300 results found
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
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
Alwan NA, Burgess RA, Ashworth S, et al., 2020, Scientific consensus on the COVID-19 pandemic: we need to act now, 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., Infect Immun, Vol: 88
Typhoid toxin is a virulence factor of Salmonella enterica serovar Typhi, the causative agent of typhoid fever, and is thought to be responsible for the symptoms of severe disease. This toxin has a unique A2B5 architecture with two active subunits, the ADP ribosyl transferase PltA and the DNase CdtB, linked to a pentameric B subunit, which is alternatively made of PltB or PltC. Here, we describe the generation and characterization of typhoid toxin-neutralizing human monoclonal antibodies by immunizing genetically engineered mice that have a full set of human immunoglobulin variable region genes. We identified several monoclonal antibodies with strong in vitro and in vivo toxin-neutralizing activity and different mechanisms of toxin neutralization. These antibodies could serve as the basis for the development of novel therapeutic strategies against typhoid fever.
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.
Shrotri M, van Schalkwyk M, Post N, et al., 2020, Cellular immune response to SARS-CoV-2 infection in humans: a systematic review, Publisher: Cold Spring Harbor Laboratory
Introduction Understanding the cellular immune 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. Methods For 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. Results 61 articles were included. Almost all studies used observational designs, were hospital-based, 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. Interpretation 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. In contrast to antibody responses, population-level surveillance of the cellular response is unlikely to be feasible in the near term. Focuse
Walls AC, Fiala B, Schäfer A, et al., 2020, Elicitation of potent neutralizing antibody responses by designed protein nanoparticle vaccines for SARS-CoV-2.
A safe, effective, and scalable vaccine is urgently needed to halt the ongoing SARS-CoV-2 pandemic. Here, 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 copies of the SARS-CoV-2 spike (S) glycoprotein receptor-binding domain (RBD) in a highly immunogenic array and induce neutralizing antibody titers roughly ten-fold higher than the prefusion-stabilized S ectodomain trimer despite a more than five-fold lower dose. Antibodies elicited by the nanoparticle immunogens target multiple distinct epitopes on the RBD, suggesting that they may not be easily susceptible to escape mutations, and exhibit a significantly 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 protein components and assembled nanoparticles, especially compared to the SARS-CoV-2 prefusion-stabilized S trimer, suggest that manufacture of the nanoparticle vaccines will be highly scalable. These results highlight the utility of robust antigen display platforms for inducing potent neutralizing antibody responses and have launched cGMP manufacturing efforts to advance the lead RBD nanoparticle vaccine into the clinic.
Sallah N, Miley W, Labo N, et al., 2020, Distinct genetic architectures and environmental factors associate with host response to the gamma 2-herpesvirus infections, NATURE COMMUNICATIONS, Vol: 11, ISSN: 2041-1723
Maes M, Dyson ZA, Smith SE, et al., 2020, A novel therapeutic antibody screening method using bacterial high-content imaging reveals functional antibody binding phenotypes of Escherichia coli ST131, Scientific Reports, Vol: 10, ISSN: 2045-2322
The increase of antimicrobial resistance (AMR), and lack of new classes of licensed antimicrobials, have made alternative treatment options for AMR pathogens increasingly attractive. Recent studies have demonstrated anti-bacterial efficacy of a humanised monoclonal antibody (mAb) targeting the O25b O-antigen of Escherichia coli ST131. To evaluate the phenotypic effects of antibody binding to diverse clinical E. coli ST131 O25b bacterial isolates in high-throughput, we designed a novel mAb screening method using high-content imaging (HCI) and image-based morphological profiling to screen a mAb targeting the O25b O-antigen. Screening the antibody against a panel of 86 clinical E. coli ST131 O25:H4 isolates revealed 4 binding phenotypes: no binding (18.60%), weak binding (4.65%), strong binding (69.77%) and strong agglutinating binding (6.98%). Impaired antibody binding could be explained by the presence of insertion sequences or mutations in O-antigen or lipopolysaccharide core biosynthesis genes, affecting the amount, structure or chain length of the O-antigen. The agglutinating binding phenotype was linked with lower O-antigen density, enhanced antibody-mediated phagocytosis and increased serum susceptibly. This study highlights the need to screen candidate mAbs against large panels of clinically relevant isolates, and that HCI can be used to evaluate mAb binding affinity and potential functional efficacy against AMR bacteria.
