Immunoprotection by monoclonal antibodies to the porins and lipopolysaccharide of Salmonella typhimurium

Decoding the invasive nature of a tropical pathogen of concern: The invasive non-Typhoidal Salmonella strains causing host-restricted extraintestinal infections worldwide

Invasive-Non-Typhoidal Salmonella (iNTS) are the major cause of health concern in the low-income, under-developed nations in Africa and Asia that lack proper sanitation facilities. Around 5% of the NTS cases give rise to invasive, extraintestinal diseases leading to focal infections like osteomyelitis, meningitis, osteoarthritis, endocarditis and neonatal sepsis. iNTS serovars like S. Typhimurium, S. Enteritidis, S. Dublin, S. Choleraesuis show a greater propensity to become invasive than others which hints at the genetic basis of their emergence. The major risk factors attributing to the invasive diseases include immune-compromised individuals having co-infection with malaria or HIV, or suffering from malnutrition. The rampant use of antibiotics leading to the emergence of multi-drug resistant strains poses a great challenge in disease management. An extensive understanding of the iNTS pathogenesis and its epidemiology will open up avenues for the development of new vaccination and therapeutic strategies to restrict the spread of this neglected disease.

Polysaccharide Vaccines: A Perspective on Non-Typhoidal Salmonella

Polysaccharides are often the most abundant antigens found on the extracellular surfaces of bacterial cells. These polysaccharides play key roles in interactions with the outside world, and for many bacterial pathogens, they represent what is presented to the human immune system. As a result, many vaccines have been or currently are being developed against carbohydrate antigens. In this review, we explore the diversity of capsular polysaccharides (CPS) in Salmonella and other selected bacterial species and explain the classification and function of CPS as vaccine antigens. Despite many vaccines being developed using carbohydrate antigens, the low immunogenicity and the diversity of infecting strains and serovars present an antigen formulation challenge to manufacturers. Vaccines tend to focus on common serovars or have changing formulations over time, reflecting the trends in human infection, which can be costly and time-consuming. We summarize the approaches to generate carbohydrate-based vaccines for Salmonella, describe vaccines that are in development and emphasize the need for an effective vaccine against non-typhoidal Salmonella strains.

Why Is Eradicating Typhoid Fever So Challenging: Implications for Vaccine and Therapeutic Design

Salmonella enterica serovar Typhi (S. Typhi) and S. Paratyphi, namely typhoidal Salmonellae, are the cause of (para) typhoid fever, which is a devastating systemic infectious disease in humans. In addition, the spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) S. Typhi in many low and middle-income countries poses a significant risk to human health. While currently available typhoid vaccines and therapeutics are efficacious, they have some limitations. One important limitation is the lack of controlling individuals who chronically carry S. Typhi. However, due to the strict host specificity of S. Typhi to humans, S. Typhi research is hampered. As a result, our understanding of S. Typhi pathogenesis is incomplete, thereby delaying the development and improvement of prevention and treatment strategies. Nonetheless, to better combat and contain S. Typhi, it is vital to develop a vaccine and therapy for controlling both acutely and chronically infected individuals. This review discusses how scientists are trying to combat typhoid fever, why it is so challenging to do so, which approaches show promise, and what we know about the pathogenesis of S. Typhi chronic infection.

Adaptive Immune Responses during Salmonella Infection

The interaction betweenSalmonella and its host is complex and dynamic: the host mounts an immune defense against the pathogen, which in turn acts to reduce, evade, or exploit these responses to successfully colonize the host. Although the exact mechanisms mediating protective immunity are poorly understood, it is known that T cells are a critical component of immunity to Salmonella infection, and a robust T-cell response is required for both clearance of primary infection and resistance to subsequent challenge. B-cell functions, including but not limited to antibody production, are also required for generation of protective immunity. Additionally, interactions among host cells are essential. For example, antigen-presenting cells (including B cells) express cytokines that participate in CD4+ T cell activation and differentiation. Differentiated CD4+ T cells secrete cytokines that have both autocrine and paracrine functions, including recruitment and activation of phagocytes, and stimulation of B cell isotype class switching and affinity maturation. Multiple bacterium-directed mechanisms, including altered antigen expression and bioavailability and interference with antigen-presenting cell activation and function, combine to modify Salmonella's "pathogenic signature" in order to minimize its susceptibility to host immune surveillance. Therefore, a more complete understanding of adaptive immune responses may provide insights into pathogenic bacterial functions. Continued identification of adaptive immune targets will guide rational vaccine development, provide insights into host functions required to resist Salmonella infection, and correspondingly provide valuable reagents for defining the critical pathogenic capabilities of Salmonella that contribute to their success in causing acute and chronic infections.

