Abundant Glycoprotein Research Articles

Glycoprotein Expression in Human Milk during Lactation

While milk proteins have been studied for decades, strikingly little effort has been applied to determining how the post-translational modifications (PTMs) of these proteins may change during the course of lactation. PTMs, particularly glycosylation, can greatly influence protein structure, function, and stability and can particularly influence the gut where their degradation products are potentially bioactive. In this work, previously undiscovered temporal variations in both expression and glycosylation of the glycoproteome of human milk are observed. Lactoferrin, one of the most abundant glycoproteins in human milk, is shown to be dynamically glycosylated during the first 10 days of lactation. Variations in expression or glycosylation levels are also demonstrated for several other abundant whey proteins, including tenascin, bile salt-stimulated lipase, xanthine dehydrogenase, and mannose receptor.

Plasmin-clipped β 2-glycoprotein-I inhibits endothelial cell growth by down-regulating cyclin A, B and D1 and up-regulating p21 and p27

β 2-Glycoprotein-I (β 2gpI), an abundant plasma glycoprotein, functions as a regulator of thrombosis. Previously, we demonstrated that plasmin-clipped β 2gpI (cβ 2gpI) exerts an anti-angiogenic effect on human umbilical vein endothelial cells (HUVEC). The present study was focused on the molecular background responsible for this phenomenon. cβ 2gpI strongly reduced HUVEC growth and proliferation as evidenced by the MTT and BrdU assay and delayed cell cycle progression arresting HUVEC in the S-and G2/M-phase. Western blot analysis indicated that cβ 2gpI inhibited cyclin A, B and D1, and enhanced p21 and p27 expression. Activity of p38 was down-regulated independently from the cβ 2gpI incubation time. Phosphorylation of ERK1/2 was not changed early (30 and 60 min) but became enhanced later (90 min, 4 h). JNK activity was reduced rapidly after cβ 2gpI treatment but compared to controls, increased thereafter. Annexin II blockade prevented growth inhibition and cell cycle delay evoked by cβ 2gpI. We assume that cβ 2gpI’s effects on HUVEC growth is mediated via cyclin A, B and D1 suppression, up-regulation of p21 and p27 and coupled to modifications of the mitogen-activated protein (MAP) kinase signalling pathway. cβ 2gpI may represent a potential endogenous angiogenesis-targeted compound, opening the possibility of a novel tool to treat cancer.

Histidine-rich glycoprotein is a novel plasma pattern recognition molecule that recruits IgG to facilitate necrotic cell clearance via FcγRI on phagocytes

AbstractUnder normal physiologic conditions, necrotic cells resulting from tissue injury are rapidly removed from the circulation and tissues by phagocytes, thus preventing the exposure of intracellular antigenic and immunostimulatory molecules that can aid the development of autoimmune disease. Histidine-rich glycoprotein (HRG), a relatively abundant plasma glycoprotein, has a multidomain structure that can interact with many ligands including components of the fibrinolytic and immune systems. Recently, it has been reported that HRG can bind strongly to cytoplasmic ligand(s) exposed in necrotic cells to enhance clearance by phagocytes. Here we describe the molecular mechanisms underpinning this process. A complex consisting of both HRG and immunoglobulin G (IgG) was found as necessary to aid necrotic cell uptake by monocytes, predominantly via an FcγRI-dependent mechanism. The findings in this study also show that HRG can potentially interact with anionic phospholipids exposed in necrotic cells. Furthermore, the enhanced phagocytosis of necrotic cells induced by HRG-IgG complexes triggers phagocytes to release proinflammatory cytokines such as interleukin-8 and tumor necrosis factor. Thus, HRG has the unique property of complexing with IgG and facilitating a proinflammatory innate immune response to promote the clearance of necrotic cells.

