The Specificity of Targeted Vaccines for APC Surface Molecules Influences the Immune Response Phenotype

Different diseases require different immune responses for efficient protection. Thus, prophylactic vaccines should prime the immune system for the particular type of response needed for protection against a given infectious agent. We have here tested fusion DNA vaccines which encode proteins that bivalently target influenza hemagglutinins (HA) to different surface molecules on antigen presenting cells (APC). We demonstrate that targeting to MHC class II molecules predominantly induced an antibody/Th2 response, whereas targeting to CCR1/3/5 predominantly induced a CD8(+)/Th1 T cell response. With respect to antibodies, the polarizing effect was even more pronounced upon intramuscular (i.m) delivery as compared to intradermal (i.d.) vaccination. Despite these differences in induced immune responses, both vaccines protected against a viral challenge with influenza H1N1. Substitution of HA with ovalbumin (OVA) demonstrated that polarization of immune responses, as a consequence of APC targeting specificity, could be extended to other antigens. Taken together, the results demonstrate that vaccination can be tailor-made to induce a particular phenotype of adaptive immune responses by specifically targeting different surface molecules on APCs

Cost-effectiveness of meningococcal vaccination of Norwegian teenagers with a quadrivalent ACWY conjugate vaccine

n Norway, the incidence of invasive meningococcal disease (IMD) is higher among 16–19-year-olds than in the general population. Most IMD cases among teenagers are caused by serogroup Y. Since 2011, one dose of meningococcal ACWY conjugate vaccine (MCV4) has been recommended for teenagers with out- of-pocket payment. The teenagers are usually vaccinated through the school health service at age 18. This study aimed to estimate costs and health gains of introducing MCV4 to Norwegian teenagers through the national immunization program (NIP). A Markov model was used to analyze the cost-effectiveness of universal MCV4 vaccination of either 15-year-olds or 18-years-olds. Occurrences of IMD were simulated from 15 until 23 years of age. Costs were estimated from a healthcare perspective. Sensitivity analyses evaluated the impact of vaccine price, vaccination uptake, IMD incidence and discount rate. Compared to today’s practice of vaccinating 18-year-olds with out-of-pocket payment, introducing MCV4 to 15-year- olds in a NIP-setting, with 90% vaccine uptake and 50% rebate on vaccine price, prevented 3.2 hospita-lizations, 0.20 sequelae and 0.47 deaths among 15–23-year-olds, annually. Total costs were reduced by €30,000 and 9.7 quality-adjusted life-years (QALYs) were gained per birth cohort. The probability of cost- effectiveness was 99.0%, assuming a willingness-to-pay threshold of €86,000/QALY for severe diseases in Norway. Cost-effectiveness was highly dependent on vaccine price. Vaccination of 18-year-olds in a NIP- setting was also cost-effective, but less than NIP-vaccination of 15-year-olds. Introduction of MCV4 to the 15-year-olds in the Norwegian NIP is likely to be cost-effective given a rebate on the vaccine price

Cost-effectiveness of meningococcal vaccination of Norwegian teenagers with a quadrivalent ACWY conjugate vaccine

n Norway, the incidence of invasive meningococcal disease (IMD) is higher among 16–19-year-olds than in the general population. Most IMD cases among teenagers are caused by serogroup Y. Since 2011, one dose of meningococcal ACWY conjugate vaccine (MCV4) has been recommended for teenagers with out- of-pocket payment. The teenagers are usually vaccinated through the school health service at age 18. This study aimed to estimate costs and health gains of introducing MCV4 to Norwegian teenagers through the national immunization program (NIP). A Markov model was used to analyze the cost-effectiveness of universal MCV4 vaccination of either 15-year-olds or 18-years-olds. Occurrences of IMD were simulated from 15 until 23 years of age. Costs were estimated from a healthcare perspective. Sensitivity analyses evaluated the impact of vaccine price, vaccination uptake, IMD incidence and discount rate. Compared to today’s practice of vaccinating 18-year-olds with out-of-pocket payment, introducing MCV4 to 15-year- olds in a NIP-setting, with 90% vaccine uptake and 50% rebate on vaccine price, prevented 3.2 hospita-lizations, 0.20 sequelae and 0.47 deaths among 15–23-year-olds, annually. Total costs were reduced by €30,000 and 9.7 quality-adjusted life-years (QALYs) were gained per birth cohort. The probability of cost- effectiveness was 99.0%, assuming a willingness-to-pay threshold of €86,000/QALY for severe diseases in Norway. Cost-effectiveness was highly dependent on vaccine price. Vaccination of 18-year-olds in a NIP- setting was also cost-effective, but less than NIP-vaccination of 15-year-olds. Introduction of MCV4 to the 15-year-olds in the Norwegian NIP is likely to be cost-effective given a rebate on the vaccine price

Antibody and T cell responses following vaccination with OVA targeted to MHC class II molecules or CCR1/3/5.

