The structure of the influenza A virus genome

Influenza A viruses (IAVs) constitute a major threat to human health. The IAV genome consists of eight single-stranded viral RNA segments contained in separate viral ribonucleoprotein (vRNP) complexes that are packaged together into a single virus particle. The structure of viral RNA is believed to play a role in assembling the different vRNPs into budding virions^1-8 and in directing reassortment between IAVs⁹. Reassortment between established human IAVs and IAVs harboured in the animal reservoir can lead to the emergence of pandemic influenza strains to which there is little pre-existing immunity in the human population^10,11. While previous studies have revealed the overall organization of the proteins within vRNPs, characterization of viral RNA structure using conventional structural methods is hampered by limited resolution and an inability to resolve dynamic components^12,13. Here, we employ multiple high-throughput sequencing approaches to generate a global high-resolution structure of the IAV genome. We show that different IAV genome segments acquire distinct RNA conformations and form both intra- and intersegment RNA interactions inside influenza virions. We use our detailed map of IAV genome structure to provide direct evidence for how intersegment RNA interactions drive vRNP cosegregation during reassortment between different IAV strains. The work presented here is a roadmap both for the development of improved vaccine strains and for the creation of a framework to 'risk assess' reassortment potential to better predict the emergence of new pandemic influenza strains.

The development of vaccine viruses against pandemic A(H1N1) influenza

Wild type human influenza viruses do not usually grow well in embryonated hens' eggs, the substrate of choice for the production of inactivated influenza vaccine, and vaccine viruses need to be developed specifically for this purpose. In the event of a pandemic of influenza, vaccine viruses need to be created with utmost speed. At the onset of the current A(H1N1) pandemic in April 2009, a network of laboratories began a race against time to develop suitable candidate vaccine viruses. Two approaches were followed, the classical reassortment approach and the more recent reverse genetics approach. This report describes the development and the characteristics of current pandemic H1N1 candidate vaccine viruses.

What Lies Beneath: Antibody Dependent Natural Killer Cell Activation by Antibodies to Internal Influenza Virus Proteins

The conserved internal influenza proteins nucleoprotein (NP) and matrix 1 (M1) are well characterised for T cell immunity, but whether they also elicit functional antibodies capable of activating natural killer (NK) cells has not been explored. We studied NP and M1-specific ADCC activity using biochemical, NK cell activation and killing assays with plasma from healthy and influenza-infected subjects. Healthy adults had antibodies to M1 and NP capable of binding dimeric FcγRIIIa and activating NK cells. Natural symptomatic and experimental influenza infections resulted in a rise in antibody dependent NK cell activation post-infection to the hemagglutinin of the infecting strain, but changes in NK cell activation to M1 and NP were variable. Although antibody dependent killing of target cells infected with vaccinia viruses expressing internal influenza proteins was not detected, opsonising antibodies to NP and M1 likely contribute to an antiviral microenvironment by stimulating innate immune cells to secrete cytokines early in infection. We conclude that effector cell activating antibodies to conserved internal influenza proteins are common in healthy and influenza-infected adults. Given the significance of such antibodies in animal models of heterologous influenza infection, the definition of their importance and mechanism of action in human immunity to influenza is essential.

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Functional antibodies to influenza matrix 1 and nucleoprotein are common in healthy and influenza-infected humans.

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Opsonising antibodies to matrix 1 and nucleoprotein can bind FcγRIIIa dimers and activate natural killer cells.

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Influenza infection increased natural killer cell activation to hemagglutinin but changes to the internal proteins varied

Influenza virus causes both seasonal outbreaks and global pandemics. The current influenza vaccine provides minimal protection against divergent strains of the virus not found in the vaccine. While neutralising antibodies induced by vaccination are able to confer strain-specific protection, antibodies directed against conserved influenza proteins may be able to provide some cross-protection. Animal models suggest a protective role for anti-nucleoprotein antibodies. Exploring the functional capacity of human antibodies against internal influenza proteins to engage Fc receptors and activate innate immune cells may present a unique approach in the development of a more universal influenza vaccine.

