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1.
ANZ J Surg ; 94(4): 585-590, 2024 Apr.
Article in English | MEDLINE | ID: mdl-38553955

ABSTRACT

BACKGROUND: Traumatic brain injuries account for up to 50% of trauma related deaths and if surgical intervention is indicated, consensus suggests a maximum of 4 hours to surgical decompression. The occurrence and outcomes of craniotomies performed by non-neurosurgeons in regional Queensland hospitals have never been reported previously in the literature. METHODS: A retrospective review was performed at all regional Queensland hospitals without an on-site neurosurgical service from January 2001 to December 2022 to identify patients undergoing emergency craniotomy. Data recorded included basic demographics, history of anti-coagulant use, mechanism of injury, type of haemorrhage, Glasgow Coma Score and Glasgow Outcome Scale (GOS) on discharge. Radiological parameters measured included midline shift and maximal coronal depth of haematoma. The primary aim of this study was to assess the clinical and radiological outcomes of patients who underwent a craniotomy performed by general surgeons. RESULTS: Over the past 20 years there have been 23 emergency decompressive procedures (one excluded) performed in regional Queensland. Preoperative imaging demonstrated 9 extradural haematomas and 13 subdural haematomas. Six of 17 transferred cases required reoperation after transfer to a neurosurgical centre. Survival was observed in 9 of 22 cases, with 'good' functional outcome (GOS ≥3) observed in 7 cases. In no cases were rurally performed burr holes effective. DISCUSSION: Qualitatively, a larger craniotomy may be associated with better clinical and radiological outcomes. Although rare occurrences, our results demonstrate that general surgeon performed craniotomies are frequently efficacious in producing radiological and/or clinical improvement and should be considered as a potentially lifesaving procedure.


Subject(s)
Craniotomy , Surgeons , Humans , Queensland/epidemiology , Glasgow Coma Scale , Hospitals , Retrospective Studies , Treatment Outcome
2.
Clin Infect Dis ; 78(4): 983-990, 2024 Apr 10.
Article in English | MEDLINE | ID: mdl-37633256

ABSTRACT

Chronic hepatitis B, a major cause of liver disease and cancer, affects >250 million people worldwide. Currently there is no cure, only suppressive therapies. Efforts to develop finite curative hepatitis B virus (HBV) therapies are underway, consisting of combinations of multiple novel agents with or without nucleos(t)ide reverse-transcriptase inhibitors. The HBV Forum convened a webinar in July 2021, along with subsequent working group discussions to address how and when to stop finite therapy for demonstration of sustained off-treatment efficacy and safety responses. Participants included leading experts in academia, clinical practice, pharmaceutical companies, patient representatives, and regulatory agencies. This Viewpoints article outlines areas of consensus within our multistakeholder group for stopping finite therapies in chronic hepatitis B investigational studies, including trial design, patient selection, outcomes, biomarkers, predefined stopping criteria, predefined retreatment criteria, duration of investigational therapies, and follow-up after stopping therapy. Future research of unmet needs are discussed.


Subject(s)
Hepatitis B, Chronic , Hepatitis B , Humans , Hepatitis B, Chronic/drug therapy , Antiviral Agents/therapeutic use , Hepatitis B virus/genetics , Treatment Outcome , Biomarkers , Hepatitis B Surface Antigens , DNA, Viral , Hepatitis B/drug therapy
3.
Environ Sci Technol ; 57(36): 13635-13645, 2023 09 12.
Article in English | MEDLINE | ID: mdl-37648245

