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  • 1
    Online Resource
    Online Resource
    Candida quercitrusa Candidemia in a 6-Year-Old Child
    American Society for Microbiology ; 2015
    In:  Journal of Clinical Microbiology Vol. 53, No. 8 ( 2015-08), p. 2785-2787
    Details
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 53, No. 8 ( 2015-08), p. 2785-2787
    Abstract: We present the first case of candidemia due to Candida quercitrusa in a pediatric patient. The identification of the isolate was protracted and ultimately dependent upon sequence analysis of the internal transcribed spacer region. To further define the antifungal susceptibility characteristics of this species, we performed antifungal susceptibility testing of clinical and type strains. In light of the antifungal susceptibility testing results, we caution against the use of fluconazole for treating C. quercitrusa infections.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    URL: Article
    DOI: 10.1128/JCM.03657-14
    RVK:
    XA 10000
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2015
    detail.hit.zdb_id: 1498353-9
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Enhancing the Thermostability and Immunogenicity of a Respiratory Syncytial Virus (RSV) Live-Attenuated Vaccine by Incorporating Unique RSV Line19F Protein Residues
    American Society for Microbiology ; 2018
    In:  Journal of Virology Vol. 92, No. 6 ( 2018-03-15)
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 92, No. 6 ( 2018-03-15)
    Abstract: Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in infants, and an effective vaccine is not yet available. We previously generated an RSV live-attenuated vaccine (LAV) candidate, DB1, which was attenuated by a low-fusion subgroup B F protein (BAF) and codon-deoptimized nonstructural protein genes. DB1 was immunogenic and protective in cotton rats but lacked thermostability and stability of the prefusion conformation of F compared to strains with the line19F gene. We hypothesized that substitution of unique residues from the thermostable A2-line19F strain could thermostabilize DB1 and boost its immunogenicity. We therefore substituted 4 unique line19F residues into the BAF protein of DB1 by site-directed mutagenesis and rescued the recombinant virus, DB1-QUAD. Compared to DB1, DB1-QUAD had improved thermostability at 4°C and higher levels of prefusion F as measured by enzyme-linked immunosorbent assays (ELISAs). DB1-QUAD was attenuated in normal human bronchial epithelial cells, in BALB/c mice, and in cotton rats but grew to wild-type titers in Vero cells. In mice, DB1-QUAD was highly immunogenic and generated significantly higher neutralizing antibody titers to a panel of RSV A and B strains than did DB1. DB1-QUAD was also efficacious against wild-type RSV challenge in mice and cotton rats. Thus, substitution of unique line19F residues into RSV LAV DB1 enhanced vaccine thermostability, incorporation of prefusion F, and immunogenicity and generated a promising vaccine candidate that merits further investigation. IMPORTANCE We boosted the thermostability and immunogenicity of an RSV live-attenuated vaccine candidate by substituting 4 unique residues from the RSV line19F protein into the F protein of the heterologous vaccine strain DB1. The resultant vaccine candidate, DB1-QUAD, was thermostable, attenuated in vivo , highly immunogenic, and protective against RSV challenge in mice and cotton rats.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.01568-17
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2018
    detail.hit.zdb_id: 1495529-5
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  • 3
    Online Resource
    Online Resource
    A Recombinant Respiratory Syncytial Virus Vaccine Candidate Attenuated by a Low-Fusion F Protein Is Immunogenic and Protective against Challenge in Cotton Rats
    American Society for Microbiology ; 2016
    In:  Journal of Virology Vol. 90, No. 16 ( 2016-08-15), p. 7508-7518
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 90, No. 16 ( 2016-08-15), p. 7508-7518
    Abstract: Although respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in infants, a safe and effective vaccine is not yet available. Live-attenuated vaccines (LAVs) are the most advanced vaccine candidates in RSV-naive infants. However, designing an LAV with appropriate attenuation yet sufficient immunogenicity has proven challenging. In this study, we implemented reverse genetics to address these obstacles with a multifaceted LAV design that combined the codon deoptimization of genes for nonstructural proteins NS1 and NS2 (dNS), deletion of the small hydrophobic protein (ΔSH) gene, and replacement of the wild-type fusion (F) protein gene with a low-fusion RSV subgroup B F consensus sequence of the Buenos Aires clade (BAF). This vaccine candidate, RSV-A2-dNS-ΔSH-BAF (DB1), was attenuated in two models of primary human airway epithelial cells and in the upper and lower airways of cotton rats. DB1 was also highly immunogenic in cotton rats and elicited broadly neutralizing antibodies against a diverse panel of recombinant RSV strains. When vaccinated cotton rats were challenged with wild-type RSV A, DB1 reduced viral titers