Cross-reactive influenza-specific antibody-dependent cellular cytotoxicity in intravenous immunoglobulin as a potential therapeutic against emerging influenza viruses

BACKGROUND

Intravenous immunoglobulin (IVIG) is a purified pool of human antibodies from thousands of donors that is used to prevent or treat primary immune deficiency, several infectious diseases, and autoimmune diseases. The antibodies that mediate antibody-dependent cellular cytotoxicity (ADCC) against heterologous influenza strains may be present in IVIG preparations.

METHODS

We tested 8 IVIG preparations prior to the 2009 H1N1 swine-origin influenza pandemic and 10 IVIG preparations made after 2010 for their ability to mediate influenza-specific ADCC.

RESULTS

ADCC mediating antibodies to A(H1N1)pdm09 hemagglutinin (HA) and neuraminidase (NA) were detected in IVIG preparations prior to the 2009-H1N1 pandemic. The HA-specific ADCC targeted both the HA1 and HA2 regions of A(H1N1)pdm09 HA and was capable of recognizing a broad range of HA proteins including those from recent avian influenza strains A(H5N1) and A(H7N9). The low but detectable ADCC recognition of A(H7N9) was likely due to rare individuals in the population contributing cross-reactive antibodies to IVIG.

CONCLUSIONS

IVIG preparations contain broadly cross-reactive ADCC mediating antibodies. IVIG may provide at least some level of protection for individuals at high risk of severe influenza disease, especially during influenza pandemics prior to the development of effective vaccines.

A single dose of unadjuvanted novel 2009 H1N1 vaccine is immunogenic and well tolerated in young and elderly adults

BACKGROUND

When the novel H1N1 influenza A strain appeared in April of 2009, development of novel H1N1 vaccines became a public health priority.

METHODS

We conducted a phase‐2, multicenter, randomized, placebo‐controlled, observer‐blind clinical trial of a 2009 H1N1 vaccine in 1313 young (age, 18-64 years) and older (age, >or=65 years) adults. Participants were randomized 1:4:4:4 to receive 2 doses of placebo or 7.5, 15, or 30 μg of H1N1 hemagglutinin administered 21 days apart. In post hoc analyses, hemagglutination inhibition (HI) titers measured at baseline and after vaccination were analyzed for young adults (age, 18-64 years), "younger elderly" adults (age, 65-74 years), and "very elderly" adults (age, >or=75 years).

RESULTS

At baseline, 28.8% of young adults, 43.9% of younger elderly adults, and 62.9% of very elderly adults had HI titers to A/2009 H1N1 of >or=1:40. A single 7.5‐μg dose induced HI titers >or=1:40 in 94.5% (95% confidence interval [CI], 91.8%-96.3%) of all adults. After one 7.5‐μg dose, the geometric mean titers achieved were 326.4 (95% CI, 275.9-386.0) in young adults, 155.4 (95% CI, 123.4-195.8) in "younger elderly" adults, and 243.9 (95% CI, 167.1-356.0) in "very elderly" adults.

CONCLUSIONS

This large phase-2 trial demonstrated that a single 7.5‐μg dose of a monovalent unadjuvanted H1N1 vaccine induced protective HI antibody levels in adults of all ages, including very elderly adults.

TRIAL REGISTRATION

Clinicaltrials.gov identifier NCT00958126.

Development of an enzyme-linked immunoassay for the quantitation of influenza haemagglutinin: an alternative method to single radial immunodiffusion

Please cite this paper as: Bodle et al. (2013) Development of an enzyme‐linked immunoassay for the quantitation of influenza haemagglutinin: an alternative method to single radial immunodiffusion. Influenza and Other Respiratory Viruses 7(2) 191–200.

