77,002 results on '"Immune Sera"'
Search Results
2. SARS-CoV-2 escape from a highly neutralizing COVID-19 convalescent plasma
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Andreano, Emanuele, Piccini, Giulia, Licastro, Danilo, Casalino, Lorenzo, Johnson, Nicole V, Paciello, Ida, Dal Monego, Simeone, Pantano, Elisa, Manganaro, Noemi, Manenti, Alessandro, Manna, Rachele, Casa, Elisa, Hyseni, Inesa, Benincasa, Linda, Montomoli, Emanuele, Amaro, Rommie E, McLellan, Jason S, and Rappuoli, Rino
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Pneumonia ,Vaccine Related ,Lung ,Immunization ,Biodefense ,Prevention ,Pneumonia & Influenza ,Emerging Infectious Diseases ,Good Health and Well Being ,Amino Acid Substitution ,Angiotensin-Converting Enzyme 2 ,Animals ,Antibodies ,Neutralizing ,Antibodies ,Viral ,Binding Sites ,COVID-19 ,Chlorocebus aethiops ,Convalescence ,Gene Expression ,Humans ,Immune Evasion ,Immune Sera ,Models ,Molecular ,Mutation ,Neutralization Tests ,Protein Binding ,Protein Conformation ,alpha-Helical ,Protein Conformation ,beta-Strand ,Protein Interaction Domains and Motifs ,SARS-CoV-2 ,Spike Glycoprotein ,Coronavirus ,Vero Cells ,emerging variants ,immune evasion ,antibodyresponse ,antibody response - Abstract
To investigate the evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the immune population, we coincupi bated the authentic virus with a highly neutralizing plasma from a COVID-19 convalescent patient. The plasma fully neutralized the virus for seven passages, but, after 45 d, the deletion of F140 in the spike N-terminal domain (NTD) N3 loop led to partial breakthrough. At day 73, an E484K substitution in the receptor-binding domain (RBD) occurred, followed, at day 80, by an insertion in the NTD N5 loop containing a new glycan sequon, which generated a variant completely resistant to plasma neutralization. Computational modeling predicts that the deletion and insertion in loops N3 and N5 prevent binding of neutralizing antibodies. The recent emergence in the United Kingdom, South Africa, Brazil, and Japan of natural variants with similar changes suggests that SARS-CoV-2 has the potential to escape an effective immune response and that vaccines and antibodies able to control emerging variants should be developed.
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- 2021
3. The Safety and Effectiveness of Hyperimmune Anti-HIV Intravenous Immunoglobulin (HVIG) Plus Zidovudine in HIV-Infected Infants
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Abbott and Glaxo Wellcome
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- 2021
4. A Phase I/II Study of Hyperimmune IVIG in Slowing Progression of Disease in HIV-Infected Children
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North American Biologicals Inc
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- 2021
5. Zika Virus-Immune Plasmas from Symptomatic and Asymptomatic Individuals Enhance Zika Pathogenesis in Adult and Pregnant Mice
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Shim, Byoung-Shik, Kwon, Young-Chan, Ricciardi, Michael J, Stone, Mars, Otsuka, Yuka, Berri, Fatma, Kwal, Jaclyn M, Magnani, Diogo M, Jackson, Cody B, Richard, Audrey S, Norris, Philip, Busch, Michael, Curry, Christine L, Farzan, Michael, Watkins, David, and Choe, Hyeryun
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Medical Microbiology ,Biomedical and Clinical Sciences ,Immunology ,Vaccine Related ,Rare Diseases ,Immunization ,Biodefense ,Vector-Borne Diseases ,Infectious Diseases ,Emerging Infectious Diseases ,Prevention ,Inflammatory and immune system ,Infection ,Good Health and Well Being ,Adult ,Animals ,Antibodies ,Viral ,Antibody-Dependent Enhancement ,Disease Models ,Animal ,Humans ,Immune Sera ,Mice ,Models ,Theoretical ,Viral Load ,Zika Virus ,Zika Virus Infection ,Zika virus ,antibody-dependent enhancement ,congenital disease ,homotypic ,microcephaly ,pregnancy ,vaccine ,viral pathogenesis ,Microbiology ,Biochemistry and cell biology ,Medical microbiology - Abstract
Preexisting immunity against dengue virus or West Nile virus was previously reported to mediate antibody-dependent enhancement (ADE) of Zika virus (ZIKV) infection in a mouse model. We show here that ZIKV-immune plasma samples from both symptomatic and asymptomatic individuals mediated ZIKV ADE of infection in vitro and in mice. In a lethal infection model with a viral inoculum 10 times higher, both ADE and protection were observed, depending on the amount of infused immune plasma. In a vertical-transmission model, ZIKV-immune plasma infused to timed pregnant mice increased fetal demise and decreased the body weight of surviving fetuses. Depletion of IgG from an immune plasma abolished ADE of infection, and the presence of purified IgG alone mediated ADE of infection. Higher viral loads and proinflammatory cytokines were detected in mice treated with ZIKV-immune plasma samples compared to those receiving control plasma. Together, these data show that passive immunization with homotypic ZIKV antibodies, depending on the concentration, could either worsen or limit a subsequent ZIKV infection.IMPORTANCE Antibody-dependent enhancement (ADE) of virus infection is common to many viruses and is problematic when plasma antibody levels decline to subneutralizing concentrations. ADE of infection is especially important among flaviviruses, many of which are the cause of global health problems. Recently, human plasma samples immune to heterologous flaviviruses were shown to promote Zika virus (ZIKV) infection. Here we showed in immunocompromised mouse models that homologous immune plasma samples protect mice from subsequent infection at high antibody concentrations but that they mediate ADE of infection and increase ZIKV pathogenesis in adult mice and fetal demise during pregnancy at low concentrations.
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- 2019
6. SHMT2 and the BRCC36/BRISC deubiquitinase regulate HIV-1 Tat K63-ubiquitylation and destruction by autophagy.
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Xu, Muyu, Moresco, James J, Chang, Max, Mukim, Amey, Smith, Davey, Diedrich, Jolene K, Yates, John R, and Jones, Katherine A
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Hela Cells ,Humans ,Aminopyridines ,Hydrazones ,Glycine Hydroxymethyltransferase ,Membrane Proteins ,RNA ,Viral ,Immune Sera ,Immunoprecipitation ,Gene Expression ,Autophagy ,tat Gene Products ,Human Immunodeficiency Virus ,Ubiquitination ,Transcriptional Activation ,Deubiquitinating Enzymes ,HeLa Cells ,HIV/AIDS ,1.1 Normal biological development and functioning ,Infection ,RNA ,Viral ,tat Gene Products ,Human Immunodeficiency Virus ,Microbiology ,Immunology ,Medical Microbiology ,Virology - Abstract
HIV-1 Tat is a key regulator of viral transcription, however little is known about the mechanisms that control its turnover in T cells. Here we use a novel proteomics technique, called DiffPOP, to identify the molecular target of JIB-04, a small molecule compound that potently and selectively blocks HIV-1 Tat expression, transactivation, and virus replication in T cell lines. Mass-spectrometry analysis of whole-cell extracts from 2D10 Jurkat T cells revealed that JIB-04 targets Serine Hydroxymethyltransferase 2 (SHMT2), a regulator of glycine biosynthesis and an adaptor for the BRCC36 K63Ub-specific deubiquitinase in the BRISC complex. Importantly, knockdown of SHMT1,2 or BRCC36, or exposure of cells to JIB-04, strongly increased Tat K63Ub-dependent destruction via autophagy. Moreover, point mutation of multiple lysines in Tat, or knockdown of BRCC36 or SHMT1,2, was sufficient to prevent destruction of Tat by JIB-04. We conclude that HIV-1 Tat levels are regulated through K63Ub-selective autophagy mediated through SHMT1,2 and the BRCC36 deubiquitinase.
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- 2018
7. Recombinant Zika NS1 Protein Secreted from Vero Cells Is Efficient for Inducing Production of Immune Serum Directed against NS1 Dimer.
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Viranaicken, Wildriss, Ndebo, Alexia, Bos, Sandra, Souque, Philippe, Gadea, Gilles, El-Kalamouni, Chaker, Krejbich-Trotot, Pascale, Charneau, Pierre, Desprès, Philippe, and Roche, Marjolaine
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NS1 antiserum ,NS1 protein ,Zika virus ,arbovirus ,emerging disease ,humoral immunity ,lentiviral vector ,recombinant antigen ,A549 Cells ,Animals ,Chlorocebus aethiops ,Cloning ,Molecular ,Genetic Vectors ,HEK293 Cells ,Humans ,Immune Sera ,Immunization ,Lentivirus ,Protein Multimerization ,Rats ,Recombinant Proteins ,Vero Cells ,Viral Nonstructural Proteins - Abstract
Zika virus (ZIKV) is a mosquito-borne flavivirus that recently emerged in the South Pacific, Americas, and Caribbean islands, where the larger epidemics were documented. ZIKV infection in humans is responsible for neurological disorders and microcephaly. Flavivirus NS1 is a non-structural glycoprotein that is expressed on the cell surface and secreted as a hexameric lipoprotein particle. Intracellular NS1 exists as a dimer that is required for viral replication, whereas the secreted NS1 hexamer interacts with host factors, leading to pathophysiological conditions. In an effort to dispose of specific anti-ZIKV NS1 immune serum, Vero cells were transduced with a lentiviral vector containing the NS1 gene from an epidemic strain of ZIKV. We showed that stably transduced Vero/ZIKV NS1 cell clone was efficient in the secretion of recombinant NS1 oligomer. Immunization of adult rat with purified extracellular NS1 developed anti-ZIKV antibodies that specifically react with the NS1 dimer produced in human cells infected with African and Asian strains of ZIKV. The rat antibody against ZIKV NS1 dimer is a reliable biological tool that enables the immunological detection of secreted NS1 from host-cells infected with ZIKV.
