Weak Antibody Response Research Articles

Immunogenicity of Two Doses of ChAdOx1 nCoV-19 Vaccine in Lung Transplant Recipients

PurposeLung transplant recipients (LTR) are at higher risk to develop severe SARS-CoV2 pneumonia, due to the immunosuppressive regimen, which further hampers their immune response to vaccination. Indeed, is has been shown that LTR mount weak antibody response after SARS-CoV2 mRNA vaccination. Nevertheless, the immunogenicity of ChAdOx1 nCoV-19 vaccine has not yet been studied in LTR.Methods49 lung-transplant SARS-CoV2 seronegative recipients were enrolled in a prospective cohort study and received the two doses regimen, day 0 and day 90, of the ChAdOx1 nCoV-19 vaccine. Immune response was assessed by measuring total anti-SARS-CoV2 antibodies (Anti-SARS-CoV2 total Ig immunoassay, Ortho Clinical Diagnostics, USA) at D0, D24, D84, D112 and D180.EndpointsAt D180, 25% of LTR had positive total antibody levels (positivity threshold, > 1 (sample signal/threshold value). Age, CMV status, gender and initial respiratory disease had no influence on the immune response. Immune response was improved in patients whose immunosuppressive regimen did not include mycophenolate mofetil (53% versus 0%, p < 0.0001), and in patients who were transplanted for more than 18 months (0% versus 41%, p < 0.05), probably due to more aggressive immunosuppressive regimen in recently transplanted patients.ConclusionsImmunogenicity of ChAdOx1 nCoV-19 vaccine is poor in LTR, with only one in four patients mounting significant anti-SARS-CoV2 immune response at D180. Of note, according to expert recommendations, most LTR received an heterologous booster dose with a SARS-CoV2 mRNA vaccine (BNT162b2). Additional serological analyses are planned to decipher whether vaccinal response is improved after the third dose in LTR. Results will be updated accordingly and presented at the 42nd ISHLT Congress.

Highly Specific Monoclonal Antibody Targeting the Botulinum Neurotoxin Type E Exposed SNAP-25 Neoepitope.

Botulinum neurotoxin type E (BoNT/E), the fastest acting toxin of all BoNTs, cleaves the 25 kDa synaptosomal-associated protein (SNAP-25) in motor neurons, leading to flaccid paralysis. The specific detection and quantification of the BoNT/E-cleaved SNAP-25 neoepitope can facilitate the development of cell-based assays for the characterization of anti-BoNT/E antibody preparations. In order to isolate highly specific monoclonal antibodies suitable for the in vitro immuno-detection of the exposed neoepitope, mice and rabbits were immunized with an eight amino acid peptide composed of the C-terminus of the cleaved SNAP-25. The immunized rabbits developed a specific and robust polyclonal antibody response, whereas the immunized mice mostly demonstrated a weak antibody response that could not discriminate between the two forms of SNAP-25. An immune scFv phage-display library was constructed from the immunized rabbits and a panel of antibodies was isolated. The sequence alignment of the isolated clones revealed high similarity between both heavy and light chains with exceptionally short HCDR3 sequences. A chimeric scFv-Fc antibody was further expressed and characterized, exhibiting a selective, ultra-high affinity (pM) towards the SNAP-25 neoepitope. Moreover, this antibody enabled the sensitive detection of cleaved SNAP-25 in BoNT/E treated SiMa cells with no cross reactivity with the intact SNAP-25. Thus, by applying an immunization and selection procedure, we have isolated a novel, specific and high-affinity antibody against the BoNT/E-derived SNAP-25 neoepitope. This novel antibody can be applied in in vitro assays that determine the potency of antitoxin preparations and reduce the use of laboratory animals for these purposes.

Humoral response to viral vector COVID-19 vaccine in hemodialysis patients.

