ABSTRACT The production of virus-like particles (VLPs) constitutes a relevant and safe model to study molecular determinants virion egress. minimal requirement for the assembly VLPs coronavirus responsible severe acute respiratory syndrome in humans (SARS-CoV) is still controversial. Recent studies have shown that SARS-CoV VLP formation depends on either M E proteins or N proteins. Here we show both must be coexpressed with protein efficient release by transfected Vero E6 cells. This...

ABSTRACT Public health measures successfully contained outbreaks of the severe acute respiratory syndrome coronavirus (SARS-CoV) infection. However, precursor SARS-CoV remains in its natural bat reservoir, and reemergence a human-adapted SARS-like plausible public concern. Vaccination is major strategy for containing resurgence SARS humans, number vaccine candidates have been tested experimental animal models. We previously reported that antibody elicited by candidate based on recombinant...

Post-translational modifications and correct subcellular localization of viral structural proteins are prerequisites for assembly budding enveloped viruses. Coronaviruses, like the severe acute respiratory syndrome-associated virus (SARS-CoV), bud from endoplasmic reticulum-Golgi intermediate compartment. In this study, distribution maturation SARS-CoV surface S, M E were analysed by using C-terminally tagged proteins. As early as 30 min post-entry into reticulum, high-mannosylated S...

Intercellular tight junctions define epithelial apicobasal polarity and form a physical fence which protects underlying tissues from pathogen invasions. PALS1, junction-associated protein, is member of the CRUMBS3-PALS1-PATJ complex, crucial for establishment maintenance in mammals. Here we report that carboxy-terminal domain SARS-CoV E small envelope protein (E) binds to human PALS1. Using coimmunoprecipitation pull-down assays, show interacts with PALS1 mammalian cells further demonstrate...

Human coronaviruses are associated with upper respiratory tract infections that occasionally spread to the lungs and other organs. Although airway epithelial cells represent an important target for infection, epithelium is also composed of elaborate network dendritic (DCs) essential sentinels immune system, sensing pathogens presenting foreign antigens T lymphocytes. In this report, we show in vitro infection by human coronavirus 229E (HCoV-229E) induces massive cytopathic effects DCs,...

Antiviral immune defenses involve natural killer (NK) cells. We previously showed that the NK-activating receptor NKp44 is involved in functional recognition of H1-type influenza virus strains by NK In present study, we investigated interaction and hemagglutinin a primary H5N1 isolate. Here show recombinant recognizes H5-expressing cells specifically interacts with soluble H5 hemagglutinin. H5-pseudotyped lentiviral particles bind to expressing NKp44. Following target H5, pseudotyped...

ABSTRACT The influenza A virus M2 ion channel protein has the longest cytoplasmic tail (CT) among three viral envelope proteins and is well conserved between different strains. It accessible to host cellular machinery after fusion with endosomal membrane during trafficking, assembly, budding processes. We hypothesized that identification of interactants CT could help us better understand molecular mechanisms regulating M2-dependent stages life cycle. Using yeast two-hybrid screening as bait,...

Background Flavivirus infected cells produce infectious virions and subviral particles, both of which are formed by the assembly prM E envelope proteins believed to undergo same maturation process. Dengue recombinant particles have been produced in cell cultures with either modified or chimeric but not using native forms E. Methodology/Principal Findings We used a codon optimization strategy obtain an efficient expression viral production (RSPs) for all four dengue virus (DV) serotypes. A...

Identification and characterization of virus-host interactions are very important steps toward a better understanding the molecular mechanisms responsible for disease progression pathogenesis. To date, few cellular factors involved in life cycle flaviviruses, which human pathogens, have been described. In this study, we demonstrate crucial role class II Arf proteins (Arf4 Arf5) dengue flavivirus cycle. We show that simultaneous depletion Arf4 Arf5 blocks recombinant subviral particle...

Background Entry of Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and its envelope fusion with host cell membrane are controlled by a series complex molecular mechanisms, largely dependent on the viral glycoprotein Spike (S). There still many unknowns implication cellular factors that regulate entry process. Methodology/Principal Findings We performed yeast two-hybrid screen using as bait carboxy-terminal endodomain S, which faces cytosol during after opening pore at early stages...

Actin polymerization plays a critical role in activated T lymphocytes both regulating cell receptor (TCR)-induced immunological synapse (IS) formation and signaling. Using gene targeting, we demonstrate that the hematopoietic specific, actin- Arp2/3 complex-binding protein coronin-1A contributes to processes. Coronin-1A-deficient mice specifically showed alterations terminal development survival of alpha beta cells, together with defects activation cytokine production following TCR...

