343 results found
Thai E, Murugan R, Binter Š, et al., 2023, Molecular determinants of cross-reactivity and potency by VH3-33 antibodies against the Plasmodium falciparum circumsporozoite protein, Cell Reports, Vol: 42, ISSN: 2211-1247
IGHV3-33-encoded antibodies are prevalent in the human humoral response against the Plasmodium falciparum circumsporozoite protein (PfCSP). Among VH3-33 antibodies, cross-reactivity between PfCSP major repeat (NANP), minor (NVDP), and junctional (NPDP) motifs is associated with high affinity and potent parasite inhibition. However, the molecular basis of antibody cross-reactivity and the relationship with efficacy remain unresolved. Here, we perform an extensive structure-function characterization of 12 VH3-33 anti-PfCSP monoclonal antibodies (mAbs) with varying degrees of cross-reactivity induced by immunization of mice expressing a human immunoglobulin gene repertoire. We identify residues in the antibody paratope that mediate cross-reactive binding and delineate four distinct epitope conformations induced by antibody binding, with one consistently associated with high protective efficacy and another that confers comparably potent inhibition of parasite liver invasion. Our data show a link between molecular features of cross-reactive VH3-33 mAb binding to PfCSP and mAb potency, relevant for the development of antibody-based interventions against malaria.
Abdullahi A, Kida IM, Maina UA, et al., 2023, Limited emergence of resistance to integrase strand transfer inhibitors (INSTIs) in ART-experienced participants failing dolutegravir-based antiretroviral therapy: a cross-sectional analysis of a Northeast Nigerian cohort, Journal of Antimicrobial Chemotherapy, Vol: 78, Pages: 2000-2007, ISSN: 0305-7453
BackgroundDue to the high prevalence of resistance to NNRTI-based ART since 2018, consolidated recommendations from the WHO have indicated dolutegravir as the preferred drug of choice for HIV treatment globally. There is a paucity of resistance outcome data from HIV-1 non-B subtypes circulating across West Africa.AimsWe characterized the mutational profiles of persons living with HIV from a cross-sectional cohort in North-East Nigeria failing a dolutegravir-based ART regimen.MethodsWGS of plasma samples collected from 61 HIV-1-infected participants following virological failure of dolutegravir-based ART were sequenced using the Illumina platform. Sequencing was successfully completed for samples from 55 participants. Following quality control, 33 full genomes were analysed from participants with a median age of 40 years and median time on ART of 9 years. HIV-1 subtyping was performed using SNAPPy.ResultsMost participants had mutational profiles reflective of exposure to previous first- and second-line ART regimens comprised NRTIs and NNRTIs. More than half of participants had one or more drug resistance-associated mutations (DRMs) affecting susceptibility to NRTIs (17/33; 52%) and NNRTIs (24/33; 73%). Almost a quarter of participants (8/33; 24.4%) had one or more DRMs affecting tenofovir susceptibility. Only one participant, infected with HIV-1 subtype G, had evidence of DRMs affecting dolutegravir susceptibility—this was characterized by the T66A, G118R, E138K and R263K mutations.ConclusionsThis study found a low prevalence of resistance to dolutegravir; the data are therefore supportive of the continual rollout of dolutegravir as the primary first-line regimen for ART-naive participants and the preferred switch to second-line ART across the region. However, population-level, longer-term data collection on dolutegravir outcomes are required to further guide implementation and policy action across the region.
Kugathasan R, Sukhova K, Moshe M, et al., 2023, Deep mutagenesis scanning using whole trimeric SARS-CoV-2 spike highlights the importance of NTD-RBD interactions in determining spike phenotype, PLoS Pathogens, Vol: 19, ISSN: 1553-7366
New variants of SARS-CoV-2 are continually emerging with mutations in spike associated with increased transmissibility and immune escape. Phenotypic maps can inform the prediction of concerning mutations from genomic surveillance, however most of these maps currently derive from studies using monomeric RBD, while spike is trimeric, and contains additional domains. These maps may fail to reflect interdomain interactions in the prediction of phenotypes. To try to improve on this, we developed a platform for deep mutational scanning using whole trimeric spike. We confirmed a previously reported epistatic effect within the RBD affecting ACE2 binding, that highlights the importance of updating the base spike sequence for future mutational scanning studies. Using post vaccine sera, we found that the immune response of vaccinated individuals was highly focused on one or two epitopes in the RBD and that single point mutations at these positions can account for most of the immune escape mediated by the Omicron BA.1 RBD. However, unexpectedly we found that the BA.1 RBD alone does not account for the high level of antigenic escape by BA.1 spike. We show that the BA.1 NTD amplifies the immune evasion of its associated RBD. BA.1 NTD reduces neutralistion by RBD directed monoclonal antibodies, and impacts ACE2 interaction. NTD variation is thus an important mechanism of immune evasion by SARS-CoV-2. Such effects are not seen when pre-stabilized spike proteins are used, suggesting the interdomain effects require protein mobility to express their phenotype.
