Mannose binding lectin (MBL) and HIV

Comparative Assessment of Water Models in Protein-Glycan Interaction: Insights from Alchemical Free Energy Calculations and Molecular Dynamics Simulations

Accurate computational simulations of protein-glycan dynamics are crucial for a comprehensive understanding of critical biological mechanisms, including host-pathogen interactions, immune system defenses, and intercellular communication. The accuracy of these simulations, including molecular dynamics (MD) simulation and alchemical free energy calculations, critically relies on the appropriate parameters, including the water model, because of the extensive hydrogen bonding with glycan hydroxyl groups. However, a systematic evaluation of water models' accuracy in simulating protein-glycan interaction at the molecular level is still lacking. In this study, we used full atomistic MD simulations and alchemical absolute binding free energy (ABFE) calculations to investigate the performance of five distinct water models in six protein-glycan complex systems. We evaluated water models' impact on structural dynamics and binding affinity through over 5.8 μs of simulation time per system. Our results reveal that most protein-glycan complexes are stable in the overall structural dynamics regardless of the water model used, while some show obvious fluctuations with specific water models. More importantly, we discover that the stability of the binding motif's conformation is dependent on the water model chosen when its residues form weak hydrogen bonds with the glycan. The water model also influences the conformational stability of the glycan in its bound state according to density functional theory (DFT) calculations. Using alchemical ABFE calculations, we find that the OPC water model exhibits exceptional consistency with experimental binding affinity data, whereas commonly used models such as TIP3P are less accurate. The findings demonstrate how different water models affect protein-glycan interactions and the accuracy of binding affinity calculations, which is crucial in developing therapeutic strategies targeting these interactions.

Current status of mannose receptor-targeted drug delivery for improved anti-HIV therapy

In the pursuit of achieving better therapeutic outcomes in the treatment of HIV, innovative drug delivery strategies have been extensively explored. Mannose receptors, which are primarily found on macrophages and dendritic cells, offer promising targets for drug delivery due to their involvement in HIV pathogenesis. This review article comprehensively evaluates recent drug delivery system advancements targeting the mannose receptor. We have systematically described recent developments in creating and utilizing drug delivery platforms, including nanoparticles, liposomes, micelles, noisomes, dendrimers, and other nanocarrier systems targeted at the mannose receptor. These strategies aim to enhance drug delivery specificity, bioavailability, and therapeutic efficacy while decreasing off-target effects and systemic toxicity. Furthermore, the article delves into how mannose receptors and HIV interact, highlighting the potential for exploiting this interaction to enhance drug delivery to infected cells. The review covers essential topics, such as the rational design of nanocarriers for mannose receptor recognition, the impact of physicochemical properties on drug delivery performance, and how targeted delivery affects the pharmacokinetics and pharmacodynamics of anti-HIV agents. The challenges of these novel strategies, including immunogenicity, stability, and scalability, and future research directions in this rapidly growing area are discussed. The knowledge synthesis presented in this review underscores the potential of mannose receptor-based targeted drug delivery as a promising avenue for advancing HIV treatment. By leveraging the unique properties of mannose receptors, researchers can design drug delivery systems that cater to individual needs, overcome existing limitations, and create more effective and patient-friendly treatments in the ongoing fight against HIV/AIDS.

Inflammation in HIV and Its Impact on Atherosclerotic Cardiovascular Disease

People living with HIV have a 1.5- to 2-fold increased risk of developing cardiovascular disease. Despite treatment with highly effective antiretroviral therapy, people living with HIV have chronic inflammation that makes them susceptible to multiple comorbidities. Several factors, including the HIV reservoir, coinfections, clonal hematopoiesis of indeterminate potential (CHIP), microbial translocation, and antiretroviral therapy, may contribute to the chronic state of inflammation. Within the innate immune system, macrophages harbor latent HIV and are among the prominent immune cells present in atheroma during the progression of atherosclerosis. They secrete inflammatory cytokines such as IL (interleukin)-6 and tumor necrosis-α that stimulate the expression of adhesion molecules on the endothelium. This leads to the recruitment of other immune cells, including cluster of differentiation (CD)8+ and CD4+ T cells, also present in early and late atheroma. As such, cells of the innate and adaptive immune systems contribute to both systemic inflammation and vascular inflammation. On a molecular level, HIV-1 primes the NLRP3 (NLR family pyrin domain containing 3) inflammasome, leading to an increased expression of IL-1β, which is important for cardiovascular outcomes. Moreover, activation of TLRs (toll-like receptors) by HIV, gut microbes, and substance abuse further activates the NLRP3 inflammasome pathway. Finally, HIV proteins such as Nef (negative regulatory factor) can inhibit cholesterol efflux in monocytes and macrophages through direct action on the cholesterol transporter ABCA1 (ATP-binding cassette transporter A1), which promotes the formation of foam cells and the progression of atherosclerotic plaque. Here, we summarize the stages of atherosclerosis in the context of HIV, highlighting the effects of HIV, coinfections, and antiretroviral therapy on cells of the innate and adaptive immune system and describe current and future interventions to reduce residual inflammation and improve cardiovascular outcomes among people living with HIV.

The Role of the Complement System in the Pathogenesis of Infectious Forms of Hemolytic Uremic Syndrome

Hemolytic uremic syndrome (HUS) is an acute disease and the most common cause of childhood acute renal failure. HUS is characterized by a triad of symptoms: microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. In most of the cases, HUS occurs as a result of infection caused by Shiga toxin-producing microbes: hemorrhagic Escherichia coli and Shigella dysenteriae type 1. They account for up to 90% of all cases of HUS. The remaining 10% of cases grouped under the general term atypical HUS represent a heterogeneous group of diseases with similar clinical signs. Emerging evidence suggests that in addition to E. coli and S. dysenteriae type 1, a variety of bacterial and viral infections can cause the development of HUS. In particular, infectious diseases act as the main cause of aHUS recurrence. The pathogenesis of most cases of atypical HUS is based on congenital or acquired defects of complement system. This review presents summarized data from recent studies, suggesting that complement dysregulation is a key pathogenetic factor in various types of infection-induced HUS. Separate links in the complement system are considered, the damage of which during bacterial and viral infections can lead to complement hyperactivation following by microvascular endothelial injury and development of acute renal failure.

Highly pathogenic coronavirus N protein aggravates inflammation by MASP-2-mediated lectin complement pathway overactivation

Excessive inflammatory responses contribute to the pathogenesis and lethality of highly pathogenic human coronaviruses, but the underlying mechanism remains unclear. In this study, the N proteins of highly pathogenic human coronaviruses, including severe acute respiratory syndrome coronavirus (SARS-CoV), middle east respiratory syndrome coronavirus (MERS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), were found to bind MASP-2, a key serine protease in the lectin pathway of complement activation, resulting in excessive complement activation by potentiating MBL-dependent MASP-2 activation, and the deposition of MASP-2, C4b, activated C3 and C5b-9. Aggravated inflammatory lung injury was observed in mice infected with adenovirus expressing the N protein. Complement hyperactivation was also observed in SARS-CoV-2-infected patients. Either blocking the N protein:MASP-2 interaction, MASP-2 depletion or suppressing complement activation can significantly alleviate N protein-induced complement hyperactivation and lung injury in vitro and in vivo. Altogether, these data suggested that complement suppression may represent a novel therapeutic approach for pneumonia induced by these highly pathogenic coronaviruses.