Background  The current method used to measure haemagglutinin (HA) content for influenza vaccine formulation, single radial immunodiffusion (SRID), is lengthy and relies on the availability of matched standardised homologous reagents. The 2009 influenza pandemic highlighted the need to develop alternate assays that are able to rapidly quantitate HA antigen for vaccine formulation.

Objectives  The aim of this work was to develop an enzyme‐linked immunoassay (EIA) for the rapid quantitation of H1, H3, H5 and B influenza HA antigens.

Methods  Monoclonal antibodies (mAbs) selected for haemagglutination inhibition (HAI) activity were conjugated with horseradish peroxidase and used to establish a capture–detection EIA for the quantitation of HA antigen. Results were compared with the appropriate reference SRID assays to investigate assay performance and utility.

Results  Quantitation of HA antigen by EIA correlated well with current reference SRID assays. EIA results showed equivalent precision and exhibited a similar capacity to detect HA antigen in virus samples that had been used in either stability or splitting studies, or subjected to physical or chemical stresses. EIA exhibited greater sensitivity than SRID and has the potential to be used in high‐throughput applications.

Conclusions  We demonstrated the utility of EIA as a suitable alternative to SRID for HA antigen quantitation and stability assessment. This approach would lead to earlier availability of both seasonal and pandemic vaccines, because of the extended cross‐reactivity of reagents.

New Technologies for Influenza Vaccines

Vaccine development has been hampered by the long lead times and the high cost required to reach the market. The 2020 pandemic, caused by a new coronavirus (SARS-CoV-2) that was first reported in late 2019, has seen unprecedented rapid activity to generate a vaccine, which belies the traditional vaccine development cycle. Critically, much of this progress has been leveraged off existing technologies, many of which had their beginnings in influenza vaccine development. This commentary outlines the most promising of the next generation of non-egg-based influenza vaccines including new manufacturing platforms, structure-based antigen design/computational biology, protein-based vaccines including recombinant technologies, nanoparticles, gene- and vector-based technologies, as well as an update on activities around a universal influenza vaccine.

Antibody-Dependent Cellular Cytotoxicity Responses to Seasonal Influenza Vaccination in Older Adults

Background

Older adults are at high risk of influenza disease, but generally respond poorly to vaccination. Antibody-dependent cellular cytotoxicity (ADCC) may be an important component of protection against influenza infection. An improved understanding of the ADCC response to influenza vaccination in older adults is required.

Methods

We studied sera samples from 3 groups of subjects aged ≥65 years (n = 16-17/group) receiving the 2008/2009 seasonal trivalent influenza vaccine (TIV). Subjects had minimal pre-existing hemagglutination inhibiting (HAI) antibodies and TIV induced either no, low, or high HAI responses. Serum ADCC activity was analyzed using Fc receptor cross-linking, NK cell activation, and influenza-infected cell killing.

Results

Most subjects from TIV nonresponder, low responder, and high responder groups had detectable ADCC antibodies prevaccination, but baseline ADCC was not predictive of HAI vaccine responsiveness. Interestingly, ADCC and HAI responses tracked closely across all groups, against all 3 TIV hemagglutinins, and in all ADCC assays tested.

Conclusions

Older adults commonly have pre-existing ADCC antibodies in the absence of high HAI titers to circulating influenza strains. In older vaccinees, ADCC response mirrored HAI antibodies and was readily detectable despite high postvaccination HAI titers. Alternate measures of vaccine responsiveness and improved vaccinations in this at-risk group are needed.

