Influenza-specific Antibody Responses Research Articles

Tissue-specific sex differences in pediatric and adult immune cell composition and function.

Sex-based differences in immune cell composition and function can contribute to distinct adaptive immune responses. Prior work has quantified these differences in peripheral blood, but little is known about sex differences within human lymphoid tissues. Here, we characterized the composition and phenotypes of adaptive immune cells from male and female ex vivo tonsils and evaluated their responses to influenza antigens using an immune organoid approach. In a pediatric cohort, female tonsils had more memory B cells compared to male tonsils direct ex vivo and after stimulation with live-attenuated but not inactivated vaccine, produced higher influenza-specific antibody responses. Sex biases were also observed in adult tonsils but were different from those measured in children. Analysis of peripheral blood immune cells from in vivo vaccinated adults also showed higher frequencies of tissue homing CD4 T cells in female participants. Together, our data demonstrate that distinct memory B and T cell profiles are present in male vs. female lymphoid tissues and peripheral blood respectively and suggest that these differences may in part explain sex biases in response to vaccines and viruses.

Effects of Extended-Release Buprenorphine on Mouse Models of Influenza.

Mice are widely used as small animal models for influenza infection and immunization studies because of their susceptibility to many strains of influenza, obvious clinical signs of infection, and ease of handling. Analgesia is rarely used in such studies even if nonstudy effects such as fight wounds, tail injuries, or severe dermatitis would otherwise justify it because of concerns that treatment might have confounding effects on primary study parameters such as the course of infection and/or the serological response to infection. However, analgesia for study-related or -unrelated effects may be desirable for animal welfare purposes. Opioids, such as extended-release buprenorphine, are well-characterized analgesics in mice and may have fewer immune-modulatory effects than other drug classes. In this study, BALB/c and DBA/2 mice were inoculated with influenza virus, and treatment groups received either no analgesics or 2 doses of extended-release buprenorphine 72 h apart. Clinical signs, mortality, and influenza-specific antibody responses were comparable in mice that did or did not receive buprenorphine. We therefore conclude that extended-release buprenorphine can be used to alleviate incidental pain during studies of influenza infection without altering the course of infection or the immune response.

Oral and intranasal Ad5 influenza vaccination induces hemagglutinin-specific and influenza neutralizing antibodies in serum and milk of pregnant and lactating ferrets

Abstract Pregnant women and young children are at increased risk for severe influenza infection. While there are intramuscular (IM) inactivated influenza vaccines available to pregnant individuals, IM immunization may not be an ideal route to boost neutralizing antibodies in breastmilk (BM). Therefore, innovative vaccine strategies are needed to increase BM antibodies that promote neonatal protection against influenza. We hypothesize that maternal mucosal immunization stimulates a protective influenza-specific antibody response, by generating antibodies in both blood and BM. To test this, we immunized pregnant and lactating ferrets at two weeks prepartum and two weeks postpartum with an H1N1 hemagglutinin (HA) adenovirus type 5 (Ad5) vaccine via oral or intranasal routes. We detected HA-specific IgG antibodies in dam serum and HA-specific IgG and IgA antibodies in secreted milk after oral and intranasal immunization by ELISA and chemiluminescence assays. We demonstrated that serum and BM from oral and intranasally immunized dams neutralized influenza virus in vitro. Additionally, ferret kits born to oral and intanasally immunized dams had HA-specific IgG antibodies in circulation at 5–6 weeks of life. These preclinical data led to the announcement by Vaxart, Inc. that they will test their oral tablet vaccine in human lactating mothers to determine if vaccination induces BM antibodies. Future work includes using our ferret model to determine the relationship between BM antibody quantity and function and neonatal protection against influenza. An easy-to-deliver mucosal vaccine that boosts systemic and mucosal protective antibodies in the maternal-neonatal dyad is an ideal strategy for protection of these vulnerable populations. Bill and Melinda Gates Foundation grant INV-22595D

Safety, tolerability, and immunogenicity of V114, a 15-valent pneumococcal conjugate vaccine, administered concomitantly with influenza vaccine in healthy adults aged ≥50 years: a randomized phase 3 trial (PNEU-FLU)