Ludwig J, Scally SW, Costa G, et al., 2023, Author Correction: Glycosylated nanoparticle-based PfCSP vaccine confers long-lasting antibody responses and sterile protection in mouse malaria model, npj Vaccines, Vol: 8, ISSN: 2059-0105
Higham SL, Baker S, Flight KE, et al., 2023, Intranasal immunisation with Outer Membrane Vesicles (OMV) protects against airway colonisation and systemic infection with Acinetobacter baumannii., Journal of Infection, Vol: 86, Pages: 563-573, ISSN: 0163-4453
OBJECTIVES: The multi-drug resistant bacteria Acinetobacter baumannii is a major cause of hospital associated infection; a vaccine could significantly reduce this burden. The aim was to develop a clinically relevant model of A. baumannii respiratory tract infection and to test the impact of different immunisation routes on protective immunity provided by an outer membrane vesicle (OMV) vaccine. METHODS: BALB/c mice were intranasally challenged with isolates of oxa23-positive global clone GC2 A. baumannii from the lungs of patients with ventilator associated pneumonia. Mice were immunised with OMVs by the intramuscular, subcutaneous or intranasal routes; protection was determined by measuring local and systemic bacterial load. RESULTS: Infection with A. baumannii clinical isolates led to a more disseminated infection than the prototype A. baumannii strain ATCC17978; with bacteria detectable in upper and lower airways and the spleen. Intramuscular immunisation induced an antibody response but did not protect against bacterial infection. However, intranasal immunisation significantly reduced airway colonisation and prevented systemic bacterial dissemination. CONCLUSION: Use of clinically relevant isolates of A. baumannii provides stringent model for vaccine development. Intranasal immunisation with OMVs was an effective route for providing protection, demonstrating that local immunity is important in preventing A. baumannii infection.
Ludwig J, Scally SW, Costa G, et al., 2023, Glycosylated nanoparticle-based PfCSP vaccine confers long-lasting antibody responses and sterile protection in mouse malaria model, npj Vaccines, Vol: 8, ISSN: 2059-0105
The development of an effective and durable vaccine remains a central goal in the fight against malaria. Circumsporozoite protein (CSP) is the major surface protein of sporozoites and the target of the only licensed Plasmodium falciparum (Pf) malaria vaccine, RTS,S/AS01. However, vaccine efficacy is low and short-lived, highlighting the need for a second-generation vaccine with superior efficacy and durability. Here, we report a Helicobacter pylori apoferritin-based nanoparticle immunogen that elicits strong B cell responses against PfCSP epitopes that are targeted by the most potent human monoclonal antibodies. Glycan engineering of the scaffold and fusion of an exogenous T cell epitope enhanced the anti-PfCSP B cell response eliciting strong, long-lived and protective humoral immunity in mice. Our study highlights the power of rational vaccine design to generate a highly efficacious second-generation anti-infective malaria vaccine candidate and provides the basis for its further development.
Richardson E, Binter S, Kosmac M, et al., 2023, Characterisation of the immune repertoire of a humanised transgenic mouse through immunophenotyping and high-throughput sequencing, eLife, Vol: 12, ISSN: 2050-084X
Immunoglobulin loci-transgenic animals are widely used in antibody discovery and increasingly in vaccine response modelling. In this study, we phenotypically characterised B-cell populations from the Intelliselect Transgenic mouse (Kymouse) demonstrating full B-cell development competence. Comparison of the naïve B-cell receptor (BCR) repertoires of Kymice BCRs, naïve human, and murine BCR repertoires revealed key differences in germline gene usage and junctional diversification. These differences result in Kymice having CDRH3 length and diversity intermediate between mice and humans. To compare the structural space explored by CDRH3s in each species’ repertoire, we used computational structure prediction to show that Kymouse naïve BCR repertoires are more human-like than mouse-like in their predicted distribution of CDRH3 shape. Our combined sequence and structural analysis indicates that the naïve Kymouse BCR repertoire is diverse with key similarities to human repertoires, while immunophenotyping confirms that selected naïve B cells are able to go through complete development.