Antigen Identification and Characterization of Lung Cancer Specific Monoclonal Antibodies Produced by mAb Proteomics

A mass spectrometric (MS)-based strategy for antigen (Ag) identification and characterization of globally produced monoclonal antibodies (mAbs) is described. Mice were immunized with a mixture of native glycoproteins, isolated from the pooled plasma of patients with nonsmall cell lung cancer (NSCLC), to generate a library of IgG-secreting hybridomas. Prior to immunization, the pooled NSCLC plasma was subjected to 3-sequential steps of affinity fractionation, including high abundant plasma protein depletion, glycoprotein enrichment, and polyclonal antibody affinity chromatography normalization. In this paper, to demonstrate the high quality of the globally produced mAbs, we selected 3 mAbs of high differentiating power against a matched, pooled normal plasma sample. After production of large quantities of the mAbs from ascites fluids, Ag identification was achieved by immunoaffinity purification, SDS-PAGE, Western blotting, and MS analysis of in-gel digest products. One antigen was found to be complement factor H, and the other two were mapped to different subunits of haptoglobin (Hpt). The 2 Hpt mAbs were characterized in detail to assess the quality of the mAbs produced by the global strategy. The affinity of one of the mAbs to the Hpt native tetramer form was found to have a K(D) of roughly 10(-9) M and to be 2 orders of magnitude lower than the reduced form, demonstrating the power of the mAb proteomics technology in generating mAbs to the natural form of the proteins in blood. The binding of this mAb to the beta-chain of haptoglobin was also dependent on glycosylation on this chain. The characterization of mAbs in this work reveals that the global mAb proteomics process can generate high-quality lung cancer specific mAbs capable of recognizing proteins in their native state.

Glycoproteome Study in Myocardial Lesions Serum by Integrated Mass Spectrometry Approach: Preliminary Insights

Bottom up proteomics requires efficient and selective pre-fractionation procedures to simplify the analysis of the enormous number of peptides resulting from the hydrolysis of a cellular extract enabling the detection, identification and the structural characterization of the post-translational modifications. Glycosylation, a well-known post-translational modification, plays a key role in the enormous complexity, and heterogeneity of the human blood serum proteome. Thereby, characterization of glycosylation from serum is a challenging task, even for the existing sophisticated analytical methodologies. Here we report a glycoproteomics study on the identification of even low abundant glycoproteins, including the localization of N-glycosylation sites and the glycan profiling in human sera from healthy and myocarditis affected donors. The strategy is simply based on proteolytic digestion of total serum proteins followed by a single enrichment step of glycopeptides on ConA lectin affinity chromatography. Glycopeptides were then deglycosylated by PNGaseF treatment and nano-liquid chromatography-electrospray ionization tandem mass spectrometry analyses of the free peptides provided the basis for both identification of the individual proteins and elucidation of their modification sites. Moreover, glycan profilings could be obtained by matrix-assisted laser desorption/ionization mass spectrometry analysis of the released oligosaccharides. Our data led to the identification of 68 different glycosylation sites within 49 different proteins. Moreover, the analyses carried out on glycans represent the first picture of a glycosylation pattern in myocardial lesions. As a whole, several differences in the glycosylation patterns from different sera were observed, thus indicating glycan profiling as a possible tool to discriminate among different diseases.

Current status of mucins in the diagnosis and therapy of cancer

Mucins are the most abundant high molecular weight glycoproteins in mucus. Their nature and glycosylation content dictates the biochemical and biophysical properties of viscoelastic secretions, pointing out an important role in diverse biological functions, such as differentiation, cell adhesions, immune responses, and cell signaling. Mucins are expressed in tubular organs by specialized epithelial cells in the body. Their aberrant expression is well documented in a variety of inflammatory or malignant diseases. From a prognosis point of view, their expression and alterations in glycosylation are associated with the development and progression of malignant diseases. Therefore, mucins can be used as valuable markers to distinguish between normal and disease conditions. Indeed, this alteration in glycosylation patterns generates several epitopes in the oligosaccharide side chains that can be used as diagnostic and/or prognostic markers. Furthermore, these characteristic tumor-associated epitopes are extensively used as appropriate immunotargets of malignant epithelial cells. Therefore, in an effort to detect and treat cancer at the earliest stage possible, mucins are analyzed as potential markers of disease for diagnosis, progression, and for therapeutic purposes. In this review, we focused on the current status of the distribution of mucins in normal and pathologic conditions and their clinical use both in cancer diagnosis and therapeutics treatments.

Major Surface Protease of Trypanosomatids: One Size Fits All?