ABSTRACT Streptococcus pneumoniae and influenza viruses are associated with significant morbidity and mortality in older adults. Concomitant vaccination against these agents reduces hospitalization and mortality rates. This phase 3 trial evaluated safety, tolerability, and immunogenicity of concomitant and non-concomitant administration of V114, a 15-valent pneumococcal conjugate vaccine containing serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19F, 19A, 22F, 23F, 33F, and quadrivalent inactivated influenza vaccine (QIV), in healthy adults aged ≥50 years. Participants (N = 1,200) were randomized 1:1 to receive either V114 administered concomitantly with QIV (concomitant group) or QIV plus placebo (non-concomitant group) on Day 1, followed by placebo (concomitant group) or V114 (non-concomitant group) 30 days later. Randomization was stratified by age and history of pneumococcal polysaccharide vaccine receipt. Overall, 426 (71.0%) and 438 (73.5%) participants in the concomitant and non-concomitant groups experienced solicited injection-site adverse events (AEs); 278 (46.3%) and 300 (50.3%) reported solicited systemic AEs. Most solicited AEs were mild or moderate in severity and of short duration. Non-inferiority for pneumococcal- and influenza-specific antibody responses (lower bound 95% confidence interval of opsonophagocytic activity [OPA] and hemagglutination inhibition geometric mean titers [GMTs] ratios ≥0.5) was demonstrated for concomitant versus non-concomitant administration for all 15 pneumococcal serotypes and all four influenza strains. Consistent with previous studies, a trend was observed toward lower pneumococcal OPA GMTs in the concomitant versus the non-concomitant group. V114 administered concomitantly with QIV is generally well tolerated and immunologically non-inferior to non-concomitant administration, supporting coadministration of both vaccines.

Generation and Characterization of Universal Live-Attenuated Influenza Vaccine Candidates Containing Multiple M2e Epitopes.

Influenza viruses constantly evolve, reducing the overall protective effect of routine vaccination campaigns. Many different strategies are being explored to design universal influenza vaccines capable of protecting against evolutionary diverged viruses. The ectodomain of influenza A M2e protein (M2e) is among the most promising targets for universal vaccine design. Here, we generated two recombinant live attenuated influenza vaccines (LAIVs) expressing additional four M2e tandem repeats (4M2e) from the N-terminus of the viral hemagglutinin (HA) protein, in an attempt to enhance the M2e-mediated cross-protection. The recombinant H1N1+4M2e and H3N2+4M2e viruses retained growth characteristics attributable to traditional LAIV viruses and induced robust influenza-specific antibody responses in BALB/c mice, although M2e-specific antibodies were raised only after two-dose vaccination with LAIV+4M2e viruses. Mice immunized with either LAIV or LAIV+4M2e viruses were fully protected against a panel of heterologous influenza challenge viruses suggesting that antibody and cell-mediated immunity contributed to the protection. The protective role of the M2e-specific antibody was seen in passive serum transfer experiments, where enhancement in the survival rates between classical LAIV and chimeric H3N2+4M2e LAIV was demonstrated for H3N2 and H5N1 heterologous challenge viruses. Overall, the results of our study suggest that M2e-specific antibodies induced by recombinant LAIV+4M2e in addition to cellular immunity by LAIV play an important role in conferring protection against heterologous viruses.

Protective Intranasal Immunization Against Influenza Virus in Infant Mice Is Dependent on IL-6.

Respiratory diseases adversely affect infants and are the focus of efforts to develop vaccinations and other modalities to prevent disease. The infant immune system differs from that of older children and adults in many ways that are as yet ill understood. We have used a C57BL/6 mouse model of infection with a laboratory- adapted strain of influenza (PR8) to delineate the importance of the cytokine IL-6 in the innate response to primary infection and in the development of protective immunity in adult mice. Herein, we used this same model in infant (14 days of age) mice to determine the effect of IL-6 deficiency. Infant wild type mice are more susceptible than older mice to infection, similar to the findings in humans. IL-6 is expressed in the lung in the early response to PR8 infection. While intramuscular immunization does not protect against lethal challenge, intranasal administration of heat inactivated virus is protective and correlates with expression of IL-6 in the lung, activation of lung CD8 cells, and development of an influenza-specific antibody response. In IL-6 deficient mice, this response is abrogated, and deficient mice are not protected against lethal challenge. These studies support the importance of the role of the tissue environment in infant immunity, and further suggest that IL-6 may be helpful in the generation of protective immune responses in infants.