Balakrishna S, Loosli T, Zaheri M, et al., 2023, Frequency matters: comparison of drug resistance mutation detection by Sanger and next-generation sequencing in HIV-1, Journal of Antimicrobial Chemotherapy, Vol: 78, Pages: 656-664, ISSN: 0305-7453
BackgroundNext-generation sequencing (NGS) is gradually replacing Sanger sequencing (SS) as the primary method for HIV genotypic resistance testing. However, there are limited systematic data on comparability of these methods in a clinical setting for the presence of low-abundance drug resistance mutations (DRMs) and their dependency on the variant-calling thresholds.MethodsTo compare the HIV-DRMs detected by SS and NGS, we included participants enrolled in the Swiss HIV Cohort Study (SHCS) with SS and NGS sequences available with sample collection dates ≤7 days apart. We tested for the presence of HIV-DRMs and compared the agreement between SS and NGS at different variant-calling thresholds.ResultsWe included 594 pairs of SS and NGS from 527 SHCS participants. Males accounted for 80.5% of the participants, 76.3% were ART naive at sample collection and 78.1% of the sequences were subtype B. Overall, we observed a good agreement (Cohen’s kappa >0.80) for HIV-DRMs for variant-calling thresholds ≥5%. We observed an increase in low-abundance HIV-DRMs detected at lower thresholds [28/417 (6.7%) at 10%–25% to 293/812 (36.1%) at 1%–2% threshold]. However, such low-abundance HIV-DRMs were overrepresented in ART-naive participants and were in most cases not detected in previously sampled sequences suggesting high sequencing error for thresholds <3%.ConclusionsWe found high concordance between SS and NGS but also a substantial number of low-abundance HIV-DRMs detected only by NGS at lower variant-calling thresholds. Our findings suggest that a substantial fraction of the low-abundance HIV-DRMs detected at thresholds <3% may represent sequencing errors and hence should not be overinterpreted in clinical practice.
Makori TO, Bargul JL, Lambisia AW, et al., 2023, Genomic epidemiology of the rotavirus G2P strains in coastal Kenya pre- and post-rotavirus vaccine introduction, 2012-8, Virus Evolution, Vol: 9, ISSN: 2057-1577
The introduction of rotavirus vaccines into the national immunization programme in many countries has led to a decline in childhood diarrhoea disease burden. Coincidentally, the incidence of some rotavirus group A (RVA) genotypes has increased, which may result from non-vaccine-type replacement. Here, we investigate the evolutionary genomics of rotavirus G2P which has shown an increase in countries that introduced the monovalent Rotarix® vaccine. We examined sixty-three RVA G2P strains sampled from children (aged below 13 years) admitted to Kilifi County Hospital, coastal Kenya, pre- (2012 to June 2014) and post-(July 2014 to 2018) rotavirus vaccine introduction. All the sixty-three genome sequences showed a typical DS-1-like genome constellation (G2-P-I2-R2-C2-M2-A2-N2-T2-E2-H2). Pre-vaccine G2 sequences predominantly classified as sub-lineage IVa-3 and co-circulated with low numbers of sub-lineage IVa-1 strains, whereas post-vaccine G2 sequences mainly classified into sub-lineage IVa-3. In addition, in the pre-vaccine period, P sub-lineage IVa strains co-circulated with low numbers of P lineage II strains, but P sub-lineage IVa strains predominated in the post-vaccine period. On the global phylogeny, the Kenyan pre- and post-vaccine G2P strains clustered separately, suggesting that different virus populations circulated in the two periods. However, the strains from both periods exhibited conserved amino acid changes in the known antigenic epitopes, suggesting that replacement of the predominant G2P cluster was unlikely a result of immune escape. Our findings demonstrate that the pre- and post-vaccine G2P strains circulating in Kilifi, coastal Kenya, differed genetically but likely were antigenically similar. This information informs the discussion on the consequences of rotavirus vaccination on rotavirus diversity.
Barton RD, 2022, Self-Amplifying RNA Vaccine Development: Transcriptomic Profiling of a Venezuelan Equine Encephalitis Virus Self-Amplifying RNA Vector in Human Muscle
Next-generation RNA constructs are emerging as exciting new platforms for both vaccination and therapeutic applications. The last few years have seen the first mRNA vaccines licensed for use in humans and the first-in-human clinical trial of a self-amplifying RNA vaccine. With their short time-to market, rapid manufacture, low cost, and ultra-low dosage, saRNA vaccines are potentially a game changer when it comes to dealing with novel disease outbreaks. Whilst the pre-clinical testing of a VEEV-derived saRNA vaccine yielded robust neutralisation and 100% seroconversion, the results from the first-in-human trial were notably more muted, with poor neutralisation and failure to induce 100% seroconversion. Our aim, therefore, was to investigate why humans and mice respond so differently to the VEEV saRNA construct; we hypothesised that there is a difference in the innate immune responses to saRNA in the cells that are responsible for taking up saRNA and synthesising antigen at the site of injection, i.e. muscle tissue. To investigate this, we used a transcriptomics approach to characterise the response of human muscle cells to VEEV saRNA and compared it with the transcriptomic changes seen in murine muscle cells. We observed that both human and mouse muscle cells produce a robust innate immune response to VEEV saRNA; however, there were several notable differences. Murine cells elevated the expression of cytokines and chemokines to a far greater extent than human muscle cells, while the expression of IRF7, a key transcription factor for orchestrating the antiviral response, was markedly higher in humans. Overall, these results indicate that there are distinct differences in the way that human cells react to saRNA compared to murine cells and that this should be taken into account when designing and testing saRNA vaccines in the future.