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- 2017
8. New Findings from Instituto Butantan in the Area of Leptospira Published (The Toxin of VapBC-1 Toxin-Antitoxin Module from Leptospira interrogans Is a Ribonuclease That Does Not Arrest Bacterial Growth but Affects Cell Viability).
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- 2024
9. New Diphtheria Findings from University of Toronto Outlined (An Enhanced Intracellular Delivery Platform Based On a Distant Diphtheria Toxin Homolog That Evades Pre-existing Antitoxin Antibodies).
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- 2024
10. Cyclic di-GMP as an Antitoxin Regulates Bacterial Genome Stability and Antibiotic Persistence in Biofilms (Updated August 17, 2024).
- Abstract
A recent preprint abstract discusses the role of cyclic di-GMP (c-di-GMP) as an antitoxin in regulating bacterial genome stability and antibiotic persistence in biofilms. Biofilms are bacterial communities that can cause chronic and relapsing infections. The study found that the toxin HipH induces DNA double strand breaks and genome instability, while c-di-GMP acts as the antitoxin, controlling HipH expression and activity. This unique toxin-antitoxin system has implications for understanding biofilm infections and potential treatments. However, it is important to note that this preprint has not yet undergone peer review. [Extracted from the article]
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- 2024
11. Phages carry orphan antitoxin-like enzymes to neutralize the DarTG1 toxin-antitoxin defense system.
- Abstract
A recent preprint abstract discusses the discovery of an orphan antitoxin counter-defense element in T4-like phages that can overcome the bacterial toxin-antitoxin phage defense system, DarTG1. The DarT1 toxin modifies phage DNA to prevent replication, while its cognate antitoxin, DarG1, reverses these modifications in uninfected bacteria. The orphan phage DarG1-like protein, called anti-DarT factor NADAR (AdfN), removes ADP-ribose modifications from phage DNA during infection, enabling replication in DarTG1-containing bacteria. This research highlights the importance of ADP-ribosylation in bacterial-phage interactions and reveals the function of a significant subset of the NADAR superfamily. [Extracted from the article]
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- 2024
12. New Data from University of Texas Medical Branch Illuminate Findings in Burkholderia pseudomallei (Unraveling the Role of Toxin-antitoxin Systems In burkholderia Pseudomallei: Exploring Bacterial Pathogenesis and Interactions Within the...).
- Abstract
A new report from the University of Texas Medical Branch provides fresh data on Burkholderia pseudomallei, a Gram-negative intracellular pathogen that causes melioidosis in humans. The research focuses on the role of toxin-antitoxin (TA) systems in the bacteria's lifecycle and their potential interactions. The study suggests that both the toxin and antitoxin of different TA systems contribute to bacterial survival, and toxins from the same family can have a cumulative effect under stressful conditions. This research sheds light on the mechanisms of Burkholderia pseudomallei and its ability to cause chronic infections. [Extracted from the article]
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- 2024
13. Researchers at Universidad Autonoma de Chile Target Immune Sera (Contribution of Toxin-Antitoxin Systems to Adherent-Invasive E. coli Pathogenesis).
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IMMUNE serums ,ESCHERICHIA coli ,RESEARCH personnel ,BLOOD proteins ,MEDICAL sciences - Abstract
Researchers at Universidad Autonoma de Chile have conducted a study on the role of toxin-antitoxin systems (TAs) in the pathogenesis of adherent-invasive Escherichia coli (AIEC), which is associated with Crohn's disease. AIEC strains are known for their ability to adhere to and invade intestinal epithelial cells, survive inside macrophages, and contribute to the inflammation and damage in the gastrointestinal tract. The study explores the potential therapeutic targets of TAs and their involvement in AIEC stress response, biofilm formation, phage inhibition, maintenance of mobile genetic elements, and host lifestyles. This research provides valuable insights into the mechanisms underlying AIEC pathogenesis. [Extracted from the article]
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- 2024
14. Vaccination and Control of Employees
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Andersen, Bjørg Marit and Andersen, Bjørg Marit
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- 2019
- Full Text
- View/download PDF
15. Prior Corneal Scarification and Injection of Immune Serum are Not Required Before Ocular HSV-1 Infection for UV-B-Induced Virus Reactivation and Recurrent Herpetic Corneal Disease in Latently Infected Mice
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BenMohamed, Lbachir, Osorio, Nelson, Khan, Arif A, Srivastava, Ruchi, Huang, Lei, Krochmal, John J, Garcia, Jairo M, Simpson, Jennifer L, and Wechsler, Steven L
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Sexually Transmitted Infections ,Eye Disease and Disorders of Vision ,Infectious Diseases ,2.2 Factors relating to the physical environment ,2.1 Biological and endogenous factors ,Aetiology ,Infection ,Animals ,Cornea ,Disease Models ,Animal ,Eye Infections ,Viral ,Female ,Herpesvirus 1 ,Human ,Immune Sera ,Immunologic Factors ,Keratitis ,Herpetic ,Mice ,Mice ,Inbred C57BL ,Rabbits ,Tears ,Ultraviolet Rays ,Virus Activation ,Virus Latency ,Virus Shedding ,Eye ,HSV-1 ,latency ,mice ,reactivation ,UV-B ,Ophthalmology & Optometry - Abstract
PurposeBlinding ocular herpetic disease in humans is due to spontaneous reactivation of herpes simplex virus type 1 (HSV-1) from latency, rather than to primary acute infection. Mice latently infected with HSV-1 undergo little or no in vivo spontaneous reactivation with accompanying virus shedding in tears. HSV-1 reactivation can be induced in latently infected mice by several in vivo procedures, with UV-B-induced reactivation being one commonly used method. In the UV-B model, corneas are scarified (lightly scratched) just prior to ocular infection to increase efficiency of the primary infection and immune serum containing HSV-1 neutralizing antibodies is injected intraperitoneally (i.p.) to increase survival and decrease acute corneal damage. Since scarification can significantly alter host gene transcription in the cornea and in the trigeminal ganglia (TG; the site of HSV-1 latency) and since injection of immune serum likely modulates innate and adaptive herpes immunity, we investigated eliminating both treatments.Material and methodsMice were infected with HSV-1 with or without corneal scarification and immune serum. HSV-1 reactivation and recurrent disease were induced by UV-B irradiation.ResultsWhen corneal scarification and immune serum were both eliminated, UV-B irradiation still induced both HSV-1 reactivation, as measured by shedding of reactivated virus in tears and herpetic eye disease, albeit at reduced levels compared to the original procedure.ConclusionDespite the reduced reactivation and disease, avoidance of both corneal scarification and immune serum should improve the clinical relevance of the UV-B mouse model.
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- 2016
16. Detection of the Antimicrobial Triclosan in Environmental Samples by Immunoassay
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Ahn, Ki Chang, Ranganathan, Anupama, Bever, Candace S, Hwang, Sung Hee, Holland, Erika B, Morisseau, Kevin, Pessah, Isaac N, Hammock, Bruce D, and Gee, Shirley J
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Environmental Sciences ,Pollution and Contamination ,Chemical Sciences ,Animals ,Anti-Infective Agents ,Cross Reactions ,Enzyme-Linked Immunosorbent Assay ,Female ,Halogenated Diphenyl Ethers ,Haptens ,Immune Sera ,Rabbits ,Reproducibility of Results ,Tandem Mass Spectrometry ,Triclosan ,Water Pollutants ,Chemical - Abstract
A sensitive, competitive enzyme-linked immunosorbent assay (ELISA) for the detection of the antimicrobial triclosan (TCS; 2,4,4'-trichloro-2'-hydroxydiphenyl ether) was developed. Novel immunizing haptens were synthesized by derivatizing at the 4-Cl position of the TCS molecule. Compounds derived from substitutions at 4'-Cl and that replaced the 2'-OH with a Cl atom were designed as unique coating antigen haptens. Polyclonal rabbit antisera were screened against the coating antigen library to identify combinations of immunoreagents resulting in the most sensitive assays. The most sensitive assay identified was one utilizing antiserum no. 1155 and a heterologous competitive hapten, where the 2'-OH group was substituted with a Cl atom. An IC50 value and the detection range for TCS in assay buffer were 1.19 and 0.21-6.71 μg/L, respectively. The assay was selective for TCS, providing low cross-reactivity (
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- 2016
17. Development of the scheme of obtaining antibodies to the ribonucleoprotein of attenuated rabies virus
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Yu. K. Gavrilova, S. V. Generalov, M. N. Kireev, N. A. Sharapova, E. G. Abramova, L. V. Savitskaya, M. V. Ovchinnikova, T. Yu. Kirillova, and A. P. Semakova
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rabies ,rabies virus ,ribonucleoprotein ,immunization schedule ,immune sera ,antibodies to ribonucleoprotein ,anti-rabies immunoglobulin ,Microbiology ,QR1-502 - Abstract
Aim. Isolation of ribonucleoprotein (RNP) of an attenuated rabies virus, develop schemes for immunizing animals with RNP-based preparations and determine the most effective scheme that allows obtaining serum with a high antibody titer to the RNP.Materials and methods. We used the transplantable cell line Vero, the strain rabies virus «Moscow 3253 Vero», adapted for reproduction on Vero, rabbits of the chinchilla breed. In order to obtain serums containing antibodies to the RNP of the rabies virus, experimental schemes have been proposed for immunizing animals with RNP, including with adjuvants: polyoxidonium and colloidal gold. The dynamics of the accumulation of antibodies to the RNP of the rabies virus in the blood serum of experimental animals was studied by dot-immunoassay.Results. The target component (RNP of the rabies virus) was isolated directly from the cytoplasm of the Vero cell culture infected with the rabies virus according to the modified M. Dastkhosh (2014) method, lyophilized and used in the development of preparations for immunizing experimental animals. In the study of the dynamics of the formation of antibodies to RNP of the rabies virus by the method of dot-immunoassay, the effectiveness of an adjuvant is established — colloidal gold nanoparticles ranging in size from 15 to 17 nm, the use of which makes it possible to increase the antibody titer by 2 times.Conclusion. The results obtained are of interest for further research related to the design of diagnostic products and the development of methodological techniques using such preparations.