Functional immune response to influenza H1N1 in children and adults after live attenuated influenza virus vaccination.

Influenza virus is a major respiratory pathogen, and vaccination is the main method of prophylaxis. In 2012, the trivalent live attenuated influenza vaccine (LAIV) was licensed in Europe for use in children. Vaccine-induced antibodies directed against the main viral surface glycoproteins, haemagglutinin (HA) and neuraminidase (NA) play important roles in limiting virus infection. The objective of this study was to dissect the influenza-specific antibody responses in children and adults, and T cell responses in children induced after LAIV immunization to the A/H1N1 virus. Blood samples were collected pre- and at 28 and 56days post-vaccination from 20 children and 20 adults. No increase in micro-neutralization (MN) antibodies against A/H1N1 was observed after vaccination. A/H1N1 stalk-specific neutralizing and NA-inhibiting (NI) antibodies were boosted in children after LAIV. Interferon γ-producing T cells increased significantly in children, and antibody-dependent cellular-mediated cytotoxic (ADCC) cell activity increased slightly in children after vaccination, although this change was not significant. The results indicate that the NI assay is more sensitive to qualitative changes in serum antibodies after LAIV. There was a considerable difference in the immune response in children and adults after vaccination, which may be related to priming and previous influenza history. Our findings warrant further studies for evaluating LAIV vaccination immunogenicity.

Long-Lasting Mucosal and Systemic Immunity against Influenza A Virus Is Significantly Prolonged and Protective by Nasal Whole Influenza Immunization with Mucosal Adjuvant N3 and DNA-Plasmid Expressing Flagellin in Aging In- and Outbred Mice.

Background: Vaccination is commonly used to prevent and control influenza infection in humans. However, improvements in the ease of delivery and strength of immunogenicity could markedly improve herd immunity. The aim of this pre-clinical study is to test the potential improvements to existing intranasal delivery of formalin-inactivated whole Influenza A vaccines (WIV) by formulation with a cationic lipid-based adjuvant (N3). Additionally, we combined WIV and N3 with a DNA-encoded TLR5 agonist secreted flagellin (pFliC(-gly)) as an adjuvant, as this adjuvant has previously been shown to improve the effectiveness of plasmid-encoded DNA antigens. Methods: Outbred and inbred mouse strains were intranasally immunized with unadjuvanted WIV A/H1N1/SI 2006 or WIV that was formulated with N3 alone. Additional groups were immunized with WIV and N3 adjuvant combined with pFliC(-gly). Homo and heterotypic humoral anti-WIV immune responses were assayed from serum and lung by ELISA and hemagglutination inhibition assay. Homo and heterotypic cellular immune responses to WIV and Influenza A NP were also determined. Results: WIV combined with N3 lipid adjuvant the pFliC(-gly) significantly increased homotypic influenza specific serum antibody responses (>200-fold), increased the IgG2 responses, indicating a mixed Th1/Th2-type immunity, and increased the HAI-titer (>100-fold). Enhanced cell-mediated IFNγ secreting influenza directed CD4+ and CD8+ T cell responses (>40-fold) to homotypic and heterosubtypic influenza A virus and peptides. Long-term and protective immunity was obtained. Conclusions: These results indicate that inactivated influenza virus that was formulated with N3 cationic adjuvant significantly enhanced broad systemic and mucosal influenza specific immune responses. These responses were broadened and further increased by incorporating DNA plasmids encoding FliC from S. typhimurum as an adjuvant providing long lasting protection against heterologous Influenza A/H1N1/CA09pdm virus challenge.