Kucharska I, Murugan R, Scally SW, et al., 2022, High-density binding to Plasmodium falciparum circumsporozoite protein repeats by inhibitory antibody elicited in mouse with human immunoglobulin repertoire, PLoS Pathogens, Vol: 18, ISSN: 1553-7366
Antibodies targeting the human malaria parasite Plasmodium falciparum circumsporozoite protein (PfCSP) can prevent infection and disease. PfCSP contains multiple central repeating NANP motifs; some of the most potent anti-infective antibodies against malaria bind to these repeats. Multiple antibodies can bind the repeating epitopes concurrently by engaging into homotypic Fab-Fab interactions, which results in the ordering of the otherwise largely disordered central repeat into a spiral. Here, we characterize IGHV3-33/IGKV1-5-encoded monoclonal antibody (mAb) 850 elicited by immunization of transgenic mice with human immunoglobulin loci. mAb 850 binds repeating NANP motifs with picomolar affinity, potently inhibits Plasmodium falciparum (Pf) in vitro and, when passively administered in a mouse challenge model, reduces liver burden to a similar extent as some of the most potent anti-PfCSP mAbs yet described. Like other IGHV3-33/IGKV1-5-encoded anti-NANP antibodies, mAb 850 primarily utilizes its HCDR3 and germline-encoded aromatic residues to recognize its core NANP motif. Biophysical and cryo-electron microscopy analyses reveal that up to 19 copies of Fab 850 can bind the PfCSP repeat simultaneously, and extensive homotypic interactions are observed between densely-packed PfCSP-bound Fabs to indirectly improve affinity to the antigen. Together, our study expands on the molecular understanding of repeat-induced homotypic interactions in the B cell response against PfCSP for potently protective mAbs against Pf infection.
Marshall VA, Fisher NC, Goodman CA, et al., 2022, Systematic analysis of Kaposi's sarcoma (KS)-associated herpesvirus genomes from a KS case-control study in Cameroon: evidence of dual infections but no association between viral sequence variation and KS risk, International Journal of Cancer, Vol: 151, Pages: 1127-1141, ISSN: 0020-7136
In sub-Saharan Africa, Kaposi's sarcoma-associated herpesvirus (KSHV) is endemic, and Kaposi's sarcoma (KS) is a significant public health problem. Until recently, KSHV genotype analysis was performed using variable gene regions, representing a small fraction of the genome, and thus the contribution of sequence variation to viral transmission or pathogenesis are understudied. We performed near full-length KSHV genome sequence analysis on samples from 43 individuals selected from a large Cameroonian KS case-control study. KSHV genomes were obtained from 21 KS patients and 22 control participants. Phylogenetic analysis of the K1 region indicated the majority of sequences were A5 or B1 subtypes and all three K15 alleles were represented. Unique polymorphisms in the KSHV genome were observed including large gene deletions. We found evidence of multiple distinct KSHV genotypes in three individuals. Additionally, our analyses indicate that recombination is prevalent suggesting that multiple KSHV infections may not be uncommon overall. Most importantly, a detailed analysis of KSHV genomes from KS patients and control participants did not find a correlation between viral sequence variations and disease. Our study is the first to systematically compare near full-length KSHV genome sequences between KS cases and controls in the same endemic region to identify possible sequence variations associated with disease risk.