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- 2019
- Full Text
- View/download PDF
18. An immunoassay for the detection of triclosan-O-glucuronide, a primary human urinary metabolite of triclosan
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Ranganathan, Anupama, Gee, Shirley J, and Hammock, Bruce D
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Analytical Chemistry ,Chemical Sciences ,Biotechnology ,Good Health and Well Being ,Animals ,Anti-Bacterial Agents ,Glucuronides ,Humans ,Hydrogen-Ion Concentration ,Immune Sera ,Immunoassay ,Osmolar Concentration ,Rabbits ,Triclosan ,Triclosan-O-glucuronide ,Urinary metabolite ,Biomarker ,Polyclonal antibodies ,ELISA ,Biological Sciences ,Engineering ,Biological sciences ,Chemical sciences - Abstract
Triclosan-O-glucuronide (TCSG) is one of the primary urinary metabolites of the antibacterial compound triclosan or TCS that is found in many personal care products and consumer goods. We have developed a competitive, indirect heterologous ELISA for the detection of the target TCSG in urine. Such an ELISA for TCSG could be developed as a useful tool to measure this important biomarker of human exposure to TCS. Immunogens were prepared by conjugating TCSG to thyroglobulin, via heterobifunctional cross-linkers AEDP or 3-[(2-aminoethyl)dithio] propionic acid•hydrochloride and TFCS or N-[ε-trifluoroacetylcaproyloxy]succinimide ester. The coating antigen was prepared by the direct conjugation of TCSG to bovine serum albumin. Antibodies raised in rabbits 2619, 2621 (immunogen TCSG-AEDP-Thy), and 2623 (immunogen TCSG-TFCS-Thy), and the coating antigen were screened and characterized to determine their optimal concentrations. The optimized ELISA, developed with antibody 2621, gave an IC50 value of 2.85 ng/mL, with the linear range (IC20-IC80) determined to be 2.6-24.8 ng/mL. Selectivity of the assay was assessed by measuring cross-reactivity of antibody 2621 to related congeners such as the aglycone TCS, triclosan-O-sulfate, triclocarban, a polybrominated diphenyl ether derivative, and 3-phenoxybenzyl alcohol glucuronide. There was virtually no recognition by antibody 2621 to any of these cross-reactants. Graphical Abstract Urinary biomarker analysis of triclosan glucuronide.
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- 2015
19. Development of an Immunoassay for the Detection of the Phenylpyrazole Insecticide Fipronil
- Author
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Vasylieva, Natalia, Ahn, Ki Chang, Barnych, Bogdan, Gee, Shirley J, and Hammock, Bruce D
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Analytical Chemistry ,Chemical Sciences ,Animals ,Antibodies ,Antigens ,Chromatography ,Liquid ,Cross Reactions ,Enzyme-Linked Immunosorbent Assay ,Haptens ,Humans ,Immune Sera ,Immunoassay ,Insecticides ,Male ,Pyrazoles ,Rats ,Reproducibility of Results ,Tandem Mass Spectrometry ,Water ,Environmental Sciences - Abstract
Phenylpyrazole insecticides such as fipronil have been used as replacements for organophosphates. The wide application of fipronil raises concern about environmental contamination and risk for fish, birds, and other nontargeted beings as well as human health. A sensitive, competitive indirect heterologous enzyme-linked immunosorbent assay (ELISA) was developed. Antibodies with different specificities to fipronil and its metabolites were produced. Two ELISAs having IC50 values of 0.58 ± 0.06 and 2.6 ± 0.4 ng/mL were developed. Design of different haptens and coating antigens resulted in two assays with distinct cross-reactivity patterns for structurally related compounds: 96, 38, and 101% versus 39, 1.4, and 25% for fipronil-sulfide, fipronil-detrifluoromethylsulfonyl, and fipronil-desulfinyl, respectively. Performance of the immunoassays was demonstrated by a recovery study from spiked water and human serum and urine matrices, giving recovery values in the range of 85-111% for different concentrations. The assays demonstrated good correlation in fipronil recovery with conventional LC-MS/MS analysis. The generic assay 2265 has the sensitivity to measure fipronil and its analogs in serum at levels relevant for exposure monitoring. The assays were used to analyze human urine samples obtained from exposure studies and serum samples from rats treated with a fipronil-containing diet.
- Published
- 2015
20. Post-translational modification of LipL32 during Leptospira interrogans infection.
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Witchell, Timothy D, Eshghi, Azad, Nally, Jarlath E, Hof, Rebecca, Boulanger, Martin J, Wunder, Elsio A, Ko, Albert I, Haake, David A, and Cameron, Caroline E
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Animals ,Humans ,Rats ,Rats ,Wistar ,Leptospira interrogans ,Leptospirosis ,Zoonoses ,Lipoproteins ,Bacterial Outer Membrane Proteins ,Immune Sera ,Protein Processing ,Post-Translational ,Amino Acid Sequence ,Molecular Sequence Data ,Male ,Immune Evasion ,Wistar ,Protein Processing ,Post-Translational ,Tropical Medicine ,Biological Sciences ,Medical and Health Sciences - Abstract
BackgroundLeptospirosis, a re-emerging disease of global importance caused by pathogenic Leptospira spp., is considered the world's most widespread zoonotic disease. Rats serve as asymptomatic carriers of pathogenic Leptospira and are critical for disease spread. In such reservoir hosts, leptospires colonize the kidney, are shed in the urine, persist in fresh water and gain access to a new mammalian host through breaches in the skin.Methodology/principal findingsPrevious studies have provided evidence for post-translational modification (PTM) of leptospiral proteins. In the current study, we used proteomic analyses to determine the presence of PTMs on the highly abundant leptospiral protein, LipL32, from rat urine-isolated L. interrogans serovar Copenhageni compared to in vitro-grown organisms. We observed either acetylation or tri-methylation of lysine residues within multiple LipL32 peptides, including peptides corresponding to regions of LipL32 previously identified as epitopes. Intriguingly, the PTMs were unique to the LipL32 peptides originating from in vivo relative to in vitro grown leptospires. The identity of each modified lysine residue was confirmed by fragmentation pattern analysis of the peptide mass spectra. A synthetic peptide containing an identified tri-methylated lysine, which corresponds to a previously identified LipL32 epitope, demonstrated significantly reduced immunoreactivity with serum collected from leptospirosis patients compared to the peptide version lacking the tri-methylation. Further, a subset of the identified PTMs are in close proximity to the established calcium-binding and putative collagen-binding sites that have been identified within LipL32.Conclusions/significanceThe exclusive detection of PTMs on lysine residues within LipL32 from in vivo-isolated L. interrogans implies that infection-generated modification of leptospiral proteins may have a biologically relevant function during the course of infection. Although definitive determination of the role of these PTMs must await further investigations, the reduced immune recognition of a modified LipL32 epitope suggests the intriguing possibility that LipL32 modification represents a novel mechanism of immune evasion within Leptospira.
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- 2014
21. Phosphorylation of VapB antitoxins affects intermolecular interactions to regulate VapC toxin activity in Mycobacterium tuberculosis.
- Abstract
A recent preprint study explores the phosphorylation of VapB antitoxins in Mycobacterium tuberculosis and its impact on VapC toxin activity. The study found that phosphorylation of VapB proteins resulted in decreased interaction with their respective VapC proteins and interfered with VapB binding to promoter region DNA sequences. This phosphorylation can regulate the toxicity activity of VapC toxins in response to extracytoplasmic and intracellular signals. The study highlights the importance of understanding the mechanisms by which antitoxins respond to stresses to alter toxin activity. However, it is important to note that this preprint has not yet undergone peer review. [Extracted from the article]
- Published
- 2024
22. Researchers at College of Veterinary Medicine Have Published New Study Findings on Brucella abortus [The (p)ppGpp synthetase Rsh promotes rifampicin tolerant persister cell formation in Brucella abortus by regulating the type II toxin-antitoxin...].
- Abstract
A new study conducted by researchers at the College of Veterinary Medicine has found that Brucella abortus, a bacterium that causes chronic infections, forms persister cells that are tolerant to antibiotics. The study focused on the role of the (p)ppGpp synthetase Rsh in promoting the formation of these persister cells during treatment with rifampicin and enrofloxacin. The researchers also discovered that Rsh is involved in persister cell formation under certain stress conditions and regulates the type II toxin-antitoxin module mbcTA. These findings suggest that targeting Rsh could be a potential strategy for developing new therapeutic approaches to treat chronic Brucella infections. [Extracted from the article]
- Published
- 2024
23. Cyclic di-GMP as an Antitoxin Regulates Bacterial Genome Stability and Antibiotic Persistence in Biofilms.
- Abstract
A recent preprint abstract discusses the role of cyclic di-GMP (c-di-GMP) as an antitoxin in regulating bacterial genome stability and antibiotic persistence in biofilms. Biofilms are bacterial communities that can cause chronic and relapsing infections, and the formation of persister cells within biofilms has been linked to their dense structures. However, the study found that persister frequency actually increases during the stage of cell adhesion, which marks the onset of biofilm development. The researchers identified a toxin-antitoxin (TA) module triggered by cell adhesion, where the toxin HipH induces DNA double strand breaks and genome instability, while c-di-GMP acts as the antitoxin, controlling HipH expression and activity. This unique TA system involving small molecules as antitoxins could have implications for treating biofilm infections. Please note that this preprint has not been peer-reviewed. [Extracted from the article]
- Published
- 2024
24. Asymmetry of both repressor and operator is important for the transcriptional regulation of the P. putida Xre-RES system.