Vaccines against invasive Salmonella disease: current status and future directions

Though primarily enteric pathogens, Salmonellae are responsible for a considerable yet under-appreciated global burden of invasive disease. In South and South-East Asia, this manifests as enteric fever caused by serovars Typhi and Paratyphi A. In sub-Saharan Africa, a similar disease burden results from invasive nontyphoidal Salmonellae, principally serovars Typhimurium and Enteritidis. The existing Ty21a live-attenuated and Vi capsular polysaccharide vaccines target S. Typhi and are not effective in young children where the burden of invasive Salmonella disease is highest. After years of lack of investment in new Salmonella vaccines, recent times have seen increased interest in the area led by emerging-market manufacturers, global health vaccine institutes and academic partners. New glycoconjugate vaccines against S. Typhi are becoming available with similar vaccines against other invasive serovars in development. With other new vaccines under investigation, including live-attenuated, protein-based and GMMA vaccines, now is an exciting time for the Salmonella vaccine field.

Membrane vesicle release in bacteria, eukaryotes, and archaea: a conserved yet underappreciated aspect of microbial life

Interaction of microbes with their environment depends on features of the dynamic microbial surface throughout cell growth and division. Surface modifications, whether used to acquire nutrients, defend against other microbes, or resist the pressures of a host immune system, facilitate adaptation to unique surroundings. The release of bioactive membrane vesicles (MVs) from the cell surface is conserved across microbial life, in bacteria, archaea, fungi, and parasites. MV production occurs not only in vitro but also in vivo during infection, underscoring the influence of these surface organelles in microbial physiology and pathogenesis through delivery of enzymes, toxins, communication signals, and antigens recognized by the innate and adaptive immune systems. Derived from a variety of organisms that span kingdoms of life and called by several names (membrane vesicles, outer membrane vesicles [OMVs], exosomes, shedding microvesicles, etc.), the conserved functions and mechanistic strategies of MV release are similar, including the use of ESCRT proteins and ESCRT protein homologues to facilitate these processes in archaea and eukaryotic microbes. Although forms of MV release by different organisms share similar visual, mechanistic, and functional features, there has been little comparison across microbial life. This underappreciated conservation of vesicle release, and the resulting functional impact throughout the tree of life, explored in this review, stresses the importance of vesicle-mediated processes throughout biology.

Salmonella enterica serovar Typhimurium lacking hfq gene confers protective immunity against murine typhoid

Salmonella enterica is an important enteric pathogen and its various serovars are involved in causing both systemic and intestinal diseases in humans and domestic animals. The emergence of multidrug-resistant strains of Salmonella leading to increased morbidity and mortality has further complicated its management. Live attenuated vaccines have been proven superior over killed or subunit vaccines due to their ability to induce protective immunity. Of the various strategies used for the generation of live attenuated vaccine strains, focus has gradually shifted towards manipulation of virulence regulator genes. Hfq is a RNA chaperon which mediates the binding of small RNAs to the mRNA and assists in post-transcriptional gene regulation in bacteria. In this study, we evaluated the efficacy of the Salmonella Typhimurium Δhfq strain as a candidate for live oral vaccine in murine model of typhoid fever. Salmonella hfq deletion mutant is highly attenuated in cell culture and animal model implying a significant role of Hfq in bacterial virulence. Oral immunization with the Salmonella hfq deletion mutant efficiently protects mice against subsequent oral challenge with virulent strain of Salmonella Typhimurium. Moreover, protection was induced upon both multiple as well as single dose of immunizations. The vaccine strain appears to be safe for use in pregnant mice and the protection is mediated by the increase in the number of CD4⁺ T lymphocytes upon vaccination. The levels of serum IgG and secretory-IgA in intestinal washes specific to lipopolysaccharide and outer membrane protein were significantly increased upon vaccination. Furthermore, hfq deletion mutant showed enhanced antigen presentation by dendritic cells compared to the wild type strain. Taken together, the studies in murine immunization model suggest that the Salmonella hfq deletion mutant can be a novel live oral vaccine candidate.