Major surface protease (MSP or GP63) is the most abundant glycoprotein localized to the plasma membrane of Leishmania promastigotes. MSP plays several important roles in the pathogenesis of leishmaniasis, including but not limited to (i) evasion of complement-mediated lysis, (ii) facilitation of macrophage (Mø) phagocytosis of promastigotes, (iii) interaction with the extracellular matrix, (iv) inhibition of natural killer cellular functions, (v) resistance to antimicrobial peptide killing, (vi) degradation of Mø and fibroblast cytosolic proteins, and (vii) promotion of survival of intracellular amastigotes. MSP homologues have been found in all other trypanosomatids studied to date including heteroxenous members of Trypanosoma cruzi, the extracellular Trypanosoma brucei, unusual intraerythrocytic Endotrypanum spp., phytoparasitic Phytomonas spp., and numerous monoxenous species. These proteins are likely to perform roles different from those described for Leishmania spp. Multiple MSPs in individual cells may play distinct roles at some time points in trypanosomatid life cycles and collaborative or redundant roles at others. The cellular locations and the extracellular release of MSPs are also discussed in connection with MSP functions in leishmanial promastigotes.

Regulation of histidine-rich glycoprotein (HRG) function via plasmin-mediated proteolytic cleavage

The plasminogen/plasmin system is involved in a variety of normal physiological and pathological processes, including tissue remodelling, angiogenesis and tumour metastasis. Plasminogen activators and receptors for plasminogen/plasminogen activators are essential for the processing of plasminogen to form the active serine protease plasmin. Plasmin can in turn positively or negatively regulate further plasminogen activation via plasmin-mediated cleavage of receptors and activators. HRG (histidine-rich glycoprotein), a relatively abundant (approx. 100-150 microg/ml) plasma glycoprotein, has a multi-domain structure that can interact with many ligands, including Zn2+, heparin, HS (heparan sulfate) and plasminogen. HRG has been shown to function as an adaptor molecule to tether plasminogen to GAG (glycosaminoglycan)-bearing surfaces and to regulate plasminogen activation via various mechanisms. As HRG itself is sensitive to plasmin cleavage, the present study examines in detail the cleavage of human HRG by plasmin and the effect of this cleavage on various functions of HRG. HRG fragments, generated by plasmin cleavage, are held together by disulfide linkages and are not released from the molecule under non-reducing conditions. Plasmin-mediated cleavage partially inhibited HRG binding to cell surface HS, but enhanced HRG binding to necrotic cells and to plasminogen. However, both intact and plasmin-cleaved HRG enhanced the binding of plasminogen to heparin-coated surfaces to a similar extent. Furthermore, the presence of heparin, Zn2+ or acidic pH was found to protect HRG from plasmin cleavage. Thus proteolytic cleavage of HRG by plasmin may provide a feedback mechanism to regulate the effects of HRG on the plasminogen/plasmin system and other functions of HRG.

HCMV‐Encoded Glycoprotein M (UL100) Interacts with Rab11 Effector Protein FIP4

The envelope of human cytomegalovirus (HCMV) consists of a large number of glycoproteins. The most abundant glycoprotein in the HCMV envelope is the glycoprotein M (UL100), which together with glycoprotein N (UL73) form the gM/gN protein complex. Using yeast two-hybrid screening, we found that the gM carboxy-terminal cytoplasmic tail (gM-CT) interacts with FIP4, a Rab11-GTPase effector protein. Depletion of FIP4 expression in HCMV-infected cells resulted in a decrease in infectious virus production that was also associated with an alteration of the HCMV assembly compartment (AC) phenotype. A similar phenotype was also observed in HCMV-infected cells that expressed dominant negative Rab11(S25N). Recently, it has been shown that FIP4 interactions with Rab11 and additionally with Arf6/Arf5 are important for the vesicular transport of proteins in the endosomal recycling compartment (ERC) and during cytokinesis. Surprisingly, FIP4 interaction with gM-CT limited binding of FIP4 with Arf5/Arf6; however, FIP4 interaction with gM-CT did not prevent recruitment of Rab11 into the ternary complex. These data argued for a contribution of the ERC during cytoplasmic envelopment of HCMV and showed a novel FIP4 function independent of Arf5 or Arf6 activity.

