Papers by Warwick Britton
Immunity, 2021
Viral mutations are an emerging concern in reducing SARS-CoV-2 vaccination efficacy. Second gener... more Viral mutations are an emerging concern in reducing SARS-CoV-2 vaccination efficacy. Second generation vaccines will need to elicit neutralizing antibodies against sites that are evolutionarily conserved across the sarbecovirus subgenus. Here, we immunized mice containing a human antibody repertoire with diverse sarbecovirus receptor binding domains (RBDs) to identify antibodies targeting conserved sites of vulnerability. Antibodies with broad reactivity against diverse clade B RBDs targeting the conserved class 4 epitope, with recurring IGHV/IGKV pairs, were readily elicited but were non-neutralizing. However, rare class 4 antibodies binding this conserved RBD supersite showed potent neutralization of SARS-CoV-2 and all variants of concern. Structural analysis revealed that neutralizing ability of cross-reactive antibodies was reserved only for those with an elongated CDRH3 that extends the antiparallel beta-sheet RBD core and orients the antibody light chain to obstruct ACE2-RBD interactions. These results identify a structurally defined pathway for vaccine strategies eliciting escape-resistant SARS-CoV-2 neutralizing antibodies.
Current vaccines against SARS-CoV-2 substantially reduce mortality, but protection against infect... more Current vaccines against SARS-CoV-2 substantially reduce mortality, but protection against infection is less effective. Enhancing immunity in the respiratory tract, via mucosal vaccination, may provide protection against infection and minimise viral spread. We tested a novel subunit vaccine in mice, consisting of SARS-CoV-2 Spike protein with a TLR2-stimulating adjuvant, delivered to mice parenterally or mucosally. Both routes of vaccination induced substantial neutralising antibody (nAb) titres, however, mucosal vaccination uniquely generated anti-Spike IgA, increased nAb in the serum and airways, and increased lung CD4+ T-cell responses. TLR2 is expressed by respiratory epithelia and immune cells. Using TLR2 deficient chimeric mice, we determined that TLR2 expression in either compartment facilitated early innate responses to mucosal vaccination. By contrast, TLR2 on hematopoietic cells was essential for optimal lung-localised, antigen-specific responses. In a K18-hACE2 mice, vacc...
Infection and Immunity, 1993
The C-terminal region of the Mycobacterium leprae 70-kDa heat-shock protein is the major target f... more The C-terminal region of the Mycobacterium leprae 70-kDa heat-shock protein is the major target for the humoral immune response to this protein and contains M. leprae-specific sequences. To examine B-cell responses to this region more closely, we constructed and expressed a recombinant fragment of the M. leprae P70 gene that encodes the C-terminal 142 residues (C-142) and synthesized a series of 10 overlapping peptides to encompass this region. The affinities of three monoclonal antibodies (MAbs) reactive with this region of P70 were measured, and the binding site of the highest-affinity MAb was determined to lie between residues 498 and 515. This reactivity was confirmed by a fluid-phase inhibition enzyme-linked immunosorbent assay. By contrast, sera from leprosy patients which were strongly reactive with the C-142 fragment failed to bind directly to the conjugated or unconjugated peptides. To determine whether the M. leprae-specific C-terminal 70 residues could stimulate B-cell re...
Infection and Immunity, 1986
An international workshop organized and sponsored by the Immunology of Tuberculosis (IMMTUB) comp... more An international workshop organized and sponsored by the Immunology of Tuberculosis (IMMTUB) component of the World Health Organization (W.H.O.) Vaccine Development Programme to characterize the specificity and reaction patterns of murine monoclonal antibodies (MAbs) raised against various mycobacteria was held in Geneva, 3 to 5 June 1985. A total of 31 MAbs (28 ascites and 3 culture supernatants) generated in nine different laboratories using several mycobacterial antigens for immunization (Mycobocterium tuberculosis, virulent and avirulent strains, M. bovis BCG, and M. leprae) were submitted in early 1985 to the IMMTUB MAb bank located in the W.H.O. Immunology Research and Training Center (W.H.O./I.R.T.C.