Richardson E, Galson JD, Kellam P, et al., 2020, A computational method for immune repertoire mining that identifies novel binders from different clonotypes, demonstrated by identifying anti-Pertussis toxoid antibodies, Publisher: Cold Spring Harbor Laboratory
<jats:title>Abstract</jats:title><jats:p>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 which 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.</jats:p>
Benfield CT, MacKenzie F, Ritzefeld M, et al., 2020, Correction: Bat IFITM3 restriction depends on S-palmitoylation and a polymorphic site within the CD225 domain, Life Science Alliance, Vol: 3, ISSN: 2575-1077
Kellam P, Barclay W, 2020, The dynamics of humoral immune responses following SARS-CoV-2 infection and the potential for reinfection, Journal of General Virology, Vol: 101, ISSN: 0022-1317
SARS-CoV-2 is a novel coronavirus that is the causative agent of coronavirus infectious disease 2019 (COVID-19). As of 17 April 2020, it has infected 2 114 269 people, resulting in 145 144 deaths. The timing, magnitude and longevity of humoral immunity is not yet understood for SARS-CoV-2. Nevertheless, understanding this is urgently required to inform the likely future dynamics of the pandemic, to guide strategies to allow relaxation of social distancing measures and to understand how to deploy limiting vaccine doses when they become available to achieve maximum impact. SARS-CoV-2 is the seventh human coronavirus to be described. Four human coronaviruses circulate seasonally and cause common colds. Two other coronaviruses, SARS and MERS, have crossed from animal sources into humans but have not become endemic. Here we review what is known about the human humoral immune response to epidemic SARS CoV and MERS CoV and to the seasonal, endemic coronaviruses. Then we summarize recent, mostly non-peer reviewed, studies into SARS-CoV-2 serology and reinfection in humans and non-human primates and summarize current pressing research needs.
Capoferri AA, Lamers SL, Grabowski MK, et al., 2020, Recombination analysis of near full-length HIV-1 sequences and the identification of a potential new circulating recombinant form from Rakai, Uganda., AIDS Research and Human Retroviruses, ISSN: 0889-2229
The Phylogenetics And Networks for Generalized HIV Epidemics in Africa (PANGEA-HIV) consortium has been vital in the generation and examination of near full-length HIV-1 sequences generated from Sub-Saharan Africa. In this study, we examined a subset (n = 275) of sequences from Rakai, Uganda, collected between August 2011 and January 2015. Sequences were initially screened with COMET for subtyping and then evaluated using bootscanning and phylogenetic inference. Among 275 sequences, 38.6% were subtype D, 19.3% were subtype A, 2.9% were subtype C, and 39.3% were recombinant. The recombinants were structurally diverse in the number of breakpoints observed, the location of recombinant segments, and represented subtypes, with AD recombinants accounting for the majority of all recombinants (29.8%). Within the AD subpopulation, we identified a potential new circulating recombinant form in five individuals where the polymerase gene was subtype D and most of env was subtype A (D-A junctures at HXB2 6760 and 8709). While the breakpoints were identical for the viruses from these individuals, the viral fragments did not cluster together. These results suggest selection for a viral strain where properties of the subtype A and subtype D portions of the virus confer a survival advantage. The continued study of recombinants will increase our breadth of knowledge for the genetic diversity and evolution of HIV-1, which can further contribute to our understanding toward a universal HIV-1 vaccine.