A mechanistic analysis of bacterial recognition and serine protease cascade initiation in larval hemolymph of Manduca sexta

Serine protease cascades have evolved in vertebrates and invertebrates to mediate rapid defense responses. Previous biochemical studies showed that in hemolymph of a caterpillar, Manduca sexta, recognition of fungi by β-1,3-glucan recognition proteins (βGRP1 and βGRP2) or recognition of bacteria by peptidoglycan recognition protein-1 (PGRP1) and microbe binding protein (MBP) results in autoactivation of hemolymph protease-14 precursor (proHP14). HP14 then activates downstream members of a protease cascade leading to the melanization immune response. ProHP14 has a complex domain architecture, with five low-density lipoprotein receptor class A repeats at its amino terminus, followed by a Sushi domain, a Sushi domain variant called Wonton, and a carboxyl-terminal serine protease catalytic domain. Its zymogen form is activated by specific proteolytic cleavage at the amino-terminal end of the protease domain. While a molecular mechanism for recognition and triggering the response to β-1,3-glucan has been delineated, it is unclear how bacterial recognition stimulates proHP14 activation. To fill this knowledge gap, we expressed the two domains of M. sexta MBP and found that the amino-terminal domain binds to diaminopimelic acid-peptidoglycan (DAP-PG). ProHP14 bound to both the carboxyl-terminal domain (MBP-C) and amino-terminal domain (MBP-N) of MBP. In the mixture of DAP-PG, MBP, and larval plasma, inclusion of an HP14 fragment composed of LDLa repeats 2-5 (LDLa2-5) or MBP-C significantly reduced prophenoloxidase activation, likely by competing with the interactions of the full-length proteins, and suggesting that molecular interactions involving these regions of proHP14 and MBP take part in proHP14 activation in response to peptidoglycan. Using a series of N-terminally truncated versions of proHP14, we found that autoactivation required LDLa2-5. The optimal ratio of PGRP1, MBP, and proHP14 is close to 3:2:1. In summary, proHP14 autoactivation by DAP-type peptidoglycan requires binding of DAP-PG by PGRP1 and the MBP N-terminal domain and association of the LDLa2-5 region of proHP14 with the MBP C-terminal domain. These interactions may concentrate the proHP14 zymogen at the bacterial cell wall surface and promote autoactivation.

Mannan-Binding Lectin via Interaction With Cell Surface Calreticulin Promotes Senescence of Activated Hepatic Stellate Cells to Limit Liver Fibrosis Progression

BACKGROUND & AIMS

Liver fibrosis represents a hallmark of most chronic liver diseases (CLD) triggered by recurrent liver injury and subsequent myofibroblast transdifferentiations of resident hepatic stellate cells (HSCs). Mannan-binding lectin (MBL) is potentially involved in hepatic fibrosis in CLD through unclear mechanisms. Therefore, we investigated the crosstalk between MBL and HSCs, and the consequent effects on fibrosis progression.

METHODS

Samples from patients with liver cirrhosis were collected. MBL deficiency (MBL-/-) and wild-type (WT) C57BL/6J mice were used to construct a CCl4-induced liver fibrosis model. Administration of MBL-expressing, liver-specific, adeno-associated virus was performed to restore hepatic MBL expression in MBL-/- mice. The human HSC line LX-2 was used for in vitro experiments.

RESULTS

MBL levels in patients with liver cirrhosis were correlated with disease severity. In the CCl4-induced liver fibrosis model, MBL-/- mice showed severer liver fibrosis accompanied by reduced senescent activated HSCs in liver tissue compared with WT mice, which could be inhibited by administering MBL-expressing, liver-specific, adeno-associated virus. Moreover, depleting senescent cells with senolytic treatment could abrogate these differences owing to MBL absence. Furthermore, MBL could interact directly with calreticulin associated with low-density lipoprotein receptor-related protein 1 on the cell surface of HSCs, which further promotes senescence in HSCs by up-regulating the mammalian target of rapamycin/p53/p21 signaling pathway.

CONCLUSIONS

MBL as a newfound senescence-promoting modulator and its crosstalk with HSCs in the liver microenvironment is essential for the control of hepatic fibrosis progression, suggesting its potential therapeutic use in treating CLD associated with liver fibrosis.

Human immunodeficiency virus type 1 impairs sumoylation

The HIV type 1 dampens host cell sumoylation in vitro and reduces the expression of UBA2 protein, a subunit of the SUMO E1–activating enzyme. In vivo, infection in patients is associated with diminished global leukocyte sumoylation activity.

During infection, the human immunodeficiency virus type 1 (HIV-1) manipulates host cell mechanisms to its advantage, thereby controlling its replication or latency, and evading immune responses. Sumoylation is an essential post-translational modification that controls vital cellular activities including proliferation, stemness, or anti-viral immunity. SUMO peptides oppose pathogen replication and mediate interferon-dependent anti-viral activities. In turn, several viruses and bacteria attack sumoylation to disarm host immune responses. Here, we show that HIV-1 impairs cellular sumoylation and targets the host SUMO E1–activating enzyme. HIV-1 expression in cultured HEK293 cells or in CD4⁺ Jurkat T lymphocytes diminishes sumoylation by both SUMO paralogs, SUMO1 and SUMO2/3. HIV-1 causes a sharp and specific decline in UBA2 protein levels, a subunit of the heterodimeric SUMO E1 enzyme, which likely serves to reduce the efficiency of global protein sumoylation. Furthermore, HIV-1–infected individuals display a significant reduction in total leukocyte sumoylation that is uncoupled from HIV-induced cytopenia. Because sumoylation is vital for immune function, T-cell expansion and activity, loss of sumoylation during HIV disease may contribute to immune system deterioration in patients.

Conserved topology of virus glycoepitopes presents novel targets for repurposing HIV antibody 2G12

Complex glycans decorate viral surface proteins and play a critical role in virus-host interactions. Viral surface glycans shield vulnerable protein epitopes from host immunity yet can also present distinct "glycoepitopes" that can be targeted by host antibodies such as the potent anti-HIV antibody 2G12 that binds high-mannose glycans on gp120. Two recent publications demonstrate 2G12 binding to high mannose glycans on SARS-CoV-2 and select Influenza A (Flu) H3N2 viruses. Previously, our lab observed 2G12 binding and functional inhibition of a range of Flu viruses that include H3N2 and H1N1 lineages. In this manuscript, we present these data alongside structural analyses to offer an expanded picture of 2G12-Flu interactions. Further, based on the remarkable breadth of 2G12 N-glycan recognition and the structural factors promoting glycoprotein oligomannosylation, we hypothesize that 2G12 glycoepitopes can be defined from protein structure alone according to N-glycan site topology. We develop a model describing 2G12 glycoepitopes based on N-glycan site topology, and apply the model to identify viruses within the Protein Data Bank presenting putative 2G12 glycoepitopes for 2G12 repurposing toward analytical, diagnostic, and therapeutic applications.

A QCM study of strong carbohydrate-carbohydrate interactions of glycopolymers carrying mannosides on substrates

Carbohydrates on cell surfaces are known to interact not only with lectins but also with other carbohydrates; the latter process is known as a carbohydrate-carbohydrate interaction. Such interactions are observed in complex oligosaccharides. It would be surprising if these interactions were observed in simple monosaccharides of mannose. In this study, the interaction between glycopolymers carrying monosaccharides of mannose was quantitatively investigated by quartz crystal microbalance measurements. We measured the interactions with glycopolymers carrying mannose, galactose and glucose. Surprisingly, the interaction between the glycopolymers and mannose was much stronger than that between other saccharides.

CD46 Genetic Variability and HIV-1 Infection Susceptibility

CD46 is the main receptor for complement protein C3 and plays an important role in adaptive immune responses. CD46 genetic variants are associated with susceptibility to several infectious and autoimmune diseases. Additionally, CD46 function can be subverted by HIV-1 to evade attack by complement, a strategy shared by viruses of other families. We sought to determine the association between CD46 gene variants and HIV-1 acquired through intravenous drug use (IDU) and sexual routes (n = 823). Study subjects were of European ancestry and were HIV-1 infected (n = 438) or exposed but seronegative (n = 387). Genotyping of the rs2796265 SNP located in the CD46 gene region was done by allele-specific real-time PCR. A meta-analysis merging IDU and sexual cohorts indicates that the minor genotype (CC) was associated with increased resistance to HIV-1 infection OR = 0.2, 95% CI (0.07–0.61), p = 0.004. The HIV-1-protective genotype is correlated with reduced CD46 expression and alterations in the ratio of CD46 mRNA splicing isoforms.