Infection and Immunity, 1992
The 70-kDa heat shock protein of Mycobacterium leprae has a high degree of homology with the huma... more The 70-kDa heat shock protein of Mycobacterium leprae has a high degree of homology with the human hsp70 protein, yet it still elicits T-lymphocyte responses in subjects infected with M. leprae or vaccinated with the related Mycobacterium bovis BCG. We examined the serological responses to this protein by using recombinant protein fragments expressed from mutants with deletions of the M. leprae p70 gene. Monoclonal antibodies raised against either M. bovis or M. leprae p70 reacted with the C-terminal fragments but not the N-terminal fragments in a solid-phase enzyme-linked immunosorbent assay and an immunoblot assay. Inhibition enzyme-linked immunosorbent assays confirmed that two separate epitopes were defined by these monoclonal antibodies. Murine polyclonal sera also showed stronger binding to the C-terminal fragments. Sera from 33 and 48% of lepromatous leprosy patients reacted with M. leprae and M. bovis p70. This reactivity was mycobacterium specific, since few sera from contr...
Clinical Diagnostic Laboratory Immunology, 1999
Quanti FERON- TB (QIFN) (CSL Limited) is a whole-blood assay for the recognition of infection wit... more Quanti FERON- TB (QIFN) (CSL Limited) is a whole-blood assay for the recognition of infection with Mycobacterium tuberculosis . QIFN measures gamma interferon (IFN-γ) production when purified protein derivatives (PPDs) of mycobacteria are incubated with venous blood samples. The specificity of QIFN in medical students before and after BCG immunization was assessed, and sensitivity in patients with tuberculosis was assessed. Antigens were PPD derived from M. tuberculosis and two M. tuberculosis -specific proteins, ESAT-6 and MPT-64. Of 60 medical students, all of whom had 0-mm tuberculin skin tests (TSTs) at study entry, 58 (97%) were initially classified as negative for M. tuberculosis infection by PPD QIFN. Five months after BCG immunization, 7 of 54 students (13%) had a TST result of ≥10 mm and 11 of 54 students (20%) tested positive by PPD QIFN. ESAT-6- and MPT-64-stimulated IFN-γ responses in the medical students were negative prior to and after BCG immunization. For patients wi...
Journal of Clinical Microbiology, 1998
In this report we demonstrate the utility of an monoclonal antibody inhibition enzyme-linked immu... more In this report we demonstrate the utility of an monoclonal antibody inhibition enzyme-linked immunosorbent assay based on theMycobacterium leprae 35-kDa protein, purified from the rapidly growing host Mycobacterium smegmatis, for the serodiagnosis of multibacillary leprosy. The assay proved highly specific (97.5%) and sensitive (90%) and compared favorably with two other established methods routinely utilized for leprosy serodiagnosis.
Molecular Microbiology, 2019
Article type : Research Article Mycobacterium tuberculosis requires glyoxylate shunt and reverse ... more Article type : Research Article Mycobacterium tuberculosis requires glyoxylate shunt and reverse methylcitrate cycle for lactate and pyruvate metabolism.
Nature communications, Jan 8, 2018
Type I interferons (IFN), best known for their anti-viral functions, have been shown to impair ho... more Type I interferons (IFN), best known for their anti-viral functions, have been shown to impair host resistance to intracellular bacteria in mice. However, the precise role of type I IFN signaling in bacterial infection in humans is unclear. Here, we show that genetic variation in the human IFNAR1 gene is associated with decreased susceptibility to tuberculosis and an increased risk of viral hepatitis in Chinese populations. Receptor mutagenesis and cell signaling studies establish that the IFNAR1 mutation corresponding to a proline deletion in the hinge region of the membrane-proximal domain of IFNAR1 decreases the binding affinity of IFNAR1 to IFN-β, impeding type I IFN signaling. Our findings suggest that IFNAR1 signaling underlies an increased risk of tuberculosis in humans and reveals a function for the IFNAR1 inter-domain region in cytokine-cytokine receptor interaction and signal transduction.