Oyen D, Torres JL, Aoto PC, et al., 2020, Structure and mechanism of monoclonal antibody binding to the junctional epitope of Plasmodium falciparum circumsporozoite protein, PLoS Pathogens, Vol: 16, Pages: 1-22, ISSN: 1553-7366
Lasting protection has long been a goal for malaria vaccines. The major surface antigen on Plasmodium falciparum sporozoites, the circumsporozoite protein (PfCSP), has been an attractive target for vaccine development and most protective antibodies studied to date interact with the central NANP repeat region of PfCSP. However, it remains unclear what structural and functional characteristics correlate with better protection by one antibody over another. Binding to the junctional region between the N-terminal domain and central NANP repeats has been proposed to result in superior protection: this region initiates with the only NPDP sequence followed immediately by NANP. Here, we isolated antibodies in Kymab mice immunized with full-length recombinant PfCSP and two protective antibodies were selected for further study with reactivity against the junctional region. X-ray and EM structures of two monoclonal antibodies, mAb667 and mAb668, shed light on their differential affinity and specificity for the junctional region. Importantly, these antibodies also bind to the NANP repeat region with equal or better affinity. A comparison with an NANP-only binding antibody (mAb317) revealed roughly similar but statistically distinct levels of protection against sporozoite challenge in mouse liver burden models, suggesting that junctional antibody protection might relate to the ability to also cross-react with the NANP repeat region. Our findings indicate that additional efforts are necessary to isolate a true junctional antibody with no or much reduced affinity to the NANP region to elucidate the role of the junctional epitope in protection.
Ratmann O, Kagaayi J, Hall M, et al., 2020, Quantifying HIV transmission flow between high-prevalence hotspots and surrounding communities: a population-based study in Rakai, Uganda, The Lancet HIV, Vol: 7, Pages: e173-e183, ISSN: 2352-3018
BackgroundInternational and global organisations advocate targeting interventions to areas of high HIV prevalence (ie, hotspots). To better understand the potential benefits of geo-targeted control, we assessed the extent to which HIV hotspots along Lake Victoria sustain transmission in neighbouring populations in south-central Uganda.MethodsWe did a population-based survey in Rakai, Uganda, using data from the Rakai Community Cohort Study. The study surveyed all individuals aged 15–49 years in four high-prevalence Lake Victoria fishing communities and 36 neighbouring inland communities. Viral RNA was deep sequenced from participants infected with HIV who were antiretroviral therapy-naive during the observation period. Phylogenetic analysis was used to infer partial HIV transmission networks, including direction of transmission. Reconstructed networks were interpreted through data for current residence and migration history. HIV transmission flows within and between high-prevalence and low-prevalence areas were quantified adjusting for incomplete sampling of the population.FindingsBetween Aug 10, 2011, and Jan 30, 2015, data were collected for the Rakai Community Cohort Study. 25 882 individuals participated, including an estimated 75·7% of the lakeside population and 16·2% of the inland population in the Rakai region of Uganda. 5142 participants were HIV-positive (2703 [13·7%] in inland and 2439 [40·1%] in fishing communities). 3878 (75·4%) people who were HIV-positive did not report antiretroviral therapy use, of whom 2652 (68·4%) had virus deep-sequenced at sufficient quality for phylogenetic analysis. 446 transmission networks were reconstructed, including 293 linked pairs with inferred direction of transmission. Adjusting for incomplete sampling, an estimated 5·7% (95% credibility interval 4·4–7·3) of transmissions occurred within lakeside areas, 89·2% (86·0–91·
Grant HE, Hodcroft EB, Ssemwanga D, et al., 2020, Pervasive and non-random recombination in near full-length HIV genomes from Uganda., Virus Evol, Vol: 6, Pages: 1-12, ISSN: 2057-1577