Modulation of the Complement System by Neoplastic Disease of the Central Nervous System

The complement system is a highly conserved component of innate immunity that is involved in recognizing and responding to pathogens. The system serves as a bridge between innate and adaptive immunity, and modulation of the complement system can affect the entire host immune response to a foreign insult. Neoplastic diseases have been shown to engage the complement system in order to evade the immune system, gain a selective growth advantage, and co-opt the surrounding environment for tumor proliferation. Historically, the central nervous system has been considered to be an immune-privileged environment, but it is now clear that there are active roles for both innate and adaptive immunity within the central nervous system. Much of the research on the role of immunological modulation of neoplastic disease within the central nervous system has focused on adaptive immunity, even though innate immunity still plays a critical role in the natural history of central nervous system neoplasms. Here, we review the modulation of the complement system by a variety of neoplastic diseases of the central nervous system. We also discuss gaps in the current body of knowledge and comment on future directions for investigation.

Proteins Binding to the Carbohydrate HNK-1: Common Origins?

The human natural killer (HNK-1) carbohydrate plays important roles during nervous system development, regeneration after trauma and synaptic plasticity. Four proteins have been identified as receptors for HNK-1: the laminin adhesion molecule, high-mobility group box 1 and 2 (also called amphoterin) and cadherin 2 (also called N-cadherin). Because of HNK-1′s importance, we asked whether additional receptors for HNK-1 exist and whether the four identified proteins share any similarity in their primary structures. A set of 40,000 sequences homologous to the known HNK-1 receptors was selected and used for large-scale sequence alignments and motif searches. Although there are conserved regions and highly conserved sites within each of these protein families, there was no sequence similarity or conserved sequence motifs found to be shared by all families. Since HNK-1 receptors have not been compared regarding binding constants and since it is not known whether the sulfated or non-sulfated part of HKN-1 represents the structurally crucial ligand, the receptors are more heterogeneous in primary structure than anticipated, possibly involving different receptor or ligand regions. We thus conclude that the primary protein structure may not be the sole determinant for a bona fide HNK-1 receptor, rendering receptor structure more complex than originally assumed.

Glycans in Virus-Host Interactions: A Structural Perspective

Many interactions between microbes and their hosts are driven or influenced by glycans, whose heterogeneous and difficult to characterize structures have led to an underappreciation of their role in these interactions compared to protein-based interactions. Glycans decorate microbe glycoproteins to enhance attachment and fusion to host cells, provide stability, and evade the host immune system. Yet, the host immune system may also target these glycans as glycoepitopes. In this review, we provide a structural perspective on the role of glycans in host-microbe interactions, focusing primarily on viral glycoproteins and their interactions with host adaptive immunity. In particular, we discuss a class of topological glycoepitopes and their interactions with topological mAbs, using the anti-HIV mAb 2G12 as the archetypical example. We further offer our view that structure-based glycan targeting strategies are ready for application to viruses beyond HIV, and present our perspective on future development in this area.

Effect of mannose-binding lectin gene polymorphisms on the risk of rheumatoid arthritis: Evidence from a meta-analysis

BACKGROUND

The effect of mannose-binding lectin (MBL) gene polymorphisms on susceptibility of rheumatoid arthritis (RA) were evaluated in ethnically different populations, whereas the results were always inconsistent.

MATERIALS AND METHODS

Fourteen articles involving 36 datasets were recruited to evaluate the association between MBL gene polymorphisms and rheumatoid arthritis in a meta-analysis. The random or fixed effect models were used to evaluate the pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CIs).

RESULTS

Stratified analysis by ethnicities was conducted and the result revealed that rs1800450 (T vs C, OR = 1.32, 95% CI: 1.04-1.67, P < .05) and MBL-A/O (T vs C, OR = 1.20, 95% CI: 1.08-1.34, P < .001) were strongly associated with RA in Brazilian populations. In addition, the significant relationship between rs11003125 (T vs C, OR = 1.16, 95% CI: 1.06-1.26, P < .05) with RA were also observed in East Asian populations. Meanwhile, the inverse associations between rs5030737 with RA in East Asians and rs1800450 with RA in Indians were acquired. However, no association between any MBL polymorphism with RA susceptibility was confirmed in Caucasians.

CONCLUSIONS

The structural polymorphisms in exon 1 of MBL gene may significantly contribute to susceptibility and development of RA in Brazilian and Indian populations, whereas the functional polymorphisms in the promoter region were more likely to associate with RA in East Asians.

Deep Gene Sequence Cluster Analyses of Multi-Virus-Infected Mucosal Tissue Reveal Enhanced Transmission of Acute HIV-1

During heterosexual HIV-1 transmission, a genetic bottleneck occurs in the newly infected individual as the virus passes from the mucosa, leading to systemic infection with a single transmitted HIV-1 clone in the recipient. This bottleneck in the recipient has just been described, and the mechanisms involved in this selection process have not been elucidated.

Exposure of the genital mucosa to a genetically diverse viral swarm from the donor HIV-1 can result in breakthrough and systemic infection by a single transmitted/founder (TF) virus in the recipient. The highly diverse HIV-1 envelope (Env) in this inoculating viral swarm may have a critical role in transmission and subsequent immune response. Thus, chronic (Env_chronic) and acute (Env_acute) Env chimeric HIV-1 were tested using multivirus competition assays in human mucosal penile and cervical tissues. Viral competition analysis revealed that Env_chronic viruses resided and replicated mainly in the tissue, while Env_acute viruses penetrated the human tissue and established infection of CD4⁺ T cells more efficiently. Analysis of the replication fitness, as tested in peripheral blood mononuclear cells (PBMCs), showed similar replication fitness of Env_acute and Env_chronic viruses, which did not correlate with transmission fitness in penile tissue. Further, we observed that chimeric Env viruses with higher replication in genital mucosal tissue (chronic Env viruses) had higher binding affinity to C-type lectins. Data presented herein suggest that the inoculating HIV-1 may be sequestered in the genital mucosal tissue (represented by chronic Env HIV-1) but that a single HIV-1 clone (e.g., acute Env HIV-1) can escape this trapped replication for systemic infection.

IMPORTANCE During heterosexual HIV-1 transmission, a genetic bottleneck occurs in the newly infected individual as the virus passes from the mucosa, leading to systemic infection with a single transmitted HIV-1 clone in the recipient. This bottleneck in the recipient has just been described (K. Klein et al., PLoS Pathog 14:e1006754, https://doi.org/10.1371/journal.ppat.1006754), and the mechanisms involved in this selection process have not been elucidated. However, understanding mucosal restriction is of the utmost importance for understanding dynamics of infections and for designing focused vaccines. Using our human penile and cervical mucosal tissue models for mixed HIV infections, we provide evidence that HIV-1 from acute/early infection, compared to that from chronic infection, can more efficiently traverse the mucosal epithelium and be transmitted to T cells, suggesting higher transmission fitness. This study focused on the role of the HIV-1 envelope in transmission and provides strong evidence that HIV transmission may involve breaking the mucosal lectin trap.

In the Crosshairs: RNA Viruses OR Complement?