PLOS Pathogens, 2016
Disruption of T cell memory during severe immune suppression results in reactivation of chronic v... more Disruption of T cell memory during severe immune suppression results in reactivation of chronic viral infections, such as Epstein Barr virus (EBV) and Cytomegalovirus (CMV). How different subsets of memory T cells contribute to the protective immunity against these viruses remains poorly defined. In this study we examined the compartmentalization of virus-specific, tissue resident memory CD8 + T cells in human lymphoid organs. This revealed two distinct populations of memory CD8 + T cells, that were CD69 + CD103 + and CD69 + CD103-, and were retained within the spleen and tonsils in the absence of recent T cell stimulation. These two types of memory cells were distinct not only in their phenotype and transcriptional profile, but also in their anatomical localization within tonsils and spleen. The EBV-specific, but not CMV-specific, CD8 + memory T cells preferentially accumulated in the tonsils and acquired a phenotype that ensured their retention at the epithelial sites where EBV replicates. In vitro studies revealed that the cytokine IL-15 can potentiate the retention of circulating effector memory CD8 + T cells by down-regulating the expression of sphingosine-1-phosphate receptor, required for T cell exit from tissues, and its transcriptional activator, Kruppel-like factor 2 (KLF2). Within the tonsils the expression of IL-15 was detected in regions where CD8 + T cells localized, further supporting a role for this cytokine in T cell retention. Together this study provides evidence for the compartmentalization of distinct types of resident memory T cells that could contribute to the long-term protection against persisting viral infections.
Vaccine, Jan 29, 2016
More than 120 million doses of BCG vaccine are administered worldwide each year. Most infants are... more More than 120 million doses of BCG vaccine are administered worldwide each year. Most infants are given BCG at birth in accordance with WHO recommendations. However, the effect of the maturing neonatal immune system on the immune response and protection conferred by BCG remains uncertain. Previous studies investigating the influence of age at immunisation on the immune response induced by BCG have reported conflicting results. This study compared BCG given at birth and at two months of age in infants in Australia. Infants born in Melbourne were randomly allocated to immunisation with BCG-Denmark at birth or two months of age. Ten weeks after immunisation, anti-mycobacterial immune responses were measured in a whole blood assay using intracellular cytokine assays and xMAP multiplex cytokine analysis. Result from 98 BCG-immunised infants were included in the final analysis. BCG immunisation at birth (n=54) and at 2months of age (n=44) induced comparable proportions of mycobacteria-spe...
PLoS pathogens, 2016
Host control of influenza A virus (IAV) is associated with exuberant pulmonary inflammation chara... more Host control of influenza A virus (IAV) is associated with exuberant pulmonary inflammation characterized by the influx of myeloid cells and production of proinflammatory cytokines including interferons (IFNs). It is unclear, however, how the immune system clears the virus without causing lethal immunopathology. Here, we demonstrate that in addition to its known anti-viral activity, STAT1 signaling coordinates host inflammation during IAV infection in mice. This regulatory mechanism is dependent on both type I IFN and IFN-γ receptor signaling and, importantly, requires the functional interplay between the two pathways. The protective function of type I IFNs is associated with not only the recruitment of classical inflammatory Ly6Chi monocytes into IAV-infected lungs, but also the prevention of excessive monocyte activation by IFN-γ. Unexpectedly, type I IFNs preferentially regulate IFN-γ signaling in Ly6Clo rather than inflammatory Ly6Chi mononuclear cell populations. In the absence...
International journal of leprosy and other mycobacterial diseases : official organ of the International Leprosy Association, 1992
The 18-kDa protein of Mycobacterium leprae, as recognized by the monoclonal antibody L5, has a re... more The 18-kDa protein of Mycobacterium leprae, as recognized by the monoclonal antibody L5, has a restricted species distribution, being confined to M. leprae and M. habana. We have developed a solid-phase ELISA using purified, recombinant M. leprae 18-kDa protein and compared the serological responses of Nepali leprosy and tuberculosis patients and endemic control subjects to the protein and the M. leprae phenolic glycolipid-I (PGL-I). Few control subjects had anti-18-kDa antibodies. A small proportion of paucibacillary (PB) leprosy and 42% of multibacillary (MB) leprosy patients had IgG anti-M. leprae antibodies. A similar proportion (47%) of Nepali tuberculosis (TB) patients were seropositive, and IgG anti-18-kDa antibody levels were significantly higher in MB and TB patients than in control subjects. By comparison, IgM anti-PGL-I antibodies were detected in 88% of MB leprosy patients and only 7% of TB patients. The possible reasons for the 18-kDa protein seroreactivity in TB patien...