The porin OmpD from nontyphoidal Salmonella is a key target for a protective B1b cell antibody response

Invasive nontyphoidal Salmonella (NTS), including Salmonella typhimurium (STm), are major yet poorly-recognized killers of infants in sub-Saharan Africa. Death in these children is usually associated with bacteremia, commonly in the absence of gastrointestinal symptoms. Evidence from humans and animal studies suggest that severe infection and bacteremia occur when specific Ab is lacking. Understanding how Ab responses to Salmonella are regulated will help develop vaccines against these devastating infections. STm induces atypical Ab responses characterized by prominent, accelerated, extrafollicular T-independent (TI) Ab against a range of surface antigens. These responses develop without concomitant germinal centers, which only appear as infection resolves. Here, we show STm rapidly induces a population of TI B220(+)CD5(-) B1b cells during infection and TI Ab from B1b cells targets the outer membrane protein (Omp) porins OmpC, OmpD and OmpF but not flagellin. When porins are used as immunogens they can ablate bacteremia and provide equivalent protection against STm as killed bacterial vaccine and this is wholly B cell-dependent. Furthermore Ab from porin-immunized chimeras, that have B1b cells, is sufficient to impair infection. Infecting with porin-deficient bacteria identifies OmpD, a protein absent from Salmonella Typhi, as a key target of Ab in these infections. This work broadens the recognized repertoire of TI protein antigens and highlights the importance of Ab from different B cell subsets in controlling STm infection. OmpD is a strong candidate vaccine target and may, in part, explain the lack of cross-protection between Salmonella Typhi and STm infections.

Salmonella porins induce a sustained, lifelong specific bactericidal antibody memory response

We examined the ability of porins from Salmonella enterica serovar typhi to induce a long-term antibody response in BALB/c mice. These porins triggered a strong lifelong production of immunoglobulin G (IgG) antibody in the absence of exogenous adjuvant. Analysis of the IgG subclasses produced during this antibody response revealed the presence of the subclasses IgG2b, IgG1, IgG2a and weak IgG3. Despite the high homology of porins, the long-lasting anti-S. typhi porin sera did not cross-react with S. typhimurium. Notably, the antiporin sera showed a sustained lifelong bactericidal-binding activity to the wild-type S. typhi strain, whereas porin-specific antibody titres measured by enzyme-linked immunosorbent assay (ELISA) decreased with time. Because our porin preparations contained the outer membrane proteins C and F (OmpC and OmpF), we evaluated the individual contribution of each porin to the long-lasting antibody response. OmpC and OmpF induced long-lasting antibody titres, measured by ELISA, which were sustained for 300 days. In contrast, although OmpC induced sustained high bactericidal antibody titres for 300 days, postimmunization, the bactericidal antibody titre induced by OmpF was not detected at day 180. These results indicate that OmpC is the main protein responsible for the antibody-mediated memory bactericidal response induced by porins. Taken together, our results show that porins are strong immunogens that confer lifelong specific bactericidal antibody responses in the absence of added adjuvant.

OmpD but not OmpC is involved in adherence ofSalmonella entericaserovar Typhimurium to human cells

Conflicting reports exist regarding the role of porins OmpC and OmpD in infections due to Salmonella enterica serovar Typhimurium. This study investigated the role of these porins in bacterial adherence to human macrophages and intestinal epithelial cells. ompC and ompD mutant strains were created by transposon mutagenesis using P22-mediated transduction of Tn10 and Tn5 insertions, respectively, into wild-type strain 14028. Fluorescein-labeled wild-type and mutant bacteria were incubated with host cells at various bacteria to cell ratios for 1 h at 37 °C and analyzed by flow cytometry. The mean fluorescence intensity of cells with associated wild-type and mutant bacteria was used to estimate the number of bacteria bound per host cell. Adherence was also measured by fluorescence microscopy. Neither assay showed a significant difference in binding of the ompC mutant and wild-type strains to the human cells. In contrast, the ompD mutant exhibited lowered binding to both cell types. Our findings suggest that OmpD but not OmpC is involved in the recognition of Salmonella serovar Typhimurium by human macrophages and intestinal epithelial cells.Key words: Salmonella, adherence, porins, intestinal epithelial cells, macrophage.