BackgroundThe coronavirus disease 2019 (COVID-19) vaccine is not readily available in many countries where dosing interval is spaced more than ideal. Patients with chronic kidney disease, especially those on maintenance hemodialysis, have a tendency for a reduced immune response. This study was undertaken to demonstrate the distinct humoral immune response to the viral vector COVID-19 vaccine in patients with kidney failure receiving maintenance hemodialysis.MethodsThe study was carried out with two cohorts: 1) patients receiving maintenance hemodialysis and 2) healthcare workers from the same dialysis center as controls, each group with 72 subjects. Participants received a dose of Covishield ChAdOx1 nCoV-19 coronavirus vaccine. The humoral immunological response was determined using electrochemiluminescence immunoassay which quantitatively measures antibodies to the severe acute respiratory syndrome coronavirus 2 spike protein receptor-binding domain.ResultsAll study subjects in the control group developed a humoral response (antibody titer of ≥0.8 U/mL), while only 64 of 72 in the dialysis group (88.9%) were responders. Age (ρ = –0.234, p = 0.04) and sodium level (ρ = 0.237, p = 0.04) correlated with low antibody titer in bivariate analysis. In multivariate analysis, only age (odds ratio, 1.10; 95% confidence interval, 1.01–1.22; p = 0.045)was associated with nonresponders.ConclusionOur study demonstrated a weak antibody response of hemodialysis patients to the viral vector COVID-19 vaccine. Older age was associated with nonresponders. Evaluation of both humoral and cellular immunity after the second vaccine dose and serial antibody titers can help determine the need for booster shots.

A fourth dose of the mRNA-1273 SARS-CoV-2 vaccine improves serum neutralization against the Delta variant in kidney transplant recipients

A fourth dose of the mRNA-1273 SARS-CoV-2 vaccine improves serum neutralization against the Delta variant in kidney transplant recipients

Polymorphism of the HLA system and weak antibody response to BNT162b2 mRNA vaccine.

The polymorphism of the HLA system has been extensively studied in COVID-19 infection, however there are no data about the role of HLA on vaccine response. We report here the HLA-A, -B, -C, and DRB1 allelic frequencies of n= 111 individuals after BNT162b2 mRNA vaccine, selected on the basis of lower antibody levels (<5% percentile) after the second dose among a total of n= 2569 vaccinees, and compare them with the frequencies of a reference population. We found that differences in the frequencies of the alleles HLA-A*03:01, A*33:03, B*58:01 and at least one haplotype (HLA-A*24:02~C*07:01~B*18:01~DRB1*11:04) are associated with a weaker antibody response after vaccination, together with the age of vaccinees. Our results might suggest a role played by some HLA alleles or haplotypes in antibody production after the BNT162b2 mRNA vaccine, giving insights into the tracking of potentially susceptible individuals across populations. Further studies are needed to better define our exploratory findings and dissect the role of HLA polymorphism on response to anti-COVID-19 vaccines.

Rituximab during the COVID-19 pandemic: time to discuss treatment options with patients

Rituximab during the COVID-19 pandemic: time to discuss treatment options with patients

Persistent pulmonary pathology after COVID-19 is associated with high viral load, weak antibody response, and high levels of matrix metalloproteinase-9

The association between pulmonary sequelae and markers of disease severity, as well as pro-fibrotic mediators, were studied in 108 patients 3 months after hospital admission for COVID-19. The COPD assessment test (CAT-score), spirometry, diffusion capacity of the lungs (DLCO), and chest-CT were performed at 23 Norwegian hospitals included in the NOR-SOLIDARITY trial, an open-labelled, randomised clinical trial, investigating the efficacy of remdesivir and hydroxychloroquine (HCQ). Thirty-eight percent had a CAT-score ≥ 10. DLCO was below the lower limit of normal in 29.6%. Ground-glass opacities were present in 39.8% on chest-CT, parenchymal bands were found in 41.7%. At admission, low pO2/FiO2 ratio, ICU treatment, high viral load, and low antibody levels, were predictors of a poorer pulmonary outcome after 3 months. High levels of matrix metalloproteinase (MMP)-9 during hospitalisation and at 3 months were associated with persistent CT-findings. Except for a negative effect of remdesivir on CAT-score, we found no effect of remdesivir or HCQ on long-term pulmonary outcomes. Three months after hospital admission for COVID-19, a high prevalence of respiratory symptoms, reduced DLCO, and persistent CT-findings was observed. Low pO2/FiO2 ratio, ICU-admission, high viral load, low antibody levels, and high levels of MMP-9 were associated with a worse pulmonary outcome.