Influenza NA and PB1 Gene Segments Interact during the Formation of Viral Progeny: Localization of the Binding Region within the PB1 Gene

The influenza A virus genome comprises eight negative-sense viral RNAs (vRNAs) that form individual ribonucleoprotein (RNP) complexes. In order to incorporate a complete set of each of these vRNAs, the virus uses a selective packaging mechanism that facilitates co-packaging of specific gene segments but whose molecular basis is still not fully understood. Recently, we used a competitive transfection model where plasmids encoding the A/Puerto Rico/8/34 (PR8) and A/Udorn/307/72 (Udorn) PB1 gene segments were competed to show that the Udorn PB1 gene segment is preferentially co-packaged into progeny virions with the Udorn NA gene segment. Here we created chimeric PB1 genes combining both Udorn and PR8 PB1 sequences to further define the location within the Udorn PB1 gene that drives co-segregation of these genes and show that nucleotides 1776–2070 of the PB1 gene are crucial for preferential selection. In vitro assays examining specific interactions between Udorn NA vRNA and purified vRNAs transcribed from chimeric PB1 genes also supported the importance of this region in the PB1-NA interaction. Hence, this work identifies an association between viral genes that are co-selected during packaging. It also reveals a region potentially important in the RNP-RNP interactions within the supramolecular complex that is predicted to form prior to budding to allow one of each segment to be packaged in the viral progeny. Our study lays the foundation to understand the co-selection of specific genes, which may be critical to the emergence of new viruses with pandemic potential.

A lipopeptide based on the M2 and HA proteins of influenza A viruses induces protective antibody

A conserved 15 amino-acid residue sequence of the ectodomain of the M2 protein of influenza A virus (M2e) induces a strong antibody (Ab) response when incorporated into a synthetic lipopeptide vaccine candidate containing a T-helper epitope from influenza A hemagglutinin and the dendritic cell-targeting lipid moiety S-[2,3-bis(palmitoyloxy)propyl]cysteine (Pam2Cys). Abs elicited by the truncated M2e sequence were specific for the M2 protein of influenza A virus and were also capable of binding to cells that were infected with influenza A viruses of different subtypes. The Ab titres against the lipopeptide were similar in magnitude to those elicited by the full-length (23 residue) M2e peptide when administered in Freund's adjuvant. Abs to the truncated M2e sequence were also able to significantly reduce the viral load in airways of BALB/c mice after challenge with live influenza virus.

Pre-pandemic and pandemic influenza vaccines

Vaccination is considered the most effective strategy to control influenza and becomes particularly important when a new subtype or distantly related strain of virus enters the human population causing a world-wide epidemic or "pandemic". Depending upon the virulence of the emerging virus, a lack of pre-existing immunity can lead to overwhelming morbidity and deaths ranging in the millions. While the correlates of immunity to influenza are yet to be fully understood, our experience with vaccines over many decades enables pre-pandemic planning to develop strategies to minimise the impact of a human pandemic. This review explores developing pandemic and pre-pandemic vaccines in the context of highly virulent avian H5N1 virus and the influenza H1N1 pandemic of 2009.

Structure of the gene encoding the murine SCL protein

We have determined the molecular structure of the gene encoding the murine SCL protein (helix-loop-helix transcription factor). The gene consists of seven exons spanning approx. 20 kb. The intron/exon structure, coding region sequences and sequences present at the splice junctions were highly conserved between mouse and human. The 5' flanking sequence contains CCAAT and TATA consensus motifs with several putative binding sites for SP-1, AP-1 and GATA-1. Multiple mRNA transcripts were generated by alternate exon usage. The transcripts differed primarily in the 5' untranslated region (UTR), but potentially also encode a smaller SCL protein. Despite the high degree of conservation between species, the heptamer/nonamer signal sequences in the 5' region of the human SCL gene (the frequent site of SCL disruption in human leukemia) were poorly represented in the murine sequence. In keeping with this, structural abnormalities of murine SCL were uncommon in murine leukemias that express the SCL transcript.