ABSTRACT

The leaching of per- and polyfluoroalkyl substances (PFASs) from Australian firefighting training grounds has resulted in extensive contamination of groundwater and nearby farmlands. Humans, farm animals, and wildlife in these areas may have been exposed to complex mixtures of PFASs from aqueous film-forming foams (AFFFs). This study aimed to identify PFAS classes in pooled whole blood (n = 4) and serum (n = 4) from cattle exposed to AFFF-impacted groundwater and potentially discover new PFASs in blood. Thirty PFASs were identified at various levels of confidence (levels 1a-5a), including three novel compounds: (i) perfluorohexanesulfonamido 2-hydroxypropanoic acid (FHxSA-HOPrA), (ii) methyl((perfluorohexyl)sulfonyl)sulfuramidous acid, and (iii) methyl((perfluorooctyl)sulfonyl)sulfuramidous acid, belonging to two different classes. Biotransformation intermediate, perfluorohexanesulfonamido propanoic acid (FHxSA-PrA), hitherto unreported in biological samples, was detected in both whole blood and serum. Furthermore, perfluoroalkyl sulfonamides, including perfluoropropane sulfonamide (FPrSA), perfluorobutane sulfonamide (FBSA), and perfluorohexane sulfonamide (FHxSA) were predominantly detected in whole blood, suggesting that these accumulate in the cell fraction of blood. The suspect screening revealed several fluoroalkyl chain-substituted PFAS. The results suggest that targeting only the major PFASs in the plasma or serum of AFFF-exposed mammals likely underestimates the toxicological risks associated with exposure. Future studies of AFFF-exposed populations should include whole-blood analysis with high-resolution mass spectrometry to understand the true extent of PFAS exposure.


Subject(s)
Fluorocarbons , Groundwater , Humans , Animals , Cattle , Australia , Animals, Wild , Plasma , Mammals
4.
Cureus ; 15(1): e34364, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36874715

ABSTRACT

Pure cutaneous recurrence after breast-conserving surgery is rare and presents a unique challenge to clinicians. Some carefully selected patients may be amenable to further breast-conserving therapy. We present the case of a 45-year-old female with a cutaneous recurrence of previously treated right breast cancer along the operative scar in the upper outer quadrant. The patient underwent a further wide local excision with lateral intercostal artery perforator flap with a skin paddle reconstruction. We achieved volume replacement with this technique, disease control, and a pleasing cosmetic result.

6.
J Hepatol ; 77(2): 525-538, 2022 08.
Article in English | MEDLINE | ID: mdl-35259469

ABSTRACT

There have been unprecedented advances in the identification of new treatment targets for chronic hepatitis B that are being developed with the goal of achieving functional cure in patients who would otherwise require lifelong nucleoside analogue treatment. Many of the new investigational therapies either directly target the immune system or are anticipated to impact immunity indirectly through modulation of the viral lifecycle and antigen production. While new viral biomarkers (HBV RNA, HBcAg, small, middle, large HBs isoforms) are proceeding through validation steps in clinical studies, immunological biomarkers are non-existent outside of clinical assays for antibodies to HBs, HBc and HBe. To develop clinically applicable immunological biomarkers to measure mechanisms of action, inform logical combination strategies, and guide clinical management for use and discontinuation of immune-targeting drugs, immune assays must be incorporated into phase I/II clinical trials. This paper will discuss the importance of sample collection, the assays available for immunological analyses, their advantages/disadvantages and suggestions for their implementation in clinical trials. Careful consideration must be given to ensure appropriate immunological studies are included as a primary component of the trial with deeper immunological analysis provided by ancillary studies. Standardising immunological assays and data obtained from clinical trials will identify biomarkers that can be deployed in the clinic, independently of specialised immunology laboratories.


Subject(s)
Hepatitis B, Chronic , Hepatitis B , Biomarkers , DNA, Viral/genetics , Hepatitis B Antibodies , Hepatitis B Core Antigens , Hepatitis B Surface Antigens , Hepatitis B virus/genetics , Humans
7.
Genome Biol ; 23(1): 2, 2022 01 03.
Article in English | MEDLINE | ID: mdl-34980216

ABSTRACT

BACKGROUND: Reproducible detection of inherited variants with whole genome sequencing (WGS) is vital for the implementation of precision medicine and is a complicated process in which each step affects variant call quality. Systematically assessing reproducibility of inherited variants with WGS and impact of each step in the process is needed for understanding and improving quality of inherited variants from WGS. RESULTS: To dissect the impact of factors involved in detection of inherited variants with WGS, we sequence triplicates of eight DNA samples representing two populations on three short-read sequencing platforms using three library kits in six labs and call variants with 56 combinations of aligners and callers. We find that bioinformatics pipelines (callers and aligners) have a larger impact on variant reproducibility than WGS platform or library preparation. Single-nucleotide variants (SNVs), particularly outside difficult-to-map regions, are more reproducible than small insertions and deletions (indels), which are least reproducible when > 5 bp. Increasing sequencing coverage improves indel reproducibility but has limited impact on SNVs above 30×. CONCLUSIONS: Our findings highlight sources of variability in variant detection and the need for improvement of bioinformatics pipelines in the era of precision medicine with WGS.