Immunogenicity and safety of zoster vaccine live administered with quadrivalent influenza virus vaccine

ObjectivesRandomized, blinded, placebo-controlled trial to evaluate the safety and immunogenicity of ZOSTAVAX™ (ZV) administered concomitantly with quadrivalent inactivated influenza vaccine (IIV4) in adults≥50years of age (NCT02519855). MethodsOverall, 440 participants were randomized into the Concomitant Group (CG) and 442 into the Sequential Group (SG). The CG received ZV and IIV4 at separate injection sites on Day 1 and matching placebo at Week 4. The SG received placebo and IIV4 (2015–2016 influenza season) at separate injection sites on Day 1 and ZV at Week 4. Immunogenicity endpointsVaricella-zoster virus (VZV) antibody geometric mean titer (GMT) and geometric mean fold-rise (GMFR) from baseline to 4weeks postvaccination, measured by glycoprotein enzyme-linked immunosorbent assay (gpELISA) and adjusted for age and prevaccination titer. Influenza strain-specific GMT at baseline and 4weeks postvaccination was measured by hemagglutination inhibition (HAI) assay. Safety endpointsInjection-site and systemic adverse experiences (AEs) within 28days following any vaccination and serious AEs throughout the study. ResultsThe adjusted VZV antibody GMT ratio (CG/SG) was 0.87 (95%CI: 0.80, 0.95), meeting the prespecified noninferiority criterion. The VZV antibody GMFR in the CG was 1.9 (95%CI: 1.76, 2.05), meeting the acceptability criterion. Influenza antibody GMT ratios for A/H1N1, A/H3N2, B/Yamagata and B/Victoria were 1.02 (95%CI: 0.88, 1.18), 1.10 (95%CI: 0.94, 1.29), 1.00 (95%CI: 0.88, 1.14), and 0.99 (95%CI: 0.87, 1.13), respectively. The frequency of vaccine-related injection-site and systemic AEs was comparable between groups. No vaccine-related serious AE was observed. ConclusionThe concomitant administration of ZV and IIV4 to adults≥50years of age induced VZV-specific and influenza-specific antibody responses that were comparable to those following administration of either vaccine alone, and was generally well tolerated.

Rituximab impairs immunoglobulin (Ig)M and IgG (subclass) responses after influenza vaccination in rheumatoid arthritis patients.

Rituximab (RTX) treatment in rheumatoid arthritis (RA) patients severely hampers humoral response after influenza vaccination as determined by haemagglutination inhibition assay (HI). It is not known whether HI reflects both immunoglobulin (Ig)M and IgG (subclass) influenza response, and whether IgM antibodies contribute to the low rate of influenza infection seen in RA patients. Twenty RA patients on methotrexate (MTX), 23 on RTX and 28 healthy controls (HC) received trivalent influenza subunit vaccination. Before and 28 days after vaccination, H1N1- and H3N2-specific antibodies were measured by HI and by IgM and IgG (subclass) enzyme-linked immunosorbent assay (ELISA). B cell activating factor (BAFF) levels were determined in serum samples before vaccination. Vaccination induced a significant increase of IgM and IgG (IgG1 and IgG3) antibodies against both strains in the HC and MTX groups (all P < 0·01), but not in the RTX group. HI correlated significantly in all cases with IgG (IgG1) but not with IgM. In RTX late patients (RTX treatment 6-10 months before vaccination), IgG (IgG1 and IgG3) response to vaccination was restored, but not IgM response. BAFF levels were significantly increased in RA-RTX patients and correlated with total IgG levels. Haemagglutination inhibition assay, used as gold standard, detects primarily IgG (IgG1) responses. IgM- and IgG influenza-specific antibodies increase after vaccination in HC and RA patients except in patients on RTX treatment. BAFF levels are increased in both early and late RTX-treated patients, but do not correlate with an influenza-specific antibody response.