Marrow proliferation and the appearance of giant neutrophils in response to recombinant human granulocyte colony stimulating factor (rhG-CSF)

During a study of recombinant human granulocyte colony stimulating factor (rhG-CSF) administration, 15 patients received twice daily i.v. infusions and nine patients received daily s.c. infusions of rhG-CSF for 5 d prior to cytotoxic therapy, and then a second course subsequent to melphalan administration. There was a striking dose-related neutrophilia and the appearance in the blood of early myeloid cells that express the intercellular adhesion molecule CD54. In addition, giant neutrophils or macropolycytes were observed in the peripheral blood of all patients. These cells were evident on the display of the Technicon H*1 as a population of large peroxidase positive cells, and using Feulgen staining these cells were shown to be tetraploid. Bone marrow kinetics studies performed on Day 4 or 5 indicated an increase in the proportion of bone marrow cells in S phase, G2 and mitosis, reflecting a proliferative response of the marrow. Large myeloid precursors and occasional binucleate promyelocytes were seen in the bone marrows done on Days 14 and 18 but not on Day 5. These findings indicate that administered G-CSF has both quantitative and qualitative effects on myeloid cells in vivo.

Intravenous Immunoglobulin Protects Against Severe Pandemic Influenza Infection

Influenza is a highly contagious, acute, febrile respiratory infection that can have fatal consequences particularly in individuals with chronic illnesses. Sporadic reports suggest that intravenous immunoglobulin (IVIg) may be efficacious in the influenza setting. We investigated the potential of human IVIg to ameliorate influenza infection in ferrets exposed to either the pandemic H1N1/09 virus (pH1N1) or highly pathogenic avian influenza (H5N1). IVIg administered at the time of influenza virus exposure led to a significant reduction in lung viral load following pH1N1 challenge. In the lethal H5N1 model, the majority of animals given IVIg survived challenge in a dose dependent manner. Protection was also afforded by purified F(ab′)₂ but not Fc fragments derived from IVIg, supporting a specific antibody-mediated mechanism of protection. We conclude that pre-pandemic IVIg can modulate serious influenza infection-associated mortality and morbidity. IVIg could be useful prophylactically in the event of a pandemic to protect vulnerable population groups and in the critical care setting as a first stage intervention.

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Intravenous immunoglobulin (IVIg), prepared prior to a pandemic, prevents pandemic influenza disease in ferrets.

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IVIg effectively reduced viral levels of pandemic H1N1 influenza and prevented disease due to avian influenza H5N1.

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This work has implications for preventing and treating pandemic influenza infections with IVIg before a vaccine is available.

Influenza pandemics cause large numbers of infections and deaths. There is a lag between the identification of a pandemic and the development of vaccines. Future pandemics may be caused by influenza strains resistant to current anti-influenza drugs. New treatments are needed for future pandemic influenza outbreaks. We show that a readily available product (intravenous immunoglobuling – pooled antibodies from human donors) can prevent viral replication and disease caused by 2 strains of pandemic influenza viruses (“swine-flu” and “bird-flu”) in an appropriate animal model of influenza. This could form the basis of future treatments for severe influenza caused by pandemic strains.

Cell-Based Manufacturing Technology Increases Antigenic Match of Influenza Vaccine and Results in Improved Effectiveness

To ensure that vaccination offers the best protection against an infectious disease, sequence identity between the vaccine and the circulating strain is paramount. During replication of nucleic acid, random mutations occur due to the level of polymerase fidelity. In traditional influenza vaccine manufacture, vaccine viruses are propagated in fertilized chicken eggs, which can result in egg-adaptive mutations in the antigen-encoding genes. Whilst this improves infection and replication in eggs, mutations may reduce the effectiveness of egg-based influenza vaccines against circulating human viruses. In contrast, egg-adaptive mutations are avoided when vaccine viruses are propagated in Madin-Darby canine kidney (MDCK) cell lines during manufacture of cell-based inactivated influenza vaccines. The first mammalian cell-only strain was included in Flucelvax® Quadrivalent in 2017. A sequence analysis of the viruses selected for inclusion in this vaccine (n = 15 vaccine strains, containing both hemagglutinin and neuraminidase) demonstrated that no mutations occur in the antigenic sites of either hemagglutinin or neuraminidase, indicating that cell adaptation does not occur during production of this cell-based vaccine. The development of this now entirely mammalian-based vaccine system, which incorporates both hemagglutinin and neuraminidase, ensures that the significant protective antigens are equivalent to the strains recommended by the World Health Organization (WHO) in both amino acid sequence and glycosylation pattern. The inclusion of both proteins in a vaccine may provide an advantage over recombinant vaccines containing hemagglutinin alone. Findings from real world effectiveness studies support the use of cell-based influenza vaccines.