The C-terminal domain of Salmonella enterica serovar typhimurium OmpA is an immunodominant antigen in mice but appears to be only partially exposed on the bacterial cell surface

We examined the way the major outer membrane protein OmpA of Salmonella enterica serovar Typhimurium is recognized by the mouse immune system, by raising a panel of 12 monoclonal antibodies (MAbs) against this protein. Interaction between OmpA and these MAbs is competitively inhibited with several-hundredfold dilutions of mouse polyclonal sera obtained by immunization with live or heat-killed whole cells, suggesting that OmpA is one of the immunodominant antigens of serovar Typhimurium. All of the MAbs were specific for an identical epitope(s) located on the C-terminal domain of OmpA, as indicated by the use of OmpA fragments generated by protease or cyanogen bromide treatment and by competitive inhibition enzyme-linked immunosorbent assay. This epitope was highly conserved within (but not outside) the family Enterobacteriaceae: The strong immunogenicity of this epitope was surprising because the C-terminal domain of OmpA, usually thought to be located in the periplasm, is not expected to be exposed on the bacterial cell surface. A MAb, however, reacted in a cytofluorometry assay more strongly with outer-membrane-permeabilized cells than with untreated cells, a result supporting the predominantly periplasmic localization of the epitope. Significant, though low-level, reactivity of intact cells nevertheless suggests that in some cells the C-terminal domain of OmpA is exposed on the surface, a result consistent with the proposal that OmpA can fold into one of the two alternate conformations.

Intranasal immunogenicity of a Deltacya Deltacrp-pabA mutant of Salmonella enterica serotype Typhimurium for the horse

The aim of this study was to investigate the intranasal immunogenicity for the horse of a Deltacya Deltacrp-pabA mutant (MGN-707) of Salmonella enterica serotype Typhimurium (S. typhimurium). MGN-707 caused no sign of disease, was not detected in feces and a single administration induced strong Salmonella-specific serum and nasal mucosal antibody responses. All ponies had made strong salmonella specific serum IgGa, IgGb, IgA and IgM antibody responses by day 25 after the first immunization. IgM responses to salmonella lipopolysaccharide (LPS) were short lived whereas salmonella specific serum IgGa and IgGb persisted at high levels in all ponies until 83 and 140 days, respectively. Specific nasal mucosal antibody responses dominated by IgA and IgM were evident by day 25 in all ponies except one in which only specific IgGa and IgGb were evident. Specific nasal mucosal IgA persisted in most ponies until day 69. A second immunization on day 140 boosted antibody responses, and stimulated a strong nasal mucosal IgA response in the pony that failed to make an IgA response after primary immunization. At the termination of the experiment, IgA and IgGb dominated jejunal antibody responses whereas vaginal responses were mainly IgA. The latter response unequivocally confirms the existence of a common mucosal immune system in equids. The results indicate that a S. typhimurium Deltacya Deltacrp-pabA mutant has potential as an intranasal vaccine against salmonellosis in the horse.

Intranasal immunogenicity of a Delta cya Delta crp-pabA mutant of Salmonella enterica serotype Typhimurium for the horse

The aim of this study was to investigate the intranasal immunogenicity for the horse of a Deltacya Deltacrp-pabA mutant (MGN-707) of Salmonella enterica serotype Typhimurium (S. typhimurium). MGN-707 caused no sign of disease, was not detected in feces and a single administration induced strong Salmonella-specific serum and nasal mucosal antibody responses. All ponies had made strong salmonella specific serum IgGa, IgGb, IgA and IgM antibody responses by day 25 after the first immunization. IgM responses to salmonella lipopolysaccharide (LPS) were short lived whereas salmonella specific serum IgGa and IgGb persisted at high levels in all ponies until 83 and 140 days, respectively. Specific nasal mucosal antibody responses dominated by IgA and IgM were evident by day 25 in all ponies except one in which only specific IgGa and IgGb were evident. Specific nasal mucosal IgA persisted in most ponies until day 69. A second immunization on day 140 boosted antibody responses, and stimulated a strong nasal mucosal IgA response in the pony that failed to make an IgA response after primary immunization. At the termination of the experiment, IgA and IgGb dominated jejunal antibody responses whereas vaginal responses were mainly IgA. The latter response unequivocally confirms the existence of a common mucosal immune system in equids. The results indicate that a S. typhimurium Deltacya Deltacrp-pabA mutant has potential as an intranasal vaccine against salmonellosis in the horse.

