Biology subjects

Biswas, P. K.

Publications and source records attributed to Biswas, P. K..

3 recordsLinked to original sources

bioRxiv2026

H9N2 avian influenza virus in Bangladesh: three genetically distinct co-circulating subgroups retain a largely conserved antigenic phenotype

Low pathogenic avian influenza (LPAI) H9N2 viruses are endemic in poultry across Bangladesh, causing substantial economic losses and posing a persistent zoonotic risk. Although genetic surveillance has documented ongoing viral evolution, the relationship between genetic diversification and antigenic change remains poorly understood. This study investigated the genetic diversity, reassortment, and antigenic characteristics of contemporary H9N2 viruses circulating in Bangladesh. Phylogenetic analysis of 219 sampled sequences revealed three genetically distinct monophyletic haemagglutinin (HA) G-lineage sub-groups, each characterised by unique amino acid substitutions. In contrast, neuraminidase (NA) displayed similar genetic diversity without distinct phylogenetic clusters. A dual-metric analysis of paired HA and NA phylogenies identified 20 putative reassortant H9N2 viruses. Further analysis showed that genetic diversity was geographically structured; however, all three HA subgroups co-circulated across multiple regions, and some live bird markets contained representatives of all three groups simultaneously, suggesting that live bird markets may facilitate mixing between genetically distinct viruses, and create opportunities for reassortment among otherwise geographically separated strains. Despite substantial genetic diversity and reassortment, all viruses remained antigenically similar based on haemagglutination inhibition and virus neutralisation assays. However, a representative strain from one subgroup induced significantly lower homologous and heterologous antibody titres, suggesting reduced immunogenicity. Our findings demonstrate a notable disconnect between genetic evolution and antigenic change in Bangladeshi H9N2 viruses. While reassortment and genetic diversification continue to shape viral populations, antigenic properties remain largely conserved, supporting the continued relevance of current vaccine strategies while highlighting the importance of ongoing genetic and antigenic surveillance.

microbiology↗

bioRxiv2026

Modeling centrosome positioning by actin--microtubule crosstalk and actin anchoring at the cell membrane

Centrosome positioning is governed by mechanical interactions between the actin and microtubule cytoskeletons, yet the contribution of different actin architectures and their attachment to the cell membrane remains unclear. We use numerical simulations to study a centrosomal array of microtubules interacting with cortical, bulk, and centrosome-associated actin networks, including passive cross-linkers, motor proteins, and ERM-mediated coupling of actin to the cell membrane. We find that bulk and centrosome-associated actin alone are insufficient for robust centrosome centering, whereas sufficiently dense cortical actin promotes centering through steric interactions with growing microtubules. ERM-mediated attachment of cortical actin to the cell membrane enhances this effect, allowing stable centering at lower actin densities. In a two-centrosome system, microtubule interactions generate a spindle-like structure, while the organization of actin and its membrane attachment through ERM regulate centrosome separation. Antagonistic microtubule motors further limit centrosome separation and establish a finite spindle length. These results demonstrate that ERM-mediated coupling of actin to the cell membrane provides an important mechanical link between the actin cortex and microtubule-driven centrosome positioning, influencing both centrosome centering and spindle geometry.

biophysics↗

bioRxiv2023

Amplification of avian influenza viruses along poultry marketing chains in Bangladesh: a controlled field experiment

The prevalence of avian influenza viruses (AIVs) is commonly found to increase dramatically from farms to live bird markets (LBMs). Viral transmission dynamics along marketing chains is, however, poorly understood. To address this gap, we implemented a field experiment altering chicken supply to an LBM in Chattogram, Bangladesh. Chickens traded along altered (intervention) and conventional (control) marketing chains were tested for AIVs. Upon arrival at the LBM, the odds of detecting AIVs did not differ between control and intervention groups. However, 12 hours later, intervention group odds were lower, particularly for broiler chickens, indicating that viral shedding in LBM resulted partly from infections during transport and trade. Curtailing AIV prevalence in LBMs requires mitigating risk in marketing chain nodes preceding chickens delivery at LBMs. Article Summary LineThe high prevalence of avian influenza viruses in marketed chickens cannot be solely attributed to viral transmission within live bird markets but is also influenced by infections occurring prior to the chickens supply to these markets.

ecology↗