- Abstract
According to a preprint abstract from biorxiv.org, researchers have studied the transcriptional regulation of the Pseudomonas putida Xre-RES system, which is a type II toxin-antitoxin system. They found that the Xre-RES complex represses transcription by binding to an imperfect inverted repeat region downstream of the sigma70 element. The researchers also discovered an unusual 4:2 stoichiometry in the Xre-RES complex and proposed a model in which the complex regulates transcription through a dynamic equilibrium between a non-binding (2:2) and a DNA-binding (4:2) form. This research has not yet undergone peer review. [Extracted from the article]
- Published
- 2024
25. University of Oxford Researcher Provides New Data on Immune Sera (Specificity of DNA ADP-Ribosylation Reversal by NADARs).
- Abstract
A recent study conducted at the University of Oxford in the United Kingdom has provided new data on immune sera. The research focused on the specificity of DNA ADP-ribosylation reversal by NADARs, which are enzymes that serve as antitoxins. The study explored the de-ADP-ribosylation activity and antitoxin functions of NADAR domains, demonstrating their biochemical activity and specificity in protecting cells from toxic guanine ADP-ribosylation. The findings contribute to the understanding of DNA ADP-ribosylation and suggest that NADARs could be potential targets for antimicrobial drugs. [Extracted from the article]
- Published
- 2024
26. Researchers at Bengbu Medical University Zero in on Escherichia coli (The biological function of the type II toxin-antitoxin system ccdAB in recurrent urinary tract infections).
- Abstract
A report from Bengbu Medical University in China discusses the role of Escherichia coli (E. coli) in recurrent urinary tract infections (rUTIs). The researchers focused on the type II toxin-antitoxin (TA) system ccdAB, which is known for maintaining plasmid stability. Through their investigation, they found that ccdAB plays a role in the development of persistent bacteria in UTIs. The findings could potentially lead to new therapeutic approaches for reducing the prevalence of rUTIs. [Extracted from the article]
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- 2024
27. New Immune Sera Data Have Been Reported by Researchers at Harvard Medical School (Molecular Stripping Underpins Derepression of a Toxin-antitoxin System).
- Abstract
Researchers at Harvard Medical School have reported new data on immune sera, specifically focusing on the molecular stripping that underpins the derepression of a toxin-antitoxin system. The study examines the autoregulation of the Salmonella enterica tacAT3 module and identifies the essential elements required for transcription control. The research reveals that excess toxin triggers the stripping of the repressor complex from the DNA, leading to derepression. This work provides important insights into the mechanisms of conditional cooperativity in the regulation of toxin-antitoxin modules. The study has been peer-reviewed and published in Nature Structural & Molecular Biology. [Extracted from the article]
- Published
- 2024
28. Fibronectin-Binding Protein of Borrelia hermsii Expressed in the Blood of Mice with Relapsing Fever
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Lewis, Eric RG, Marcsisin, Renee A, Miller, Shelley A Campeau, Hue, Fong, Phillips, April, AuCoin, David P, and Barbour, Alan G
- Subjects
Medical Microbiology ,Biochemistry and Cell Biology ,Biomedical and Clinical Sciences ,Biological Sciences ,Vaccine Related ,Biotechnology ,Emerging Infectious Diseases ,Vector-Borne Diseases ,Prevention ,Infectious Diseases ,Infection ,Adhesins ,Bacterial ,Animals ,Antigens ,Bacterial ,Borrelia ,Borrelia Infections ,Disease Models ,Animal ,Immune Sera ,Mice ,Recombinant Proteins ,Relapsing Fever ,Sequence Analysis ,DNA ,Spirochaetales ,Agricultural and Veterinary Sciences ,Medical and Health Sciences ,Microbiology ,Immunology ,Medical microbiology - Abstract
To identify and characterize surface proteins expressed by the relapsing fever (RF) agent Borrelia hermsii in the blood of infected mice, we used a cell-free filtrate of their blood to immunize congenic naive mice. The resultant antiserum was used for Western blotting of cell lysates, and gel slices corresponding to reactive bands were subjected to liquid chromatography-tandem mass spectrometry, followed by a search of the proteome database with the peptides. One of the immunogens was identified as the BHA007 protein, which is encoded by a 174-kb linear plasmid. BHA007 had sequence features of lipoproteins, was surface exposed by the criteria of in situ protease susceptibility and agglutination of Vtp(-) cells by anti-BHA007 antibodies, and was not essential for in vitro growth. BHA007 elicited antibodies during experimental infection of mice, but immunization with recombinant protein did not confer protection against needle-delivered infection. Open reading frames (ORFs) orthologous to BHA007 were found on large plasmids of other RF species, including the coding sequences for the CihC proteins of Borrelia duttonii and B. recurrentis, but not in Lyme disease Borrelia species. Recombinant BHA007 bound both human and bovine fibronectin with Kd (dissociation constant) values of 22 and 33 nM, respectively, and bound to C4-binding protein with less affinity. The distant homology of BHA007 and its orthologs to BBK32 proteins of Lyme disease species, as well as to previously described BBK32-like proteins in relapsing fever species, indicates that BHA007 is a member of a large family of multifunctional proteins in Borrelia species that bind to fibronectin as well as other host proteins.
- Published
- 2014
29. The O-glycan is essential for the induction of protective antibodies against lethal infection by flagella A-bearing Pseudomonas aeruginosa .
- Author
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Choi M, Shridhar S, Fox H, Luo K, Amin MN, Tennant SM, Simon R, and Cross AS
- Subjects
- Mice, Animals, Antibodies, Klebsiella pneumoniae, Polysaccharides, Flagella metabolism, Immune Sera, Flagellin metabolism, Pseudomonas aeruginosa
- Abstract
To address the problem of increased antimicrobial resistance, we developed a glycoconjugate vaccine comprised of O-polysaccharides (OPS) of the four most prevalent serotypes of Klebsiella pneumoniae (KP) linked to recombinant flagellin types A and B (rFlaA and rFlaB) of Pseudomonas aeruginosa (PA). Flagellin is the major subunit of the flagellar filament. Flagella A and B, essential virulence factors for PA, are glycosylated with different glycans. We previously reported that while both rFlaA and rFlaB were highly immunogenic, only the rFlaB antisera reduced PA motility and protected mice from lethal PA infection in a mouse model of thermal injury. Since recombinant flagellin is not glycosylated, we examined the possibility that the glycan on native FlaA (nFlaA) might be critical to functional immune responses. We compared the ability of nFlaA to that of native, deglycosylated FlaA (dnFlaA) to induce functionally active antisera. O glycan was removed from nFlaA with trifluoromethanesulfonic acid. Despite the similar high-titered anti-FlaA antibody levels elicited by nFlaA, rFlaA, and dnFlaA, only the nFlaA antisera inhibited PA motility and protected mice following lethal intraperitoneal bacterial challenge. Both the protective efficacy and carrier protein function of nFlaA were retained when conjugated to KP O1 OPS. We conclude that unlike the case with FlaB O glycan, the FlaA glycan is an important epitope for the induction of functionally active anti-FlaA antibodies., Competing Interests: A.S.C., S.M.T., and R.S. have an issued patent on the Klebsiella/Pseudomonas glycoconjugate vaccine.
- Published
- 2024
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30. Urine Immunofixation Electrophoresis for Diagnosis of Monoclonal Gammopathy: Evaluation of Methods for Urine Concentration.
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Ye Mon M, Ufondu O, Mortley S, Bollag RJ, and Singh G
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- Humans, Ammonium Sulfate, Immunoglobulin Light Chains, Acetonitriles, Ethanol, Immune Sera, Monoclonal Gammopathy of Undetermined Significance
- Abstract
Background: Examination of urine by immunofixation electrophoresis (UIFE) is one of the tests recommended for screening and monitoring of monoclonal gammopathies, especially multiple myeloma. Unlike the serum free light chain measurement, a positive result on urine immunofixation is diagnostic for monoclonal immunoglobulin light chains. Urine is usually concentrated, generally by membrane filtration, prior to electrophoresis., Methods: Alternative methods to membrane filtration for urine concentration were examined. Residual urine specimens submitted for urine protein electrophoresis were concentrated by precipitation of the proteins by ammonium sulfate salt precipitation, precipitation with ethanol and acetonitrile, and by desiccation. The concentrated specimens were subjected to immunofixation electrophoresis using antisera to free light chains (FLC). The results were compared with those from conventional immunofixation electrophoresis using specimens concentrated by membrane filtration., Results: Ammonium sulfate, ethanol, and acetonitrile precipitation results were less than satisfactory. Concentration by desiccation provided results comparable, if not better than, those by membrane filtration and conventional UIFE. The cost of desiccation is minimal compared to more than $5.00/specimen cost of concentration by membrane filtration. The differences in the results with conventional UIFE and the method described here are likely due to (a) variability in the reactivity of different antisera to free monoclonal light chains, and (b) obscuration of monoclonal free light chains by co-migration with intact immunoglobulin monoclonal proteins., Conclusions: Concentrating urine by desiccation for immunofixation electrophoresis is technically simple, inexpensive, and provides results comparable to concentrating by membrane filtration. Using FLC provides a more sensitive assay than using conventional antisera., (© Association for Diagnostics & Laboratory Medicine 2024. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
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- 2024
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31. Design of universal Ebola virus vaccine candidates via immunofocusing.
