Multiplex evaluation of influenza neutralizing antibodies with potential applicability to in-field serological studies

The increased number of outbreaks of H5 and H7 LPAI and HPAI viruses in poultry has major public and animal health implications. The continuous rapid evolution of these subtypes and the emergence of new variants influence the ability to undertake effective surveillance. Retroviral pseudotypes bearing influenza haemagglutinin (HA) and neuraminidase (NA) envelope glycoproteins represent a flexible platform for sensitive, readily standardized influenza serological assays. We describe a multiplex assay for the study of neutralizing antibodies that are directed against both influenza H5 and H7 HA. This assay permits the measurement of neutralizing antibody responses against two antigenically distinct HAs in the same serum/plasma sample thus increasing the amount and quality of serological data that can be acquired from valuable sera. Sera obtained from chickens vaccinated with a monovalent H5N2 vaccine, chickens vaccinated with a bivalent H7N1/H5N9 vaccine, or turkeys naturally infected with an H7N3 virus were evaluated in this assay and the results correlated strongly with data obtained by HI assay. We show that pseudotypes are highly stable under basic cold-chain storage conditions and following multiple rounds of freeze-thaw. We propose that this robust assay may have practical utility for in-field sero-surveillance and vaccine studies in resource-limited regions worldwide

Amino acid substitutions in the H5N1 avian influenza haemagglutinin alter pH of fusion and receptor binding to promote a highly pathogenic phenotype in chickens

Highly pathogenic H5N1 avian influenza viruses cause devastating outbreaks in farmed poultry with serious consequences for animal welfare and economic losses. Zoonotic infection of humans through close contact with H5N1 infected birds is often severe and fatal. England experienced an outbreak of H5N1 in turkeys in 1991 that led to thousands of farmed bird mortalities. Isolation of clonal populations of one such virus from this outbreak uncovered amino acid differences in the virus haemagglutinin (HA) gene whereby the different genotypes could be associated with distinct pathogenic outcomes in chickens; both low pathogenic (LP) and high pathogenic (HP) phenotypes could be observed despite all containing a multi-basic cleavage site (MBCS) in the HA gene. Using reverse genetics, three amino acid substitutions in HA were examined for their ability to affect pathogenesis in the chicken. Restoration of amino acid polymorphisms close to the receptor binding site that are commonly found in H5 viruses only partially improved viral fitness in vitro and in vivo. A third novel substitution in the fusion peptide, HA2G4R, enabled the HP phenotype. HA2G4R decreased the pH stability of HA and increased the pH of HA fusion. The substitutions close to the receptor binding site optimised receptor binding while modulating the pH of HA fusion. Importantly, this study revealed pathogenic determinants beyond the MBCS

Getting More Out of Less - A Quantitative Serological Screening Tool for Simultaneous Detection of Multiple Influenza A Hemagglutinin-Types in Chickens

Current avian influenza surveillance in poultry primarily targets subtypes of interest for the veterinary sector (H5, H7). However, as virological and serological evidence suggest, surveillance of additional subtypes is important for public health as well as for the poultry industry. Therefore, we developed a protein microarray enabling simultaneous identification of antibodies directed against different HA-types of influenza A viruses in chickens. The assay successfully discriminated negative from experimentally and naturally infected, seropositive chickens. Sensitivity and specificity depended on the cut-off level used but ranged from 84.4% to 100% and 100%, respectively, for a cut off level of =1:40, showing minimal cross reactivity. As this testing platform is also validated for the use in humans, it constitutes a surveillance tool that can be applied in human-animal interface studies

Improved adjuvanting of seasonal influenza vaccines: Pre-clinical studies of MVA-NP+M1 co-administration with inactivated influenza vaccine.

Licensed seasonal influenza vaccines induce antibody responses against influenza hemagglutinin that are limited in their ability to protect against different strains of influenza. Cytotoxic T lymphocytes (CTLs) recognizing the conserved internal nucleoprotein (NP) and matrix protein (M1) are capable of mediating a cross-subtype immune response against influenza. Modified vaccinia virus Ankara encoding NP and M1 (MVA-NP+M1) is designed to boost pre-existing T-cell responses in adults in order to elicit a cross-protective immune response. We examined the co-administration of hemagglutinin (HA) protein formulations and candidate MVA-NP+M1 influenza vaccines in murine, avian, and swine models. Antibody responses post-immunization were measured by ELISA and pseudotype neutralization assays. Here we demonstrate that MVA-NP+M1 can act as an adjuvant enhancing antibody (Ab) responses to HA while simultaneously inducing potent T-cell responses to conserved internal antigens. We show that this regimen leads to the induction of cytophilic Ab isotypes that are capable of inhibiting hemagglutination and in the context of H5 exhibit cross-clade neutralization. The simultaneous induction of T cells and antibody responses has the potential to improve seasonal vaccine performance and could be employed in pandemic situations