Enhanced protection for influenza vaccines using a novel rOv-ASP-1 adjuvant aqueous formulation (VAC2P.933)

Abstract Adjuvants have been used to enhance the efficacy of a variety of vaccines; however, no adjuvant is included in current influenza vaccines used in the United States. In this study, we found that a novel adjuvant, rOv-ASP-1, co-administrated with inactivated influenza vaccine using an aqueous formulation, substantially improved the influenza-specific antibody response and protection against lethal infection in a mouse model. rOv-ASP-1 enhanced the magnitude of the specific antibody response after immunization with low doses of influenza vaccine, allowing antigen-sparring by 10-fold. The rOv-ASP-1 formulated vaccine induced a more rapid response and a stronger Th1-associated antibody response compared to vaccine alone and to the vaccine formulated with the adjuvant alum. Importantly, rOv-ASP-1 significantly enhanced cross-reactive antibody responses and protection when challenged with a heterologous influenza virus strain. These results demonstrate that rOv-ASP-1 is an effective adjuvant that: 1) accelerates and enhances the specific antibody response induced by influenza vaccine; 2) allows for antigen sparing; and 3) augments a Th1-biased and cross-reactive antibody response that confers heterologous protection.

Antigen sparing and enhanced protection using a novel rOv-ASP-1 adjuvant in aqueous formulation with influenza vaccines

Influenza is one of the most common infectious diseases endangering the health of humans, especially young children and the elderly. Although vaccination is the most effective means of protection against influenza, frequent mutations in viral surface antigens, low protective efficacy of the influenza vaccine in the elderly, slow production process and the potential of vaccine supply shortage during a pandemic are significant limitations of current vaccines. Adjuvants have been used to enhance the efficacy of a variety of vaccines; however, no adjuvant is included in current influenza vaccines approved in the United States. In this study, we found that a novel adjuvant, rOv-ASP-1, co-administrated with inactivated influenza vaccine using an aqueous formulation, substantially improved the influenza-specific antibody response and protection against lethal infection in a mouse model. rOv-ASP-1 enhanced the magnitude of the specific antibody response after immunization with low doses of influenza vaccine, allowing antigen-sparring by 10-fold. The rOv-ASP-1 formulated vaccine induced a more rapid response and a stronger Th1-associated antibody response compared to vaccine alone and to the vaccine formulated with the adjuvant alum. Importantly, rOv-ASP-1 significantly enhanced cross-reactive antibody responses and protection against challenge with an antigenically distinct strain. These results demonstrate that rOv-ASP-1 is an effective adjuvant that: (1) accelerates and enhances the specific antibody response induced by influenza vaccine; (2) allows for antigen sparing; and (3) augments a Th1-biased and cross-reactive antibody response that confers protection against an antigenically distinct strain.

MVA Vectors Expressing Conserved Influenza Proteins Protect Mice against Lethal Challenge with H5N1, H9N2 and H7N1 Viruses

BackgroundThe availability of a universal influenza vaccine able to induce broad cross-reactive immune responses against diverse influenza viruses would provide an alternative to currently available strain-specific vaccines. We evaluated the ability of vectors based on modified vaccinia virus Ankara (MVA) expressing conserved influenza proteins to protect mice against lethal challenge with multiple influenza subtypes.MethodsMice were immunized with MVA vectors expressing H5N1-derived nucleoprotein (NP), the stem region of hemagglutinin (HA), matrix proteins 1 and 2 (M1 and M2), the viral polymerase basic protein 1 (PB1), or the HA stem fused to a quadrivalent matrix protein 2 extracellular domain (M2e). Immunized mice were challenged with lethal doses of H5N1, H7N1 or H9N2 virus and monitored for disease symptoms and weight loss. To investigate the influence of previous exposure to influenza virus on protective immune responses induced by conserved influenza proteins, mice were infected with pandemic H1N1 virus (H1N1pdm09) prior to immunization and subsequently challenged with H5N1 virus. Antibody and T cell responses were assessed by ELISA and flow cytometry, respectively.ResultsMVA vectors expressing NP alone, or co-expressed with other conserved influenza proteins, protected mice against lethal challenge with H5N1, H7N1 or H9N2 virus. Pre-exposure to H1N1pdm09 increased protective efficacy against lethal H5N1 challenge. None of the other conserved influenza proteins provided significant levels of protection against lethal challenge. NP-expressing vectors induced high numbers of influenza-specific CD4+ and CD8+ T cells and high titer influenza-specific antibody responses. Higher influenza-specific CD4+ T cell responses and NP-specific CD8+ T cell responses were associated with increased protective efficacy.ConclusionsMVA vectors expressing influenza NP protect mice against lethal challenge with H5N1, H7N1 and H9N2 viruses by a mechanism involving influenza-specific CD4+ and CD8+ T cell responses.