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Xu D, Powell AE, Utz A, Sanyal M, Do J, Patten JJ, Moliva JI, Sullivan NJ, Davey RA, and Kim PS
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- Humans, Animals, Mice, Antibodies, Viral, Antibodies, Neutralizing, Immune Sera, Hemorrhagic Fever, Ebola, Ebola Vaccines, Ebolavirus, Viral Vaccines
- Abstract
The Ebola virus causes hemorrhagic fever in humans and poses a significant threat to global public health. Although two viral vector vaccines have been approved to prevent Ebola virus disease, they are distributed in the limited ring vaccination setting and only indicated for prevention of infection from orthoebolavirus zairense (EBOV)-one of three orthoebolavirus species that have caused previous outbreaks. Ebola virus glycoprotein GP mediates viral infection and serves as the primary target of neutralizing antibodies. Here, we describe a universal Ebola virus vaccine approach using a structure-guided design of candidates with hyperglycosylation that aims to direct antibody responses away from variable regions and toward conserved epitopes of GP. We first determined the hyperglycosylation landscape on Ebola virus GP and used that to generate hyperglycosylated GP variants with two to four additional glycosylation sites to mask the highly variable glycan cap region. We then created vaccine candidates by displaying wild-type or hyperglycosylated GP variants on ferritin nanoparticles (Fer). Immunization with these antigens elicited potent neutralizing antisera against EBOV in mice. Importantly, we observed consistent cross-neutralizing activity against Bundibugyo virus and Sudan virus from hyperglycosylated GP-Fer with two or three additional glycans. In comparison, elicitation of cross-neutralizing antisera was rare in mice immunized with wild-type GP-Fer. These results demonstrate a potential strategy to develop universal Ebola virus vaccines that confer cross-protective immunity against existing and emerging filovirus species., Competing Interests: Competing interests statement:A.E.P. is an employee of, and P.S.K. is a co-founder and member of the Board of Directors of Vaccine Company, Inc. D.X., A.E.P. and P.S.K. are named as inventors on a patent application applied for by Stanford University and the Chan Zuckerberg Biohub on immunogenic ebolavirus fusion proteins and related methods. N.J.S. is a named inventor for filovirus vaccines.
- Published
- 2024
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32. Differential laboratory passaging of SARS-CoV-2 viral stocks impacts the in vitro assessment of neutralizing antibodies.
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Avila-Herrera A, Kimbrel JA, Manuel Martí J, Thissen J, Saada EA, Weisenberger T, Arrildt KT, Segelke BW, Allen JE, Zemla A, and Borucki MK
- Subjects
- Humans, SARS-CoV-2 genetics, Antibodies, Viral, Neutralization Tests, Immune Sera, Spike Glycoprotein, Coronavirus genetics, Antibodies, Neutralizing, COVID-19
- Abstract
Viral populations in natural infections can have a high degree of sequence diversity, which can directly impact immune escape. However, antibody potency is often tested in vitro with a relatively clonal viral populations, such as laboratory virus or pseudotyped virus stocks, which may not accurately represent the genetic diversity of circulating viral genotypes. This can affect the validity of viral phenotype assays, such as antibody neutralization assays. To address this issue, we tested whether recombinant virus carrying SARS-CoV-2 spike (VSV-SARS-CoV-2-S) stocks could be made more genetically diverse by passage, and if a stock passaged under selective pressure was more capable of escaping monoclonal antibody (mAb) neutralization than unpassaged stock or than viral stock passaged without selective pressures. We passaged VSV-SARS-CoV-2-S four times concurrently in three cell lines and then six times with or without polyclonal antiserum selection pressure. All three of the monoclonal antibodies tested neutralized the viral population present in the unpassaged stock. The viral inoculum derived from serial passage without antiserum selection pressure was neutralized by two of the three mAbs. However, the viral inoculum derived from serial passage under antiserum selection pressure escaped neutralization by all three mAbs. Deep sequencing revealed the rapid acquisition of multiple mutations associated with antibody escape in the VSV-SARS-CoV-2-S that had been passaged in the presence of antiserum, including key mutations present in currently circulating Omicron subvariants. These data indicate that viral stock that was generated under polyclonal antiserum selection pressure better reflects the natural environment of the circulating virus and may yield more biologically relevant outcomes in phenotypic assays. Thus, mAb assessment assays that utilize a more genetically diverse, biologically relevant, virus stock may yield data that are relevant for prediction of mAb efficacy and for enhancing biosurveillance., Competing Interests: The authors have declared that no competing interests exist., (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)
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- 2024
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33. Immunity of two novel hepatitis C virus polyepitope vaccines
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Tian, Feng, Mingzhi, Li, Lirong, Zhang, Sha, Li, Zibing, Yang, Lumei, Kang, Yunli, Guo, Lingbao, Kong, and Ting, Wang
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Mice, Inbred BALB C ,General Veterinary ,General Immunology and Microbiology ,Immune Sera ,Public Health, Environmental and Occupational Health ,Viral Vaccines ,Hepacivirus ,Antibodies, Neutralizing ,Hepatitis C ,Recombinant Proteins ,Enterotoxins ,Epitopes ,Mice ,Infectious Diseases ,Adjuvants, Immunologic ,Escherichia coli ,Animals ,Molecular Medicine ,Interleukin-4 - Abstract
Hepatitis C virus (HCV) infection remains a serious public health burden around the world. So far there is no effective vaccine against this virus. Neutralizing antibody (NAb) responses to the epitopes within HCV E1 and E2 proteins are related to the resolution of hepatitis C infection. E. coli heat-labile enterotoxin B subunit (LTB) has been described as potent immunity adjuvants. In this study, we constructed recombinant pET vectors: pET-R9-Bp (B cell polyepitopes) expressing 7 epitopes from HCV E1 and E2 proteins including R9 (E2
- Published
- 2022
34. Researchers Submit Patent Application, "Type E Botulinum Toxin To Treat Botulism", for Approval (USPTO 20230405098).
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BOTULINUM A toxins ,BOTULINUM toxin ,BOTULISM ,PATENT applications ,RESEARCH personnel ,NEUROMUSCULAR transmission - Abstract
A patent application has been submitted for the use of Type E Botulinum toxin (BoNT/E) to treat botulism, a potentially fatal illness caused by a toxin produced by the bacterium Clostridium botulinum. The current treatments for botulism are limited, but this new method aims to provide a safe and effective treatment with minimal side effects. The patent application includes details on the composition, administration, and dosage of BoNT/E for therapeutic use. It also provides definitions and explanations of terms used in the application, information about the different types and serotypes of Clostridium botulinum, and the ways in which botulism can be contracted. The patent application also includes claims outlining the method of treatment using Type E Botulinum toxin, including the administration of antitoxins and antibiotics. For more information, readers are directed to the full patent application. [Extracted from the article]
- Published
- 2024
35. Ser/Thr Phosphorylation of Mycobacterium tuberculosis Type II Rel TA module by Protein Kinase K interferes with toxin neutralization: A novel mode of TA regulation.
- Abstract
This article discusses a novel regulatory mechanism for Type II toxin-antitoxin (TA) modules in Mycobacterium tuberculosis. TA modules are genetic elements that play a role in bacterial persistence and antibiotic tolerance. The researchers found that over 85% of the TA proteins in M. tuberculosis have potential Ser/Thr phosphorylation sites, suggesting that they may be substrates for M. tuberculosis Ser/Thr protein kinases. They demonstrated that phosphorylation of a specific residue in the RelK toxin compromised its binding to the RelJ antitoxin. This research provides insights into the regulation and coordination of TA modules in M. tuberculosis. [Extracted from the article]
- Published
- 2024
36. Patent Application Titled "Plasmid Stabilisation" Published Online (USPTO 20230399650).
- Abstract
The US Patent and Trademark Office has published a patent application titled "Plasmid Stabilisation" that discusses improving the stability of the Shigella sonnei and Shigella flexneri virulence plasmid. The inventors have identified modifications to the VapB toxin-antitoxin system that can increase plasmid maintenance in bacterial hosts. This research could contribute to understanding the behavior of these bacteria, studying host-pathogen interactions, and designing vaccines. The application also describes the development of an isolated plasmid encoding a bacterial VapBC toxin-antitoxin system, which can be modified to encode therapeutic molecules or other products. Additionally, the application outlines methods for producing polypeptides or nucleic acid products using the modified plasmid and for screening antibiotics. [Extracted from the article]
- Published
- 2024
37. NEUTRALIZATION OF THE LETHAL ACTIVITY FROM Bothrops atrox VENOM BY HYPERIMUNE LLAMA SERUM (Lama glama)
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Calderon, Henri Bailon, Colque Alave, Elizabeth Gaby, Yaniro Coronel, Verónica Olga, Padilla Rojas, Carlos, Galarza Pérez, Marco, Cáceres Rey, Omar Alberto, Bonilla Ferreyra, César, Felix, Benigno Tintaya, García Neyra, David, Inga Arellano, Rosalina Rosio, Ormachea, Silvia Seraylan, and Arevalo, Harrison Montejo
- Abstract
Objectives: To evaluate the capacity of the hyperimmune llama serum (Lama glama) to neutralize the lethal activity of Bothrops atrox venom in laboratory mice. Materials and methods: Mean lethal dose (LD50) was calculated from a Bothrops atrox venom sample pool from Peru. The antibody titers were measured by ELISA assay; and the immune serum neutralization potency was measured by calculating the mean effective dose (ED50) during the immunization period. Results: The venom’s LD50 was 3.96 μg/g; similar to what was found in other studies about Bothrops atrox carried out in Peru. The titers of antibodies against the venom increased rapidly in the llama, demonstrating a fast immune response; however, the neutralization capacity increased slowly and required several doses and immunization reinforcements, obtaining a ED50 of 3.30 μL/g mouse and a neutralization potency of 3.6 mg/mL after 15 immunizations. Conclusions: The hyperimmune llama serum is able to neutralize the lethality of the Bothrops atrox venom from Peru in laboratory mice. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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38. Paratrygon aiereba irradiated anti-mucus serum reduce edematogenic activity induced in experimental model.