Subject(s)
Genome, Human , Polymorphism, Single Nucleotide , High-Throughput Nucleotide Sequencing , Humans , INDEL Mutation , Reproducibility of Results , Whole Genome Sequencing
8.
Drug Discov Today ; 27(4): 1108-1114, 2022 04.
Article in English | MEDLINE | ID: mdl-35077912

ABSTRACT

This project demonstrates the use of the IEEE 2791-2020 Standard (BioCompute Objects [BCO]) to enable the complete and concise communication of results from next generation sequencing (NGS) analysis. One arm of a clinical trial was replicated using synthetically generated data made to resemble real biological data and then two independent analyses were performed. The first simulated a pharmaceutical regulatory submission to the US Food and Drug Administration (FDA) including analysis of results and a BCO. The second simulated an FDA review that included an independent analysis of the submitted data. Of the 118 simulated patient samples generated, 117 (99.15%) were in agreement in the two analyses. This process exemplifies how a template BCO (tBCO), including a verification kit, facilitates transparency and reproducibility, thereby reinforcing confidence in the regulatory submission process.


Subject(s)
High-Throughput Nucleotide Sequencing , Humans , Pharmaceutical Preparations , Reproducibility of Results , United States , United States Food and Drug Administration
9.
Antiviral Res ; 195: 105182, 2021 11.
Article in English | MEDLINE | ID: mdl-34582915

ABSTRACT

The development and approval of brincidofovir for the treatment of smallpox, a disease that was eradicated from the world over 40 years ago, has resulted in the second antiviral approved via the Medical Countermeasure Initiative (MCMi) to combat this disease. Approval of brincidofovir required a unique regulatory approach based on the FDA Animal Rule, and development was supported by many years of research and collaboration among academic investigators, the pharmaceutical industry and multiple government agencies. This article summarizes the FDA regulatory pathway and describes the challenges involved.


Subject(s)
Antiviral Agents/therapeutic use , Cytosine/analogs & derivatives , Drug Approval , Organophosphonates/therapeutic use , Smallpox/drug therapy , Animals , Cytosine/therapeutic use , Disease Eradication , Disease Models, Animal , Humans , Risk Assessment , Treatment Outcome , United States , United States Food and Drug Administration
10.
ANZ J Surg ; 91(9): 1919-1922, 2021 09.
Article in English | MEDLINE | ID: mdl-34224195

ABSTRACT

BACKGROUND: Recent research has shown that knee arthroscopy does not provide a meaningful clinical benefit for degenerative knee changes in the older population. The 2016 Australian Orthopaedic Association (AOA) Annual Scientific Meeting held a plenary session on this topic to educate surgeons about these research findings and communicate their clinical practice statement on this issue. This paper set out to find if there has been a change in clinical practice since this meeting. METHODS: The analysis consisted of all knee arthroscopies performed in a single city of Far North Queensland, Australia, over an 8-year period. The number and type of arthroscopies performed in patients <50 and ≥50 years of age was compared before and after the 2016 AOA plenary session. RESULTS: After the 2016 AOA educational session, there was a significant reduction in the number of debridement procedures performed in patients aged 50 years or older (275 vs. 142 per year, P < 0.01) but not in patients under 50 years of age (192 vs. 135 per year, P = 0.91). The annual number of repair procedures for all ages combined, increased from 11 per year to 60 per year (P < 0.01). CONCLUSION: The surgeons of this city have changed their knee arthroscopy clinical practice in line with the evidence and advice from their professional body.