Nanoemulsion W805EC improves immune responses upon intranasal delivery of an inactivated pandemic H1N1 influenza vaccine

Currently available influenza vaccines provide suboptimal protection. In order to improve the quality of protective immune responses elicited following vaccination, we developed an oil-in-water nanoemulsion (NE)-based adjuvant for an intranasally-delivered inactivated influenza vaccine. Using a prime-boost vaccination regimen, we show that intranasal vaccines containing the W805EC NE elicited higher titers of serum hemagglutination inhibiting (HAI) antibody and influenza-specific IgG and IgA titers compared to vaccines that did not contain the NE. Similarly, vaccines containing the W805EC NE resulted in higher influenza-specific IgA levels in the bronchoalveolar lavage (BAL) fluid and nasal wash when compared to vaccines formulated without NE. The higher antibody titers in mice immunized with the NE-containing vaccines correlated with reduced viral loads in the lungs and nasal turbinates following a high dose viral challenge. Mice immunized with vaccines containing the W805EC NE also showed a reduction in body weight loss following challenge compared to mice immunized with equivalent vaccines produced without NE. Taken together, our results show that the W805EC NE substantially improves the magnitude of protective influenza-specific antibody responses and is a promising mucosal adjuvant for influenza vaccines and vaccines against other mucosal pathogens.

Durable immune response to inactivated H1N1 vaccine is less likely in children with sickle cell anemia receiving chronic transfusions

Defects in the immune system may affect vaccine responsiveness. Because of the splenic hypofunction and abnormal opsonic activity, it was unknown whether patients with sickle cell disease (SCD) would respond appropriately to H1N1 vaccination. The objective of this study was to assess seroprotective post-vaccine H1N1 antibody response in children with SCD. Serum antibody titers were measured by hemagglutination inhibition and microneutralization (MN) assays. Correlations were established between clinical and treatment parameters and immune response. Twenty-nine of 38 (76.3%) subjects (mean age 11 ± 5.4 years) had durable protective antibody titers 8 ± 1.6 months (range 5-12 months) post-vaccination. Lessened immune response was not associated with time interval from vaccination, splenectomy, or hydroxyurea treatment. Lack of antibody response was associated with age less than 3 years and treatment with chronic transfusions. Of the nine non-responders, seven were on chronic transfusions (39% unresponsiveness rate in the transfused group). The difference in the number of patients with seropositivity between the non-transfused and the transfused groups was statistically significant (P = 0.039). Most subjects were able to mount an influenza-specific antibody response against the inactivated H1N1 vaccine. Similar to the general population, children less than 3 years were less likely to respond. In addition, patients on chronic transfusions were less likely to respond when compared to non-transfused children. Clinicians should be aware of the possibility of decreased vaccine response in patients with SCD on chronic transfusions. We postulate that transfusion-related immunomodulation (TRIM) may be related to decreased response.

Bacterium-like particles supplemented with inactivated influenza antigen induce cross-protective influenza-specific antibody responses through intranasal administration