Vaccine complacency and dose distribution inequities limit the benefits of seasonal influenza vaccination, despite a positive trend in use

Sustainable demand for seasonal influenza vaccines is a component of national security strategies for pandemic preparedness. However, the ongoing COVID-19 pandemic has revealed many weaknesses in the capacity of countries to design and execute sustainable vaccination programs. An influenza pandemic remains a global threat and yet there is no global monitoring system for assessing progress towards influenza vaccination coverage targets. The International Federation of Pharmaceutical Manufacturers and Associations’ (IFPMA) Influenza Vaccine Supply International Task Force (IVS) developed a survey method in 2008 to estimate seasonal influenza vaccination coverage rates, which in turn serves as a crude estimate of pandemic preparedness. It provides evidence to guide expanded efforts for pandemic preparedness, specifically for increasing COVID-19 vaccine immunization levels. Furthermore, the results presented herein serve as a proxy for assessing the state of pandemic preparedness at a global and regional level. This paper adds data from 2018 and 2019 to the previous analyses. The current data show an upward or stable global trend in seasonal influenza vaccine dose distributed per 1,000 population with a 7% increase between 2017 and 2018 and 6% increase between 2018 and 2019. However, considerable regional inequities in access to vaccine persist. Three regions, Africa, the Middle-east, and Southeast Asia together account for 50% of the global population but only 6% of distributed seasonal influenza vaccine doses. This is an important finding in the context of the ongoing COVID-19 pandemic, as distribution of influenza vaccine doses in many ways reflects access to COVID-19 vaccines. Moreover, improving seasonal vaccine uptake rates is critical for optimizing the annual benefits by reducing the huge annual influenza-associated societal burdens and by providing protection to vulnerable individuals against serious complications from seasonal influenza infections.

Rapid generation of pandemic influenza virus vaccine candidate strains using synthetic DNA

Please cite this paper as: Verity et al. (2011) Rapid generation of pandemic influenza virus vaccine candidate strains using synthetic DNA. Influenza and Other Respiratory Viruses DOI:10.1111/j.1750‐2659.2011.00273.x.

Background  Vaccination is considered the most effective means of reducing influenza burden. The emergence of H5N1 and pandemic spread of novel H1N1/2009 viruses reinforces the need to have strategies in place to rapidly develop seed viruses for vaccine manufacture.

Methods  Candidate pandemic vaccine strains consisting of the circulating strain haemagglutinin (HA) and neuraminidase (NA) in an A/PR/8/34 backbone were generated using alternative synthetic DNA approaches, including site‐directed mutagenesis of DNA encoding related virus strains, and rapid generation of virus using synthetic DNA cloned into plasmid vectors.

Results  Firstly, synthetic A/Bar Headed Goose/Qinghai/1A/2005 (H5N1) virus was generated from an A/Vietnam/1194/2004 template using site‐directed mutagenesis. Secondly, A/Whooper Swan/Mongolia/244/2005 (H5N1) and A/California/04/09 (H1N1) viruses were generated using synthetic DNA encoding the viral HA and NA genes. Replication and antigenicity of the synthetic viruses were comparable to that of the corresponding non‐synthetic viruses.

Conclusions  In the event of an influenza pandemic, the use of these approaches may significantly reduce the time required to generate and distribute the vaccine seed virus and vaccine manufacture. These approaches also offer the advantage of not needing to handle wild‐type virus, potentially diminishing biocontainment requirements.

