Emergency Rooms (ERs) of the 3 government Children’s Hospitals in Chile’s Metropolitan Region (MR) in 1999; thereafter, invasive pneumococcal disease (IPD) incidence doubled over preceding years’ estimates limited to hospitalizations. We studied IPD among children with moderate (>39ºC but <40ºC, rectal) rather than high fever visiting Pediatric ERs. Recruitment ensued Monday to Friday, 1 - 5 PM, September 1, 2002 through August 31, 2003. Age < 36 months; rectal temperature >39º but <40ºC; outpatient management; parental consent for hemoculture were inclusion criteria. 13,577 children < age 36 months with moderate and 3,214 children with high fever sought ER care. Of 1,134 moderate fever children seen in ERs during the enrollment, parents of 837 consented (73.8%). During these days and hours, 714 children < age 36 months presented with high fever and 651 (91.2%) had a “routine” blood culture. Pneumococcemia was detected among 0.7% with moderate and 1.2% with high fever (6/837 vs 8/651, p>0.05). Extrapolating these rates to all ER outpatients < age 36 months with moderate and high fever, we estimate the true burden as 95 and 39 cases, respectively. The burden of pediatric IPD in the MR is currently underestimated because bacteremias among ER outpatients with moderate fever are not detected. If blood cultures were systematically collected from outpatients with moderate fever, recorded pediatric IPD burden would rise > 2-fold. However, economic and logistical constraints preclude such a practice.

Open Access Article

Dose-Response Relationship of DNA and Recombinant Fowlpox Virus Prime-Boost HIV Vaccines: Implications for Future Trials

Robert De Rose, Mark T. Sullivan, C. Jane Dale, Anthony D. Kelleher, Sean Emery, David A Cooper, Ian A. Ramshaw, David B. Boyle and Stephen J. Kent
Pages 134 - 136
Abstract | PDF

Estimating effective doses of novel HIV vaccines is challenging. Dose-response analyses of DNA and fowlpoxvirus HIV vaccines showed that 1 mg of DNA vaccine and 5 x 10⁷ pfu of fowlpoxvirus booster was immunogenic in macaques. However, this dose was poorly immunogenic in humans. When adjusted for body surface area, the human dose studied was equivalent to a poorly immunogenic lower dose in monkeys. These data provide a rationale for guiding dosing in future trials of HIV vaccine technologies.




COMMENTARY

Open Access Article

Cancer Vaccines Targeting Carbohydrate Antigens

Philip O. Livingston and Govind Ragupathi
Pages 137 - 143
Abstract | PDF

Cancer carbohydrate antigens have been surprisingly potent targets for immune recognition and attack by antibodies, both because of their abundance at the cell surface and their unexpected immunogenicity. Antibodies are ideally suited for eradicating pathogens from the bloodstream and from early tissue invasion. Passively administered and vaccine induced antibodies have accomplished this, eliminating circulating tumor cells and systemic or intraperitoneal micrometastases in a variety of preclinical models. A series of carbohydrate cancer cell-surface differentiation antigens have now been identified and synthesized. Antibodies against each can be induced in the majority of vaccinated patients using KLH conjugate vaccines with a potent saponin immunological adjuvant. Polyvalent vaccines will probably be required due to tumor cell heterogeneity, heterogeneity of the human immune response and the correlation between overall antibody titer against tumor cells and antibody effector mechanisms. Trials testing the clinical impact of these polyvalent vaccines in the adjuvant setting are planned for the near future.