Administration of influenza vaccines through the intranasal (IN) route forms an attractive alternative to conventional intramuscular (IM) injection. It is not only a better accepted form of vaccine administration but it also has the potential to induce, in addition to systemic antibodies, local protective antibodies, i.e. S-IgA. Most commercially available vaccines however are inactivated non-replicating vaccines and have a low immunogenicity when administered intranasally. Local administration of these vaccines would therefore need an adjuvant to boost systemic and local antibody responses. Here we explored the use of a safe adjuvant system, i.e. bacterium-like particles (BLPs) derived from the food-grade bacterium in Lactococcus lactis, in the induction of protective antibody responses after intranasal immunization of mice. Supplementation of H1N1 split vaccine with BLPs significantly increased levels of serum influenza-specific IgG and hemagglutination-inhibiting antibodies: this was dependent on the dose of admixed BLPs and number of immunizations. Admixing BLPs further boosted local influenza-specific S-IgA antibody levels at lung and nasal mucosal sites, but also at distant mucosal sites such as the vaginal mucosal tissue. Mice immunized IN with BLP-adjuvanted vaccine and IM with non-adjuvanted vaccine were protected against weight loss upon homologous infection with H1N1 A/PR/8/34. Full protection against weight loss upon heterologous challenge with H1N1 A/PR/8/34 was seen in mice immunized IN with BLP-adjuvanted H1N1 A/New Caledonia-derived split virus vaccine, but not in those receiving the split virus vaccine IM. Mice immunized IN with BLP-adjuvanted vaccine had significantly lower lung viral titers upon homologous and heterologous challenge when compared to titers detected in mice immunized by IM injection of non-adjuvanted vaccine. Thus, adjuvantation of IN-administered influenza vaccines with BLPs effectively enhances systemic and local antibody responses leading to a superior protection against homologous and heterologous influenza infection compared to conventional IM immunization.

Comparative Analyses of Pandemic H1N1 and Seasonal H1N1, H3N2, and Influenza B Infections Depict Distinct Clinical Pictures in Ferrets

Influenza A and B infections are a worldwide health concern to both humans and animals. High genetic evolution rates of the influenza virus allow the constant emergence of new strains and cause illness variation. Since human influenza infections are often complicated by secondary factors such as age and underlying medical conditions, strain or subtype specific clinical features are difficult to assess. Here we infected ferrets with 13 currently circulating influenza strains (including strains of pandemic 2009 H1N1 [H1N1pdm] and seasonal A/H1N1, A/H3N2, and B viruses). The clinical parameters were measured daily for 14 days in stable environmental conditions to compare clinical characteristics. We found that H1N1pdm strains had a more severe physiological impact than all season strains where pandemic A/California/07/2009 was the most clinically pathogenic pandemic strain. The most serious illness among seasonal A/H1N1 and A/H3N2 groups was caused by A/Solomon Islands/03/2006 and A/Perth/16/2009, respectively. Among the 13 studied strains, B/Hubei-Wujiagang/158/2009 presented the mildest clinical symptoms. We have also discovered that disease severity (by clinical illness and histopathology) correlated with influenza specific antibody response but not viral replication in the upper respiratory tract. H1N1pdm induced the highest and most rapid antibody response followed by seasonal A/H3N2, seasonal A/H1N1 and seasonal influenza B (with B/Hubei-Wujiagang/158/2009 inducing the weakest response). Our study is the first to compare the clinical features of multiple circulating influenza strains in ferrets. These findings will help to characterize the clinical pictures of specific influenza strains as well as give insights into the development and administration of appropriate influenza therapeutics.

Influenza vaccination responses in human systemic lupus erythematosus: Impact of clinical and demographic features

Vaccination against common pathogens, such as influenza, is recommended for patients with systemic lupus erythematosus (SLE) to decrease infections and improve health. However, most reports describing the vaccination response are limited to evaluations of SLE patients with quiescent disease. This study focuses on understanding the clinical, serologic, therapeutic, and demographic factors that influence the response to influenza vaccination in SLE patients with a broad range of disease activity. Blood specimens and information on disease activity were collected from 72 patients with SLE, at baseline and at 2, 6, and 12 weeks after influenza vaccination. Influenza-specific antibody responses were assessed by determining the total serum antibody concentration (B(max)), relative affinity (K(a)), and level of hemagglutination inhibition in the plasma. Using a cumulative score, the patients were evenly divided into groups of high or low vaccine responders. Autoantibody levels were evaluated at each time point using immunofluorescence tests and standard enzyme-linked immunosorbent assays. Compared to high responders, low responders to the vaccine were more likely to have hematologic criteria (P = 0.009), to have more American College of Rheumatology classification criteria for SLE (P = 0.05), and to be receiving concurrent prednisone treatment (P = 0.04). Interestingly, European American patients were more likely to be low responders than were African American patients (P = 0.03). Following vaccination, low responders were more likely to experience disease flares (P = 0.01) and to have increased titers of antinuclear antibodies (P = 0.04). Serum interferon-α activity at baseline was significantly higher in patients in whom a flare occurred after vaccination compared to a matched group of patients who did not experience a disease flare (P = 0.04). Ancestral background, prednisone treatment, hematologic criteria, and evidence of increased likelihood of disease flares were associated with low antibody responses to influenza vaccination in SLE patients.