<p>(a,b) Supernatants of 293E cells transfected with the indicated plasmids were tested for secreted proteins in ELISA (a) and examined by Western blotting with anti-OVA mAb under reducing (+ME) or non-reducing (-ME) conditions (b). Vaccine proteins are indicated below lanes. (c-f) Mice were immunized once i.d. with 25 µg DNA/EP, as indicated. (c-e) Sera were assayed for total IgG (c), IgG1 (d) or IgG2a (e) against OVA. (f) Splenocytes collected at day 14 post immunization were stimulated <i>in vitro</i> with OVA protein or controls as indicated, and analyzed by an IFNγ EliSpot. *indicates p<0.008 and **p<0.002.</p

Detection of anti‐NS1 antibodies after pandemic influenza exposure: Evaluation of a serological method for distinguishing H1N1pdm09 infected from vaccinated cases

Background Reliable exposure information is crucial for assessing health outcomes of influenza infection and vaccination. Current serological methods are unable to distinguish between anti‐hemagglutinin (HA) antibodies induced by infection or vaccination. Objectives We aimed to explore an alternative method for differentiating influenza infection and vaccination. Methods Sera from animals inoculated with influenza viruses or purified H1N1pdm09 HA were obtained. Human samples were selected from a pregnancy cohort established during the 2009 H1N1 pandemic. Unvaccinated, laboratory‐confirmed cases (N = 18), vaccinated cases without influenza‐like‐illness (N = 18) and uninfected, unvaccinated controls (N = 18) were identified based on exposure data from questionnaires, national registries and maternal hemagglutination inhibition (HI) titres at delivery. Animal and human samples were tested for antibodies against the non‐structural protein 1 (NS1) and HA from H1N1pdm09, using a Luciferase Immunoprecipitation System (LIPS). Results Anti‐NS1 H1N1pdm09 antibodies were detected in sera from experimentally infected, but not from vaccinated, animals. Anti‐HA H1N1pdm09 antibodies were detectable after either of these exposures. In human samples, 28% of individuals with laboratory‐confirmed influenza were seropositive for H1N1pdm09 NS1, whereas vaccinated cases and controls were seronegative. There was a trend for H1N1pdm09 NS1 seropositive cases reporting more severe and longer duration of symptomatic illness than seronegative cases. Anti‐HA H1N1pdm09 antibodies were detected in all cases and in 61% of controls. Conclusions The LIPS method could differentiate between sera from experimentally infected and vaccinated animals. However, in human samples obtained more than 6 months after the pandemic, LIPS was specific, but not sufficiently sensitive for ascertaining cases by exposure

Characterization of fusion vaccine proteins.

<p>a) Schematic overview of homodimeric vaccine proteins. The fusion proteins consists of HA antigen connected to a targeting unit via a shortened Ig hinge and a dimerizing human γ3 CH3 domain and Ig hinge. As targeting units we used a scFv directed against the MHC class II molecule I-E^d (αMHCII-HA), or the mouse chemokine MIP-1α (MIP-1α-HA). For non-targeted controls, a scFv directed against the hapten NIP (αNIP-HA), or a mutated MIP-1α (MIP-1α(C11S)-HA), replaced functional targeting units. b) Supernatants of transfected 293E cells were examined by Western blotting with anti-HA mAb under reducing (-ME) or non-reducing (+ME) conditions. Vaccine proteins are indicated below lanes, and MW by arrows. c) Binding of vaccine proteins to anti-C_H3 mAb in Sandwich ELISA, followed by detection with an anti-HA mAb. d) Binding of vaccine proteins to MHCII I-E^d-transfected L cell fibroblasts. Vaccine proteins were detected by anti-HA mAb. e) Supernatants of 293E cells transfected with MIP-1α-HA or the mutated counterpart (C11S) were examined for chemotaxis. Recombinant human MIP-1α(rLD78β) was included as positive control. Chemotactic index is shown. f, g) Binding of vaccine proteins to CD11b⁺ BALB/c splenocytes.</p

Risk of pregnancy complications and adverse birth outcomes after maternal A(H1N1)pdm09 influenza: a Norwegian population-based cohort study