Wymant C, Bezemer D, Blanquart F, et al., 2022, A highly virulent variant of HIV-1 circulating in the Netherlands, Science, Vol: 375, Pages: 540-545, ISSN: 0036-8075
Changes in viral load and CD4+ T cell decline are expected signals of HIV evolution. By examining data from well-characterized European cohorts, Wymant et al. report an exceptionally virulent subtype of HIV that has been circulating in the Netherlands for several years (see the Perspective by Wertheim). More than one hundred individuals infected with a characteristic subtype B lineage of HIV-1 were found who experienced double the rate of CD4+ cell count declines than expected. By the time they were diagnosed, these individuals were vulnerable to developing AIDS within 2 to 3 years. This virus lineage, which has apparently arisen de novo since around the millennium, shows extensive change across the genome affecting almost 300 amino acids, which makes it hard to discern the mechanism for elevated virulence. —CA
Phan MVT, Agoti CN, Munywoki PK, et al., 2022, Identification of missed viruses by metagenomic sequencing of clinical respiratory samples from Kenya, Scientific Reports, Vol: 12, ISSN: 2045-2322
Pneumonia remains a major cause of mortality and morbidity. Most molecular diagnoses of viruses rely on polymerase chain reaction (PCR) assays that however can fail due to primer mismatch. We investigated the performance of routine virus diagnostics in Kilifi, Kenya, using random-primed viral next generation sequencing (viral NGS) on respiratory samples which tested negative for the common viral respiratory pathogens by a local standard diagnostic panel. Among 95 hospitalised pneumonia patients and 95 household-cohort individuals, analysis of viral NGS identified at least one respiratory-associated virus in 35 (37%) and 23 (24%) samples, respectively. The majority (66%; 42/64) belonged to the Picornaviridae family. The NGS data analysis identified a number of viruses that were missed by the diagnostic panel (rhinovirus, human metapneumovirus, respiratory syncytial virus and parainfluenza virus), and these failures could be attributed to PCR primer/probe binding site mismatches. Unexpected viruses identified included parvovirus B19, enterovirus D68, coxsackievirus A16 and A24 and rubella virus. The regular application of such viral NGS could help evaluate assay performance, identify molecular causes of missed diagnoses and reveal gaps in the respiratory virus set used for local screening assays. The results can provide actionable information to improve the local pneumonia diagnostics and reveal locally important viral pathogens.
Zhao L, Wymant C, Blanquart F, et al., 2022, Phylogenetic estimation of the viral fitness landscape of HIV-1 set-point viral load, Virus Evolution, Vol: 8, ISSN: 2057-1577
Set-point viral load (SPVL), a common measure of human immunodeficiency virus (HIV)-1 virulence, is partially determined by viral genotype. Epidemiological evidence suggests that this viral property has been under stabilising selection, with a typical optimum for the virus between 104 and 105 copies of viral RNA per ml. Here we aimed to detect transmission fitness differences between viruses from individuals with different SPVLs directly from phylogenetic trees inferred from whole-genome sequences. We used the local branching index (LBI) as a proxy for transmission fitness. We found that LBI is more sensitive to differences in infectiousness than to differences in the duration of the infectious state. By analysing subtype-B samples from the Bridging the Evolution and Epidemiology of HIV in Europe project, we inferred a significant positive relationship between SPVL and LBI up to approximately 105 copies/ml, with some evidence for a peak around this value of SPVL. This is evidence of selection against low values of SPVL in HIV-1 subtype-B strains, likely related to lower infectiousness, and perhaps a peak in the transmission fitness in the expected range of SPVL. The less prominent signatures of selection against higher SPVL could be explained by an inherent limit of the method or the deployment of antiretroviral therapy.
ISARIC Clinical Characterisation Group, 2021, The value of open-source clinical science in pandemic response: lessons from ISARIC., Lancet Infectious Diseases, Vol: 21, Pages: 1623-1624, ISSN: 1473-3099
Hastie KM, Li H, Bedinger D, et al., 2021, Defining variant-resistant epitopes targeted by SARS-CoV-2 antibodies: a global consortium study, Science, Vol: 374, Pages: 472-478, ISSN: 0036-8075
The severe acute respiratory syndrome coronavirus 2 spike protein is the basis of many vaccines and is a primary target of neutralizing antibodies after COVID-19 infection. The Coronavirus Immunotherapeutic Consortium (CoVIC), comprising 56 partners across the world, has analyzed a panel of 269 monoclonal antibodies (mAbs) and, on the basis of competition profiles, sorted 186 mAbs that target the receptor binding domain into seven communities. Hastie et al. went on to structurally analyze representative antibody binding and used pseudovirus neutralization assays to study the effect of spike mutations on antibody function, including the combinations of mutations found in certain variants of concern. These results are important to guide both treatment and prevention efforts. —VV
van Bunnik BAD, Morgan ALK, Bessell PR, et al., 2021, Segmentation and shielding of the most vulnerable members of the population as elements of an exit strategy from COVID-19 lockdown, Philosophical Transactions of the Royal Society B: Biological Sciences, Vol: 376, ISSN: 0962-8436
This study demonstrates that an adoption of a segmenting and shielding strategy could increase the scope to partially exit COVID-19 lockdown while limiting the risk of an overwhelming second wave of infection. We illustrate this using a mathematical model that segments the vulnerable population and their closest contacts, the ‘shielders’. Effects of extending the duration of lockdown and faster or slower transition to post-lockdown conditions and, most importantly, the trade-off between increased protection of the vulnerable segment and fewer restrictions on the general population are explored. Our study shows that the most important determinants of outcome are: (i) post-lockdown transmission rates within the general and between the general and vulnerable segments; (ii) fractions of the population in the vulnerable and shielder segments; (iii) adherence to protective measures; and (iv) build-up of population immunity. Additionally, we found that effective measures in the shielder segment, e.g. intensive routine screening, allow further relaxations in the general population. We find that the outcome of any future policy is strongly influenced by the contact matrix between segments and the relationships between physical distancing measures and transmission rates. This strategy has potential applications for any infectious disease for which there are defined proportions of the population who cannot be treated or who are at risk of severe outcomes.