Pandemic Influenza Vaccines: What did We Learn from the 2009 Pandemic and are We Better Prepared Now?

In 2009, a novel A(H1N1) influenza virus emerged with rapid human-to-human spread and caused the first pandemic of the 21st century. Although this pandemic was considered mild compared to the previous pandemics of the 20th century, there was still extensive disease and death. This virus replaced the previous A(H1N1) and continues to circulate today as a seasonal virus. It is well established that vaccines are the most effective method to alleviate the mortality and morbidity associated with influenza virus infections, but the 2009 A(H1N1) influenza pandemic, like all significant infectious disease outbreaks, presented its own unique set of problems with vaccine supply and demand. This manuscript describes the issues that confronted governments, international agencies and industries in developing a well-matched vaccine in 2009, and identifies the key improvements and remaining challenges facing the world as the next influenza pandemic inevitably approaches.

Efficacy of a trivalent influenza vaccine against seasonal strains and against 2009 pandemic H1N1: A randomized, placebo-controlled trial

BACKGROUND

Before pandemic H1N1 vaccines were available, the potential benefit of existing seasonal trivalent inactivated influenza vaccines (IIV3s) against influenza due to the 2009 pandemic H1N1 influenza strain was investigated, with conflicting results. This study assessed the efficacy of seasonal IIV3s against influenza due to 2008 and 2009 seasonal influenza strains and against the 2009 pandemic H1N1 strain.

METHODS

This observer-blind, randomized, placebo-controlled study enrolled adults aged 18-64years during 2008 and 2009 in Australia and New Zealand. Participants were randomized 2:1 to receive IIV3 or placebo. The primary objective was to demonstrate the efficacy of IIV3 against laboratory-confirmed influenza. Participants reporting an influenza-like illness during the period from 14days after vaccination until 30 November of each study year were tested for influenza by real-time reverse transcription polymerase chain reaction.

RESULTS

Over a study period of 2years, 15,044 participants were enrolled (mean age±standard deviation: 35.5±14.7years; 54.4% female). Vaccine efficacy of the 2008 and 2009 IIV3s against influenza due to any strain was 42% (95% confidence interval [CI]: 30%, 52%), whereas vaccine efficacy against influenza due to the vaccine-matched strains was 60% (95% CI: 44%, 72%). Vaccine efficacy of the 2009 IIV3 against influenza due to the 2009 pandemic H1N1 strain was 38% (95% CI: 19%, 53%). No vaccine-related deaths or serious adverse events were reported. Solicited local and systemic adverse events were more frequent in IIV3 recipients than placebo recipients (local: IIV3 74.6% vs placebo 20.4%, p<0.001; systemic: IIV3 46.6% vs placebo 39.1%, p<0.001).

CONCLUSIONS

The 2008 and 2009 IIV3s were efficacious against influenza due to seasonal influenza strains and the 2009 IIV3 demonstrated moderate efficacy against influenza due to the 2009 pandemic H1N1 strain. Funded by CSL Limited, ClinicalTrials.gov identifier NCT00562484.

Evaluation and calibration of a fluorescence-activated cell sorter for the interpretation of the granulocyte immunofluorescence test (GIFT)

The increasing availability of fluorescence-activated cell sorters (FACS) and flow cytometers makes it reasonable to consider the routine use of these machines for the evaluation of the granulocyte immunofluorescence test (GIFT). A comparison of microscopic reading and FACS reading of the standard GIFT demonstrated equivalent simplicity, specificity, sensitivity, reproducibility and duration of test procedure. Differentiation of a negative GIFT from a weakly positive GIFT using the FACS reading method was, however, made difficult by considerable variation in background fluorescence for different neutrophil donors. However, we demonstrate that the FACS reading method was superior for the interpretation of immunofluorescence on chloroquine-treated neutrophils used in the differentiation of HLA from neutrophil-specific antibodies. The systematic study highlighted the fact that any laboratory contemplating conversion from microscopic reading of the GIFT should carefully evaluate and standardize their interpretation of FACS results with their manual reference method.

