Biology subjects

Jafri, M. S.

Publications and source records attributed to Jafri, M. S..

5 recordsLinked to original sources

bioRxiv2025

Zoonotic and Avian Pathogen Detections in Fecal and Sediment Samples - A Low-risk, High-throughput One Health Approach to Surveillance

Many pathogens, both those with human spillover potential as well as avian-specific viruses, are maintained in wild bird populations. While routine surveillance for influenza A viruses (IAVs) is performed annually, surveillance for other pathogens is limited. Sampling of wild birds is time-consuming, labour-intensive, often limited in sample size, and involves handling of wild and potentially infected birds, posing an increased risk of direct exposure for personnel. Additional methods for surveillance are needed given these significant challenges. Longitudinal fecal and sediment sampling was performed at various sites in southern Manitoba, Canada, particularly focused in Winnipeg from May to October 2025. Sites were chosen based on the suitability of the area for waterfowl habitat, the presence of waterfowl in the area, as well as proximity to reported outbreaks of H5N1 influenza virus. Fecal and sediment samples were collected and screened for the presence of influenza A virus (IAV), Newcastle disease virus (NDV), avian reovirus (ARV), and avian poxvirus (APXV). In total, 782 combined fecal and sediment samples were collected. Of the 714 fecal samples, 34 tested positive for IAV RNA (4.8% prevalence). None of the IAV-positive fecal samples tested positive for H5 RNA. Of the 68 sediments, 15 were positive for IAV RNA (22.1% prevalence), four of which were positive for H5 RNA. NDV RNA positivity was low, with only four positive fecal samples (0.6% prevalence) that were all collected on the same day. ARV RNA positivity was also low, with five positive sediment samples (7.4% prevalence in sediment samples). None of the samples tested positive for APXV DNA. This study builds on previous work showing the utility of environmental sampling for a variety of avian and zoonotic pathogens using a One Health approach that is low-risk, efficient, and high-throughput.

microbiology↗

bioRxiv2025

The decameric repeat (DR) of PSGL-1 functions as a basic antiviral unit in restricting HIV-1 infectivity

PSGL-1 (P-selectin glycoprotein ligand-1) is a dimeric, mucin-like surface glycoprotein that interacts with selectins on the endothelium, facilitating leukocyte tethering and rolling during transmigration. Previous studies have demonstrated that PSGL-1 acts as an HIV restriction factor, blocking HIV infectivity by hindering particle attachment to target cells. A large part of PSGL-1s extracellular region consists of a mucin-like domain, characterized by decameric repeats (DR), which comprise 14 to 16 DR tandems. Each DR is composed of 10 consensus amino acids (-A-T/M-E-A-Q-T-T-X-P/L-A/T-) and is notably rich in O-glycosylated threonines (30%) and prolines (10%). A proposed function of the DR is to elongate the protein backbone needed for selectin binding. However, the precise role of DR in PSGL-1s antiviral mechanisms has yet to be fully elucidated. In this study, we performed DR deletion mutagenesis and molecular modeling, systematically deleting from one DR to all DRs, and quantified their effects on PSGL-1s antiviral functions. Here, we demonstrate that DR is necessary for PSGL-1s antiviral activity. Deleting DR did not affect virion incorporation of PSGL-1, but diminished PSGL-1s ability to hinder virion attachment to target cells. We also discovered that individual single DR mutants retained 3.5 to 18% of the antiviral activity exhibited by full-length PSGL-1, and the basic antiviral activity of DR is cumulative; increasing the number of DRs correlates with heightened antiviral activity. Additionally, the intrinsic anti-HIV capability of DR was found to be transferrable; inserting the DR domain into the extracellular Ig-like domain of CD2 permitted the hybrid CD2-DR molecules to partially acquire the anti-HIV properties of PSGL-1. Further molecular modeling utilizing all-atom replica exchange molecular dynamics simulations highlighted a structure-function relationship between the anti-HIV potency of DR and the elongation of the DR backbone, as measured by DR backbone dihedral angles ({varphi}) and the radial distributions of peptide atom number density (rmax). These results collectively suggest that DR serves as an essential antiviral unit within the framework of PSGL-1s restriction mechanism against HIV.

immunology↗

bioRxiv2024

PSGL-1 excludes HIV Env from virion surface through spatial hindrance involving structural folding of the decameric repeats (DR)

P-selectin glycoprotein ligand-1 (PSGL-1), a mucin-like surface glycoprotein, is primarily expressed on lymphoid and myeloid cells. PSGL-1 has recently been identified as an HIV restriction factor, blocking HIV infectivity mainly through virion incorporation that sterically hinders virion attachment to target cells. PSGL-1 also inhibits HIV Env incorporation into virions. However, the molecular mechanisms of PSGL-1-mediated Env exclusion remained unclear. Here, we investigated the role of PSGL-1s extracellular (EC) and intracellular (IC) domains in Env exclusion. We demonstrate that both EC and IC are important for Env exclusion; when EC was deleted, PSGL-1 completely lost its ability to inhibit Env incorporation, whereas when IC was deleted, PSGL-1 partially lost this activity. In addition, when the decameric repeats (DR) were deleted from EC, PSGL-1 also lost its ability to inhibit Env incorporation. Sequential DR deletion mutagenesis further demonstrated that a minimum of 9 DRs is necessary for Env exclusion. Molecular modeling of the DR structure revealed that PSGL-1 mutants with 7 or fewer DRs pose as an extended "rod-like" structure, whereas those with 9 or more DRs collapse into a "coil-like" structure that spatially excludes Env. Our studies suggest a model in which Env exclusion involves Gag-mediated PSGL-1 targeting to the virion assembly site where DR-mediated spatial exclusion blocks Env incorporation.

microbiology↗

bioRxiv2019

lncRNAKB: A comprehensive knowledgebase of long non-coding RNAs

We have assembled a comprehensive long non-coding RNA knowledgebase (lncRNAKB) of 77,199 annotated human lncRNAs (224,286 transcripts) by methodically integrating widely used lncRNAs resources. To facilitate functional characterization of lncRNAs, we employed Genotype-Tissue Expression (GTEx) project to provide tissue-specific gene expression profiles of lncRNAs in 31 solid organ tissues. Additional information includes network analysis to identify co-expressed gene modules to potentially delineate lncRNA function. Tissue-specificity, phylogenetic conservation scores and coding potential for lncRNAs are included. Finally, using whole genome sequencing data from GTEx, expression quantitative trait loci (cis-eQTL) regulated lncRNAs were calculated in all tissues. lncRNAKB is available at http://www.lncrnakb.org.

bioinformatics↗

bioRxiv2018

SNP2SIM: A modular workflow for standardizing molecular simulation and functional analysis of protein variants

Molecular simulations are used to provide insight into protein structure and function, and have the potential to provide important context when predicting the impact of sequence variation on protein function. In addition to understanding molecular mechanisms and interactions on the atomic scale, translational applications of those approaches include drug screening, development of novel molecular therapies, and treatment planning when selecting targeted therapies. Supporting the continued development of these applications, we have developed the SNP2SIM workflow generates reproducible molecular dynamics and molecular docking simulations for downstream functional variant analysis. Three modules execute molecular dynamics simulations of solvated protein variant structures, analyze the resulting trajectories for unique structural conformations, and bind small molecule ligands to representative variant scaffolds. In addition to availability as a command line workflow, SNP2SIM modules are also available as individual apps on the Seven Bridges Cancer Genomics Cloud.

bioinformatics↗