Recombination is an important feature of HIV evolution, occurring both within and between the major branches of diversity (subtypes). The Ugandan epidemic is primarily composed of two subtypes, A1 and D, that have been co-circulating for 50 years, frequently recombining in dually infected patients. Here, we investigate the frequency of recombinants in this population and the location of breakpoints along the genome. As part of the PANGEA-HIV consortium, 1,472 consensus genome sequences over 5 kb have been obtained from 1,857 samples collected by the MRC/UVRI & LSHTM Research unit in Uganda, 465 (31.6 per cent) of which were near full-length sequences (>8 kb). Using the subtyping tool SCUEAL, we find that of the near full-length dataset, 233 (50.1 per cent) genomes contained only one subtype, 30.8 per cent A1 (n = 143), 17.6 per cent D (n = 82), and 1.7 per cent C (n = 8), while 49.9 per cent (n = 232) contained more than one subtype (including A1/D (n = 164), A1/C (n = 13), C/D (n = 9); A1/C/D (n = 13), and 33 complex types). K-means clustering of the recombinant A1/D genomes revealed a section of envelope (C2gp120-TMgp41) is often inherited intact, whilst a generalized linear model was used to demonstrate significantly fewer breakpoints in the gag-pol and envelope C2-TM regions compared with accessory gene regions. Despite similar recombination patterns in many recombinants, no clearly supported circulating recombinant form (CRF) was found, there was limited evidence of the transmission of breakpoints, and the vast majority (153/164; 93 per cent) of the A1/D recombinants appear to be unique recombinant forms. Thus, recombination is pervasive with clear biases in breakpoint location, but CRFs are not a significant feature, characteristic of a complex, and diverse epidemic.
Benfield CT, MacKenzie F, Ritzefeld M, et al., 2020, Bat IFITM3 restriction depends on S-palmitoylation and a polymorphic site within the CD225 domain, Life Science Alliance, Vol: 3, ISSN: 2575-1077
Host interferon-induced transmembrane proteins (IFITMs) are broad-spectrum antiviral restriction factors. Of these, IFITM3 potently inhibits viruses that enter cells through acidic endosomes, many of which are zoonotic and emerging viruses with bats (order Chiroptera) as their natural hosts. We previously demonstrated that microbat IFITM3 is antiviral. Here, we show that bat IFITMs are characterized by strong adaptive evolution and identify a highly variable and functionally important site-codon 70-within the conserved CD225 domain of IFITMs. Mutation of this residue in microbat IFITM3 impairs restriction of representatives of four different virus families that enter cells via endosomes. This mutant shows altered subcellular localization and reduced S-palmitoylation, a phenotype copied by mutation of conserved cysteine residues in microbat IFITM3. Furthermore, we show that microbat IFITM3 is S-palmitoylated on cysteine residues C71, C72, and C105, mutation of each cysteine individually impairs virus restriction, and a triple C71A-C72A-C105A mutant loses all restriction activity, concomitant with subcellular re-localization of microbat IFITM3 to Golgi-associated sites. Thus, we propose that S-palmitoylation is critical for Chiropteran IFITM3 function and identify a key molecular determinant of IFITM3 S-palmitoylation.
Petrova VN, Sawatsky B, Han AX, et al., 2019, Incomplete genetic reconstitution of B cell pools contributes to prolonged immunosuppression after measles, Science Immunology, Vol: 4, Pages: 1-14, ISSN: 2470-9468
Measles is a disease caused by the highly infectious measles virus (MeV) that results in both viremia and lymphopenia. Lymphocyte counts recover shortly after the disappearance of measles-associated rash, but immunosuppression can persist for months to years after infection, resulting in increased incidence of secondary infections. Animal models and in vitro studies have proposed various immunological factors underlying this prolonged immune impairment, but the precise mechanisms operating in humans are unknown. Using B cell receptor (BCR) sequencing of human peripheral blood lymphocytes before and after MeV infection, we identified two immunological consequences from measles underlying immunosuppression: (i) incomplete reconstitution of the naïve B cell pool leading to immunological immaturity and (ii) compromised immune memory to previously encountered pathogens due to depletion of previously expanded B memory clones. Using a surrogate model of measles in ferrets, we investigated the clinical consequences of morbillivirus infection and demonstrated a depletion of vaccine-acquired immunity to influenza virus, leading to a compromised immune recall response and increased disease severity after secondary influenza virus challenge. Our results show that MeV infection causes changes in naïve and memory B lymphocyte diversity that persist after the resolution of clinical disease and thus contribute to compromised immunity to previous infections or vaccinations. This work highlights the importance of MeV vaccination not only for the control of measles but also for the maintenance of herd immunity to other pathogens, which can be compromised after MeV infection.