Roach M, Cantu A, Vieri MK, et al., 2021, No evidence known viruses play a role in the pathogenesis of onchocerciasis-associated epilepsy. An explorative metagenomic case-control study, Pathogens, Vol: 10, ISSN: 2076-0817
Despite the increasing epidemiological evidence that the Onchocerca volvulus parasite is strongly associated with epilepsy in children, hence the name onchocerciasis-associated epilepsy (OAE), the pathophysiological mechanism of OAE remains to be elucidated. In June 2014, children with unprovoked convulsive epilepsy and healthy controls were enrolled in a case control study in Titule, Bas-Uélé Province in the Democratic Republic of the Congo (DRC) to identify risk factors for epilepsy. Using a subset of samples collected from individuals enrolled in this study (16 persons with OAE and 9 controls) plasma, buffy coat, and cerebrospinal fluid (CSF) were subjected to random-primed next-generation sequencing. The resulting sequences were analyzed using sensitive computational methods to identify viral DNA and RNA sequences. Anneloviridae, Flaviviridae, Hepadnaviridae (Hepatitis B virus), Herpesviridae, Papillomaviridae, Polyomaviridae (Human polyomavirus), and Virgaviridae were identified in cases and in controls. Not unexpectedly, a variety of bacteriophages were also detected in all cases and controls. However, none of the identified viral sequences were found enriched in OAE cases, which was our criteria for agents that might play a role in the etiology or pathogenesis of OAE.
Ferrara F, Del Rosario JMM, da Costa KAS, et al., 2021, Development of lentiviral vectors pseudotyped with Influenza B hemagglutinins: application in vaccine immunogenicity, mAb potency, and sero-surveillance studies, Frontiers in Immunology, Vol: 12, ISSN: 1664-3224
Influenza B viruses (IBV) cause respiratory disease epidemics in humans and are therefore components of seasonal influenza vaccines. Serological methods are employed to evaluate vaccine immunogenicity prior to licensure. However, classical methods to assess influenza vaccine immunogenicity such as the hemagglutination inhibition assay (HI) and the serial radial hemolysis assay (SRH), have been proven to have many limitations. As such, there is a need to develop innovative methods that can improve on these traditional assays and provide advantages such as ease of production and access, safety, reproducibility, and specificity. It has been previously demonstrated that the use of replication-defective viruses, such as lentiviral vectors pseudotyped with influenza A hemagglutinins in microneutralization assays (pMN) is a safe and sensitive alternative to study antibody responses elicited by natural influenza infection or vaccination. Consequently, we have produced Influenza B hemagglutinin-pseudotypes (IBV PV) using plasmid-directed transfection. To activate influenza B hemagglutinin, we have explored the use of proteases in increasing PV titers via their co-transfection during pseudotype virus production. When tested for their ability to transduce target cells, the influenza B pseudotypes produced exhibit tropism for different cell lines. The pseudotypes were evaluated as alternatives to live virus in microneutralization assays using reference sera standards, mouse and human sera collected during vaccine immunogenicity studies, surveillance sera from seals, and monoclonal antibodies (mAbs) against IBV. The influenza B pseudotype pMN was found to effectively detect neutralizing and cross-reactive responses in all assays and shows promise as an effective and versatile tool in influenza research.