Complement, a part of the innate arm of the immune system, is integral to the frontline defense of the host against innumerable pathogens, which includes RNA viruses. Among the major groups of viruses, RNA viruses contribute significantly to the global mortality and morbidity index associated with viral infection. Despite multiple routes of entry adopted by these viruses, facing complement is inevitable. The initial interaction with complement and the nature of this interaction play an important role in determining host resistance versus susceptibility to the viral infection. Many RNA viruses are potent activators of complement, often resulting in virus neutralization. Yet, another facet of virus-induced activation is the exacerbation in pathogenesis contributing to the overall morbidity. The severity in disease and death associated with RNA virus infections shows a tip in the scale favoring viruses. Growing evidence suggest that like their DNA counterparts, RNA viruses have co-evolved to master ingenious strategies to remarkably restrict complement. Modulation of host genes involved in antiviral responses contributed prominently to the adoption of unique strategies to keep complement at bay, which included either down regulation of activation components (C3, C4) or up regulation of complement regulatory proteins. All this hints at a possible “hijacking” of the cross-talk mechanism of the host immune system. Enveloped RNA viruses have a selective advantage of not only modulating the host responses but also recruiting membrane-associated regulators of complement activation (RCAs). This review aims to highlight the significant progress in the understanding of RNA virus–complement interactions.

Quantitative trait loci and genes associated with salmonid alphavirus load in Atlantic salmon: implications for pancreas disease resistance and tolerance

Salmonid alphavirus infection results in pancreas disease causing severe economic losses for Atlantic salmon aquaculture. Knowledge about genes and pathways contributing to resistance is limited. A 54 K SNP panel was used to genotype 10 full-sibling families each consisting of ~ 110 offspring challenged with salmonid alphavirus subtype 3. Relative heart viral load was assessed at 4- and 10-weeks post-infection using quantitative PCR. A moderate genomic heritability of viral load at 4 weeks (0.15–0.21) and a high positive correlation with survival (0.91–0.98) were detected. Positions of QTL detected on chromosome 3 matched those for survival detected by other studies. The SNP of highest significance occurred in the 3′ untranslated region of gig1, a fish-specific antiviral effector. Locus B of immunoglobulin heavy chain mapped to an area containing multiple SNPs with genome-wide association. Heart mRNA-seq comparing parr from families with high- versus low-genomic breeding value, and matching sample genotypes for SNPs, identified two eQTL for salmonid alphavirus load. Immune genes associated with trans-eQTL were numerous and spread throughout the genome. QTL regions contained several genes with known or predicted immune functions, some differentially expressed. The putative functional genes and variants identified could help improve marker-based selection for pancreas disease resistance.

Bottlebrush Glycopolymers from 2-Oxazolines and Acrylamides for Targeting Dendritic Cell-Specific Intercellular Adhesion Molecule-3-Grabbing Nonintegrin and Mannose-Binding Lectin

Lectins are omnipresent carbohydrate binding proteins that are involved in a multitude of biological processes. Unearthing their binding properties is a powerful tool toward the understanding and modification of their functions in biological applications. Herein, we present the synthesis of glycopolymers with a brush architecture via a "grafting from" methodology. The use of a versatile 2-oxazoline inimer was demonstrated to open avenues for a wide range of 2-oxazoline/acrylamide bottle brush polymers utilizing aqueous Cu-mediated reversible deactivation radical polymerization (Cu-RDRP). The polymers in the obtained library were assessed for their thermal properties in aqueous solution and their binding toward the C-type animal lectins dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and mannose-binding lectin (MBL) via surface plasmon resonance spectrometry. The encapsulation properties of a hydrophobic drug-mimicking compound demonstrated the potential use of glyco brush copolymers in biological applications.

Friend retrovirus studies reveal complex interactions between intrinsic, innate and adaptive immunity

Approximately 4.4% of the human genome is comprised of endogenous retroviral sequences, a record of an evolutionary battle between man and retroviruses. Much of what we know about viral immunity comes from studies using mouse models. Experiments using the Friend virus (FV) model have been particularly informative in defining highly complex anti-retroviral mechanisms of the intrinsic, innate and adaptive arms of immunity. FV studies have unraveled fundamental principles about how the immune system controls both acute and chronic viral infections. They led to a more complete understanding of retroviral immunity that begins with cellular sensing, production of type I interferons, and the induction of intrinsic restriction factors. Novel mechanisms have been revealed, which demonstrate that these earliest responses affect not only virus replication, but also subsequent innate and adaptive immunity. This review on FV immunity not only surveys the complex host responses to a retroviral infection from acute infection to chronicity, but also highlights the many feedback mechanisms that regulate and counter-regulate the various arms of the immune system. In addition, the discovery of molecular mechanisms of immunity in this model have led to therapeutic interventions with implications for HIV cure and vaccine development.

Synthesis and comparison of linear and hyperbranched multivalent glycosides for C-type lectin binding

Hyperbranched and linear polyglycerol-based mannoside and fucosyllactoside residues with different ligand densities showed nanomolar binding affinities for MBL and DC-SIGN proteins.

Neurocognitive Impairment and Associated Genetic Aspects in HIV Infection

HIV enters the central nervous system (CNS) early after infection. HIV-associated neurocognitive disorders (HAND) remain a serious complication of HIV infection despite available antiretroviral therapy (ART). Neurocognitive deficits observed in HAND are heterogeneous, suggesting a variability in individuals' susceptibility or resiliency to the detrimental CNS effects of HIV infection. This chapter reviews primary host genomic changes (immune-related genes, genes implicated in cognitive changes in primary neurodegenerative diseases), epigenetic mechanisms, and genetic interactions with ART implicated in HIV progression or HAND/neurocognitive complications of HIV. Limitations of the current findings include diversity of the HAND phenotype and limited replication of findings across cohorts. Strategies to improve the precision of future (epi)genetic studies of neurocognitive consequences of HIV infection are offered.

MBL2 gene polymorphisms in HHV-8 infection in people living with HIV/AIDS

Background

Host genetic factors such as MBL2 gene polymorphisms cause defects in the polymerization of MBL protein and result in a functional deficiency and/or in low serum levels that can influence susceptibility to various viral infections. The aim of this study was to estimate the frequency of alleles, genotypes and haplotypes related to -550, -221 and exon 1 polymorphisms of the MBL2 gene and investigate their association with HHV-8 in people living with HIV/AIDS (PLWHA), as well as the impacts on CD4 cell count and HIV viral load in HIV/HHV-8 coinfected and HIV monoinfected patients.

Results

A cross sectional study in PLWHA, with and without HHV-8 infection, exploring associations between different factors, was performed in the outpatient infectious and parasitic diseases clinic at a referral hospital. Genomic DNA extractions from leukocytes were performed using a commercial Wizard^®Genomic DNA Purification kit (Promega, Madison, WI). The promoter region (-550 and -221) was genotyped with the TaqMan system (Applied TaqMan Biosystems^® genotyping Assays), and the structural region (exon1) was genotyped with Express Sybr Greener Supermix kit (Invitrogen, USA). In total, 124 HIV/HHV-8 coinfected and 213 HIV monoinfected patients were analysed. Median TCD4 counts were significantly lower in HIV/HHV-8 coinfected patients, whereas the mean of the first and last viral load of HIV did not present significant difference. There was no difference in frequency between the LL, YY and AA genotypes between the HIV/HHV-8 coinfected or HIV monoinfected patients. However, in a multivariate analysis, coinfected patients with the intermediate expression haplotype of the MBL2 gene had an odds ratio of 3.1-fold (CI = 1.2–7.6) of their last CD4 cell count being below 350 cells/mm³. Among the coinfected individuals, four developed KS and presented the intermediate expression MBL haplotype, with three being HYA/LXA and one being LYA/LYO.

Conclusions

Host genetic factors, such as -550, -221 and exon 1 polymorphisms, can be related to the may modify coinfections and/or to the development clinical manifestations caused by HHV-8, especially in HIV/HHV-8 coinfected patients who present the intermediate expression haplotypes of MBL.