International journal of leprosy and other mycobacterial diseases : official organ of the International Leprosy Association, 1999
A new rapid immuno-chromatographic test card for the detection of antibodies to the Mycobacterium... more A new rapid immuno-chromatographic test card for the detection of antibodies to the Mycobacterium leprae 35-kD protein is described. The new assay is compared in the same group of subjects with a direct enzyme ELISA method for 35-kD antibodies and with assays for anti-phenolic glycolipid-I (PGL-I) antibodies using a standard ELISA as well as the recently described "dipstick" method. Good concordance was found between the rapid methods and the corresponding ELISA methods. The detection of untreated paucibacillary leprosy by the 35-kD test card was 59% compared with 27% for the PGL-I dipstick; however, the specificity for the 35-kD test card was 90% compared with 100% for the PGL-I dipstick in an endemic population. The potential application of these new, rapid serologic methods for the diagnosis of leprosy under field conditions is discussed.
Journal of general microbiology, 1993
Study of Mycobacterium leprae, the causative agent of leprosy, has been advanced by the isolation... more Study of Mycobacterium leprae, the causative agent of leprosy, has been advanced by the isolation of genes encoding mycobacterial proteins including dnaK encoding the M. leprae 70 kDa heat shock protein. The sequence downstream from dnaK revealed a second open reading frame coding for a protein of 389 amino acids with a calculated molecular mass of 41.2 kDa. Sequence analysis demonstrated significant DNA homology with the dnaJ gene of other organisms. High amino acid sequence identity was obtained between the DnaJ protein of M. leprae and M. tuberculosis (89%) with significant divergence between the two occurring only at the C-terminal end. The expressed recombinant DnaJ protein had a molecular mass of 42 kDa.
The Journal of Infectious Diseases, 2000
An adoptive-transfer model using recombinase activation gene-deficient (RAG-1 Ϫ/Ϫ) mice was devel... more An adoptive-transfer model using recombinase activation gene-deficient (RAG-1 Ϫ/Ϫ) mice was developed to evaluate CD4 + and CD8 + T cell responses to infection with Mycobacterium bovis bacillus Calmette-Guérin (BCG). After receiving immune, unfractionated T cells or T cell subsets isolated by fluorescence-activated cell sorter, the RAG-1 Ϫ/Ϫ mice were exposed to aerosol BCG, and the bacteria load in the infected organs was examined 4 weeks later. Adoptive immunity was expressed more effectively in the spleens than in the lungs. Although CD4 + or unfractionated T cells protected both lungs and spleens, CD8 + T cells conferred significant protection only in the spleens and not in the lungs. The results confirm that in addition to CD4 + , CD8 + T cells also play a role in the prevention of bacterial dissemination. This transfer model may be useful for dissecting T cell responses to mycobacterial infection.
Journal of Biological Chemistry, 2005
The P2X 7 receptor is a ligand-gated cation channel that is highly expressed on mononuclear leuko... more The P2X 7 receptor is a ligand-gated cation channel that is highly expressed on mononuclear leukocytes and that mediates ATP-induced apoptosis and killing of intracellular pathogens. There is a wide variation in P2X 7 receptor function between subjects, explained in part by four loss-of-function polymorphisms (R307Q, E496A, I568N, and a 5-intronic splice site polymorphism), as well as rare mutations. In this study, we report the allele frequencies of 11 non-synonymous P2X 7 polymorphisms and describe a fifth loss-of-function polymorphism in the gene (1096C 3 G), which changes Thr 357 to Ser (T357S) with an allele frequency of 0.08 in the Caucasian population. P2X 7 function was measured by ATP-induced ethidium ؉ influx into peripheral blood lymphocytes and monocytes and, when compared with wild-type subjects, was reduced to 10-65% in heterozygotes, 1-18% in homozygotes, and 0-10% in compound heterozygotes carrying T357S and a second loss-of-function polymorphism. Overexpression of the T357S mutant P2X 7 in either HEK-293 cells or Xenopus oocytes gave P2X 7 function of ϳ50% that of wild-type constructs. Differentiation of monocytes to macrophages, which also up-regulates P2X 7 , restored P2X 7 function to near normal in cells heterozygous for T357S and to a value 50-65% of wild-type in cells homozygous for T357S or compound heterozygous for T357S/E496A. However, macrophages from subjects that are compound heterozygous for either T357S/ R307Q or T357S/stop codon had near-to-absent P2X 7 function. These functional deficits induced by T357S were paralleled by impaired ATP-induced apoptosis and mycobacteria killing in macrophages from these subjects. Lymphocytes, monocytes, and macrophages from subjects homozygous for T357S or compound heterozygous for T357S and a second loss-of-function allele have reduced or absent P2X 7 receptor function.
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Papers by Warwick Britton