Weak antibody response to three doses of mRNA vaccine in kidney transplant recipients treated with belatacept

Poor responses to mRNA COVID-19 vaccine have been reported after 2 vaccine injections in kidney transplant recipients (KTRs) treated with belatacept. We analyzed the humoral response in belatacept-treated KTRs without a history of SARS-CoV-2 infection who received three injections of BNT162b2-mRNA COVID-19 vaccine. We also investigated vaccine immunogenicity in belatacept-treated KTRs with prior COVID-19 and characterized symptomatic COVID-19 infections after the vaccine in belatacept-treated KTRs. Among the 62 belatacept-treated KTRs (36 [58%] males), the median age (63.5 years IQR [51–72]), without COVID-19 history, only four patients (6.4%) developed anti-SARS-CoV-2 IgG with low antibody titers (median 209, IQR [20–409] AU/ml). 71% were treated with mycophenolic acid and 100% with steroids in association with belatacept. In contrast, in all the 5 KTRs with prior COVID-19 history, mRNA vaccine induced a strong antibody response with high antibody titers (median 10 769 AU/ml, IQR [6410–20 069]) after two injections. Seroprevalence after three-vaccine doses in 35 non-belatacept-treated KTRs was 37.1%. Twelve KTRs developed symptomatic COVID-19 after vaccination, including severe forms (50% of mortality). Breakthrough COVID-19 occurred in 5% of fully vaccinated patients. Administration of a third dose of BNT162b2 mRNA COVID-19 vaccine did not improve immunogenicity in KTRs treated with belatacept without prior COVID-19. Other strategies aiming to improve patient protection are needed.

Heterogeneity in antiviral B cell responses: Lessons from the movies.

Humoral and cellular responses to viral infections coexist in a dynamic equilibrium that often results in efficient viral clearance. However, in some infections one of the two responses prevails, for instance when an overactivation of cytotoxic T cells is accompanied by weak and insufficient antibody responses. Although the cellular response is usually sufficient to control a primary viral infection, in some cases clearance is not complete and persistent infections ensue. In order to design effective therapeutic or vaccination strategies aiming at inducing early and potent neutralizing antibody responses, a deep knowledge of the cellular and molecular determinants of antiviral immune responses is needed. Here, we review our understanding on the spatiotemporal dynamics of antiviral humoral immune responses, with a particular focus on recent studies using intravital imaging approaches as an insightful complement to more traditional techniques.

SARS-CoV-2-specific Humoral and Cellular Immunities in Kidney Transplant Recipients and Dialyzed Patients Recovered From Severe and Nonsevere COVID-19.

Background.Kidney transplantation and dialysis are two major risk factors for severe forms of coronavirus disease 2019 (COVID-19). The dynamics of the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in this population remain largely unknown.Methods.We report here the analysis of anti–SARS-CoV-2 antibody– and T cell–mediated immune responses in 26 kidney transplant recipients (KTRs) and 11 dialyzed patients (DPs) who recovered from COVID-19.Results.After a mean time of 83 ± 26 d post–symptom onset for KTRs and 97 ± 31 d for DPs, 20 KTRs (76.9%) and 10 DPs (90.9%) displayed anti-S1 immunoglobulin G SARS-CoV-2 antibodies (P = 0.34), at similar titers in both groups. SARS-CoV-2–specific interferon-γ–producing T cells were evidenced in 26 KTRs (100%) and 10 DPs (90.9%). Total numbers of SARS-CoV-2–reactive T cells were high and not statistically different between the 2 groups. No correlation between the severity of the disease and the number of reactive T cells was found in KTRs. In 5 KTRs, also evaluated 10 mo after COVID-19, weak or absent antibody response was observed, whereas specific memory T-cell response was detected in all cases.Conclusion.T-cell response persisted up to 3 mo post–symptom onset, even in KTRs in whom full immunosuppressive regimen was reinstated at recovery, and seems to be present up to 10 mo after infection. Our findings have implications in the understanding of the natural course of the disease in transplant patients and DPs.