Maes M, Dyson ZA, Smith SE, et al., 2021, Publisher Correction: A novel therapeutic antibody screening method using bacterial high-content imaging reveals functional antibody binding phenotypes of Escherichia coli ST131, Scientific Reports, Vol: 11, ISSN: 2045-2322
Shrotri M, van Schalkwyk MCI, Post N, et al., 2021, T cell response to SARS-CoV-2 infection in humans: a systematic review, PLoS One, Vol: 16, Pages: 1-21, ISSN: 1932-6203
BackgroundUnderstanding the T cell response to SARS-CoV-2 is critical to vaccine development, epidemiological surveillance and control strategies. This systematic review critically evaluates and synthesises the relevant peer-reviewed and pre-print literature published in recent months.MethodsFor this systematic review, independent keyword-structured literature searches were carried out in MEDLINE, Embase and COVID-19 Primer for studies published from 01/01/2020-26/06/2020. Papers were independently screened by two researchers, with arbitration of disagreements by a third researcher. Data were independently extracted into a pre-designed Excel template and studies critically appraised using a modified version of the MetaQAT tool, with resolution of disagreements by consensus. Findings were narratively synthesised.Results61 articles were included. 55 (90%) studies used observational designs, 50 (82%) involved hospitalised patients with higher acuity illness, and the majority had important limitations. Symptomatic adult COVID-19 cases consistently show peripheral T cell lymphopenia, which positively correlates with increased disease severity, duration of RNA positivity, and non-survival; while asymptomatic and paediatric cases display preserved counts. People with severe or critical disease generally develop more robust, virus-specific T cell responses. T cell memory and effector function has been demonstrated against multiple viral epitopes, and, cross-reactive T cell responses have been demonstrated in unexposed and uninfected adults, but the significance for protection and susceptibility, respectively, remains unclear. Conclusion A complex pattern of T cell response to SARS-CoV-2 infection has been demonstrated, but inferences regarding population level immunity are hampered by significant methodological limitations and heterogeneity between studies, as well as a striking lack of research in asymptomatic or pauci-symptomatic individuals. In contrast to antibody respo
Richardson E, Galson JD, Kellam P, et al., 2021, A computational method for immune repertoire mining that identifies novel binders from different clonotypes, demonstrated by identifying anti-pertussis toxoid antibodies, mAbs, Vol: 13, ISSN: 1942-0862
Due to their shared genetic history, antibodies from the same clonotype often bind to the same epitope. This knowledge is used in immune repertoire mining, where known binders are used to search bulk sequencing repertoires to identify new binders. However, current computational methods cannot identify epitope convergence between antibodies from different clonotypes, limiting the sequence diversity of antigen-specific antibodies that can be identified. We describe how the antibody binding site, the paratope, can be used to cluster antibodies with common antigen reactivity from different clonotypes. Our method, paratyping, uses the predicted paratope to identify these novel cross clonotype matches. We experimentally validated our predictions on a pertussis toxoid dataset. Our results show that even the simplest abstraction of the antibody binding site, using only the length of the loops involved and predicted binding residues, is sufficient to group antigen-specific antibodies and provide additional information to conventional clonotype analysis.
Post N, Eddy D, Huntley C, et al., 2020, Antibody response to SARS-CoV-2 infection in humans: a systematic review, PLoS One, Vol: 15, Pages: 1-27, ISSN: 1932-6203
BackgroundProgress in characterising the humoral immune response to Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) has been rapid but areas of uncertainty persist. Assessment of the full range of evidence generated to date to understand the characteristics of the antibody response, its dynamics over time, its determinants and the immunity it confers will have a range of clinical and policy implications for this novel pathogen. This review comprehensively evaluated evidence describing the antibody response to SARS-CoV-2 published from 01/01/2020-26/06/2020.MethodsSystematic review. Keyword-structured searches were carried out in MEDLINE, Embase and COVID-19 Primer. Articles were independently screened on title, abstract and full text by two researchers, with arbitration of disagreements. Data were double-extracted into a pre-designed template, and studies critically appraised using a modified version of the MetaQAT tool, with resolution of disagreements by consensus. Findings were narratively synthesised. Results150 papers were included. Most studies (113 or 75%) were observational in design, were based wholly or primarily on data from hospitalised patients (108, 72%) and had important methodological limitations. Few considered mild or asymptomatic infection. Antibody dynamics were well described in the acute phase, up to around 3 months from disease onset, but the picture regarding correlates of the antibody response was inconsistent. IgM was consistently detected before IgG in included studies, peaking at weeks 2-5 and declining over a further 3-5 weeks post-symptom onset depending on the patient group; IgG peaked around weeks 3-7 post-symptom onset then plateaued, generally persisting for at least 8 weeks. Neutralising antibodies were detectable within 7-15 days following disease onset, with levels increasing until days 14-22 before levelling and then decreasing, but titres were lower in those with asymptomatic or clinically mild disease. Specific and potent neu
Sallah N, Miley W, Labo N, et al., 2020, The contribution of host genetics and environmental variation to immune response in gamma-herpesvirus infections, Publisher: ELSEVIER SCI LTD, Pages: 408-408, ISSN: 1201-9712
Walls AC, Fiala B, Schäfer A, et al., 2020, Elicitation of potent neutralizing antibody responses by designed protein nanoparticle vaccines for SARS-CoV-2, Cell, Vol: 183, Pages: 1367-1382.e17, ISSN: 0092-8674
A safe, effective, and scalable vaccine is needed to halt the ongoing SARS-CoV-2 pandemic. We describe the structure-based design of self-assembling protein nanoparticle immunogens that elicit potent and protective antibody responses against SARS-CoV-2 in mice. The nanoparticle vaccines display 60 SARS-CoV-2 spike receptor-binding domains (RBDs) in a highly immunogenic array and induce neutralizing antibody titers 10-fold higher than the prefusion-stabilized spike despite a 5-fold lower dose. Antibodies elicited by the RBD nanoparticles target multiple distinct epitopes, suggesting they may not be easily susceptible to escape mutations, and exhibit a lower binding:neutralizing ratio than convalescent human sera, which may minimize the risk of vaccine-associated enhanced respiratory disease. The high yield and stability of the assembled nanoparticles suggest that manufacture of the nanoparticle vaccines will be highly scalable. These results highlight the utility of robust antigen display platforms and have launched cGMP manufacturing efforts to advance the SARS-CoV-2-RBD nanoparticle vaccine into the clinic.