Silencing of GRP94 expression promotes apoptosis in pancreatic cancer cells

As a molecular chaperone, GRP94 is the most abundant glycoprotein in the endoplasmic reticulum, playing an important role in maintaining cellular homeostasis. Here, we investigated the expression and the role of GRP94 in regulating cell growth and apoptosis in pancreatic cancer cells. GRP94 mRNA levels were analyzed by QRT-PCR. Immunohistochemistry was performed to localize GRP94 in tissues of the normal pancreas (n=20), chronic pancreatitis (n=20) and pancreatic ductal adenocarcinoma (n=44). Silencing of GRP94 expression was carried out by transfection with specific siRNA oligonucleotides. Apoptosis was induced by treatment with actinomycin D. Compared to normal pancreatic tissues, median mRNA levels of GRP94 were 1.5- and 3.7-fold (p<0.05) lower in chronic pancreatitis and pancreatic cancer tissues, respectively. GRP94 protein was strongly expressed in normal acinar cells and moderately expressed in normal ductal cells. GRP94 expression was lost in 48% of the cancer cases. Moderate or strong staining in cancer cells was observed in 32 and 20% of pancreatic cancer tissues, respectively. Silencing GRP94 by siRNA increased apoptosis of pancreatic cancer cells in vitro. Patients with higher than the median expression have a tendency for a worsened survival. When the small number of patients with the highest expression (n=3) were compared with the rest of the group (n=41), the survival difference was significantly worse (5 vs. 18 months, respectively, p=0.006). Down-regulation of GRP94 decreases apoptosis resistance in pancreatic cancer cells. Clinically, patients with high GRP94 expression show a tendency for a worsened survival.

Venom-Sweet-Venom: N-Linked Glycosylation in Snake Venom Toxins

Protein glycosylation represents one of the most important post-translational events, and is a mean of diversifying a protein without recourse to the genome. The venoms produced by snakes contain an abundance of glycoproteins with N-linked carbohydrates. N-linked glycosylation can ensure the correct folding of important functional domains. Characterization of carbohydrates structures aids in development of human therapeutics by snake venom toxins.

Subcellular localization of the carbohydrate Lewis x adhesion structure in hippocampus cell cultures

The Lewis x (Le x) epitope (Gal(β1–4)[Fuc(α1–3)]GlcNAc-R) has been associated with the development of the central nervous system of diverse species including human and rodents. In this work, Le x has been found in the tetanus neurotoxin insensitive vesicle-associated membrane protein (TI-VAMP) compartment of rat hippocampus neurons in culture, at 7 days in vitro (DIV), when neurite extension is abundant. The TI-VAMP compartment is known to be associated with neurite outgrowth. Le x was found predominantly in neurites but also in somata and in growth cones. Abundant Le x-carrier glycoproteins specific to neurons have been identified at this stage of differentiation. At a later stage of differentiation, at 14 DIV, Le x appeared in extrasynaptic sites of GABAergic neurons, and in synaptic sites of glutamatergic neurons.

Lysosomal exocytosis: An important event during invasion of lamp deficient cells by extracellular amastigotes of Trypanosoma cruzi

Trypanosoma cruzi is an obligate intracellular organism in vertebrate hosts. Lysosomes are involved in parasite invasion. LAMP-1 and LAMP-2 are the most abundant glycoproteins of the lysosomal membrane. This study is the first report on the invasion of T. cruzi extracellular amastigotes (EA) in single LAMP-1 or LAMP-2 knockouts, respectively, or in two independent LAMP-1/2 double-knockout cell lines. When compared to their respective wild type clones, the EA show higher infectivity in LAMP-2 knockouts, but no difference was seen in LAMP-1 knockout cells. Similarly, EA invasion rate was higher for one of the double knockout clones but not for the other. Higher lysosomal exocytosis correlated with a higher invasion rate and early lysosomal marker acquisition. These findings suggest that lysosomal exocytosis is important to EA cell invasion. Also, phagolysosome maturation in knockout cell lines differed from previous results revealing that EA enter cells by a mechanism other than receptor-mediated phagocytosis.

Pathogenic P0 mutations are blocked at various quality control check points.