COVID-19 Vaccination Imperatives in People on Maintenance Dialysis: An International Perspective.

COVID-19 Vaccination Imperatives in People on Maintenance Dialysis: An International Perspective.

A poor and delayed anti-SARS-CoV2 IgG response is associated to severe COVID-19 in children.

BackgroundMost children and youth develop mild or asymptomatic disease during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, a very small number of patients suffer severe Coronavirus induced disease 2019 (COVID-19). The reasons underlying these different outcomes remain unknown.MethodsWe analyzed three different cohorts: children with acute infection (n=550), convalescent children (n=138), and MIS-C (multisystem inflammatory syndrome in children, n=42). IgG and IgM antibodies to the spike protein of SARS-CoV-2, serum-neutralizing activity, plasma cytokine levels, and the frequency of circulating Follicular T helper cells (cTfh) and plasmablasts were analyzed by conventional methods.FindingsFifty-eight percent of the children in the acute phase of infection had no detectable antibodies at the time of sampling while a seronegative status was found in 25% and 12% of convalescent and MIS-C children, respectively. When children in the acute phase of the infection were stratified according disease severity, we found that contrasting with the response of children with asymptomatic, mild and moderate disease, children with severe COVID-19 did not develop any detectable response. A defective antibody response was also observed in the convalescent cohort for children with severe disease at the time of admission. This poor antibody response was associated to both, a low frequency of cTfh and a high plasma concentration of inflammatory cytokines.InterpretationA weak and delayed kinetic of antibody response to SARS-CoV-2 together with a systemic pro-inflammatory profile characterize pediatric severe COVID-19. Because comorbidities are highly prevalent in children with severe COVID-19, further studies are needed to clarify their contribution in the weak antibody response observed in severe disease.FundingNational Agency for Scientific and Technological Promotion from Argentina (IP-COVID-19-0277 and PMO-BID-PICT2018-2548).

The Long-Term Characteristics of Immunity Conferred by COVID-19 Using Antibody Tests.

IntroductionSince December 2019, more than 184 Million cases and 3.97 Million COVID-19 related deaths have been reported around the world. Since these statistics are laboratory-based confirmed cases, the true burden of disease may be underestimated. Many populations like those who are regularly visiting health care facilities and those with end-stage renal disease (ESRD) for visiting dialysis units, patients with malignancies, on regular chemo and radiotherapy, and healthcare workers (HCW) are considered high risk for nosocomial COVID-19 re-infections.ObjectiveTo understand the long-term behaviour and protective efficacy of already formed anti-SARS-CoV-2 antibody against spike-S protein and nucleocapsid antigen in different populations keeping in view their risk of re-exposure and re-infection is high. To delineate seropositivity with respect to age, gender, and other co-morbidities like diabetes mellitus (DM), hypertension (HTN), and chronic kidney disease (CKD)/ESRD as well as the general population.MethodologyDuring the study, 480 cases of COVID-19 with a post-exposure antibody reactive were followed. These patients were followed on telemedicine for the development of reinfection symptoms and persistence of antibody response. Around 115 patients agreed for regular monitoring of their immunity against the COVID-19 virus through testing through the anti-SARS-CoV-2 antibody test. The rest of the patients were followed on telemedicine until the date of development of any re-infection, but none reported to have typical symptoms of COVID-19 along with positive polymerase chain reaction (PCR).ResultsAmong 115 patients, the mean age was 42.44 + 15.755 years. 61.7% of patients were males and 66.1% were non-health workers while 26.1% of patients had DM/HTN or both. Among these patients, 76.5% had mild/no symptoms and antibodies were found present among 51.3% patients for 3-6 months. Only 2.6% of patients were re-infected. Significant association (p<0.05) of age was found with re-infection while insignificant association (p>0.05) of sex, co-morbidities, profession, symptoms, and persistence of antibodies with re-infection.ConclusionThe study concluded that natural immune response was adequate to protect against reinfection as long as more than 9 months. It was more pronounced among patients with ESRD and those with severe disease. Surprisingly, among patients with haematological malignancies, either there was no seropositivity or a very weak positive antibody response. All other malignancies had similar seropositivity behaviour compared to the general population or other co-morbidity like DM, HTN, and coronary artery disease (CAD).