Identification of murine B-cell and T-cell epitopes of Escherichia coli outer membrane protein F with synthetic polypeptides

The major pore-forming outer membrane proteins (Omps) of gram-negative bacteria demonstrate numerous immunomodulating properties and are involved in the virulence of pathogenic strains. Because Escherichia coli OmpF is the best-characterized porin in terms of structural and functional characteristics, in vitro B-cell and T-cell responses to this porin in six different strains of mice were analyzed. Mice were immunized with purified OmpF trimers or overlapping synthetic polypeptides (20-mers) spanning the entire 340-amino-acid sequence of the OmpF monomer. T-cell proliferative responses and immunoglobulin G antibody responses to native OmpF and the peptide analogues were determined. For each strain, patterns of T-cell proliferation were similar regardless of whether native OmpF or synthetic peptides were inoculated, although all strains recognized one or more cryptic determinants. Mice exhibited several haplotype-specific responses, but genetically permissive epitopes were also identified. Four peptides (75-94, 265-284, 295-314, and 305-324) elicited strong T-cell proliferative responses from all strains of mice when mice were presensitized with native OmpF or a homologous peptide. In general, 10 or fewer peptides were recognized by sera from mice immunized with native OmpF or synthetic peptides, and most sera from peptide-immunized mice reacted poorly with the native protein. Four peptides spanning amino acids 45 to 64, 95 to 114, 115 to 134, and 275 to 294 were recognized by sera from all strains immunized with native OmpF but not by sera from peptide-immunized mice. Peptides 245-264 and 305-324 were universally recognized by sera from peptide-immunized mice, but these sera reacted weakly or were negative when tested against the native protein. Based on the pattern of cytokine secretion by proliferating T cells, immunization with native OmpF polarizes T helper cells toward development of a TH1 response. T-cell and B-cell responses have been investigated based on the assumption that differences in epitope specificity could influence protective or pathologic host reactions. Because of the high level of structural homology of OmpF to porins isolated from other enteric pathogens, the identification of T- and B-cell-stimulatory determinants of E. coli OmpF may have broader application.

Immune recognition of porin and lipopolysaccharide epitopes of Salmonella typhimurium in mice

We investigated the antigenic specificity of the humoral immune response to infection by Salmonella typhimurium, by competitive inhibition enzyme-linked immunosorbent assay and Western immunoblots. A panel of eight murine monoclonal antibodies, raised to OmpC and OmpD porins and lipopolysaccharide (LPS)-O antigens, was used to define the specificity of the polyclonal immune response in mice. The monoclonal antibody panel recognized five distinct epitopes; these were localized to surface-exposed loops of OmpC and OmpD porin, to the "eye-let" forming loop L3 of OmpC/OmpD, and to LPS-O4 and O5 factors. The immune mouse serum raised to infections with S. typhimurium LT-2 strain WB600 (wild-type) competitively inhibited the binding of biotin-labelled monoclonal antibodies to the epitopes that they recognize, indicating that all five epitopes were targets of the host immune response to natural infection. However, only two epitopes, one within a surface-exposed loop of OmpC porin, and the other in the LPS-O4 factor, were immunodominant. Furthermore, the bacterial LPS core and O-antigen structure influenced the immune response to the porins. Surface epitopes of porins were dominant in the rough strain SH5014 (rfa), whereas the immune recognition of LPS epitopes was predominant in mice infected with the smooth, wild-type strain (WB600). Finally, the immune response to LPS epitopes O4 and O5 was more pronounced in mice immunized with heat-killed cells than those infected with live S. typhimurium.