in the upper and lower airways by 3.8 log 10 total PFU and 2.7 log 10 PFU/g of tissue, respectively, compared to those in unvaccinated animals ( P 〈 0.0001). DB1 was thus attenuated, highly immunogenic, and protective against RSV challenge in cotton rats. DB1 is the first RSV LAV to incorporate a low-fusion F protein as a strategy to attenuate viral replication and preserve immunogenicity. IMPORTANCE RSV is a leading cause of infant hospitalizations and deaths. The development of an effective vaccine for this high-risk population is therefore a public health priority. Although live-attenuated vaccines have been safely administered to RSV-naive infants, strategies to balance vaccine attenuation with immunogenicity have been elusive. In this study, we introduced a novel strategy to attenuate a recombinant RSV vaccine by incorporating a low-fusion, subgroup B F protein in the genetic background of codon-deoptimized nonstructural protein genes and a deleted small hydrophobic protein gene. The resultant vaccine candidate, DB1, was attenuated, highly immunogenic, and protective against RSV challenge in cotton rats.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.00012-16
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2016
    detail.hit.zdb_id: 1495529-5
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  • 4
    Online Resource
    Online Resource
    Loss of Pfizer (BNT162b2) Vaccine-Induced Antibody Responses against the SARS-CoV-2 Omicron Variant in Adolescents and Adults
    American Society for Microbiology ; 2022
    In:  Journal of Virology Vol. 96, No. 17 ( 2022-09-14)
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 96, No. 17 ( 2022-09-14)
    Abstract: Emerging variants, especially the recent Omicron variant, and gaps in vaccine coverage threaten mRNA vaccine mediated protection against SARS-CoV-2. While children have been relatively spared by the ongoing pandemic, increasing case numbers and hospitalizations are now evident among children. Thus, it is essential to better understand the magnitude and breadth of vaccine-induced immunity in children against circulating viral variant of concerns (VOCs). Here, we compared the magnitude and breadth of humoral immune responses in adolescents and adults 1 month after the two-dose Pfizer (BNT162b2) vaccination. We found that adolescents (aged 11 to 16) demonstrated more robust binding antibody and neutralization responses against the wild-type SARS-CoV-2 virus spike protein contained in the vaccine compared to adults (aged 27 to 55). The quality of the antibody responses against VOCs in adolescents were very similar to adults, with modest changes in binding and neutralization of Beta, Gamma, and Delta variants. In comparison, a significant reduction of binding titers and a striking lack of neutralization was observed against the newly emerging Omicron variant for both adolescents and adults. Overall, our data show that a two-dose BNT162b2 vaccine series may be insufficient to protect against the Omicron variant. IMPORTANCE While plasma binding and neutralizing antibody responses have been reported for cohorts of infected and vaccinated adults, much less is known about the vaccine-induced antibody responses to variants including Omicron in children. This illustrates the need to characterize vaccine efficacy in key vulnerable populations. A third (booster) dose of BNTb162b was approved for children 12 to 15 years of age by the Food and Drug Administration (FDA) on January 1, 2022, and pediatric clinical trials are under way to evaluate the safety, immunogenicity, and effectiveness of a third dose in younger children. Similarly, variant-specific booster doses and pan-coronavirus vaccines are areas of active research. Our data show adolescents mounted stronger humoral immune responses after vaccination than adults. It also highlights the need for future studies of antibody durability in adolescents and children as well as the need for future studies of booster vaccination and their efficacy against the Omicron variant.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/jvi.00582-22
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
    detail.hit.zdb_id: 1495529-5
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  • 5
    Online Resource
    Online Resource
    A Respiratory Syncytial Virus Attachment Gene Variant Associated with More Severe Disease in Infants Decreases Fusion Protein Expression, Which May Facilitate Immune Evasion
    American Society for Microbiology ; 2020
    In:  Journal of Virology Vol. 95, No. 2 ( 2020-12-22)
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 95, No. 2 ( 2020-12-22)