The importance of influenza vaccination during the COVID-19 pandemic

The COVID-19 pandemic and the measures taken to mitigate its spread have had a dramatic effect on the circulation patterns of other respiratory viruses, most especially influenza viruses. Since April 2020, the global circulation of influenza has been markedly reduced; however, it is still present in a number of different countries and could pose a renewed threat in the upcoming Northern Hemisphere winter. Influenza vaccination remains the most effective preventive measure that we have at our disposal against influenza infections and should not be ignored for the 2021-2022 season.

Molecular cloning and characterization of pig, cow and sheep MAdCAM-1 cDNA and the demonstration of cross-reactive epitopes amongst mammalian homologues

Full-length cDNA clones for the pig, cow and sheep mucosal addressin cellular adhesion molecule (MAdCAM)-1 homologues were isolated from Peyer's patches by a combination of reverse transcription (RT)-polymerase chain reaction and 5' and 3' RACE strategies. Degenerate primers based on conserved amino acid (aa) sequences within the N-terminal immunoglobulin (Ig)-like domains of the human and rodent MAdCAM-1 molecules were used for initial sequencing of the Ig-like domains. MAdCAM-1 transcripts of 1425 bp, 1525 bp and 1510 bp obtained for the pig, cow and sheep contained an open-reading frame for proteins of 390, 424 and 418 aa, respectively. The pig and ruminant MAdCAM-1 had two N-terminal Ig-like domains, a mucin-like region and a third Ig-like domain found in rodent but not human MAdCAM-1. Antibodies raised against bacterially expressed N-terminal Ig-like domains of pig, human and sheep MAdCAM-1 demonstrated the existence of cross-reactive epitopes, raising the possibility of producing monoclonal antibodies which can be used as multi-species MAdCAM-1-targeting reagent for the development of mucosal vaccines.

A study of granular lymphoproliferative disorders including a CD3 negative case with a rearrangement of the T-cell receptor locus

The clinical, and laboratory features of 9 patients presenting with chronic proliferations of large granular lymphocytes (LGL) are described. The median patient age was 61 years (33-80) and median patient follow up was 3.5 years (28 mo-10 years) with all patients surviving. Clinical features and blood and bone marrow findings are documented. Immunophenotypic analysis showed lymphocytes from 4 patients were CD3 negative and 5 were CD3 positive with natural killer associated cell surface antigens expressed in both these groups. Analysis of the T-cell receptor (TCR) loci revealed a clonal rearrangement in 4 samples including one CD3 negative sample. Clonality did not correlate with immunophenotype or clinical or haematological features. We conclude that patients with persistent LGL have a wide diversity of cell surface marker expression and that whilst some patients with CD3 negative LGL proliferations have cells which are most likely of natural killer (NK) cell origin, in others TCR rearrangements can be demonstrated suggesting these cells are possibly of T-cell, not NK cell, origin.

Development and testing of the Australian pandemic influenza vaccine – a timely response

In April 2009 a novel virus strain appeared which would cause the first influenza pandemic of the 21st century. This pandemic was the first to occur in an era where bioinformatic technologies contributed to the response to this virus; still, the creation of a vaccine relied largely on existing egg-based technology. The ongoing threat of a H5N1 pandemic spurred the development of strategies to rapidly produce a pandemic vaccine. These plans were implemented and allowed CSL and Australia to conduct the first clinical trials and produce one of the first 2009 pandemic vaccines. However, new candidate influenza vaccine viruses often present challenges to manufacturing a new vaccine. This pandemic virus was no exception. Being in the post-pandemic phase, it is important to review lessons learned to improve our response to future pandemics. In hindsight, the production of a pandemic vaccine is similar to that of seasonal influenza vaccines, yet the urgency of the pandemic response compresses timelines. This report explores those timelines and implications for producing a pandemic vaccine for Australia.