Novitsky V, Zahralban-Steele M, Moyo S, et al., 2020, Mapping of HIV-1C transmission networks reveals extensive spread of viral lineages across villages in Botswana treatment-as-prevention trial, Journal of Infectious Diseases, Vol: 222, Pages: 1670-1680, ISSN: 0022-1899
BackgroundPhylogenetic mapping of HIV-1 lineages circulating across defined geographical locations is promising for better understanding HIV transmission networks to design optimal prevention interventions.MethodsWe obtained near full-length HIV-1 genome sequences from people living with HIV (PLWH), including participants on antiretroviral treatment in the Botswana Combination Prevention Project, conducted in 30 Botswana communities in 2013–2018. Phylogenetic relationships among viral sequences were estimated by maximum likelihood.ResultsWe obtained 6078 near full-length HIV-1C genome sequences from 6075 PLWH. We identified 984 phylogenetically distinct HIV-1 lineages (molecular HIV clusters) circulating in Botswana by mid-2018, with 2–27 members per cluster. Of these, dyads accounted for 62%, approximately 32% (n = 316) were found in single communities, and 68% (n = 668) were spread across multiple communities. Men in clusters were approximately 3 years older than women (median age 42 years, vs 39 years; P < .0001). In 65% of clusters, men were older than women, while in 35% of clusters women were older than men. The majority of identified viral lineages were spread across multiple communities.ConclusionsA large number of circulating phylogenetically distinct HIV-1C lineages (molecular HIV clusters) suggests highly diversified HIV transmission networks across Botswana communities by 2018.
Alwan NA, Burgess RA, Ashworth S, et al., 2020, Scientific consensus on the COVID-19 pandemic: we need to act now, The Lancet, Vol: 396, Pages: E71-E72, ISSN: 0140-6736
Jiao X, Smith S, Stack G, et al., 2020, Generation and Characterization of Typhoid Toxin-Neutralizing Human Monoclonal Antibodies, INFECTION AND IMMUNITY, Vol: 88, ISSN: 0019-9567
Tregoning J, Busse D, Kaforou M, et al., 2020, Interferon-induced Protein-44 and Interferon-induced Protein 44-like restrict replication of Respiratory Syncytial Virus, Journal of Virology, Vol: 94, Pages: 1-15, ISSN: 0022-538X
Cellular intrinsic immunity, mediated by the expression of an array of interferon-stimulated antiviral genes, is a vital part of host defence. We have previously used a bioinformatic screen to identify two interferon stimulated genes (ISG) with poorly characterised function, Interferon-induced protein 44 (IFI44) and interferon-induced protein 44-like (IFI44L), as potentially being important in Respiratory Syncytial Virus (RSV) infection. Using overexpression systems, CRISPR-Cas9-mediated knockout, and a knockout mouse model we investigated the antiviral capability of these genes in the control of RSV replication. Over-expression of IFI44 or IFI44L was sufficient to restrict RSV infection at an early time post infection. Knocking out these genes in mammalian airway epithelial cells increased levels of infection. Both genes express antiproliferative factors that have no effect on RSV attachment but reduce RSV replication in a minigenome assay. The loss of Ifi44 was associated with a more severe infection phenotype in a mouse model of infection. These studies demonstrate a function for IFI44 and IFI44L in controlling RSV infection.
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