Neutralizing SARS-CoV-2 Antibody Response to 1st Dose of Astrazeneca-Oxford AZD1222 Vaccine Among Health Workers in North-Central Nigeria

Speed is an effective catalyst that can differentiate a time of war from other times. Thus, in a global record time of 11 months, the leading COVID-19 vaccine manufacturers completed the first COVID-19 vaccines. However, curbing the epidemic of anti-vaxxers has not been so easy globally. The world, particularly, in Africa has been largely influenced by the myths and conspiracy theories dissuading the public from accepting COVID-19 vaccination as the most effective response against the pandemic. Hesitancy remains the status quo of many Africans to the innovation.This paper is a report of the scientific findings from a multi-centre study in Ilorin located in North Central, Nigeria among 92 Health Workers (HCWs). The primary objective of the study was to evaluate the efficacy of the first dose of the ChAdOx1 nCoV-19 vaccine. The blood samples of 92 health workers who received their first AstraZeneca-Oxford AZD1222 vaccination dose between March and April 2021 were taken to determine their antibody responses with the hope to ascertain vaccine effectiveness and also to serve as a means of encouragement to Africans in a hope to allay their fears. The overall goal of the study is to provide a scientific basis for advocacy of vaccination in Africa.This study is limited to single dose and owing to scare resources, blood samples were ran once using the cPass kit which is designed based wildtype S protein Receptor Binding Protein (RBD). As a secondary objective, the researchers evaluated but found no association between the level of neutralizing antibodies generated by this first dose and the demographics or the clinical characteristics of the participants. The demographics considered include age (p > 0.05), Gender (p > 0.05) and BMI (p > 0.05). Existing comorbidities of interest in the study were hypertension (p > 0.05), diabetes (p > 0.05) and drug misuse (p >0.05). The study concluded that over 81.5% of the vaccinated study participants mounted a strong neutralizing antibody response to their first vaccine dose, while only about 11% of the study participants had a weak antibody response.Funding: Study funded by PreciseMed, PreciseMed has legal responsibility as sponsor of thestudy, heartfelt appreciation goes to its director Daniel Onifade for funding the study.Declaration of Interest: None to declare. Ethical Approval: The study protocol was reviewed and approved by the Kwara State Ethics Committee before study initiation with Ethics approval number MOH/KS/EU/777/491 granted.

Relative COVID-19 Viral Persistence and Antibody Kinetics.

A total of 15 RT-PCR confirmed COVID-19 patients were admitted to our hospital during the in-itial outbreak in Taiwan. The average time of virus clearance was delayed in seven patients, 24.14 ± 4.33 days compared to 10.25 ± 0.56 days post-symptom onset (PSO) in the other eight pa-tients. There was strong antibody response in patients with viral persistence at the pharynx, with peak values of serum antibody 677.2 ± 217.8 vs. 76.70 ± 32.11 in patients with delayed versus rapid virus clearance. The patients with delayed viral clearance had excessive antibodies of compromised quality in an early stage with the delay in peak virus neutralization efficacy, 34.14 ± 7.15 versus 12.50 ± 2.35 days PSO in patients with rapid virus clearance. Weak antibody re-sponse of patients with rapid viral clearance was also effective, with substantial and comparable neutralization efficacy, 35.70 ± 8.78 versus 41.37 ± 11.49 of patients with delayed virus clearance. Human Cytokine 48-Plex Screening of the serial sera samples revealed elevated concentrations of proinflammatory cytokines and chemokines in a deceased patient with delayed virus clear-ance and severe disease. The levels were comparatively less in the other two patients who suf-fered from severe disease but eventually survived.