Black rockfish C-type lectin, SsCTL4: A pattern recognition receptor that promotes bactericidal activity and virus escape from host immune defense

C-type lectin (CTL) is an immune receptor and is received extensive attention of its important roles in immune response and immune escape. Some CTL, such as CTL4, has been well characterized in human and several other mammals, but much less documentation exists about the immunological function of CTL4 in lower vertebrates. In the present study, a C-type lectin domain family 4 member, SsCTL4, which is also high homology with CD209 antigen-like protein, from the teleost fish black rockfish (Sebastes schlegelii) was identified and examined at expression and functional levels. The open reading frame of SsCTL4 is 765 bp, and the deduced amino acid sequence of SsCTL4 shares 78%-84% overall identities with the C-type lectin of several fish species. In silico analysis identified several conserved C-type lectin features, including a carbohydrate-recognition domain and four disulfide bond-forming cysteine residues. Expression of SsCTL4 occurred in multiple tissues and was upregulated during bacterial and viral infection. Recombinant SsCTL4 (rSsCTL4) exhibited apparent binding activities against bacteria (Edwardsiella tarda and Vibrio anguillarum) and virus (infectious spleen and kidney necrosis virus, ISKNV). rSsCTL4 was able to agglutinate the Gram-negative and Gram-positive bacteria in a Ca²⁺-dependent manner. The agglutinating ability of rSsCTL4 was abolished in the absence of calcium or presence of mannose. rSsCTL4 also increased macrophage bactericidal activity. In the presence of rSsCTL4, fish exhibited enhanced resistance against bacterial infection but increased susceptibility to viral infections. Collectively, these results indicate that SsCTL4 serves as a pattern recognition receptor that not only promotes bactericidal activity, but may also serve as targets for virus manipulation of host defense system.

C-Type Lectin Receptors in Antiviral Immunity and Viral Escape

C-type lectin receptors (CLRs) are important pattern recognition receptors involved in recognition and induction of adaptive immunity to pathogens. Certain CLRs play an important role in viral infections as they efficiently interact with viruses. However, it has become clear that deadly viruses subvert the function of CLRs to escape antiviral immunity and promote infection. In particular, viruses target CLRs to suppress or modulate type I interferons that play a central role in the innate and adaptive defense against viruses. In this review, we discuss the function of CLRs in binding to enveloped viruses like HIV-1 and Dengue virus, and how uptake and signaling cascades have decisive effects on the outcome of infection.

Bispecific chimeric antigen receptors targeting the CD4 binding site and high-mannose Glycans of gp120 optimized for anti-human immunodeficiency virus potency and breadth with minimal immunogenicity

BACKGROUND AIMS

Chimeric antigen receptors (CARs) offer great potential toward a functional cure of human immunodeficiency virus (HIV) infection. To achieve the necessary long-term virus suppression, we believe that CARs must be designed for optimal potency and anti-HIV specificity, and also for minimal probability of virus escape and CAR immunogenicity. CARs containing antibody-based motifs are problematic in the latter regard due to epitope mutation and anti-idiotypic immune responses against the variable regions.

METHODS

We designed bispecific CARs, each containing a segment of human CD4 linked to the carbohydrate recognition domain of a human C-type lectin. These CARs target two independent regions on HIV-1 gp120 that presumably must be conserved on clinically significant virus variants (i.e., the primary receptor binding site and the dense oligomannose patch). Functionality and specificity of these bispecific CARs were analyzed in assays of CAR-T cell activation and spreading HIV-1 suppression.

RESULTS

T cells expressing a CD4-dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DCSIGN) CAR displayed robust stimulation upon encounter with Env-expressing targets, but negligible activity against intercellular adhesion molecule (ICAM)-2 and ICAM-3, the natural dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin ligands. Moreover, the presence of the lectin moiety prevented the CD4 from acting as an entry receptor on CCR5-expressing cells, including CD8⁺ T cells. However, in HIV suppression assays, the CD4-DCSIGN CAR and the related CD4-liver/lymph node-specific intercellular adhesion molecule-3-grabbing non-integrin CAR displayed only minimally increased potency compared with the CD4 CAR against some HIV-1 isolates and reduced potency against others. By contrast, the CD4-langerin and CD4-mannose binding lectin (MBL) CARs uniformly displayed enhanced potency compared with the CD4 CAR against all the genetically diverse HIV-1 isolates examined. Further experimental data, coupled with known biological features, suggest particular advantages of the CD4-MBL CAR.

DISCUSSION

These studies highlight features of bispecific CD4-lectin CARs that achieve potency enhancement by targeting two distinct highly conserved Env determinants while lacking immunogenicity-prone antibody-based motifs.

Genetic and immune determinants of immune activation in HIV-exposed seronegative individuals and their role in protection against HIV infection

Soon thereafter infection is established, hosts strive for an efficient eradication of microorganisms, with as limited tissue damage as possible, and durable immunological protection against re-infection. On the other hand, pathogens have developed countermeasures to escape host surveillance and to warrant diffusion to other hosts. In this molecular arms race the final results relies on multiple variables, including the genetic and immunologic e correlates of protection available for the host. In the field of HIV-infection, natural protection has been repeatedly associated to the presence of an immune activation state, at least in some cohorts of HESN (HIV-exposed seronegative). Indeed, these subjects, who naturally resist HIV-infection despite repeated exposure to the virus, are characterized by an increased expression of activation markers on circulating cells and greater production of immunological effector molecules both in basal condition and upon specific-stimulation. Although these results are not univocally shared, several publications emphasize the existence of a correlation between polymorphisms in genes associated with increased immune activation and the HESN phenotype. In this review, we will describe some of the genetic variants associated with protection against HIV infection. Understanding the basis of HIV resistance in HESN is mandatory to develop new preventative and therapeutic interventions.

MBL2 genetic polymorphisms and HIV-1 mother-to-child transmission in Zambia

Since antiretroviral drugs have been introduced to prevent mother-to-child transmission, the risk of HIV-1 infection in infants has decreased considerably worldwide. Nevertheless, many factors are involved in viral transmission and host susceptibility to infection. The immune system and its components, including mannose binding protein C (encoding by MBL2 gene), are already known to play an important role in this scenario. In the present study, 313 children and 98 of their mothers from Zambia were genotyped for the MBL2 promoter HL (rs11003125) and XY (rs7096206) polymorphisms and exon 1 D (rs5030737, at codon 52) B (rs1800450, at codon 54) and C (rs1800451, at codon 57) polymorphisms in order to investigate the potential role of these genetic variants in HIV-1 mother-to-child transmission. No statistical significant association was observed comparing transmitter and non-transmitter mothers and also confronting HIV-positive and HIV-negative children. The findings of the current study obtained on mother and children from Zambia evidence lack of association between MBL2 functional polymorphisms and HIV-1 mother-to-child transmission.

The Role of Immune Responses in HIV Mother-to-Child Transmission

HIV mother-to-child transmission (MTCT) represents a success story in the HIV/AIDS field given the significant reduction in number of transmission events with the scale-up of antiretroviral treatment and other prevention methods. Nevertheless, MTCT still occurs and better understanding of the basic biology and immunology of transmission will aid in future prevention and treatment efforts. MTCT is a unique setting given that the transmission pair is known and the infant receives passively transferred HIV-specific antibodies from the mother while in utero. Thus, infant exposure to HIV occurs in the face of HIV-specific antibodies, especially during delivery and breastfeeding. This review highlights the immune correlates of protection in HIV MTCT including humoral (neutralizing antibodies, antibody-dependent cellular cytotoxicity, and binding epitopes), cellular, and innate immune factors. We further discuss the future implications of this research as it pertains to opportunities for passive and active vaccination with the ultimate goal of eliminating HIV MTCT.