- Author
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Coelho Thomazi, Gabriela Ortega, da Costa, Andrea, Rodrigues, Jaqueline Polizeli, Alves, Glaucie Jussilane, Prezotto Neto, José Pedro, de Oliveira Turíbio, Thompson, Rocha, André Moreira, da Silva Aires, Raquel, Seibert, Carla Simone, Spencer, Patrick Jack, Galisteo Júnior, Andrés Jimenez, de Andrade Júnior, Heitor Franco, and do Nascimento, Nanci
- Subjects
- *
MUCUS , *HUMORAL immunity , *SERUM , *IONIZING radiation , *IMMUNE serums - Abstract
Accidents by freshwater stingrays are common in northern Brazil, there is no specific therapy for high morbidity and local tissue destruction. The irradiation of venoms and toxins by ionizing radiation has been used to produce appropriate immunogens for the production of antisera. We planned to study the efficacy of stinging mucus irradiation in the production of antisera, with serum neutralization assays of edematogenic activity and quantification of cytokines performed in animal models of immunization with native and irradiated mucus of Paratrygon aiereba , a large freshwater stingray. Antiserum potency and its cross-reactivity with mucus from other freshwater stingrays were detected by ELISA. Immunization models demonstrated the ability to stimulate a strong humoral response with elevated levels of serum IgG detectable by ELISA, and both native and irradiated mucus were immunogenic and capable of recognizing mucus proteins from other freshwater neotropical stingrays. Mucus P. aiereba causes cellular and humoral adaptive immune responses in cells of immunized mice producing antibodies and cytokines such as TNF-α, IL-6 and IL-17. Rabbit antisera immunized with mucus from P. aiereba irradiated at 2 kGy showed a significant reduction of mucus-induced edematogenic activity in mice. Our data suggest that the use of antisera against freshwater stingray mucus show the possibility of specific therapy for these accidents. • Native and irradiated mucus from Paratrygon aiereba were immunogenic. • Mucus stimulate a strong humoral response with elevated levels of IgG. • Antiserum is capable of recognizing mucus proteins from other freshwater stingrays. • Rabbit antisera immunized with mucus irradiated reduced of edematogenic activity. • Native and irradiated mucus induces the production of cytokines. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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39. Association between Pseudomonas aeruginosa O-antigen serotypes, resistance profiles and high-risk clones: results from a Spanish nationwide survey.
- Author
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Barrio-Tofiño, Ester del, Sánchez-Diener, Irina, Zamorano, Laura, Cortes-Lara, Sara, López-Causapé, Carla, Cabot, Gabriel, Bou, Germán, Martínez-Martínez, Luis, Oliver, Antonio, GEMARA-SEIMC/REIPI, and Del Barrio-Tofiño, Ester
- Subjects
- *
CEFTAZIDIME , *PSEUDOMONAS aeruginosa , *AMIKACIN , *SEROTYPES , *INFECTION prevention , *FOOT & mouth disease , *IMMUNE serums , *MOLECULAR cloning - Abstract
Objectives: To evaluate the correlation of O-antigen serotypes with resistance profiles and high-risk clones in a Spanish nationwide survey.Methods: Up to 30 consecutive healthcare-associated Pseudomonas aeruginosa isolates were collected during October 2017 from each of 51 hospitals (covering all Spanish regions) with a total of 1445 isolates studied. MICs of 13 antipseudomonal agents and MDR/XDR profiles had been previously determined, as well as whole-genome sequences of 185 representative XDR isolates. O-antigen serotypes (O1-O16) were determined by agglutination using serotype-specific antisera (BioRad). The Pseudomonas aeruginosa serotyper (PAst) program was used for in silico serotyping.Results: The most frequent serotypes were O6 (17.8%), O1 (15.4%) and O11 (13.3%). In contrast, the most frequent serotype among XDR isolates (17.3%) was O4 (34.1%), distantly followed by O11 (15.9%). Within serotypes, XDR phenotypes were more frequent for O12 (60.0%) and O4 (57.3%). The most frequent clone among the XDR isolates was ST175 (40.9%), followed by CC235 (10.7%), ST308 (5.2%) and CC111 (3.6%). Up to 81.6% of XDR ST175 isolates typed O4, whereas 18.4% were non-typeable. O4 genotype was detected in all sequenced (n=55) ST175 isolates. On the other hand, CC235 and ST308 were associated with O11, whereas CC111 was linked to serotype O12.Conclusions: O4 serotype is linked to the MDR/XDR profile of widespread ST175 (typically only susceptible to colistin, amikacin and the novel combinations ceftolozane/tazobactam and ceftazidime/avibactam) and therefore, after local validation, its detection in the microbiology laboratory might be useful for guiding semi-empirical antipseudomonal therapies and infection control measures in Spanish hospitals. [ABSTRACT FROM AUTHOR]- Published
- 2019
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40. Effectiveness of oral aciclovir in preventing maternal chickenpox: A comparison with VZIG
- Author
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Bersabeh Sile, Kevin E Brown, Charlotte Gower, Johanna Bosowski, Amanda Dennis, Michelle Falconer, Julia Stowe, Nick Andrews, and Gayatri Amirthalingam
- Subjects
Male ,Microbiology (medical) ,Chickenpox ,Infectious Diseases ,Pregnancy ,Immune Sera ,Infant, Newborn ,Acyclovir ,Humans ,Female ,Antibodies, Viral ,Child ,Antiviral Agents - Abstract
Although often presenting as a self-limiting childhood disease, chickenpox can have serious consequences if acquired in pregnancy. Until April 2022, the UK recommendations were that varicella immunoglobulin (VZIG) should be administered intramuscularly to susceptible pregnant women exposed to chickenpox prior to 20 weeks gestation. Oral aciclovir or VZIG was recommended if exposure occurred at 20+ weeks gestation. Our objective was to compare the effectiveness of oral aciclovir to VZIG in preventing maternal and neonatal chickenpox.We identified and followed up 186 pregnant women who were exposed to chickenpox and compared their outcomes.171/186 (91.9%) of these women received either VZIG or oral aciclovir. Of the 145 women who received VZIG, 53/145 (36.6%) went on to develop chickenpox compared to 8 of the 26 (30.8%) women who received oral aciclovir (p = 0.32). No statistical difference was found between the oral aciclovir and VZIG groups even after controlling for maternal age, gestational stage, type of exposure and IgG titre (adjusted OR:0.83; 95%CI:0.26-2.65; p = 0.75).These findings support the use of oral aciclovir as first-line prophylaxis in pregnant women exposed to varicella as they suggest its effectiveness at preventing maternal chickenpox is either better or equal to VZIG.
- Published
- 2022
41. Neutralizing antibodies and cellular immune response after two doses of inactivated SARS-CoV-2 vaccine in China
- Author
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Li-Na Yan, Zhong-Xin Zhao, Zhen-Dong Wang, Xiao Xiao, Pan-Pan Liu, Wen-Kang Zhang, Xiao-Lan Gu, Bang Li, Li-Ping Yu, and Xue-Jie Yu
- Subjects
Pharmacology ,Immunity, Cellular ,COVID-19 Vaccines ,SARS-CoV-2 ,Immune Sera ,Immunology ,COVID-19 ,Viral Vaccines ,Antibodies, Viral ,Antibodies, Neutralizing ,Vaccines, Inactivated ,Drug Discovery ,Humans ,Molecular Medicine - Abstract
As of 2022, inactivated SARS-CoV-2 vaccines had been used in more than 91 countries. However, limited real world information was available on the immune responses of the inactivated SARS-CoV-2 vaccine.We used SARS-CoV-2 pseudovirues to determine the neutralizing antibodies (NAbs) to wild type and several global variants and utilized enzyme-linked immunosorbent assay to investigate IFN-γ-secreting T-cell responses to SARS-CoV-2 among 240 vaccinated individuals after two doses of inactivated vaccine in China.A majority of the vaccinated (90%) developed robust NAbs and T-cell responses to SARS-CoV-2 in the first two months after the second dose. After six months, only 37.0% and 44.0% of vaccinees had NAbs and T-cell immunity to SARS-CoV-2, respectively. Immune serum retained most of its neutralizing potency against the Alpha and Iota variants, but lost significant neutralizing potency against the Beta, Kappa, Delta, and Omicron variants. Only 40% of vaccine-sera retained low-level neutralization activities to Omicron, with a 14.7-fold decrease compared to the wild type.The inactivated SARS-CoV-2 vaccine stimulated robust NAbs and T-cell immune responses in the first two months after the second dose but the immune effect dropped rapidly, highlighing that a third dose or additional booster immunizations may be required to boost immunity against SARS-CoV-2.