A hepatitis B virus causes chronic infections in equids worldwide

Preclinical testing of novel therapeutics for chronic hepatitis B (CHB) requires suitable animal models. Equids host homologs of hepatitis C virus (HCV). Because coinfections of hepatitis B virus (HBV) and HCV occur in humans, we screened 2,917 specimens from equids from five continents for HBV. We discovered a distinct HBV species (Equid HBV, EqHBV) in 3.2% of donkeys and zebras by PCR and antibodies against EqHBV in 5.4% of donkeys and zebras. Molecular, histopathological, and biochemical analyses revealed that infection patterns of EqHBV resembled those of HBV in humans, including hepatotropism, moderate liver damage, evolutionary stasis, and potential horizontal virus transmission. Naturally infected donkeys showed chronic infections resembling CHB with high viral loads of up to 2.6 × 109 mean copies per milliliter serum for >6 mo and weak antibody responses. Antibodies against Equid HCV were codetected in 26.5% of donkeys seropositive for EqHBV, corroborating susceptibility to both hepatitis viruses. Deltavirus pseudotypes carrying EqHBV surface proteins were unable to infect human cells via the HBV receptor NTCP (Na+/taurocholate cotransporting polypeptide), suggesting alternative viral entry mechanisms. Both HBV and EqHBV deltavirus pseudotypes infected primary horse hepatocytes in vitro, supporting a broad host range for EqHBV among equids and suggesting that horses might be suitable for EqHBV and HBV infections in vivo. Evolutionary analyses suggested that EqHBV originated in Africa several thousand years ago, commensurate with the domestication of donkeys. In sum, EqHBV naturally infects diverse equids and mimics HBV infection patterns. Equids provide a unique opportunity for preclinical testing of novel therapeutics for CHB and to investigate HBV/HCV interplay upon coinfection.

The Emergence of Long Haul - continuing typical Covid-19 symptoms long after infection

Since December 2019 COVID-19 pandemic have affected the whole world and due to this, there is a rapid increase in demand of health care system of global communities. Coronavirus, so called COVID-19, is causing a flu-like common cold and many people come back to normal healthy life without any side effects. While in other case, people who have survived mild covid-19 infections are facing health issues while carrying the symptoms such as headaches, chest pain, muscle pain, neurocognitive problems, metabolic disruption that are lasting for more than weeks or months which makes people’s recovery prolonged due to weak antibody response. It is not well-defined yet but is still in the infancy stage of research and the term "Long-haulers" is used to differentiate individuals with the symptoms which may develop or persist after the initial infection with pathogenesis and an indefinite duration as it manifests itself in different variant which makes it difficult for a single treatment approach. Side effects are as notably heterogeneous as found in acute COVID-19 and might be steady, change, or show up and be supplanted by symptoms identifying with different frequency. "Long hauler," is a person who tested negative experiences the same set of symptoms long after recovery from covid-19. Numerous people with long-COVID will be overseen in essential consideration, others will require more attention from recovery medication specialists.

Subdominance in Antibody Responses: Implications for Vaccine Development.

Vaccines work primarily by eliciting antibodies, even when recovery from natural infection depends on cellular immunity. Large efforts have therefore been made to identify microbial antigens that elicit protective antibodies, but these endeavors have encountered major difficulties, as witnessed by the lack of vaccines against many pathogens. This review summarizes accumulating evidence that subdominant protein regions, i.e., surface-exposed regions that elicit relatively weak antibody responses, are of particular interest for vaccine development. This concept may seem counterintuitive, but subdominance may represent an immune evasion mechanism, implying that the corresponding region potentially is a key target for protective immunity. Following a presentation of the concepts of immunodominance and subdominance, the review will present work on subdominant regions in several major human pathogens: the protozoan Plasmodium falciparum, two species of pathogenic streptococci, and the dengue and influenza viruses. Later sections are devoted to the molecular basis of subdominance, its potential role in immune evasion, and general implications for vaccine development. Special emphasis will be placed on the fact that a whole surface-exposed protein domain can be subdominant, as demonstrated for all of the pathogens described here. Overall, the available data indicate that subdominant protein regions are of much interest for vaccine development, not least in bacterial and protozoal systems, for which antibody subdominance remains largely unexplored.