Blackburn RM, Frampton D, Smith CM, et al., 2019, Nosocomial transmission of influenza: A retrospective cross-sectional study using next generation sequencing at a hospital in England (2012-2014), Influenza and Other Respiratory Viruses, Vol: 13, Pages: 556-563, ISSN: 1750-2640
BackgroundThe extent of transmission of influenza in hospital settings is poorly understood. Next generation sequencing may improve this by providing information on the genetic relatedness of viral strains.ObjectivesWe aimed to apply next generation sequencing to describe transmission in hospital and compare with methods based on routinely‐collected data.MethodsAll influenza samples taken through routine care from patients at University College London Hospitals NHS Foundation Trust (September 2012 to March 2014) were included. We conducted Illumina sequencing and identified genetic clusters. We compared nosocomial transmission estimates defined using classical methods (based on time from admission to sample) and genetic clustering. We identified pairs of cases with space‐time links and assessed genetic relatedness.ResultsWe sequenced influenza sampled from 214 patients. There were 180 unique genetic strains, 16 (8.8%) of which seeded a new transmission chain. Nosocomial transmission was indicated for 32 (15.0%) cases using the classical definition and 34 (15.8%) based on genetic clustering. Of the 50 patients in a genetic cluster, 11 (22.0%) had known space‐time links with other cases in the same cluster. Genetic distances between pairs of cases with space‐time links were lower than for pairs without spatial links (P < .001).ConclusionsGenetic data confirmed that nosocomial transmission contributes significantly to the hospital burden of influenza and elucidated transmission chains. Prospective next generation sequencing could support outbreak investigations and monitor the impact of infection and control measures.
Bashford-Rogers RJM, Bergamaschi L, McKinney EF, et al., 2019, Analysis of the B cell receptor repertoire in six immune-mediated diseases, Nature, Vol: 574, Pages: 122-126, ISSN: 0028-0836
B cells are important in the pathogenesis of many, and perhaps all, immune-mediated diseases. Each B cell expresses a single B cell receptor (BCR)1, and the diverse range of BCRs expressed by the total B cell population of an individual is termed the ‘BCR repertoire’. Our understanding of the BCR repertoire in the context of immune-mediated diseases is incomplete, and defining this could provide new insights into pathogenesis and therapy. Here, we compared the BCR repertoire in systemic lupus erythematosus, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, Crohn’s disease, Behçet’s disease, eosinophilic granulomatosis with polyangiitis, and immunoglobulin A (IgA) vasculitis by analysing BCR clonality, use of immunoglobulin heavy-chain variable region (IGHV) genes and—in particular—isotype use. An increase in clonality in systemic lupus erythematosus and Crohn’s disease that was dominated by the IgA isotype, together with skewed use of the IGHV genes in these and other diseases, suggested a microbial contribution to pathogenesis. Different immunosuppressive treatments had specific and distinct effects on the repertoire; B cells that persisted after treatment with rituximab were predominately isotype-switched and clonally expanded, whereas the inverse was true for B cells that persisted after treatment with mycophenolate mofetil. Our comparative analysis of the BCR repertoire in immune-mediated disease reveals a complex B cell architecture, providing a platform for understanding pathological mechanisms and designing treatment strategies.