Subject(s)
Osteoarthritis, Knee , Surgeons , Aged , Arthroscopy , Australia/epidemiology , Humans , Knee , Knee Joint/surgery , Osteoarthritis, Knee/surgery
11.
Clin Gastroenterol Hepatol ; 19(3): 463-472, 2021 03.
Article in English | MEDLINE | ID: mdl-32473348

ABSTRACT

BACKGROUND & AIMS: Seroclearance of hepatitis B surface antigen (HBsAg) is the desired end point of treatment for chronic hepatitis B virus (HBV) infection, according to guidelines. We performed a systematic review and meta-analysis to evaluate the strength of the association between HBsAg seroclearance and long-term clinical outcomes. METHODS: We performed a systematic review of the PubMed, EMBASE, and Cochrane Library databases for articles that assessed HBsAg status and reported the incidence of hepatocellular carcinoma (HCC), liver decompensation, liver transplantation, and/or all-cause mortality during follow-up evaluation. We performed a meta-analysis of rate ratios (RR) using a random-effects model independently for each end point and for a composite end point. RESULTS: We analyzed data from 28 studies, comprising a total of 188,316 patients with chronic HBV infection (treated and untreated), and 1,486,081 person-years (PY) of follow-up evaluation; 26 reported data on HCC, 7 on liver decompensation, and 13 on liver transplantation and/or death. The composite event rates were 0.19/1000 PY for the HBsAg seroclearance group and 2.45/1000 PY for the HBsAg-persistent group. Pooled RRs for the HBsAg seroclearance group were 0.28 for liver decompensation (95% CI, 0.13-0.59; P = .001), 0.30 for HCC (95% CI, 0.20-0.44; P < .001), 0.22 for liver transplantation and/or death (95% CI, 0.13-0.39; P < .001), and 0.31 for the composite end point (95% CI, 0.23-0.43; P < .001). No differences in RR estimates were observed among subgroups of different study or patient characteristics. CONCLUSIONS: In a systematic review and meta-analysis, we found seroclearance of HBsAg to be associated significantly with improved patient outcomes. The results are consistent among different types of studies, in all patient subpopulations examined, and support the use of HBsAg seroclearance as a primary end point of trials of patients with chronic HBV infection.


Subject(s)
Carcinoma, Hepatocellular , Hepatitis B, Chronic , Hepatitis B , Liver Neoplasms , Carcinoma, Hepatocellular/epidemiology , DNA, Viral , Hepatitis B Surface Antigens , Hepatitis B e Antigens , Hepatitis B virus/genetics , Hepatitis B, Chronic/epidemiology , Humans
13.
Virol J ; 16(1): 149, 2019 11 29.
Article in English | MEDLINE | ID: mdl-31783761

ABSTRACT

BACKGROUND: Vaccination and the use of neuraminidase inhibitors (NAIs) are currently the front lines of defense against seasonal influenza. The activity of influenza vaccines and antivirals drugs such as the NAIs can be affected by mutations in the influenza hemagglutinin (HA) protein. Numerous HA substitutions have been identified in nonclinical NAI resistance-selection experiments as well as in clinical specimens from NAI treatment or surveillance studies. These mutations are listed in the prescribing information (package inserts) for FDA-approved NAIs, including oseltamivir, zanamivir, and peramivir. METHODS: NAI treatment-emergent H1 HA mutations were mapped onto the H1N1 HA1 trimeric crystal structure and most of them localized to the HA antigenic sites predicted to be important for anti-influenza immunity. Recombinant A/California/04/09 (H1N1)-like viruses carrying HA V152I, G155E, S162 N, S183P, and D222G mutations were generated. We then evaluated the impact of these mutations on the immune reactivity and replication potential of the recombinant viruses in a human respiratory epithelial cell line, Calu- 3. RESULTS: We found that the G155E and D222G mutations significantly increased viral titers ~ 13-fold compared to the wild-type virus. The hemagglutination and microneutralization activity of goat and ferret antisera, monoclonal antibodies, and human serum samples raised against pandemic A(H1N1)pdm09 viruses was ~ 100-fold lower against mutants carrying G155E or D222G compared to the wild-type virus. CONCLUSIONS: Although the mechanism by which HA mutations emerge during NAI treatment is uncertain, some NAI treatment-emergent HA mutations correlate with decreased immunity to influenza virus.