Serum mannan-binding lectin in patients with pulmonary tuberculosis: Its lack of a relationship to the disease and response to treatment

Background: Lectin pathway mediates complement activation, which is activated by many microorganisms. This study aimed at determining the serum levels of mannose-binding lectin (MBL) in patients with pulmonary tuberculosis, assessing its relationship to antiuberculosis treatment response, and comparing them with a control group. Methods: This cross-sectional study was conducted on patients with pulmonary tuberculosis during 2012 and 2013 in South West of Iran. PPD-ST-negative individuals were selected as controls from healthy relatives of patients. Serum MBL levels were measured using ELISA kit (Human MBL HK323, Hycultbiotech Company, Netherlands). All patients were followed- up for response to treatment. We applied Mann-Whitney and Fisher's exact tests and used SPSS Version 17 software for statistical analysis. Results: The study included 62 patients as the case group and 63 noninfected TB patients as the control group. The MBL (ng/mL) in patients with pulmonary tuberculosis (median = 1012) was significantly (p= 0.037) higher than that of the control group (median= 296.2). No significant difference was found in the MBL level (ng/mL) between patients with response to antituberculosis treatment (median= 1012) and patients with treatment failure (median= 798.9) (p= 0.84). Conclusion: MBL may be involved in the pathogenesis of tuberculosis and in the low values that are protective against tuberculosis, and it seems that it has no effect on the antituberculosis treatment response.

Mannose Surfaces Exhibit Self-Latching, Water Structuring, and Resilience to Chaotropes: Implications for Pathogen Virulence

Several viral and fungal pathogens, including HIV, SARS, Dengue, Ebola, and Cryptococcus neoformans, display a preponderance of mannose residues on their surface, particularly during the infection cycle or in harsh environments. The innate immune system, on the other hand, abounds in mannose receptors which recognize mannose residues on pathogens and trigger their phagocytosis. We pose the question if there is an advantage for pathogens to display mannose on their surface, despite these residues being recognized by the immune system. The surface properties and interactions of opposing monolayers of mannobiose (disaccharide of mannose) were probed using atomic force spectroscopy. Unlike its diastereoisomer lactose, mannobiose molecules exhibited lateral packing interactions that manifest on the surface scale as a self-recognizing latch. A break-in force is required for opposing surfaces to penetrate and a breakout (or self-adhesion force) of similar magnitude is required for penetrated surfaces to separate. A hierarchy of self-adhesion forces was distinguished as occurring at the single residue (∼25 pN), cluster (∼250 pN), monolayer (∼1.1 nN), and supramonolayer level. The break-in force and break-out force appear resilient to the presence of simple chaotropes that attenuate a layer of structured water around the mannose surface. The layer of structured water otherwise extends to distances several times longer than a mannobiose residue, indicating a long-range propagation of the hydrogen bonding imposed by the residues. The span of the structured water increases with the velocity of an approaching surface, similar to shear thickening, but fissures at higher approach velocities. Our studies suggest that mannose residues could guide interpathogen interactions, such as in biofilms, and serve as a moated fortress for pathogens to hide behind to resist detection and harsh environments.

A C-type lectin that inhibits bacterial infection and facilitates viral invasion in black rockfish, Sebastes schlegelii

C-type lectins (CTLs) are important pattern recognition receptors (PRRs) that play vital roles in innate immunity. In teleosts, a number of CTLs have been reported, but their in vivo effects on host defense are still limited. In this study, a CTL homolog (SsLec1) was identified from black rockfish, Sebastes schlegelii, and its structure, expression and biological function was analyzed. The open reading frame of SsLec1 is 633 bp, with a 5'- untranslated region (UTR) of 36 bp and a 3'- UTR of 117 bp. The deduced amino acid sequence of SsLec1 shares the highest overall identity (73.20%) with the CTL of Oplegnathus fasciatus. SsLec1 possesses conserved CTL features, including a carbohydrate-recognition domain, four disulfide bond-forming cysteine residues, the mannose-type carbohydrate-binding motif, the conserved calcium binding sites and a putative signal peptide. The expression of SsLec1 was highest in liver and could be induced by experimental infection with Listonella anguillarum. Recombinant SsLec1 (rSsLec1) purified from E. coli was able to bind and agglutinate the Gram-negative fish pathogens Vibrio ichthyoenteri and Vibrio vulnificus. The agglutinating ability of rSsLec1 was abolished in the presence of mannose or ethylenediaminetetraacetic acid. Further analysis showed that rSsLec1 could enhance phagocytosis by macrophages. In vivo experiments indicated that rSsLec1 could inhibit bacterial infection and promote viral invasion. Taken together, these results suggest that SsLec1 is a novel CTL that possesses apparent immunoregulation property and plays a critical role in host defense against pathogens invasion.

The Effects of Hormones and Vaginal Microflora on the Glycome of the Female Genital Tract: Cervical-Vaginal Fluid

In this study, we characterized the glycome of cervical-vaginal fluid, collected with a Catamenial cup. We quantified: glycosidase levels; sialic acid and high mannose specific lectin binding; mucins, MUC1, MUC4, MUC5AC, MUC7; and albumin in the samples collected. These data were analyzed in the context of hormonal status (day of menstrual cycle, hormonal contraception use) and role, if any, of the type of the vaginal microflora present. When the Nugent score was used to stratify the subjects by microflora as normal, intermediate, or bacterial vaginosis, several important differences were observed. The activities of four of six glycosidases in the samples from women with bacterial vaginosis were significantly increased when compared to normal or intermediate women: sialidase, P = <0.001; α-galactosidase, P = 0.006; β-galactosidase, P = 0.005; α-glucosidase, P = 0.056. Sialic acid binding sites as measured by two lectins, Maackia amurensis and Sambucus nigra binding, were significantly lower in women with BV compared to women with normal and intermediate scores (P = <0.0001 and 0.008 respectively). High mannose binding sites, a measure of innate immunity were also significantly lower in women with BV (P = <0.001). Additionally, we observed significant increases in MUC1, MUC4, MUC5AC, and MUC7 concentrations in women with BV (P = <0.001, 0.001, <0.001, 0.02 respectively). Among normal women we found that the membrane bound mucin MUC4 and the secreted MUC5AC were decreased in postmenopausal women (P = 0.02 and 0.07 respectively), while MUC7 (secreted) was decreased in women using levonorgestrel-containing IUDs (P = 0.02). The number of sialic acid binding sites was lower in the postmenopausal group (P = 0.04), but the number of high mannose binding sites, measured with Griffithsin, was not significantly different among the 6 hormonal groups. The glycosidase levels in the cervical-vaginal mucus were rather low in the groups, with exception of α-glucosidase activity that was much lower in the postmenopausal group (P<0.001). These studies present compelling evidence that the vaginal ecosystem responds to the presence of different vaginal microorganisms. These effects were so influential that it required us to remove subjects with BV for data interpretation of the impact of hormones. We also suggest that certain changes occurring in vaginal/cervical proteins are due to bacteria or their products. Therefore, the quantitation of vaginal mucins and lectin binding offers a new method to monitor bacteria-host interactions in the female reproductive tract. The data suggest that some of the changes in these components are the result of host processing, such as the increases in mucin content, while the microflora is responsible for the increases in glycosidases and the decreases in lectin binding. The methods should be considered a valid marker for insult to the female genital tract.