- Published
- 2022
42. Neutralization of chemokines RANTES and MIG increases virus antigen expression and spinal cord pathology during Theiler's virus infection
- Author
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Ure, Daren R, Lane, Thomas E, Liu, Michael T, and Rodriguez, Moses
- Subjects
Infectious Diseases ,Aetiology ,2.1 Biological and endogenous factors ,2.2 Factors relating to the physical environment ,Inflammatory and immune system ,Infection ,Animals ,Antigens ,Viral ,Cardiovirus Infections ,Chemokine CCL5 ,Chemokine CXCL9 ,Chemokines ,CXC ,Cytokines ,Immune Sera ,Lymphocytes ,Mice ,RNA ,Spinal Cord ,Theilovirus ,chemokines ,demyelination ,interleukins ,virus persistence ,Immunology - Abstract
The role of chemokines during some viral infections is unpredictable because the inflammatory response regulated by these molecules can have two, contrasting effects-viral immunity and immunopathologic injury to host tissues. Using Theiler's virus infection of SJL mice as a model of this type of disease, we have investigated the roles of two chemokines-regulated on activation, normal T cell-expressed and secreted (RANTES) chemokine and monokine induced by IFN-gamma (MIG)-by treating mice with antisera that block lymphocyte migration. Control, infected mice showed virus persistence, mild inflammation and a small degree of demyelination in the white matter of the spinal cord at 6 weeks post-infection. Treatment of mice with RANTES antiserum starting at 2 weeks post-infection increased both viral antigen expression and the severity of inflammatory demyelination at 6 weeks post-infection. MIG antiserum increased the spread of virus and the proportion of spinal cord white matter with demyelination. Overall, viral antigen levels correlated strongly with the extent of pathology. At the RNA level, high virus expression was associated with low IL-2 and high IL-10 levels, and RANTES antiserum decreased the IL-2/IL-10 ratio. Our results suggest that RANTES and MIG participate in an immune response that attempts to restrict viral expression while limiting immunopathology and that anti-chemokine treatment poses the risk of exacerbating both conditions in the long term.
- Published
- 2005
43. Serogroups and genetic diversity of diarrheagenic strains of Escherichia coli: a retrospective study
- Author
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Anca Mare, Adrian Man, Cristina Nicoleta Ciurea, Ionela Anca Pintea-Simon, Edith Simona Ianoși, Cristina Elena Gîrbovan, and Felicia Toma
- Subjects
Diarrhea ,Immune Sera ,Genetic Variation ,Infant ,General Medicine ,Serogroup ,Microbiology ,Enteropathogenic Escherichia coli ,Infectious Diseases ,Virology ,Humans ,Parasitology ,Child ,Escherichia coli Infections ,Retrospective Studies - Abstract
Introduction: Diverse serogroups of Escherichia coli cause sporadic cases and outbreaks of diarrhea among children. Our study aimed to evaluate the serogroups of diarrheagenic strains of E. coli that cause diarrheal disease in children under two years old, and clarify if the cases were sporadic or outbreaks. Methodology: The retrospective study included 130 strains of pathogenic E. coli, isolated from children who were less than two years of age, and had diarrheal disease, between May 2016 and July 2019. The study was conducted in the Bacteriology Laboratory (County Clinical Hospital, Mureș, Romania). The 130 strains were sero-grouped using polyvalent and monovalent O antisera. Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR) was performed to evaluate the similarity between different E. coli strains, and a simplex polymerase chain reaction (PCR) was performed to detect the presence of the hlyA gene that is specific to the enterohemorrhagic strains. Results: After agglutination with polyvalent O antisera, slightly more than half of the strains (50.77%) were sero-grouped as Shiga toxin-producing E. coli (STEC), and the rest of the strains belonged to the Enteropathogenic Escherichia coli (EPEC) serogroups. Serogroup O157 was the most frequently identified (16.51% of the total number of typeable strains), and one strain was positive for hlyA. ERIC-PCR revealed a high diversity of strains, with an overall 50% similarity. Conclusions: STEC serogroups were the most common strains causing diarrheal disease, and O-157 was the dominant serogroup identified. The strains included in our study presented high genetic diversity, suggesting that most of the cases were sporadic.
- Published
- 2022
44. Reduced SARS-CoV-2 disease outcomes in Syrian hamsters receiving immune sera: Quantitative image analysis in pathologic assessments
- Author
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Cesar Piedra-Mora, Sally R. Robinson, Lisa H. Tostanoski, Denise A. E. Dayao, Abishek Chandrashekar, Katherine Bauer, Linda Wrijil, Sarah Ducat, Tammy Hayes, Jingyou Yu, Esther A. Bondzie, Katherine McMahan, Daniel Sellers, Victoria Giffin, David Hope, Felix Nampanya, Noe B. Mercado, Swagata Kar, Hanne Andersen, Saul Tzipori, Dan H. Barouch, and Amanda J. Martinot
- Subjects
COVID-19 Vaccines ,Mesocricetus ,General Veterinary ,SARS-CoV-2 ,Immune Sera ,COVID-19 ,Macaca mulatta ,Rodent Diseases ,Disease Models, Animal ,Cricetinae ,Immunoglobulin G ,Weight Loss ,Animals ,Humans ,Lung - Abstract
There is a need to standardize pathologic endpoints in animal models of SARS-CoV-2 infection to help benchmark study quality, improve cross-institutional comparison of data, and assess therapeutic efficacy so that potential drugs and vaccines for SARS-CoV-2 can rapidly advance. The Syrian hamster model is a tractable small animal model for COVID-19 that models clinical disease in humans. Using the hamster model, the authors used traditional pathologic assessment with quantitative image analysis to assess disease outcomes in hamsters administered polyclonal immune sera from previously challenged rhesus macaques. The authors then used quantitative image analysis to assess pathologic endpoints across studies performed at different institutions using different tissue processing protocols. The authors detail pathological features of SARS-CoV-2 infection longitudinally and use immunohistochemistry to quantify myeloid cells and T lymphocyte infiltrates during SARS-CoV-2 infection. High-dose immune sera protected hamsters from weight loss and diminished viral replication in tissues and reduced lung lesions. Cumulative pathology scoring correlated with weight loss and was robust in distinguishing IgG efficacy. In formalin-infused lungs, quantitative measurement of percent area affected also correlated with weight loss but was less robust in non-formalin-infused lungs. Longitudinal immunohistochemical assessment of interstitial macrophage infiltrates showed that peak infiltration corresponded to weight loss, yet quantitative assessment of macrophage, neutrophil, and CD3+ T lymphocyte numbers did not distinguish IgG treatment effects. Here, the authors show that quantitative image analysis was a useful adjunct tool for assessing SARS-CoV-2 treatment outcomes in the hamster model.
- Published
- 2022
45. Genotype analysis to clarify RhD variants in discrepant samples of Chilean population.
- Author
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Aburto A, Zapata D, Retamales E, Fernández J, Barra G, Peña F, Cárcamo S, Saavedra N, Sandoval C, Orellana J, and Caamaño J
- Subjects
- Female, Humans, Pregnancy, Chile, Genotype, Immune Sera, Phenotype, Polymerase Chain Reaction, Rh-Hr Blood-Group System genetics
- Abstract
Introduction: The D antigen variants are classified as weak, partial, and extremely weak (DEL) and can be differentiated using molecular tests. In Chile, the laboratories of local blood centers do not identify variants of the D antigen, referring them for study to the Reference Laboratory of the Public Health Institute of Chile. So, our aim was to talk about the results of the molecular analysis of variants of the D antigen in samples that had different results in the serological classification., Methods: In the D antigen classification of the Rh system, 479 samples with serological discrepant results were sent for molecular analysis. The Rh phenotype was performed with monoclonal anti-C, anti-c, anti-E, and anti-e antisera by direct agglutination. To find the D antigen, researchers used direct agglutination with monoclonal antisera and indirect antiglobulin testing with the column (gel) agglutination method. Molecular analysis was performed with a polymerase chain reaction with sequence-specific primers (SSP-PCR) and sequencing., Results and Discussion: The presence of D antigen variants was confirmed in 332 samples (69.3%), with an initial discrepancy in serological classification. In this group of discrepant samples, the frequency of weak RhD variants was 66% (219/332), that of extremely weak RhD was 28% (93/332), and that of partial RhD was 6% (20/332). The weak variants type 2 (27.4%), type 3 (8.4%), type 48 (8.4%), and type 1 (8.1%) were the next most prevalent variants after RHD*DEL43 (28%). The ccEe (R2r) phenotype was the most frequently detected (38.4%) and is present in 87% of the RHD*DEL43 samples. The E antigen is associated with the presence of this variant. Our analyses give the first description of D antigen variants in Chile. The most common variants are DEL type (RHD*DEL43) and weak (weak type 2), which are linked to the ccDEe (R2r) phenotype. These findings allow us to characterize the variants of the D antigen in Chile and, according to the obtained data, to design strategies for the management of donors, patients, and pregnant women., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Aburto, Zapata, Retamales, Fernández, Barra, Peña, Cárcamo, Saavedra, Sandoval, Orellana and Caamaño.)
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- 2023
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46. Production of polyclonal viperin antisera using N-terminal deleted recombinant bovine viperin.
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Sravanthi M, Sebastian R, Krishnaswamy N, Mahadappa P, Dechamma HJ, Umapathi V, and Sanyal A
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- Animals, Cattle, Humans, Rabbits, Immune Sera, Mammals metabolism, Proteins genetics, Proteins chemistry, Proteins metabolism, Methionine
- Abstract
Viperin, also known as radical S-adenosyl methionine domain-containing protein (RSAD2) is a multifunctional interferon-stimulated gene (ISG) that is activated during the viral infections. Viperin belongs to S-adenosyl methionine (SAM) superfamily of enzymes known to catalyze radical-mediated reactions and viperin inhibits a wide range of DNA and RNA viruses through its broad range of activity. The present study reports cloning and expression of bovine viperin in a bacterial expression system. PCR-based site-directed mutagenesis was carried out for deletion of N-terminal 1-70 amino acid containing amphipathic helix of viperin that interferes in protein expression and purification. The resultant truncated viperin protein was expressed in Escherichia coli , BL-21(DE3) competent cells and purified using nickel charged affinity column. The truncated 54 kDa protein was confirmed by western blot using human RSAD2 as a probe. Further, in house, hyperimmune serum was raised against the truncated viperin in the rabbit and the reactivity was confirmed by western blot using mammalian expression vector construct of viperin transfected in Baby Hamster kidney (BHK) cells and in MDBK cells infected with Foot and Mouth disease Asia I virus.