Benfield C, MacKenzie F, Ritzefeld M, et al., 2019, Comparative analysis reveals adaptive evolution of bat IFITMs and a novel antiviral determinant, Publisher: bioRxiv
ABSTRACT Host interferon-induced transmembrane proteins (IFITMs) are broad-spectrum antiviral restriction factors. Of these, IFITM3 potently inhibits viruses that enter cells through acidic endosomes, many of which are zoonotic and emerging viruses with bats (order Chiroptera) as natural hosts. We previously demonstrated that microbat IFITM3 is antiviral. Here we show that bat IFITMs are characterized by strong adaptive evolution and identify a highly variable and functionally important site - codon 70 - within the conserved CD225 domain of IFITMs. Mutation of this residue in microbat IFITM3 impairs restriction of four different virus families that enter cells via endosomes. This mutant shows altered subcellular localization and reduced S-palmitoylation, a phenotype copied by mutation of conserved cysteine residues in microbat IFITM3. Furthermore, we show that microbat IFITM3 is S-palmitoylated on cysteine residues C71, C72 and C105, mutation of each cysteine residue individually impairs virus restriction, and a triple C71-C72-C105 mutant loses all restriction, concomitant with subcellular re-localization of microbat IFITM3 to Golgi-associated sites. Thus, we propose that S-palmitoylation is critical for Chiropteran IFITM3 function and identify a key molecular determinant of IFITM3 S-palmitoylation.
Kellam P, Weiss RA, 2019, Protecting fetal development., Science, Vol: 365, Pages: 118-119, ISSN: 1095-9203
The interferon-induced transmembrane (IFITM) protein family includes members that protect multiple cell types from infection by many viruses by preventing the fusion of virus envelopes with host cell membranes (1). The syncytiotrophoblast at the maternal-fetal interface of the placenta develops through cell-cell fusion of cytotrophoblast cells by a mechanism akin to virus-cell fusion (see the figure). This cell fusion is mediated by syncytins. These are membrane glycoproteins encoded by ancient endogenous retroviral envelope genes, which were acquired and have become repurposed for placental development (2). On page 176 of this issue, Buchrieser et al. (3) show that interferon stimulation causes IFITM expression in trophoblast cells, which blocks syncytin-mediated cell fusion, and that interferon stimulation also leads to placental dysfunction and fetal resorption in wild-type mice, but not in mice lacking Ifitm genes. These findings have implications for understanding how infections and other complications during pregnancy can lead to miscarriage
Agoti CN, Phan MVT, Munywoki PK, et al., 2019, Genomic analysis of respiratory syncytial virus infections in households and utility in inferring who infects the infant, Scientific Reports, Vol: 9, ISSN: 2045-2322
Infants (under 1-year-old) are at most risk of life threatening respiratory syncytial virus (RSV) disease. RSV epidemiological data alone has been insufficient in defining who acquires infection from whom (WAIFW) within households. We investigated RSV genomic variation within and between infected individuals and assessed its potential utility in tracking transmission in households. Over an entire single RSV season in coastal Kenya, nasal swabs were collected from members of 20 households every 3-4 days regardless of symptom status and screened for RSV nucleic acid. Next generation sequencing was used to generate >90% RSV full-length genomes for 51.1% of positive samples (191/374). Single nucleotide polymorphisms (SNPs) observed during household infection outbreaks ranged from 0-21 (median: 3) while SNPs observed during single-host infection episodes ranged from 0-17 (median: 1). Using the viral genomic data alone there was insufficient resolution to fully reconstruct within-household transmission chains. For households with clear index cases, the most likely source of infant infection was via a toddler (aged 1 to <3 years-old) or school-aged (aged 6 to <12 years-old) co-occupant. However, for best resolution of WAIFW within households, we suggest an integrated analysis of RSV genomic and epidemiological data.
Bridges R, Correia S, Wegner F, et al., 2019, Essential role of inverted repeat in Epstein–Barr virus IR-1 in B cell transformation; geographical variation of the viral genome, Philosophical Transactions B: Biological Sciences, Vol: 374, ISSN: 0962-8436
Many regions of the Epstein‐Barr virus (EBV) genome, repeated and unique sequences, contribute to the geographic variation observed between strains. Here we use a large alignment of curated EBV genome sequences to identify major sites of variation in the genome of type 1 EBV strains; the CAO deletion in latent membrane protein 1 (LMP1) is the most frequent major indel present in the unique regions of EBV strains from various parts of the world. Principal component analysis was used to identify patterns of sequence variation and nucleotide positions in the sequences which can distinguish EBV from some different geographic regions. Viral genome sequence variation also affects interpretation of genetic content; known genes, origins of replication and gene expression control regions explain most of the viral genome but there are still a few sections of unknown function. One of these EBV genome regions contains a large inverted repeat sequence (invR) within the IR‐1 major internal repeat array. We deleted this invR sequence and showed that this abolished the ability of the virus to transform human B cells into lymphoblastoid cell lines.