The Viral Pseudotype Unit: viral pseudotype R&D, dissemination and education

The Viral Pseudotype Unit was established in 2010 to act as an interface between academia, industry and public/animal health laboratories with the purpose of translating basic virus research (on viral pseudotypes) into in vitro cell culture-based assays that can be readily employed for the immunogenicity testing of preclinical vaccine candidates, and for the functional screening of new antivirals and therapeutic antibodies. More recently the Viral Pseudotype Unit has become involved with the exploitation of pseudotypes for the development of serological standards, and with training and education via traditional and new media platforms

An Exploratory Study of Emotional Dysregulation Dimensions in Youth With Attention Deficit Hyperactivity Disorder and/or Bipolar Spectrum Disorders

Emotional dysregulation (ED) is currently the most frequently used term to describe children with an impaired regulation of emotional states. Recent research studies speculate whether ED may be a neurodevelopmental disorder itself, a shared risk factor, or a common key feature of several psychiatric disorders, including, among others, attention deficit hyperactivity disorder (ADHD), and bipolar spectrum disorders (BSD). The association between ADHD and ED is one of the main reasons of misconceptions in the definition of boundaries between ADHD and BSD, leading to the frequent misdiagnosis of ADHD as BSD. Since ED is a multidimensional concept, a novel instrument—the Reactivity, Intensity, Polarity and Stability (RIPoSt) scale—was recently developed to assess the different dimensions of ED, which could help in detecting specific ED profiles in clinical youths. Our study included 154 patients, aged 13.8 ± 2.3 years, diagnosed with either ADHD, BSD, or comorbid condition, and a school-based sample of 40 healthy control (HC) adolescents, aged 12.5 ± 1.2 years. The RIPoSt scale and the Child Behavior Checklist were administered to both groups. Our results indicate that affective instability and negative emotionality subscales, as well as negative emotional dysregulation, are higher in BSD, both pure and comorbid with ADHD, while emotional impulsivity is higher in the comorbid condition and similar in the ADHD and BSD alone group; all clinical groups scored higher than HC. Conversely, positive emotionality is similar among clinical groups and within them and HC. Our findings also support the validity of the RIPoSt questionnaire, since the instrument proved to have good-to-excellent internal consistency, and strongly significant positive correlations were found with the CBCL-Dysregulation Profile, which is a commonly used, indirect measure of ED. Hence, the five subscales of the RIPoSt can be reliably used as an effective tool to study the emotional dysregulation in different clinical conditions, to help disentangle the complex relationship between ADHD and juvenile BSD and to provide clinicians with crucial evidence for better diagnostic characterization and therapeutic indications

The application of pseudotypes to Influenza pandemic preparedness

Human and animal populations are constantly exposed to multiple influenza strains due to zoonotic spillover and rapid viral evolution driven by intrinsic error­prone replication and immunological pressure. In this context, antibody responses directed against the haemagglutinin protein on the surface of the virus are of importance since they have been shown to correlate with protective immunity. Serological techniques, detecting these responses, play a critical role in influenza pandemic preparedness in particular with regards to the measurement of vaccine immunogenicity. As the recent human pandemics (H1N1) and avian influenza outbreaks (H5 and H7) have demonstrated, there is an urgent need to be better prepared to assess the contribution of the antibody response to protection against newly emerged viruses and to evaluate the extent of pre-existing hetero-subtypic immunity in populations. This review compares pseudotype-based assays with wildtype and VLP virus assays and discusses their place in the pandemic preparedness against the influenza virus. It additionally addresses the state of the art developments of pseudotype-based assays (chimeric haemagglutinins, multiplex and post-attachment) including the development and future deployment of assay kits and approaches towards standardization to both pre-clinical and clinical endpoints. Progress towards the development of an influenza pseudotype library for the purposes of pandemic preparedness is also outlined and discussed