Enhanced in vivo immunity and protection provided by cationic lipid-DNA complex adjuvanted influenza vaccination is independent of Toll-like receptor 9 (106.16)

Abstract As current licensed influenza vaccines provide little or no cross-protective immunity, we have pursued using cationic lipid-DNA complex (CLDC) adjuvant to boost adaptive immunity to inactivated influenza vaccines. CLDC consists of a non-coding plasmid DNA, rich in immunostimulatory CpG motifs, which is encapsulated in cationic lipids. Previous murine and non-human primate studies showed that CLDC adjuvanted influenza vaccination induced more robust immunity and cross-protection. We hypothesized that the CLDC plasmid mediates these effects, at least in part, in a TLR9-dependent manner. Bone-marrow derived dendritic cells (BMDCs) incubated in vitro with CLDC secreted high levels of interferon-alpha (IFN-α), and this induction required CLDC’s DNA component. CLDC-induced IFN-α expression was significantly reduced using TLR9-/- BMDCs. We next vaccinated wildtype and TLR9-/- mice with CLDC-adjuvanted inactivated influenza vaccines. Surprisingly, CLDC’s immunostimulatory responses in vivo were TLR9-independent in that there was no significant difference between wildtype and knockouts for either vaccine immunogenicity (influenza-specific antibody and T-cell responses) or for cross-protection after viral challenge. These studies suggest that the DNA moiety of CLDC enhances immune responses in vivo by a novel, TLR9-independent mechanism. Determining this mechanism will likely be important in the optimal application of CLDC as an adjuvant to human vaccination.

Immune Protection Induced on Day 10 Following Administration of the 2009 A/H1N1 Pandemic Influenza Vaccine

BackgroundThe 2009 swine-origin influenza virus (S-OIV) H1N1 pandemic has caused more than 18,000 deaths worldwide. Vaccines against the 2009 A/H1N1 influenza virus are useful for preventing infection and controlling the pandemic. The kinetics of the immune response following vaccination with the 2009 A/H1N1 influenza vaccine need further investigation.Methodology/Principal Findings58 volunteers were vaccinated with a 2009 A/H1N1 pandemic influenza monovalent split-virus vaccine (15 µg, single-dose). The sera were collected before Day 0 (pre-vaccination) and on Days 3, 5, 10, 14, 21, 30, 45 and 60 post vaccination. Specific antibody responses induced by the vaccination were analyzed using hemagglutination inhibition (HI) assay and enzyme-linked immunosorbent assay (ELISA). After administration of the 2009 A/H1N1 influenza vaccine, specific and protective antibody response with a major subtype of IgG was sufficiently developed as early as Day 10 (seroprotection rate: 93%). This specific antibody response could maintain for at least 60 days without significant reduction. Antibody response induced by the 2009 A/H1N1 influenza vaccine could not render protection against seasonal H1N1 influenza (seroconversion rate: 3% on Day 21). However, volunteers with higher pre-existing seasonal influenza antibody levels (pre-vaccination HI titer ≥1∶40, Group 1) more easily developed a strong antibody protection effect against the 2009 A/H1N1 influenza vaccine as compared with those showing lower pre-existing seasonal influenza antibody levels (pre-vaccination HI titer <1∶40, Group 2). The titer of the specific antibody against the 2009 A/H1N1 influenza was much higher in Group 1 (geometric mean titer: 146 on Day 21) than that in Group 2 (geometric mean titer: 70 on Day 21).Conclusions/SignificanceRecipients could gain sufficient protection as early as 10 days after vaccine administration. The protection could last at least 60 days. Individuals with a stronger pre-existing seasonal influenza antibody response may have a relatively higher potential for developing a stronger humoral immune response after vaccination with the 2009 A/H1N1 pandemic influenza vaccine.