Bassano I, Ong SH, Sanz Hernandez M, et al., 2019, Comparative analysis of the chicken IFITM locus by targeted genome sequencing reveals evolution of the locus and positive selection in IFITM1 and IFITM3, BMC Genomics, Vol: 20, ISSN: 1471-2164
BackgroundThe interferon-induced transmembrane (IFITM) protein family comprises a class of restriction factors widely characterised in humans for their potent antiviral activity. Their biological activity is well documented in several animal species, but their genetic variation and biological mechanism is less well understood, particularly in avian species.ResultsHere we report the complete sequence of the domestic chicken Gallus gallus IFITM locus from a wide variety of chicken breeds to examine the detailed pattern of genetic variation of the locus on chromosome 5, including the flanking genes ATHL1 and B4GALNT4. We have generated chIFITM sequences from commercial breeds (supermarket-derived chicken breasts), indigenous chickens from Nigeria (Nsukka) and Ethiopia, European breeds and inbred chicken lines from the Pirbright Institute, totalling of 206 chickens. Through mapping of genetic variants to the latest chIFITM consensus sequence our data reveal that the chIFITM locus does not show structural variation in the locus across the populations analysed, despite spanning diverse breeds from different geographic locations. However, single nucleotide variants (SNVs) in functionally important regions of the proteins within certain groups of chickens were detected, in particular the European breeds and indigenous birds from Ethiopia and Nigeria. In addition, we also found that two out of four SNVs located in the chIFITM1 (Ser36 and Arg77) and chIFITM3 (Val103) proteins were simultaneously under positive selection.ConclusionsTogether these data suggest that IFITM genetic variation may contribute to the capacities of different chicken populations to resist virus infection.
Ratmann O, Grabowski MK, Hall M, et al., 2019, Inferring HIV-1 transmission networks and sources of epidemic spread in Africa with deep-sequence phylogenetic analysis, Nature Communications, Vol: 10, ISSN: 2041-1723
To prevent new infections with human immunodeficiency virus type 1 (HIV-1) in sub-Saharan Africa, UNAIDS recommends targeting interventions to populations that are at high risk of acquiring and passing on the virus. Yet it is often unclear who and where these ‘source’ populations are. Here we demonstrate how viral deep-sequencing can be used to reconstruct HIV-1 transmission networks and to infer the direction of transmission in these networks. We are able to deep-sequence virus from a large population-based sample of infected individuals in Rakai District, Uganda, reconstruct partial transmission networks, and infer the direction of transmission within them at an estimated error rate of 16.3% [8.8–28.3%]. With this error rate, deep-sequence phylogenetics cannot be used against individuals in legal contexts, but is sufficiently low for population-level inferences into the sources of epidemic spread. The technique presents new opportunities for characterizing source populations and for targeting of HIV-1 prevention interventions in Africa.