The porin OmpC ofSalmonella typhimuriummediates adherence to macrophages

Macrophages recognize, adhere to, and phagocytose Salmonella typhimurium. The major outer membrane protein OmpC is a candidate ligand for macrophage recognition. To confirm this we used transposon mutagenesis to develop an ompC-deficient mutant in a known virulent strain of S. typhimurium; mutant and wild type were compared in macrophage adherence and association assays. Radiolabeled wild type S. typhimurium bound to macrophages at five-fold higher levels than did the ompC mutant. In association assays, macrophages in monolayers bound and internalized three-fold more wild type than mutant, while macrophages in suspension bound and internalized 40-fold more wild type than mutant. The ompC gene of our test strain of S. typhimurium contains several discrete differences compared with the ompC genes of Salmonella typhi and Escherichia coli. The deduced OmpC amino acid sequence of S. typhimurium shares 77 and 98% identity with OmpC amino acid sequences of E. coli and S. typhi, respectively. Evidence from this study supports a role for the OmpC protein in initial recognition by macrophages and distinguishes regions of this protein that potentially participate in host-cell recognition of bacteria by phagocytic cells.Key words: Salmonella, porin, macrophage, outer membrane protein, DNA sequencing.

Influence of immunopotentiators on the antiporin immunoglobulin G subclass: distribution and protective immunity against murine salmonellosis

To improve the immune potential of porin (a pore-forming protein of Salmonella sp.), different immunopotentiators such as Freund's complete adjuvant (FCA), lipopolysaccharide (LPS) and polyoxydonium (PO) were evaluated by studying the nature of the protective immune response induced against murine Salmonellosis. The nontoxic, synthetic heteropolymer polyoxydonium was as good as LPS at inducing antiporin immunoglobulin G (IgG) antibodies and protective immunity. Analysis of the antiporin IgG subclass pattern revealed a preferential increase in a particular subclass based on the immunopotentiator used. Porin, alone or emulsified in FCA, elicited predominantly antiporin IgG1 antibodies, whereas LPS preferentially evoked antiporin IgG2a, IgG2b and IgG3 antibodies. Polyoxydonium induced a clear shift towards antiporin IgG2b antibodies. The significance of these antiporin IgG subclass antibodies in protection against murine Salmonellosis was studied by passive immunization and by analysing the infected mouse sera.

Recognition specificity of monoclonal antibodies which protect mice against Salmonella typhimurium infection

We used enzyme-linked immunosorbent assay (ELISA), competitive inhibition ELISA, flow cytometry and western immunoblots to study the antigenic specificity of two monoclonal antibodies (mAbs) raised against the cell surface antigens of Salmonella typhimurium. These mAbs (SH6.11 and WB60.4) protect CAF1 (Ity(r)) mice against endotoxemia and mouse typhoid. We found that SH6.11 and WB60.4 recognize Salmonella serogroup B-specific lipopolysaccharide O4 and O5 factors, respectively. These mAbs did not bind to Salmonella serotypes that belong to serogroup A, D1, E4, G2, or R and did not cross-react with other enteric and nonenteric bacterial species.

Effect of Pasteurella haemolytica outer membrane proteins on bovine neutrophils

The major outer membrane proteins (OMPs) isolated from Pasteurella haemolytica induce alterations of the biological activity of bovine polymorphonuclear leukocytes (PMNs). A dose-dependent reduction of the capacity of adherence to nylon wool in vitro was observed. OMPs also acted as chemotaxins at concentrations between 5 and 20 microg/ml. Concentrations lower than 5 microg/ml did not give considerable results. Preincubation with 5 microg/ml of OMPs led to modifications in the values of the phagocytic index and of intracellular killing, which were found to be diminished with respect to controls.

Structural studies of the putative O-specific polysaccharide of Acinetobacter baumannii O24 containing 5,7-diamino-3,5,7,9-tetradeoxy-L-glycero-D-galacto-nonulosonic acid

A polysaccharide containing D-GlcN, 2-amino-2,6-dideoxy-L-galactose (L-FucN), and 7-acetamido-5-acylamino-3,5,7,9-tetradeoxy-L-glycero-D-galacto-nonulo sonic acid (LegAX), in which the acyl group (X) is either S-3-hydroxybutyryl (50%) or acetyl (50%), was isolated by mild acid hydrolysis treatment, followed by gel-permeation chromatography, of the water-soluble lipopolysaccharide from Acinetobacter baumannii serogroup O24. The polysaccharide, characterised by means of monosaccharide analyses, partial acid hydrolysis, methylation analysis and NMR studies, was shown to have a linear tetrasaccharide repeating unit, as depicted below. Serological tests indicated that the polymer corresponded to the O24 antigen. -->6)-alpha-D-GlcpNAc-(1-->3)-alpha-L-FucpNAc-(1-->3)-alpha-D-Glcp NAc-(1-->4)-beta-LegpAX-(1-->.