Coronin has been described as an actin-binding protein of Dictyostelium discoideum, and it demonstrated to play a role in cell migration, cytokinesis phagocytosis. Coronin-related proteins are found many eukaryotic species, including Coronin-1 mammals whose expression is enriched the hematopoietic tissues. Here, we characterize gene mouse embryonic adult T lymphocytes. expressed throughout ontogeny peripheral alphabeta cells. Expression varies along thymic development, with maximum levels...

To identify new host factors that modulate the replication of influenza A virus, we performed a yeast two-hybrid screen using cytoplasmic tail matrix protein 2 from highly pathogenic H5N1 strain. The revealed high-score interaction with cyclin D3, key regulator cell cycle early G1 phase. M2-cyclin D3 was validated through GST pull-down and recapitulated in A/WSN/33-infected cells. Knockdown Ccnd3 by small interfering RNA significantly enhanced virus progeny titers culture supernatants....

Hydrophilic lung surfactant proteins have emerged as key immunomodulators which are potent at the recognition and clearance of pulmonary pathogens. Surfactant protein A (SP-A) is a surfactant-associated innate immune molecule, known to interact with variety pathogens, display anti-microbial effects. SP-A, being carbohydrate pattern has wide range functions against respiratory including influenza virus (IAV). Some pandemic pH1N1 strains resist neutralization by SP-A due differences in...

C4b Binding Protein (C4BP) is a major fluid phase inhibitor of the classical and lectin pathways complement system. Complement inhibition achieved by binding to restricting role activated component C4b. C4BP functions as co-factor for factor I in proteolytic inactivation both soluble cell surface-bound C4b, thus formation C3-convertase, C4b2a. also accelerates natural decay/dissociation C3 convertase. This makes prime target exploitation pathogens escape attack, seen Streptococcus pyogenes...

Surfactant protein D (SP-D), a C-type collagen containing lectin (collectin), is expressed in the mucosal secretion of lung and contribute to innate host defence against variety pathogens, including influenza A virus (IAV). SP-D has been shown inhibit haemagglutination activity infectivity IAV, addition reducing neuraminidase (NA) activity. exhibits strong anti-IAV by virtue its carbohydrate recognition domain (CRD) binding pattern (N-linked mannosylated) on NA hemagglutinin (HA) IAV. Here,...

Intercellular tight junctions define epithelial apicobasal polarity and form a physical fence which protects underlying tissues from pathogen invasions. PALS1, junction-associated protein, is member of the CRUMBS3-PALS1-PATJ complex, crucial for establishment maintenance in mammals. Here we report that carboxy-terminal domain SARS-CoV E small envelope protein (E) binds to human PALS1. Using co-immunoprecipitation pull-down assays, show interacts with PALS1 mammalian cells further demonstrate...

Surfactant protein D (SP-D) is a soluble C-type lectin, belonging to the collectin (collagen-containing calcium-dependent lectin) family, which acts as an innate immune pattern recognition molecule in lungs at other mucosal surfaces. Immune regulation and surfactant homeostasis are salient functions of SP-D. SP-D can bind range viral, bacterial, fungal pathogens trigger clearance mechanisms. binds gp120, envelope expressed on HIV-1, through its lectin or carbohydrate domain. This importance...

The complement system is designed to recognise and eliminate invading pathogens via activation of classical, alternative lectin pathways. Human properdin stabilises the pathway C3 convertase, resulting in an amplification loop that leads formation C5 thereby acting as a positive regulator pathway. It has been noted human on its own can operate pattern recognition receptor exert immune functions outside involvement activation. Properdin bind directly microbial targets DNA, sulfatides...

The complement system is an ancient innate immune defence mechanism that can recognise molecular patterns on the invading pathogens. Factor H, as inhibitor of alternative pathway, down-regulates activation host cell surface. Locally synthesised factor H at site infection/injury, including lungs, act a pattern recognition molecule without involving activation. Here, we report sialic acid binder, interacts with influenza A virus (IAV) and modulates IAV replication, observed by upregulation...

The complement system is an innate immune mechanism against microbial infections. It involves a cascade of effector molecules that activated via classical, lectin and alternative pathways. Consequently, many pathogens bind to or incorporate in their structures host negative regulators the pathways as evasion mechanism. Factor H (FH) regulator pathway protects "self" cells from non-specific attack. FH has been shown viruses including human influenza A (IAVs). In addition its involvement...