Subject(s)
Drug Resistance, Viral , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Hemagglutinin Glycoproteins, Influenza Virus/immunology , Mutant Proteins/genetics , Mutant Proteins/immunology , Mutation, Missense , Acids, Carbocyclic , Antiviral Agents/pharmacology , Cell Line , Crystallography, X-Ray , Cyclopentanes/pharmacology , Epithelial Cells/virology , Epitopes/genetics , Guanidines/pharmacology , Hemagglutinin Glycoproteins, Influenza Virus/chemistry , Humans , Influenza A Virus, H1N1 Subtype/drug effects , Influenza A Virus, H1N1 Subtype/immunology , Mutant Proteins/chemistry , Neuraminidase/antagonists & inhibitors , Oseltamivir/pharmacology , Protein Conformation , Selection, Genetic , Viral Proteins/antagonists & inhibitors , Virus Replication , Zanamivir/pharmacology
14.
Antiviral Res ; 169: 104549, 2019 09.
Article in English | MEDLINE | ID: mdl-31279814

ABSTRACT

Letermovir is a human cytomegalovirus (HCMV) terminase inhibitor recently approved in the United States for prophylaxis of HCMV infection or disease in adult HCMV-seropositive recipients [R+] of an allogeneic hematopoietic stem cell transplant. In the registrational trial, the rate of clinically significant HCMV infection, defined as the development of HCMV DNAemia leading to preemptive antiviral therapy or the diagnosis of HCMV end-organ disease, through 24 weeks post-transplant, was significantly lower among subjects who received letermovir prophylaxis through 14 weeks post-transplant compared to those who received placebo. We performed independent analyses of the HCMV nucleotide sequencing data generated by next-generation sequencing from this phase 3 registrational trial of letermovir to identify viral genetic characteristics associated with virologic failure during and following letermovir prophylaxis. The pUL56 substitutions V236M, E237G, and C325W, identified at previously known resistance-associated positions, were detected in the virus of subjects who were treated with letermovir and failed letermovir prophylaxis. Several additional substitutions were detected in pUL56 and pUL89, and further characterization is needed to determine if any of these substitutions are clinically relevant. The analyses reported herein were conducted to confirm sponsor-reported drug-resistance pathways, to assess the frequency of resistance, and to better understand the risk of prophylaxis failures and treatment-emergent drug resistance.


Subject(s)
Cytomegalovirus/genetics , Drug Resistance, Viral/genetics , Genomics , Viral Proteins/genetics , Viral Structural Proteins/genetics , Acetates/pharmacology , Amino Acid Substitution , Antiviral Agents/pharmacology , Cytomegalovirus/drug effects , Endodeoxyribonucleases/drug effects , High-Throughput Nucleotide Sequencing , Humans , Quinazolines/pharmacology , Stem Cell Transplantation
16.
Lancet Infect Dis ; 19(6): 641-647, 2019 06.
Article in English | MEDLINE | ID: mdl-31000465

ABSTRACT

BACKGROUND: The 2018 Ebola virus disease (EVD) outbreak in Équateur Province, Democratic Republic of the Congo, began on May 8, and was declared over on July 24; it resulted in 54 documented cases and 33 deaths. We did a retrospective genomic characterisation of the outbreak and assessed potential therapeutic agents and vaccine (medical countermeasures). METHODS: We used target-enrichment sequencing to produce Ebola virus genomes from samples obtained in the 2018 Équateur Province outbreak. Combining these genomes with genomes associated with known outbreaks from GenBank, we constructed a maximum-likelihood phylogenetic tree. In-silico analyses were used to assess potential mismatches between the outbreak strain and the probes and primers of diagnostic assays and the antigenic sites of the experimental rVSVΔG-ZEBOV-GP vaccine and therapeutics. An in-vitro flow cytometry assay was used to assess the binding capability of the individual components of the monoclonal antibody cocktail ZMapp. FINDINGS: A targeted sequencing approach produced 16 near-complete genomes. Phylogenetic analysis of these genomes and 1011 genomes from GenBank revealed a distinct cluster, confirming a new Ebola virus variant, for which we propose the name "Tumba". This new variant appears to have evolved at a slower rate than other Ebola virus variants (0·69 × 10-3 substitutions per site per year with "Tumba" vs 1·06 × 10-3 substitutions per site per year without "Tumba"). We found few sequence mismatches in the assessed assay target regions and antigenic sites. We identified nine amino acid changes in the Ebola virus surface glycoprotein, of which one resulted in reduced binding of the 13C6 antibody within the ZMapp cocktail. INTERPRETATION: Retrospectively, we show the feasibility of using genomics to rapidly characterise a new Ebola virus variant within the timeframe of an outbreak. Phylogenetic analysis provides further indications that these variants are evolving at differing rates. Rapid in-silico analyses can direct in-vitro experiments to quickly assess medical countermeasures. FUNDING: Defense Biological Product Assurance Office.