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- 2023
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47. A novel Galleria mellonella experimental model for zoonotic pathogen Brucella .
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Wang S, Yin Y, Zai X, Gu Y, Guo F, Shao F, Zhang Y, Li Y, Li R, Zhang J, Xu J, and Chen W
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- Animals, Mice, Guinea Pigs, Larva microbiology, Virulence, Immune Sera, Disease Models, Animal, Mammals, Brucella, Moths microbiology
- Abstract
Brucellosis is a major threat to public health and animal husbandry. Several in vivo vertebrate models, such as mice, guinea pigs, and nonhuman primates, have been used to study Brucella pathogenesis, bacteria-host interactions, and vaccine efficacy. However, these models have limitations whereas the invertebrate Galleria mellonella model is a cost-effective and ethical alternative. The aim of the present study was to examine the invertebrate G. mellonella as an in vivo infection model for Brucella . Infection assays were employed to validate the fitness of the larval model for Brucella infection and virulence evaluation. The protective efficacy of immune sera was evaluated by pre-incubated with a lethal dose of bacteria before infection. The consistency between the mouse model and the larval model was confirmed by assessing the protective efficacy of two Brucella vaccine strains. The results show that G. mellonella could be infected by Brucella strains, in a dose- and temperature-dependent way. Moreover, this larval model can effectively evaluate the virulence of Brucella strains in a manner consistent with that of mammalian infection models. Importantly, this model can assess the protective efficacy of vaccine immune sera within a day. Further investigation implied that haemolymph played a crucial role in the protective efficacy of immune sera. In conclusion, G. mellonella could serve as a quick, efficient, and reliable model for evaluating the virulence of Brucella strains and efficacy of immune sera in an ethical manner.
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- 2023
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48. Risk assessment of the newly emerged H7N9 avian influenza viruses.
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Chang P, Sadeyen JR, Bhat S, Daines R, Hussain A, Yilmaz H, and Iqbal M
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- Animals, Dogs, Humans, Ferrets, Hemagglutinins, Poultry, Risk Assessment, Immune Sera, Hemagglutinin Glycoproteins, Influenza Virus, Influenza A Virus, H7N9 Subtype, Influenza, Human, Influenza in Birds
- Abstract
Since the first human case in 2013, H7N9 avian influenza viruses (AIVs) have caused more than 1500 human infections with a mortality rate of approximately 40%. Despite large-scale poultry vaccination regimes across China, the H7N9 AIVs continue to persist and evolve rapidly in poultry. Recently, several strains of H7N9 AIVs have been isolated and shown the ability to escape vaccine-induced immunity. To assess the zoonotic risk of the recent H7N9 AIV isolates, we rescued viruses with hemagglutinin (HA) and neuraminidase (NA) from these H7N9 AIVs and six internal segments from PR8 virus and characterized their receptor binding, pH of fusion, thermal stability, plaque morphology and in ovo virus replication. We also assessed the cross-reactivity of the viruses with human monoclonal antibodies (mAbs) against H7N9 HA and ferret antisera against H7N9 AIV candidate vaccines. The H7N9 AIVs from the early epidemic waves had dual sialic acid receptor binding characteristics, whereas the more recent H7N9 AIVs completely lost or retained only weak human sialic acid receptor binding. Compared with the H7N9 AIVs from the first epidemic wave, the 2020/21 viruses formed larger plaques in Madin-Darby canine kidney (MDCK) cells and replicated to higher titres in ovo , demonstrating increased acid stability but reduced thermal stability. Further analysis showed that these recent H7N9 AIVs had poor cross-reactivity with the human mAbs and ferret antisera, highlighting the need to update the vaccine candidates. To conclude, the newly emerged H7N9 AIVs showed characteristics of typical AIVs, posing reduced zoonotic risk but a heightened threat for poultry.
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- 2023
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49. Antibody landscape of C57BL/6 mice cured of B78 melanoma via a combined radiation and immunocytokine immunotherapy regimen.
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Hoefges A, McIlwain SJ, Erbe AK, Mathers N, Xu A, Melby D, Tetreault K, Le T, Kim K, Pinapati RS, Garcia BH, Patel J, Heck M, Feils AS, Tsarovsky N, Hank JA, Morris ZS, Ong IM, and Sondel PM
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- Animals, Mice, Proteome, Mice, Inbred C57BL, Immunotherapy, Peptides, Epitopes, Immune Sera, Melanoma
- Abstract
Sera of immune mice that were previously cured of their melanoma through a combined radiation and immunocytokine immunotherapy regimen consisting of 12 Gy of external beam radiation and the intratumoral administration of an immunocytokine (anti-GD2 mAb coupled to IL-2) with long-term immunological memory showed strong antibody-binding against melanoma tumor cell lines via flow cytometric analysis. Using a high-density whole-proteome peptide array (of 6.090.593 unique peptides), we assessed potential protein-targets for antibodies found in immune sera. Sera from 6 of these cured mice were analyzed with this high-density, whole-proteome peptide array to determine specific antibody-binding sites and their linear peptide sequence. We identified thousands of peptides that were targeted by these 6 mice and exhibited strong antibody binding only by immune (after successful cure and rechallenge), not naïve (before tumor implantation) sera and developed a robust method to detect these differentially targeted peptides. Confirmatory studies were done to validate these results using 2 separate systems, a peptide ELISA and a smaller scale peptide array utilizing a slightly different technology. To the best of our knowledge, this is the first study of the full set of germline encoded linear peptide-based proteome epitopes that are recognized by immune sera from mice cured of cancer via radio-immunotherapy. We furthermore found that although the generation of B-cell repertoire in immune development is vastly variable, and numerous epitopes are identified uniquely by immune serum from each of these 6 immune mice evaluated, there are still several epitopes and proteins that are commonly recognized by at least half of the mice studied. This suggests that every mouse has a unique set of antibodies produced in response to the curative therapy, creating an individual "fingerprint." Additionally, certain epitopes and proteins stand out as more immunogenic, as they are recognized by multiple mice in the immune group., Competing Interests: RSP, BG & JP are all employees of Nimble Therapeutics, the producer of the high-density peptide arrays used for this research. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Hoefges, McIlwain, Erbe, Mathers, Xu, Melby, Tetreault, Le, Kim, Pinapati, Garcia, Patel, Heck, Feils, Tsarovsky, Hank, Morris, Ong and Sondel.)
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- 2023
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50. Characterization of intrinsic and effective fitness changes caused by temporarily fixed mutations in the SARS-CoV-2 spike E484 epitope and identification of an epistatic precondition for the evolution of E484A in variant Omicron.
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Schröder S, Richter A, Veith T, Emanuel J, Gudermann L, Friedmann K, Jeworowski LM, Mühlemann B, Jones TC, Müller MA, Corman VM, and Drosten C
- Subjects
- Animals, Cricetinae, Humans, Epitopes genetics, Mutation, Immune Sera, Immunodominant Epitopes, Spike Glycoprotein, Coronavirus genetics, Antibodies, Neutralizing, SARS-CoV-2 genetics, COVID-19
- Abstract
Background: Intrinsic fitness costs are likely to have guided the selection of lineage-determining mutations during emergence of variants of SARS-CoV-2. Whereas changes in receptor affinity and antibody neutralization have been thoroughly mapped for individual mutations in spike, their influence on intrinsic replicative fitness remains understudied., Methods: We analyzed mutations in immunodominant spike epitope E484 that became temporarily fixed over the pandemic. We engineered the resulting immune escape mutations E484K, -A, and -Q in recombinant SARS-CoV-2. We characterized viral replication, entry, and competitive fitness with and without immune serum from humans with defined exposure/vaccination history and hamsters monospecifically infected with the E484K variant. We additionally engineered a virus containing the Omicron signature mutations N501Y and Q498R that were predicted to epistatically enhance receptor binding., Results: Multistep growth kinetics in Vero-, Calu-3, and NCI-H1299 were identical between viruses. Synchronized entry experiments based on cold absorption and temperature shift identified only an insignificant trend toward faster entry of the E484K variant. Competitive passage experiments revealed clear replicative fitness differences. In absence of immune serum, E484A and E484Q, but not E484K, were replaced by wildtype (WT) in competition assays. In presence of immune serum, all three mutants outcompeted WT. Decreased E484A fitness levels were over-compensated for by N501Y and Q498R, identifying a putative Omicron founder background that exceeds the intrinsic and effective fitness of WT and matches that of E484K. Critically, the E484A/Q498R/N501Y mutant and E484K have equal fitness also in presence of pre-Omicron vaccinee serum, whereas the fitness gain by E484K is lost in the presence of serum raised against the E484K variant in hamsters., Conclusions: The emergence of E484A and E484Q prior to widespread population immunity may have been limited by fitness costs. In populations already exposed to the early immune escape epitope E484K, the Omicron founder background may have provided a basis for alternative immune escape evolution via E484A. Studies of major antigenic epitope changes with and without their epistatic context help reconstruct the sequential adjustments of intrinsic fitness versus neutralization escape during the evolution of major SARS-CoV-2 variants in an increasingly immune human population., (© 2023. The Author(s).)
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- 2023
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