In peripheral nerve, Schwann cells enwrap axons and form myelin. P0 is the most abundant transmembrane glycoprotein produced by Schwann cells, where it is normally delivered to the myelin sheath. Alterations of the dosage or the sequence of P0 cause diverse peripheral neuropathies, like Charcot Marie Tooth (CMT) or Dejerine Sottas Syndrome (DSS). Deletion of serine 63 (S63del), the first amino acid (aa) of the β‐strand C of the extracellular domain, causes the retention of the protein in the endoplasmic reticulum (ER)‐Golgi complex. Protein quality control in the ER ensures that only correctly synthesized proteins are delivered to the final destination. Here we correlate mutations in aa important for the maturation of P0, with their neuropathy phenotypes. Alteration of the glycosylation site does not alter the trafficking, whereas mutation of aa important for the formation of the disulfide bond cause retention of the mutant proteins in the ER‐Golgi compartment. Interestingly, the retention of mutants in the β‐strand C or in the cysteines of the disulfide bond is mediated by two different sets of chaperones, suggesting multiple check points mediate P0 maturation. Therefore, some P0 mutants exit the quality control and are pathogenic in the myelin sheath, whereas others are retained at various points of maturation in the ER. However, the location of intracellular P0 retention does not define the neuropathy phenotype.

Investigating Therapeutic Approach of IBD Using Recombinant Glycoprotein Mucin2

Inflammatory bowel disease (IBD) is characterized by a chronically inflamed mucosa of the gastrointestinal tract, caused by an underlying immune imbalance and alteration of mucosal barrier function. No effective medical cure has been developed for IBD due to our limited understanding of disease pathogenesis. Previous studies have demonstrated that the patients with Ulcerative colitis (UC)‐like mucosal inflammation exhibit a disrupted mucosal barrier. We speculate that the alteration of mucosal barrier integrity is initiated by the destructive interactions between abnormal enteric microbiota and mucous layer. Consistently, analysis of O‐glycan, a major component of colonic mucin in bowel rinse samples from patients with UC has revealed an alteration of mucin structure. This study further explores a novel therapeutic approach for IBD treatment by using exogenous recombinant glycoprotein to block the harmful interactions driven by the colonic bacteria. We established the CHO‐DG44 cell lines producing a recombinant Mucin2, the most abundant secretary glycoprotein in the colon and characterized the O‐glycans on the recombinant Mucin2 protein. Purified O‐glycosylated Mucin2 are being evaluated for the therapeutic effect in the mice model of mucosal inflammation caused by an impaired mucosal barrier. The study would provide a proof of concept to the therapeutic benefit of treating human IBD with recombinant glycoprotein administration.

β2‐glycoprotein i is a cofactor for tissue plasminogen activator–mediated plasminogen activation

Regulation of the conversion of plasminogen to plasmin by tissue plasminogen activator (tPA) is critical in the control of fibrin deposition. While several plasminogen activators have been described, soluble plasma cofactors that stimulate fibrinolysis have not been characterized. The purpose of this study was to investigate the effects of beta(2)-glycoprotein I (beta(2)GPI), an abundant plasma glycoprotein, on tPA-mediated plasminogen activation. The effect of beta(2)GPI on tPA-mediated activation of plasminogen was assessed using amidolytic assays, a fibrin gel, and plasma clots. Binding of beta(2)GPI to tPA and plasminogen was determined in parallel. The effects of IgG fractions and anti-beta(2)GPI antibodies from patients with antiphospholipid syndrome (APS) on tPA-mediated plasminogen activation were also measured. Beta(2)-glycoprotein I stimulated tPA-dependent plasminogen activation in the fluid phase and within a fibrin gel. The beta(2)GPI region responsible for stimulating tPA activity was shown to be at least partly contained within beta(2)GPI domain V. In addition, beta(2)GPI bound tPA with high affinity (K(d) approximately 20 nM), stimulated tPA amidolytic activity, and caused an overall 20-fold increase in the catalytic efficiency (K(cat)/K(m)) of tPA-mediated conversion of Glu-plasminogen to plasmin. Moreover, depletion of beta(2)GPI from plasma led to diminished rates of clot lysis, with restoration of normal lysis rates following beta(2)GPI repletion. Stimulation of tPA-mediated plasminogen activity by beta(2)GPI was inhibited by monoclonal anti-beta(2)GPI antibodies as well as by anti-beta(2)GPI antibodies from patients with APS. These findings suggest that beta(2)GPI may be an endogenous regulator of fibrinolysis. Impairment of beta(2)GPI-stimulated fibrinolysis by anti-beta(2)GPI antibodies may contribute to the development of thrombosis in patients with APS.