Identification of Circulating Biomarker Candidates for Hepatocellular Carcinoma (HCC): An Integrated Prioritization Approach

Hepatocellular carcinoma (HCC) is the world's third most widespread cancer. Currently available circulating biomarkers for this silently progressing malignancy are not sufficiently specific and sensitive to meet all clinical needs. There is an imminent and pressing need for the identification of novel circulating biomarkers to increase disease-free survival rate. In order to facilitate the selection of the most promising circulating protein biomarkers, we attempted to define an objective method likely to have a significant impact on the analysis of vast data generated from cutting-edge technologies. Current study exploits data available in seven publicly accessible gene and protein databases, unveiling 731 liver-specific proteins through initial enrichment analysis. Verification of expression profiles followed by integration of proteomic datasets, enriched for the cancer secretome, filtered out 20 proteins including 6 previously characterized circulating HCC biomarkers. Finally, interactome analysis of these proteins with midkine (MDK), dickkopf-1 (DKK-1), current standard HCC biomarker alpha-fetoprotein (AFP), its interacting partners in conjunction with HCC-specific circulating and liver deregulated miRNAs target filtration highlighted seven novel statistically significant putative biomarkers including complement component 8, alpha (C8A), mannose binding lectin (MBL2), antithrombin III (SERPINC1), 11β-hydroxysteroid dehydrogenase type 1 (HSD11B1), alcohol dehydrogenase 6 (ADH6), beta-ureidopropionase (UPB1) and cytochrome P450, family 2, subfamily A, polypeptide 6 (CYP2A6). Our proposed methodology provides a swift assortment process for biomarker prioritization that eventually reduces the economic burden of experimental evaluation. Further dedicated validation studies of potential putative biomarkers on HCC patient blood samples are warranted. We hope that the use of such integrative secretome, interactome and miRNAs target filtration approach will accelerate the selection of high-priority biomarkers for other diseases as well, that are more amenable to downstream clinical validation experiments.

Anti-Retroviral Lectins Have Modest Effects on Adherence of Trichomonas vaginalis to Epithelial Cells In Vitro and on Recovery of Tritrichomonas foetus in a Mouse Vaginal Model

Trichomonas vaginalis causes vaginitis and increases the risk of HIV transmission by heterosexual sex, while Tritrichomonas foetus causes premature abortion in cattle. Our goals were to determine the effects, if any, of anti-retroviral lectins, which are designed to prevent heterosexual transmission of HIV, on adherence of Trichomonas to ectocervical cells and on Tritrichomonas infections in a mouse model. We show that Trichomonas Asn-linked glycans (N-glycans), like those of HIV, bind the mannose-binding lectin (MBL) that is part of the innate immune system. N-glycans of Trichomonas and Tritrichomonas bind anti-retroviral lectins (cyanovirin-N and griffithsin) and the 2G12 monoclonal antibody, each of which binds HIV N-glycans. Binding of cyanovirin-N appears to be independent of susceptibility to metronidazole, the major drug used to treat Trichomonas. Anti-retroviral lectins, MBL, and galectin-1 cause Trichomonas to self-aggregate and precipitate. The anti-retroviral lectins also increase adherence of ricin-resistant mutants, which are less adherent than parent cells, to ectocervical cell monolayers and to organotypic EpiVaginal tissue cells. Topical application of either anti-retroviral lectins or yeast N-glycans decreases by 40 to 70% the recovery of Tritrichomonas from the mouse vagina. These results, which are explained by a few simple models, suggest that the anti-retroviral lectins have a modest potential for preventing or treating human infections with Trichomonas.

Role of mannose-binding lectin deficiency in HIV-1 and schistosoma infections in a rural adult population in Zimbabwe

BACKGROUND

Polymorphism in the MBL2 gene lead to MBL deficiency, which has been shown to increase susceptibility to various bacterial, viral and parasitic infections. We assessed role of MBL deficiency in HIV-1 and schistosoma infections in Zimbabwean adults enrolled in the Mupfure Schistosomiasis and HIV Cohort (MUSH Cohort).

METHODS

HIV-1, S. haematobium and S. mansoni infections were determined at baseline. Plasma MBL concentration was measured by ELISA and MBL2 genotypes determined by PCR. We calculated and compared the proportions of plasma MBL deficiency, MBL2 structural variant alleles B (codon 54A>G), C (codon 57A>G), and D (codon 52T>C) as well as MBL2 promoter variants -550(H/L), -221(X/Y) and +4(P/Q) between HIV-1 and schistosoma co-infection and control groups using Chi Square test.

RESULTS

We assessed 379 adults, 80% females, median age (IQR) 30 (17-41) years. HIV-1, S. haematobium and S. mansoni prevalence were 26%, 43% and 18% respectively in the MUSH baseline survey. Median (IQR) plasma MBL concentration was 800μg/L (192-1936μg/L). Prevalence of plasma MBL deficiency was 18% with high frequency of the C (codon 57G>A) mutant allele (20%). There was no significant difference in median plasma MBL levels between HIV negative (912μg/L) and HIV positive (688μg/L), p = 0.066. However plasma MBL levels at the assay detection limit of 20μg/L were more frequent among the HIV-1 infected (p = 0.007). S. haematobium and S. mansoni infected participants had significantly higher MBL levels than uninfected. All MBL2 variants were not associated with HIV-1 infection but promoter variants LY and LL were significantly associated with S. haematobium infection.

CONCLUSION

Our data indicate high prevalence of MBL deficiency, no evidence of association between MBL deficiency and HIV-1 infection. However, lower plasma MBL levels were protective against both S. haematobium and S. mansoni infections and MBL2 promoter and variants LY and LL increased susceptibility to S. haematobium infection.

HIV Coinfection Enhances Complement Activation During Sepsis

BACKGROUND

Human immunodeficiency virus (HIV)-induced complement activation may play a role in chronic immune activation in patients with HIV infection and influence the complement system during acute illness. We determined the impact of HIV infection on the complement system in patients with asymptomatic HIV infection and HIV-infected patients with sepsis or malaria.

METHODS

We performed a prospective observational study of 268 subjects with or without HIV infection who were asymptomatic, were septic, or had malaria. We measured complement activation products (C3bc and C4bc) and native complement proteins (C3 and C4). levels of mannose-binding lectin and C1q-C4 were measured to examine activation of the lectin and classical pathways, respectively.

RESULTS

Asymptomatic HIV infection was associated with increased C4 activation, especially in patients with high HIV loads, and was accompanied by elevated C1q-C4 levels. Similarly, sepsis and malaria resulted in increased C4 activation and elevated C1q-C4 concentrations. HIV coinfection enhanced C4 activation and consumption in patients with sepsis; this effect was not detected in patients with malaria. Mannose-binding lectin deficiency (defined as a mannose-binding lectin level of <500 ng/mL) did not influence complement activation in any group.

CONCLUSIONS

HIV activates the complement system, predominantly via the classical pathway, and causes increased C4 activation and consumption during sepsis. HIV-induced complement activation may contribute to tissue injury during chronic infection and acute intercurrent bacterial infections.

Association of complement receptor 2 polymorphisms with innate resistance to HIV-1 infection

HIV-1 induces activation of complement through the classical and lectin pathways. However, the virus incorporates several membrane-bound or soluble regulators of complement activation (RCA) that inactivate complement. HIV-1 can also use the complement receptors (CRs) for complement-mediated antibody-dependent enhancement of infection (Ć-ADE). We hypothesize that hypofunctional polymorphisms in RCA or CRs may protect from HIV-1 infection. For this purpose, 139 SNPs located in 19 RCA and CRs genes were genotyped in a population of 201 Spanish HIV-1-exposed seronegative individuals (HESN) and 250 HIV-1-infected patients. Two SNPs were associated with infection susceptibility, rs1567190 in CR2 (odds ratio (OR) = 2.27, P = 1 × 10(-4)) and rs2842704 in C4BPA (OR = 2.11, P = 2 × 10(-4)). To replicate this finding, we analyzed a cohort of Italian, sexually HESN individuals. Although not significant (P = 0.25, OR = 1.57), similar genotypic proportions were obtained for the CR2 marker rs1567190. The results of the two association analyses were combined through a random effect meta-analysis, with a significant P-value of 2.6 x 10(-5) (OR = 2.07). Furthermore, we found that the protective CR2 genotype is correlated with lower levels CR2 mRNA as well as differences in the ratio of the long and short CR2 isoforms.

Complement and the control of HIV infection: an evolving story

PURPOSE OF REVIEW

Thirty years ago, investigators isolated and later determined the structure of HIV-1 and its envelope proteins. Using techniques that were effective with other viruses, they prepared vaccines designed to generate antibody or T-cell responses, but they were ineffective in clinical trials. In this article, we consider the role of complement in host defense against enveloped viruses, the role it might play in the antibody response and why complement has not controlled HIV-1 infection.