Subject(s)
Antiviral Agents/therapeutic use , Disease Outbreaks , Ebola Vaccines/therapeutic use , Ebolavirus/genetics , Genomics , Hemorrhagic Fever, Ebola/drug therapy , Hemorrhagic Fever, Ebola/epidemiology , Democratic Republic of the Congo/epidemiology , Humans , Retrospective Studies
17.
Int J Surg Case Rep ; 55: 230-232, 2019.
Article in English | MEDLINE | ID: mdl-30776586

ABSTRACT

INTRODUCTION: The gram-negative bacteria known as Capnocytophaga canimorsus (C. canimorsus) is found in dog saliva and rarely can cause severe infection in humans following a bite or scratch. There has previously been just a single case described in the literature of Acute Acalculous Cholecystitis (AAC) secondary to C. canimorsus. PRESENTATION OF CASE: Here we describe the second ever published case of C. canimorsus bacteremia presenting with acute cholecystitis. The patient presented with epigastric pain and sepsis three weeks post domestic dog bite. On further examination, he was Murphy's sign positive. Investigations included blood cultures, Ultrasound Scan and Computed Tomography of the Abdomen. He was treated with intravenous fluid resuscitation, and intravenous ceftriaxone and metronidazole. He required an extended course of antibiotics for complete symptom resolution. His blood cultures were positive for C. Canimorsus. DISCUSSION: This case highlights the ever-present need for thorough history and examination, and consideration of prolonged antibiotics for cases of cholecystitis that could be secondary to C. canimorsus bacteremia. CONCLUSION: We strongly advocate blood cultures in patients who present with abdominal pain and sepsis, particularly when they have a recent history of animal bite. In cases of cholecystitis secondary to C. canimorsus it may be necessary to monitor the patient's progress more closely and treat with prolonged targeted antibiotic therapy.