Background The effects of maternal influenza infection on the fetus remain unclear. We studied mild influenza and influenza antibodies in relation to birth weight and risks of pre-eclampsia, preterm birth (PTB), and small for gestational age (SGA) birth among the unvaccinated participants in the Norwegian Influenza Pregnancy Cohort. Methods Pregnant women attending a routine ultrasound were recruited from four hospitals in Norway shortly after the 2009 A(H1N1) pandemic. The present study was restricted to unvaccinated participants who were pregnant during the pandemic. Information on the participants was obtained through questionnaires and linkage with national registries. Maternal blood samples were collected at delivery. Women with laboratory-confirmed A(H1N1)pdm09 influenza, a clinical diagnosis of influenza, or self-reported influenza during the pandemic were classified as having had influenza. A(H1N1)pdm09-specific antibodies in serum were detected with the hemagglutination-inhibition assay. Detection of antibodies was considered an indicator of infection during the pandemic in the unvaccinated participants. Odds ratios were estimated with logistic regression. Quantile regression was used to estimate differences in the distribution of birth weight. Results Among the 1258 women included in this study, there were 37 cases of pre-eclampsia, 41 births were PTB, and 103 births were SGA. 226 women (18.0%) had influenza during the pandemic. The majority of cases did not receive medical care, and only a small proportion (1.3%) of the cases were hospitalized. Thus, the cases consisted primarily of women with mild illness. No significant associations between influenza and risk of pre-eclampsia, PTB, or SGA birth were observed. Detection of A(H1N1)pdm09-specific antibodies was associated with a lower 10th percentile of birth weight, β = − 159 g (95% CI − 309, − 9). Conclusions Mild influenza illness during pregnancy was not associated with increased risk of pre-eclampsia, PTB or SGA birth. However, influenza infection during pregnancy may reduce the birth weight of the smallest children

Antibodies in sera after intradermal DNA vaccination.

<p>(a-g) Mice were immunized once i.d. with 25 µg DNA/EP as indicated (n = 6/group), and assayed for total IgG (a), IgG1 (b), IgG2a (c), IgG2b (d) and IgG3 (e) against PR8 in ELISA (mean+/-SEM). f) Hemagglutination-inhibition (HI) titers (mean+/-SEM) in sera. g) Sera from day 14 were assayed in a micro neutralization assay (PR8 virus). Dotted line indicates threshold for positive neutralization (50%). (h,i) Mice were immunized twice i.d. at days 0 and 50 as indicated by arrows (↑), and sera assayed in ELISA against PR8 for induced IgG1 (h) and IgG2a (i) (mean +/- SEM).</p

Targeted DNA fusion vaccines enhance immune responses after intramuscular delivery.

<p>Mice were vaccinated once i.m. with 25 µg DNA/electroporation (EP) as indicated (n = 6/group). (a-c) Serum samples were assayed for total IgG (a), IgG1 (b) and IgG2a (c) against PR8 in ELISA (mean+/-SEM). (d-f) Three weeks after vaccination, splenocytes were harvested and stimulated <i>in vitro</i> with either class II restricted HA peptides [d, (SVSSFERFEIFPK) or e, (HNTNGVTAACSHEG)], a class I restricted HA peptide [f, (IYSTVASSL)], or a control peptide (GYKDGNEYI). Frequencies of IFNγ-producing cells were evaluated by EliSpot. The control peptide did not elicit responses beyond that observed for NaCl. Horizontal lines indicate sample means.</p

Meningococcal carriage in Norwegian teenagers: strain characterisation and assessment of risk factors

Abstract Teenagers have a higher risk of invasive meningococcal disease (IMD) than the general population. This cross-sectional study aimed to characterise strains of Neisseria meningitidis circulating among Norwegian teenagers and to assess risk factors for meningococcal carriage. Oropharyngeal swabs were collected from secondary-school students in southeastern Norway in 2018–2019. Meningococcal isolates were characterised using whole genome sequencing. Risk factors for meningococcal carriage were assessed from questionnaire data. Samples were obtained from 2296 12–24-year-olds (majority 13–19-year-olds). N. meningitidis was identified in 167 (7.3%) individuals. The highest carriage rate was found among 18-year-olds (16.4%). Most carriage isolates were capsule null (40.1%) or genogroup Y (33.5%). Clonal complexes cc23 (35.9%) and cc198 (32.3%) dominated and 38.9% of carriage strains were similar to invasive strains currently causing IMD in Norway. Use of Swedish snus (smokeless tobacco) (OR 1.56, 95% CI 1.07–2.27), kissing &gt;two persons/month (OR 2.76, 95% CI 1.49–5.10) and partying &gt;10 times/3months (OR 3.50, 95% CI 1.45–8.48) were associated with carriage, while age, cigarette smoking, sharing of drinking bottles and meningococcal vaccination were not. The high meningococcal carriage rate among 18-year-olds is probably due to risk-related behaviour. Use of Swedish snus is possibly a new risk factor for meningococcal carriage. Almost 40% of circulating carriage strains have invasive potential