RECENT FINDINGS

Complement consists of a large group of cell-bound and plasma proteins that are an integral part of the innate immune system. They provide a first line of defense against microbes and also play a role in the immune response. Here we review the studies of complement-mediated HIV destruction and the role of complement in the HIV antibody response.

SUMMARY

HIV-1 has evolved a complex defense to prevent complement-mediated killing reviewed here. As part of these studies, we have discovered that HIV-1 envelope, on administration into animals, is rapidly broken down into small peptides that may prove to be very inefficient at provident the type of antigenic stimulation that leads to an effective immune response. Improving complement binding and stabilizing envelope may improve the vaccine response.

An extracorporeal blood-cleansing device for sepsis therapy

Here we describe a blood-cleansing device for sepsis therapy inspired by the spleen, which can continuously remove pathogens and toxins from blood without first identifying the infectious agent. Blood flowing from an infected individual is mixed with magnetic nanobeads coated with an engineered human opsonin--mannose-binding lectin (MBL)--that captures a broad range of pathogens and toxins without activating complement factors or coagulation. Magnets pull the opsonin-bound pathogens and toxins from the blood; the cleansed blood is then returned back to the individual. The biospleen efficiently removes multiple Gram-negative and Gram-positive bacteria, fungi and endotoxins from whole human blood flowing through a single biospleen unit at up to 1.25 liters per h in vitro. In rats infected with Staphylococcus aureus or Escherichia coli, the biospleen cleared >90% of bacteria from blood, reduced pathogen and immune cell infiltration in multiple organs and decreased inflammatory cytokine levels. In a model of endotoxemic shock, the biospleen increased survival rates after a 5-h treatment.

Collaboration between a Soluble C-Type Lectin and Calreticulin Facilitates White Spot Syndrome Virus Infection in Shrimp

White spot syndrome virus (WSSV) mainly infects crustaceans through the digestive tract. Whether C-type lectins (CLs), which are important receptors for many viruses, participate in WSSV infection in the shrimp stomach remains unknown. In this study, we orally infected kuruma shrimp Marsupenaeus japonicus to model the natural transmission of WSSV and identified a CL (designated as M. japonicus stomach virus–associated CL [MjsvCL]) that was significantly induced by virus infection in the stomach. Knockdown of MjsvCL expression by RNA interference suppressed the virus replication, whereas exogenous MjsvCL enhanced it. Further analysis by GST pull-down and coimmunoprecipitation showed that MjsvCL could bind to viral protein 28, the most abundant and functionally relevant envelope protein of WSSV. Furthermore, cell-surface calreticulin was identified as a receptor of MjsvCL, and the interaction between these proteins was a determinant for the viral infection–promoting activity of MjsvCL. The MjsvCL–calreticulin pathway facilitated virus entry likely in a cholesterol-dependent manner. This study provides insights into a mechanism by which soluble CLs capture and present virions to the cell-surface receptor to facilitate viral infection.

Targeting strategies for delivery of anti-HIV drugs

Human Immunodeficiency Virus (HIV) infection remains a significant cause of mortality globally. Though antiretroviral therapy has significantly reduced AIDS-related morbidity and mortality, there are several drawbacks in the current therapy, including toxicity, drug–drug interactions, development of drug resistance, necessity for long-term drug therapy, poor bio-availability and lack of access to tissues and reservoirs. To circumvent these problems, recent anti-HIV therapeutic research has focused on improving drug delivery systems through drug delivery targeted specifically to host cells infected with HIV or could potentially get infected with HIV. In this regard, several surface molecules of both viral and host cell origin have been described in recent years, that would enable targeted drug delivery in HIV infection. In the present review, we provide a comprehensive overview of the need for novel drug delivery systems, and the successes and challenges in the identification of novel viral and host-cell molecules for the targeted drug delivery of anti-HIV drugs. Such targeted anti-retroviral drug delivery approaches could pave the way for effective treatment and eradication of HIV from the body.

The lectin pathway of complement: advantage or disadvantage in HIV pathogenesis?

The pattern recognition molecules of the lectin complement pathway are important components of the innate immune system with known functions in host-virus interactions. This paper summarizes current knowledge of how these intriguing molecules, including mannose-binding lectin (MBL), Ficolin-1, -2 and -3, and collectin-11 (CL-11) may influence HIV-pathogenesis. It has been demonstrated that MBL is capable of binding and neutralizing HIV and may affect host susceptibility to HIV infection and disease progression. In addition, MBL may cause variations in the host immune response against HIV. Ficolin-1, -2 and -3 and CL-11 could have similar functions in HIV infection as the ficolins have been shown to play a role in other viral infections, and CL-11 resembles MBL and the ficolins in structure and binding capacity.

Intracellular mannose binding lectin mediates subcellular trafficking of HIV-1 gp120 in neurons

Human immunodeficiency virus-1 (HIV-1) enters the brain early during infection and leads to severe neuronal damage and central nervous system impairment. HIV-1 envelope glycoprotein 120 (gp120), a neurotoxin, undergoes intracellular trafficking and transport across neurons; however mechanisms of gp120 trafficking in neurons are unclear. Our results show that mannose binding lectin (MBL) that binds to the N-linked mannose residues on gp120, participates in intravesicular packaging of gp120 in neuronal subcellular organelles and also in subcellular trafficking of these vesicles in neuronal cells. Perinuclear MBL:gp120 vesicular complexes were observed and MBL facilitated the subcellular trafficking of gp120 via the endoplasmic reticulum (ER) and Golgi vesicles. The functional carbohydrate recognition domain of MBL was required for perinuclear organization, distribution and subcellular trafficking of MBL:gp120 vesicular complexes. Nocodazole, an agent that depolymerizes the microtubule network, abolished the trafficking of MBL:gp120 vesicles, suggesting that these vesicular complexes were transported along the microtubule network. Live cell imaging confirmed the association of the MBL:gp120 complexes with dynamic subcellular vesicles that underwent trafficking in neuronal soma and along the neurites. Thus, our findings suggest that intracellular MBL mediates subcellular trafficking and transport of viral glycoproteins in a microtubule-dependent mechanism in the neurons.

NMR of glycans: shedding new light on old problems

The diversity in molecular arrangements and dynamics displayed by glycans renders traditional NMR strategies, employed for proteins and nucleic acids, insufficient. Because of the unique properties of glycans, structural studies often require the adoption of a different repertoire of tailor-made experiments and protocols. We present an account of recent developments in NMR techniques that will deepen our understanding of structure-function relations in glycans. We open with a survey and comparison of methods utilized to determine the structure of proteins, nucleic acids and carbohydrates. Next, we discuss the structural information obtained from traditional NMR techniques like chemical shifts, NOEs/ROEs, and coupling-constants, along with the limitations imposed by the unique intrinsic characteristics of glycan structure on these approaches: flexibility, range of conformers, signal overlap, and non-first-order scalar (strong) coupling. Novel experiments taking advantage of isotopic labeling are presented as an option for overcoming spectral overlap and raising sensitivity. Computational tools used to explore conformational averaging in conjunction with NMR parameters are described. In addition, recent developments in hydroxyl detection and hydrogen bond detection in protonated solvents, in contrast to traditional sample preparations in D2O for carbohydrates, further increase the tools available for both structure information and chemical shift assignments. We also include previously unpublished data in this context. Accurate determination of couplings in carbohydrates has been historically challenging due to the common presence of strong-couplings. We present new strategies proposed for dealing with their influence on NMR signals. We close with a discussion of residual dipolar couplings (RDCs) and the advantages of using (13)C isotope labeling that allows gathering one-bond (13)C-(13)C couplings with a recently improved constant-time COSY technique, in addition to the commonly measured (1)H-(13)C RDCs.