19.
mBio ; 9(3)2018 05 22.
Article in English | MEDLINE | ID: mdl-29789360

ABSTRACT

Emerging zoonotic viral diseases remain a challenge to global public health. Recent surveillance studies have implicated bats as potential reservoirs for a number of viral pathogens, including coronaviruses and Ebola viruses. Caliciviridae represent a major viral family contributing to emerging diseases in both human and animal populations and have been recently identified in bats. In this study, we blended metagenomics, phylogenetics, homology modeling, and in vitro assays to characterize two novel bat calicivirus (BtCalV) capsid sequences, corresponding to strain BtCalV/A10/USA/2009, identified in Perimyotis subflavus near Little Orleans, MD, and bat norovirus. We observed that bat norovirus formed virus-like particles and had epitopes and receptor-binding patterns similar to those of human noroviruses. To determine whether these observations stretch across multiple bat caliciviruses, we characterized a novel bat calicivirus, BtCalV/A10/USA/2009. Phylogenetic analysis revealed that BtCalV/A10/USA/2009 likely represents a novel Caliciviridae genus and is most closely related to "recoviruses." Homology modeling revealed that the capsid sequences of BtCalV/A10/USA/2009 and bat norovirus resembled human norovirus capsid sequences and retained host ligand binding within the receptor-binding domains similar to that seen with human noroviruses. Both caliciviruses bound histo-blood group antigens in patterns that overlapped those seen with human and animal noroviruses. Taken together, our results indicate the potential for bat caliciviruses to bind histo-blood group antigens and overcome a significant barrier to cross-species transmission. Additionally, we have shown that bat norovirus maintains antigenic epitopes similar to those seen with human noroviruses, providing further evidence of evolutionary descent. Our results reiterate the importance of surveillance of wild-animal populations, especially of bats, for novel viral pathogens.IMPORTANCE Caliciviruses are rapidly evolving viruses that cause pandemic outbreaks associated with significant morbidity and mortality globally. The animal reservoirs for human caliciviruses are unknown; bats represent critical reservoir species for several emerging and zoonotic diseases. Recent reports have identified several bat caliciviruses but have not characterized biological functions associated with disease risk, including their potential emergence in other mammalian populations. In this report, we identified a novel bat calicivirus that is most closely related to nonhuman primate caliciviruses. Using this new bat calicivirus and a second norovirus-like bat calicivirus capsid gene sequence, we generated virus-like particles that have host carbohydrate ligand binding patterns similar to those of human and animal noroviruses and that share antigens with human noroviruses. The similarities to human noroviruses with respect to binding patterns and antigenic epitopes illustrate the potential for bat caliciviruses to emerge in other species and the importance of pathogen surveillance in wild-animal populations.


Subject(s)
Antigens, Viral/immunology , Blood Group Antigens/immunology , Caliciviridae/immunology , Norovirus/immunology , Animals , Antigens, Viral/chemistry , Antigens, Viral/genetics , Blood Group Antigens/chemistry , Blood Group Antigens/genetics , Caliciviridae/chemistry , Caliciviridae/classification , Caliciviridae/genetics , Caliciviridae Infections/virology , Capsid Proteins/chemistry , Capsid Proteins/genetics , Capsid Proteins/immunology , Chiroptera/virology , Humans , Norovirus/chemistry , Norovirus/classification , Norovirus/genetics , Phylogeny , Protein Domains
20.
mSphere ; 3(1)2018.
Article in English | MEDLINE | ID: mdl-29435493

ABSTRACT

Extensive antigenic diversity within the GII.4 genotype of human norovirus is a major driver of pandemic emergence and a significant obstacle to development of cross-protective immunity after natural infection and vaccination. However, human and mouse monoclonal antibody studies indicate that, although rare, antibodies to conserved GII.4 blockade epitopes are generated. The mechanisms by which these epitopes evade immune surveillance are uncertain. Here, we developed a new approach for identifying conserved GII.4 norovirus epitopes. Utilizing a unique set of virus-like particles (VLPs) representing the in vivo-evolved sequence diversity within an immunocompromised person, we identify key residues within epitope F, a conserved GII.4 blockade antibody epitope. The residues critical for antibody binding are proximal to evolving blockade epitope E. Like epitope F, antibody blockade of epitope E was temperature sensitive, indicating that particle conformation regulates antibody access not only to the conserved GII.4 blockade epitope F but also to the evolving epitope E. These data highlight novel GII.4 mechanisms to protect blockade antibody epitopes, map essential residues of a GII.4 conserved epitope, and expand our understanding of how viral particle dynamics may drive antigenicity and antibody-mediated protection by effectively shielding blockade epitopes. Our data support the notion that GII.4 particle breathing may well represent a major mechanism of humoral immune evasion supporting cyclic pandemic virus persistence and spread in human populations. IMPORTANCE In this study, we use norovirus virus-like particles to identify key residues of a conserved GII.4 blockade antibody epitope. Further, we identify an additional GII.4 blockade antibody epitope to be occluded, with antibody access governed by temperature and particle dynamics. These findings provide additional support for particle conformation-based presentation of binding residues mediated by a particle "breathing core." Together, these data suggest that limiting antibody access to blockade antibody epitopes may be a frequent mechanism of immune evasion for GII.4 human noroviruses. Mapping blockade antibody epitopes, the interaction between adjacent epitopes on the particle, and the breathing core that mediates antibody access to epitopes provides greater mechanistic understanding of epitope camouflage strategies utilized by human viral pathogens to evade immunity.

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