Role of Platelets in Atherothrombosis

Platelets play a pivotal role in atherothrombosis and therefore are primary targets of antithrombotic therapy. They release an array of agonists, such as adenosine diphosphate (ADP); adhesive molecules, such as P-selectin, thrombospondin, fibrinogen, and von Willebrand factor; coagulation factors; and growth factors. In turn, they present transmembrane receptors for a plethora of agonists and ligands. Heterodimeric glycoproteins of the integrin family bind extracellular matrix and plasma proteins; mediate adhesion, activation, spreading, and aggregation; and facilitate intercellular bidirectional signal transduction. Glycoprotein IIb/IIIa is the most abundant platelet integrin and membrane surface glycoprotein. Glycolipids, heparins, proteoglycans, tetraspanins, and a multitude of other molecules, such as tumor necrosis factor-alpha, CD40L, growth arrest-specific 6, Eph receptor tyrosine kinases, and signaling lymphocytic activation molecule receptors, have been implicated in atherothrombosis. ADP promotes platelet aggregation by binding to platelet surface receptors P2Y(1) and P2Y(12); the thienopyridines inhibit aggregation by binding covalently to P2Y(12). Thrombin, a potent initiator of platelet aggregation, activates platelets by cleaving protease-activated receptors (PARs) PAR-1 and PAR-4 and further propagates its effect by activating nearby platelets. A number of pharmacologic agents with antiplatelet actions have been developed, but the search continues for agents that strike an optimal balance between control of thrombosis and serious bleeding.

Deletion of the First Cysteine-Rich Region of the Varicella-Zoster Virus Glycoprotein E Ectodomain Abolishes the gE and gI Interaction and Differentially Affects Cell-Cell Spread and Viral Entry

Varicella-zoster virus (VZV) glycoprotein E (gE) is the most abundant glycoprotein in infected cells and, in contrast to those of other alphaherpesviruses, is essential for viral replication. The gE ectodomain contains a unique N-terminal region required for viral replication, cell-cell spread, and secondary envelopment; this region also binds to the insulin-degrading enzyme (IDE), a proposed VZV receptor. To identify new functional domains of the gE ectodomain, the effect of mutagenesis of the first cysteine-rich region of the gE ectodomain (amino acids 208 to 236) was assessed using VZV cosmids. Deletion of this region was compatible with VZV replication in vitro, but cell-cell spread of the rOka-DeltaCys mutant was reduced significantly. Deletion of the cysteine-rich region abolished the binding of the mutant gE to gI but not to IDE. Preventing gE binding to gI altered the pattern of gE expression at the plasma membrane of infected cells and the posttranslational maturation of gI and its incorporation into viral particles. In contrast, deletion of the first cysteine-rich region did not affect viral entry into human tonsil T cells in vitro or into melanoma cells infected with cell-free VZV. These experiments demonstrate that gE/gI heterodimer formation is essential for efficient cell-cell spread and incorporation of gI into viral particles but that it is dispensable for infectious varicella-zoster virion formation and entry into target cells. Blocking gE binding to gI resulted in severe impairment of VZV infection of human skin xenografts in SCIDhu mice in vivo, documenting the importance of cell fusion mediated by this complex for VZV virulence in skin.

Expression of Apalbumin1 of Apis cerana cerana in the Larvae of Silkworm, Bombyx mori

Royal jelly (RJ) is a thick, milky material produced by both the hypopharyngeal and the mandibular glands of nurse honeybees. The main proteins of RJ, named apalbumins or major royal jelly proteins (MRJPs), have multiple biological functions. Apalbumin1 is the most abundant glycoprotein of RJ. In this study, Bacmid- apalbumin1 was constructed for Apis cerana cerana using the newly established Bac-to-Bac/BmNPV baculovirus expression system (BES). This procedure allowed us to obtain the recombinant A. cerana cerana ( Acc) apalbumin1 (r Accapalbumin1) from the hemolymph of silkworm larvae through the BmNPV bacmid system, 96 h postinfection. The r Accapalbumin1 was then purified by Ni-NTA spin columns and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting. A 55 kDa protein with good solubility was then obtained. The peptide Ile-Phe was identified from trypsin production of r Accapalbumin1. Such a peptide has been reported to have an antihypertensive ability. Our results have therefore potential applications in biomedical research and open new perspectives for the study of apalbumins.

Pathogenesis of severe acute respiratory syndrome

Pathogenesis of severe acute respiratory syndrome