    Abstract: This study identified a genotype of respiratory syncytial virus (RSV) associated with increased acute respiratory disease severity in a cohort of previously healthy term infants. The genotype (2stop+A4G) consists of two components. The A4G component is a prevalent point mutation in the 4th position of the gene end transcription termination signal of the G gene of currently circulating RSV strains. The 2stop component is two tandem stop codons at the G gene terminus, preceding the gene end transcription termination signal. To investigate the biological role of these RSV G gene mutations, recombinant RSV strains harboring either a wild-type A2 strain G gene (one stop codon preceding a wild-type gene end signal), an A4G gene end signal preceded by one stop codon, or the 2stop+A4G virulence-associated combination were generated and characterized. Infection with the recombinant A4G (rA4G) RSV mutant resulted in transcriptional readthrough and lower G and fusion (F) protein levels than for the wild type. Addition of a second stop codon preceding the A4G point mutation (2stop+A4G) restored G protein expression but retained lower F protein levels. These data suggest that RSV G and F glycoprotein expression is regulated by transcriptional and translational readthrough. Notably, while rA4G and r2stop+A4G RSV were attenuated in cells and in naive BALB/c mice compared to that for wild-type RSV, the r2stop+A4G RSV was better able to infect BALB/c mice in the presence of preexisting immunity than rA4G RSV. Together, these factors may contribute to the maintenance and virulence of the 2stop+A4G genotype in currently circulating RSV-A strains. IMPORTANCE Strain-specific differences in respiratory syncytial virus (RSV) isolates are associated with differential pathogenesis in mice. However, the role of RSV genotypes in human infection is incompletely understood. This work demonstrates that one such genotype, 2stop+A4G, present in the RSV attachment (G) gene terminus is associated with greater infant disease severity. The genotype consists of two tandem stop codons preceding an A-to-G point mutation in the 4th position of the G gene end transcription termination signal. Virologically, the 2stop+A4G RSV genotype results in reduced levels of the RSV fusion (F) glycoprotein. A recombinant 2stop+A4G RSV was better able to establish infection in the presence of existing RSV immunity than a virus harboring the common A4G mutation. These data suggest that regulation of G and F expression has implications for virulence and, potentially, immune evasion.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.01201-20
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2020
    detail.hit.zdb_id: 1495529-5
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  • 6
    Online Resource
    Online Resource
    Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera
    American Society for Microbiology ; 2021
    In:  Microbiology Spectrum Vol. 9, No. 2 ( 2021-10-31)
    Details
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 9, No. 2 ( 2021-10-31)
    Abstract: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for a global pandemic with over 152 million cases and 3.19 million deaths reported by early May 2021. Understanding the serological response to SARS-CoV-2 is critical to determining the burden of infection and disease (coronavirus disease 2019 [COVID-19]) and transmission dynamics. We developed a capture IgM assay because it should have better sensitivity and specificity than the commonly used indirect assay. Here, we report the development and performance of a capture IgM enzyme-linked immunosorbent assay (ELISA) and a companion indirect IgG ELISA for the spike (S) and nucleocapsid (N) proteins and the receptor-binding domain (RBD) of S. We found that among the IgM ELISAs, the S ELISA was positive in 76% of 55 serum samples from SARS-CoV-2 PCR-positive patients, the RBD ELISA was positive in 55% of samples, and the N ELISA was positive in 15% of samples. The companion indirect IgG ELISAs were positive for S in 89% of the 55 serum samples, RBD in 78%, and N in 85%. While the specificities for IgM RBD, S, and N ELISAs and IgG S and RBD ELISAs were 97% to 100%, the specificity of the N IgG ELISA was lower (89%). RBD-specific IgM antibodies became undetectable by 3 to 6 months, and S IgM reached low levels at 6 months. The corresponding IgG S, RBD, and N antibodies persisted with some decreases in levels over this time period. These capture IgM ELISAs and the companion indirect IgG ELISAs should enhance serologic studies of SARS-CoV-2 infections. IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has inflicted tremendous loss of lives, overwhelmed health care systems, and disrupted all aspects of life worldwide since its emergence in Wuhan, China, in December 2019. Detecting current and past infection by PCR or serology is important to understanding and controlling SARS-CoV-2. With increasing prevalence of past infection or vaccination, IgG antibodies are less helpful in diagnosing a current infection. IgM antibodies indicate a more recent infection and can supplement PCR diagnosis. We report an alternative method, capture IgM, to detect serum IgM antibodies, which should be more sensitive and specific than most currently used methods. We describe this capture IgM assay and a companion indirect IgG assay for the SARS-CoV-2 spike (S), nucleocapsid (N), and receptor-binding domain (RBD) proteins. These assays can add value to diagnostic and serologic studies of coronavirus disease 2019 (COVID-19).
    Type of Medium: Online Resource
    ISSN: 2165-0497
    URL: Article
    DOI: 10.1128/Spectrum.00458-21
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2021
    detail.hit.zdb_id: 2807133-5
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