Biology subjects

Idris, F.

Publications and source records attributed to Idris, F..

3 recordsLinked to original sources

bioRxiv2025

N153-linked glycans on envelope protein protect orthoflaviviruses from antibody-mediated clearance

The envelope (E) protein of dengue virus (DENV) is glycosylated at two highly conserved asparagine (N) sites (N67 and N153). The role and importance of these N-linked glycans in DENV pathogenesis has been elusive. Here, we report the critical role of N153-linked glycans on E protein in preventing antibody-mediated viral clearance. A DENV2 mutant lacking N153-linked glycans (N153Q mutant) was engineered and found to be mildly impaired in vitro but drastically attenuated in a symptomatic mouse model of severe dengue, as evidenced by accelerated viral clearance. In B cell-deficient mouse models, N153Q mutant displayed parental virulence and viremia profile. Homologous and heterologous passive transfers of purified IgM from infected B cell-proficient mice into B cell-deficient mice demonstrated the role of N153Q-specific IgM in N153Q attenuation and accelerated clearance, while WT DENV was unaffected by IgM from both WT- and N153Q-infected mice. Furthermore, in vitro neutralization assay supported that the accelerated clearance of N153Q mutant in mice was mediated by non-neutralizing IgM. Furthermore, using plasma samples from convalescent dengue patients and monoclonal antibodies, in vitro neutralization assays showed that N153Q virus was more susceptible than WT to IgG-mediated neutralization. Glycoproteomics combined with molecular dynamics (MD) simulations revealed that glycan composition on E protein influenced IgG binding. Our findings were extended to all DENV serotypes and ZIKV, hence supporting that the N153 glycans-mediated immune evasion strategy is conserved across orthoflaviviruses.

microbiology↗

bioRxiv2018

Establishment of murine in vitro blood-brain barrier models using immortalized cell lines: co-cultures of brain endothelial cells, astrocytes, and neurons

Blood-brain barrier (BBB) is a selective barrier formed by the endothelial cells that line cerebral microvessels. It serves as a physical barrier due to the presence of complex tight junctions between adjacent endothelial cells which limits the paracellular movement of most molecules across the BBB. Many in vitro models of the BBB have been established to mimic these in vivo properties with limited success. In this study, we described the properties of a cell-based murine in vitro BBB model in five configurations constructed using immortalized cell lines in a 12-well format Transwell system: murine brain endothelial cells (bEnd.3) grown in a monoculture, or as co-culture in contact with astrocytes, or without contact with astrocytes or neurons, and triple co-culture combining the three cell lines. We found that only contact and triple co-culture model closely mimic the in vivo BBB tightness as evaluated by apparent permeability (Papp) of sucrose and albumin producing the lowest Papp values of 0.56 {+/-} 0.16 x 10-6 cms-1 and 3.30 {+/-} 0.51 x 10-6 cms-1, respectively, obtained in triple co-culture model. Co-culturing of bEnd.3 with astrocytes increased the expression of occludin as shown by western blot analysis, and immunohistochemistry showed an increase in peripheral localization of occludin and claudin-5. In addition, we found conditioned media were able to increase in vitro BBB model tightness through the modulation of tight junction proteins localization. We conclude that the presence of astrocytes and neurons in close proximity to brain endothelial cells is essential to produce a tight in vitro BBB model.

cell biology↗

bioRxiv2018

Effectiveness of physical inactivation methods of dengue virus: heat- versus UV-inactivation

IntroductionComplete inactivation of virus is crucial before samples are manipulated outside of biological containment areas or general cleaning. There are several control methods that could decrease the risk from viral contamination on surfaces, which include chemical disinfectants, heating sterilisation, and ultraviolet germicidal irradiation depending on the nature and properties of the materials to be sterilised. To date, there are limited studies reporting the effectiveness of physical inactivation methods of dengue virus. Therefore, this study was designed to evaluate the effectiveness of two physical inactivation methods, which are heat- and ultraviolet-inactivation, against dengue virus.\n\nMaterial and methodsAll dengue virus serotypes were subjected to heat treatment at various temperatures and exposed to UV light (wavelength of 250-270 nm) at a distance of approximately 75 cm in a Class II Biosafety cabinet (ESCO) at room temperature. The effectiveness of inactivation methods was tested using viability testing on Vero cells and immunofluorescence assay.\n\nResultsDengue virus can be effectively inactivated by heat treatment at 56{degrees}C for at least 30 minutes or at higher temperature. On the other hand, the virus required 45 minutes or longer of ultraviolet light exposure at 75 cm distance from the source to be completely inactivated.\n\nConclusionThe results indicated that DENV can be effectively inactivated using high temperature, i.e. 56{degrees}C or above, and UV light irradiation. This result would serve as guidelines in proper decontamination and control of dengue virus in laboratory settings, provided proper conditions are met.

microbiology↗