Le Ngoc C, Tran Thi Thanh T, Tran Thi Lan P, et al., 2019, Differential prevalence and geographic distribution of hepatitis C virus genotypes in acute and chronic hepatitis C patients in Vietnam, PLoS ONE, Vol: 14, ISSN: 1932-6203
BackgroundThe highest burden of disease from hepatitis C virus (HCV) is found in Southeast Asia, but our understanding of the epidemiology of infection in many heavily burdened countries is still limited. In particular, there is relatively little data on acute HCV infection, the outcome of which can be influenced by both viral and host genetics which differ within the region. We studied HCV genotype and IL28B gene polymorphism in a cohort of acute HCV-infected patients in Southern Vietnam alongside two other cohorts of chronic HCV-infected patients to better understand the epidemiology of HCV infection locally and inform the development of programs for therapy with the increasing availability of directly acting antiviral therapy (DAAs).MethodsWe analysed plasma samples from patients with acute and chronic HCV infection, including chronic HCV mono-infection and chronic Human Immunodeficiency Virus (HIV)-HCV coinfection, who enrolled in four epidemiological or clinical research studies. HCV infection was confirmed with RNA testing. The 5’ UTR, core and NSB5 regions of HCV RNA positive samples were sequenced, and the genotype and subtype of the viral strains were determined. Host DNA from all HCV positive patients and age- and sex-matched non-HCV-infected control individuals were analysed for IL28B single nucleotide polymorphism (SNP) (rs12979860 and rs8099917). Geolocation of the patients were mapped using QGIS.Results355 HCV antibody positive patients were analysed; 54.6% (194/355) and 46.4% (161/355) were acute and chronic infections, respectively. 50.4% (81/161) and 49.6.4% (80/161) of chronic infections had HCV mono-infection and HIV-HCV coinfection, respectively. 88.7% (315/355) and 10.1% (36/355) of the patients were from southern and central regions of Vietnam, respectively. 92.4% (328/355) of patients were HCV RNA positive, including 86.1% (167/194) acute and 100% (161/161) chronic infections. Genotype could be determined in 98.4% (322/328) patients. Gen
Smith SE, Busse DC, Binter Š, et al., 2019, Interferon-induced transmembrane protein 1 restricts replication of virus that enter cells via the plasma membrane, Journal of Virology, Vol: 93, ISSN: 1098-5514
The acute anti-viral response is mediated by a family of interferon stimulated genes (ISG), providing cell-intrinsic immunity. Mutations in genes encoding these proteins are often associated with increased susceptibility to viral infections. One family of ISGs with anti-viral function are the interferon-inducible transmembrane proteins (IFITM) of which IFITM3 has been studied extensively. By contrast, IFITM1 has not been studied in detail. Since IFITM1 can localise to the plasma membrane, we investigated its function with a range of enveloped viruses thought to infect cells by fusion with the plasma membrane. Overexpression of IFITM1 prevented infection by a number of Paramyxoviridae and Pneumoviridae, including Respiratory Syncytial Virus (RSV), mumps virus and human metapneumovirus (HMPV). IFITM1 also restricted infection with an enveloped DNA virus that can enter via the plasma membrane, herpes simplex virus 1 (HSV-1). To test the importance of plasma membrane localisation for IFITM1 function, we identified blocks of amino acids in the conserved intracellular loop (CIL) domain that altered the subcellular localisation of the protein and reduced anti-viral activity. Screening published datasets, twelve rare non-synonymous SNPs were identified in human IFITM1, some of which are in the CIL domain. Using an Ifitm1-/- knock-out mouse we show that RSV infection was more severe, thereby extending the range of viruses restricted in vivo by IFITM proteins and suggesting overall that IFITM1 is broadly anti-viral and this anti-viral function is associated with cell surface localisation.IMPORTANCE Host susceptibility to viral infection is multifactorial, but early control of viruses not previously encountered is predominantly mediated by the interferon stimulated gene (ISG) family. There are upwards of 300 of these genes, the majority of which do not have a clearly defined function or mechanism of action. The cellular location of these proteins may have an important effect o
Dunning J, Blankley S, Hoang LT, et al., 2019, Author Correction: Progression of whole-blood transcriptional signatures from interferon-induced to neutrophil-associated patterns in severe influenza., Nature Immunology, Vol: 20, Pages: 373-373, ISSN: 1529-2908
In the version of this article initially published, a source of funding was not included in the Acknowledgements section. That section should include the following: P.J.M.O. was supported by EU FP7 PREPARE project 602525. The error has been corrected in the HTML and PDF version of the article.
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