Neutralizing epitope of the Fusion Protein of Respiratory Syncytial Virus Embedded in the HA Molecule of LAIV Virus is not Sufficient to Prevent RS Virus Pulmonary Replication but Ameliorates Lung Pathology following RSV Infection in Mice

Aims:To develop experimental bivalent vaccines against influenza and RSV using a cold-adapted LAIV backbone.Background:Respiratory syncytial virus (RSV) is a causative agent of bronchiolitis and pneumonia in young children, elderly and immunocompromised adults. No vaccine against RSV has been licensed to date for various reasons. One of the promising platforms for designing RSV vaccine is the use of live attenuated influenza vaccine (LAIV) viruses to deliver RSV epitopes to the respiratory mucosa.Objective:To generate recombinant LAIV viruses encoding a neutralizing epitope of the RSV fusion protein and assess their protective potential against both influenza and RSV infections in a mouse model.Methods:Reverse genetics methods were used to rescue recombinant LAIV+HA/RSV viruses expressing chimeric hemagglutinins encoding the RSV-F epitope at its N-terminus using two different flexible linkers. BALB/c mice were intranasally immunized with two doses of the recombinant viruses and then challenged with the influenza virus or RSV. The LAIV viral vector and formalin-inactivated RSV (FI-RSV) were included as control vaccines. Protection was assessed by the reduction of virus pulmonary titers. In addition, RSV-induced lung pathology was evaluated by histopathology studies.Results:Two rescued chimeric LAIV+HA/RSV viruses were identical to the LAIV vector in terms of replication capacityin vitroandin vivo. The RSV-F neutralizing epitope was successfully expressed only if inserted into the HA molecule via G-linker, but not A-linker. Both chimeric viruses induced high influenza-specific antibody levels and fully protected mice against a lethal influenza challenge virus. However, they induced weak anti-RSV antibody responses which did not prevent RS virus replication upon challenge, and only LAIV-HA+G-RSV variant protected mice against RSV-induced lung pathology.Conclusion:Although the designed LAIV-RSV chimeric viruses were unable to neutralize the RS virus pulmonary replication, the LAIV-HA+G-RSV reduced RSV-induced lung pathology and can be considered a promising bivalent vaccine against influenza and RSV infections and warrants its further development.

Tetravalent dengue DNA vaccine is not immunogenic when delivered by retrograde infusion into salivary glands

Introduction and backgroundA tetravalent DNA vaccine for Dengue virus is under development but has not yet achieved optimal immunogenicity. Salivary glands vaccination has been reported efficacious in rodents and dogs. We report on a pilot study testing the salivary gland as a platform for a Dengue DNA vaccine in a non-human primate model.Materials and methodsFour cynomolgus macaques were used in this study. Each macaque was pre-medicated with atropine and sedated with ketamine. Stensen’s duct papilla was cannulated with a P10 polyethylene tube, linked to a 500ul syringe. On the first two infusions, all macaques were infused with 300ul of TVDV mixed with 2 mg of zinc. For the 3rd infusion, to increase transfection into salivary tissue, two animals received 100uL TVDV mixed with 400uL polyethylenimine 1μg/ml (PEI) and the other two animals received 500uL TVDV with zinc. Antibody titers were assessed 4 weeks following the second and third infusion.Results and conclusionsSGRI through Stensen’s duct is a well-tolerated, simple and easy to reproduce procedure. TVDV infused into macaques salivary glands elicited a significantly weaker antibody response than with different delivery methods.