Biology subjects

Vasilev, K.

Publications and source records attributed to Vasilev, K..

4 recordsLinked to original sources

bioRxiv2025

A surface-engineered microfluidic device for antibody-mediated negative selection of high-quality sperm for assisted reproduction

Preparation of spermatozoa with optimal developmental competence remains a challenge in assisted reproduction. Conventional techniques based on sperm motility and morphology fail to adequately remove sperm with DNA damage. Here, we report development of a microfluidic device with a functionalized surface, inspired by the physiological processes of immune cell-mediated sperm selection in the female reproductive tract. A plasma-polymerized polyoxazoline (PPOx) film is applied to glass channel slides by deposition of 2-methyl-2-oxazoline, to establish a stable, biocompatible interface confirmed by X-ray Photoelectron Spectroscopy (XPS), ellipsometry, and sperm culture assays. To selectively eliminate pre-apoptotic and apoptotic spermatozoa wherein DNA damage is common, anti-phosphatidylserine (Anti-PS) antibody is immobilized to the PPOx-coated surface proximal to the channel slide inlet, while the sperm chemoattractant progesterone is adsorbed near the outlet. To optimise selective functionality, the surface topography is tailored by covalent immobilization of gold nanoparticles and addition of microchannels. Sperm recovered after processing whole liquified semen then consistently exhibit high motility and morphology, with <1% showing apoptosis-associated membrane damage or DNA fragmentation. Compared with conventional swim-up or other microfluidic approaches, the device yields sperm with improved quality, offering a simple one-step sperm selection strategy with potential for application in human and animal assisted reproduction. Short text and graphic for 45 the Table of Contents (ToC)This study reports a microfluidic device with a functionalized surface utilizing a polyoxazoline coating and covalently immobilized gold nanoparticles and anti-phosphatidylserine antibody. The device selectively eliminates pre-apoptotic and apoptotic spermatozoa and yields sperm with substantially improved quality and low DNA damage, offering a simple one-step sperm selection device with potential for application in human and animal assisted reproduction. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=166 SRC="FIGDIR/small/673619v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@b07026org.highwire.dtl.DTLVardef@192e5b5org.highwire.dtl.DTLVardef@127095aorg.highwire.dtl.DTLVardef@1d70ceb_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

A clade 2.3.4.4b H5N1 virus vaccine that elicits cross-protective antibodies against conserved domains of H5 and N1 glycoproteins

The continuous evolution and widespread dissemination of highly pathogenic avian influenza (HPAI) H5N1 viruses, particularly clade 2.3.4.4b, pose critical challenges to global pandemic preparedness. In this study, we assessed a low-dose inactivated split virus vaccine derived from clade 2.3.4.4b H5N1, formulated with an Alum/CpG adjuvant, using a preclinical mouse model. This vaccine induced potent humoral and cellular immune responses, generating high titers of cross-reactive antibodies targeting both hemagglutinin (HA) and neuraminidase (NA) glycoproteins across homologous and heterologous H5 clades. The Alum/CpG adjuvant enabled significant antigen dose-sparing while promoting a balanced Th1/Th2 immune profile. Functional analyses demonstrated strong virus neutralization, neuraminidase inhibition, and potent antibody-dependent cellular cytotoxicity activity. Additionally, the vaccine elicited robust antigen-specific CD4+ and CD8+ T cell responses and effectively controlled viral replication in the lungs, accompanied by reduced lung inflammation. Importantly, vaccinated mice were fully protected against lethal challenges with both the homologous clade 2.3.4.4b and heterologous clade 1 H5N1 viruses, despite low hemagglutination inhibition titers. Electron microscopy polyclonal epitope mapping revealed serum antibodies targeting multiple epitopes on homologous HA and NA, with some cross-reacting to conserved epitopes on heterologous proteins, underscoring broad immune recognition. Collectively, these results highlight the potential of this vaccine candidate to provide broad, multifunctional, and durable immunity against both current and emerging H5N1 threats, supporting its further development for pandemic preparedness.

microbiology↗

bioRxiv2025

Characterization of the glycoproteins of novel fish influenza B-like viruses

Novel influenza-like virus sequences previously identified in fish and amphibians were found to cluster as a sister clade of influenza B viruses, but have thus far remained uncharacterized. We demonstrate that salamander influenza-like virus (SILV) HA is functionally divergent from influenza B virus HA and does not bind to 2,3- and 2,6-linked sialic acids. However, the HAs of Siamese algae-eater influenza-like virus (SAEILV) and chum salmon influenza-like virus (CSILV) bind to 2,3 linked sialic acid. Furthermore, SAEILV HA binds to sialyated Lewis X, is activated by human airway enzymes and is fusogenic at a wide range of pH conditions. SAEILV NA has a highly conserved active site and a similar structure to other known NAs. We also determined the cryo-electron microscopy structure of the HA of a previously described virus from the same sister clade, the Wuhan spiny eel influenza virus (WSEIV). Importantly, no cross-reactive antibodies against these HAs or NAs were found in the human serum, suggesting that humans are immunologically naive to these viruses. One sentence summaryNovel influenza like-viruses, displayed different target receptor specificity and limited antigenic conservation of the HA and NA relative to influenza B Viruses.

microbiology↗

bioRxiv2025

Immunogenicity and protective efficacy of an intranasal neuraminidase-based influenza virus vaccine adjuvanted with bacterial cell membrane-derived adjuvants

Influenza virus neuraminidase (NA) has emerged as a promising vaccine candidate due to its relatively stable antigenic structure and the ability of NA-specific antibodies to provide cross-protection within influenza virus subtypes. Since the influenza virus causes respiratory infections in humans, developing mucosal vaccines to protect the entry site of the virus is of high importance. Recombinant NA requires adjuvants to induce a protective immune response after mucosal administration. In the current study, we analyze the immunogenicity and protective efficacy of a recombinant NA-based influenza virus vaccine administered intranasally in combination with adjuvants consisting of outer membrane proteins from Neisseria meningitidis complexed with exogenous lipopolysaccharides (LPS) from Shigella flexneri or endogenous LPS from N. meningitidis. We evaluated the local and systemic humoral and cellular immune responses to adjuvanted recombinant N1 NA, analyzing the dynamics of local follicular T-helper (Tfh) cells and germinal center B cells (GCB) in nasal-associated lymphoid tissue (NALT) and tissue-resident memory T cells in lungs, as well as the levels of IgA and IgG in the upper and lower respiratory tracts. Finally, we performed a heterologous challenge study to test the ability of the investigated vaccine formulations to induce cross-protection. The study demonstrates that bacterial cell membrane-derived adjuvants significantly improve the immunogenicity and protective efficacy of the recombinant N1 NA-based influenza vaccine leading to protection against clade 2.3.4.4b H5N1 challenge. This finding supports the potential of these adjuvanted vaccines in providing effective mucosal immunity against influenza virus.

microbiology↗