Centre for Equine Virology, School of Veterinary Science, The University of Melbourne, Parkville, VIC 3010, Australia
Correspondence
Carol A. Hartley
carolah{at}unimelb.edu.au
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Present address: Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.
Present address: Pfizer, Animal Health R & D, 45 Poplar Road, Parkville, VIC 3052, Australia.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
While picornaviruses share a range of similar physical properties including structural and sequence similarities, they nevertheless recognize a wide range of different cellular receptors. FMDV is most closely related to ERAV and uses various cell-surface molecules as receptors in vitro. These include the integrins v
3,
v
6 and
v
1, heparan sulphate and Fc receptors (Baranowski et al., 1998
; Baxt & Mason, 1995
; Berinstein et al., 1995
; Jackson et al., 1996
, 2000
, 2002
; Rieder et al., 1996
). The major group of human rhinoviruses (HRVs) use intracellular adhesion molecule-1 (ICAM-1) as a cell receptor, while the minor group of HRVs use members of the low-density-lipoprotein receptor family (Greve et al., 1989
; Marlovits et al., 1998
; Staunton et al., 1989
; Tomassini et al., 1989
). Many enteroviruses use immunoglobulin superfamily (IgSF) cell-surface molecules such as ICAM-1 as their receptors. Other enteroviruses use cell-surface molecules such as decay-accelerating factor and integrins
v
3 (vitronectin receptor) and
v
1 (Roivainen et al., 1994
; Xiao et al., 2001
). Other IgSF molecules used as receptors by picornaviruses include the coxsackievirusadenovirus receptor used by many of the coxsackie B viruses and the poliovirus receptor (Rossmann et al., 2002
; Newcombe et al., 2003
).
In this study, a viruscell-binding assay was developed, which measured binding of purified biotinylated ERAV isolate 393/76 (ERAV.393/76) to cells using flow cytometry. Using this assay, molecules on several cell lines that bind ERAV and facilitate ERAV infection were characterized using a variety of chemical and enzymic treatments and inhibitions. Biochemical treatments that affected cell binding were further studied using an immunofluorescence infectivity assay (IFA) to determine their effects on cell infection by ERAV.393/76.
![]() |
METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
IFA.
Confluent monolayer cultures of Vero cells in 96-well flat-bottomed microtitre plates (Nunc) were infected with approximately 3000 TCID50 ERAV.393/76 (m.o.i. of 0·1) in DMEM for 1 h in 5 % CO2 at 37 °C. Following incubation, the cell monolayers were washed twice with DMEM before being incubated in 5 % CO2 at 37 °C. After 24 h, the cells were fixed in 90 % methanol for 10 min, dried at room temperature and blocked with PBS containing 10 mg BSA ml1 (BSA10PBS) for 1 h at room temperature prior to the addition of 50 µl primary antibody per well, either rabbit ERAV antisera or rabbit pre-bleed diluted 1 : 1000 in PBST (BSA5PBS containing 0·05 % Tween 20), and incubation for 1 h. Cells were washed three times with PBST and probed with 50 µl FITC-conjugated swine anti-rabbit antibodies (Dako) at a dilution of 1 : 40 for 1 h. Plates were washed as above and examined immediately by fluorescence microscopy. The total number of fluorescent cells was counted over four fields at 40x magnification. To examine the inhibition of infectivity, cells were treated or pre-incubated with the proteins, enzymes or lectins of interest (described below), prior to the addition of virus and infection; staining then proceeded as described above. All assays included virus controls (virus and untreated cells only) and cell controls (cells only). Each assay was carried out in triplicate and the results presented as the mean. Results were expressed as a percentage of the virus controls and consisted of the number of fluorescent cells per four non-overlapping fields per well.
Treatment of cells with metabolic inhibitors.
Monolayer cell cultures were treated with the glycosylation inhibitors tunicamycin (Sigma) or benzyl N-acetyl--D-galactosamide (benzylGalNAc; Sigma), or with the inhibitor of glycolipid synthesis D,L-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP; Sigma), essentially as described by Guerrero et al. (2000)
. Control-cell flasks were grown and incubated with DMEM without metabolic inhibitor present. After treatment with the respective drug, cells were washed twice with PBS and detached from the flasks as above before being used in the virus-binding assay or being resuspended in 5 ml DMEM and used to seed 96-well trays (100 µl per well) for 4 h for use in the IFA.
Treatment of cells with sodium periodate (NaIO4).
Cell suspensions were incubated with 0·011 mM NaIO4 (AJAX) in PBS for 30 min at 4 °C. Twice the volume of 0·22 % (v/v) glycerol in PBS was added to neutralize unreacted periodate. Cells were washed twice with fluorescence-activated cell sorter (FACS) wash buffer (Warner et al., 2001) before being used in the virus-binding assay. As a control, cells were also mock treated; 0·22 % glycerol in PBS was added to 0·011 mM NaIO4 in PBS and incubated for 30 min at 4 °C before being added to a cell suspension.
For the IFA, cells in a 96-well tray were treated with NaIO4 and incubated as above before the reaction was stopped using 0·22 % glycerol. Cells were washed twice with DMEM before being used in the assay.
Enzyme treatment of cells.
Cell suspensions in 100 µl FACS wash buffer were incubated with 150 µg factor X (Sigma), dispase (Difco), trypsin (Gibco) or proteinase K (ICN Biomedicals) or with 160 mU Vibrio cholerae (VC) or Clostridium perfringens (CP) neuraminidase (Sigma) for 1 h at 37 °C. Prior to use in the assay, cell suspensions were washed twice in FACS wash buffer. For the IFA, 10 and 20 mU CP neuraminidase in PBS was added to cells in a 96-well tray and the tray was incubated for 1 h at 37 °C. The cells were washed twice with DMEM before being used in the assay.
Glycosaminoglycan, glycoconjugate and lectin treatment of virus.
Prior to incubation with cell suspensions, biotinylated virions (in 100 µl FACS wash buffer) were incubated with the glycosaminoglycans heparan sulphate, heparin and chondroitin sulphate A, B or C (Sigma) at concentrations of 100 and 1000 µg ml1, the glycoconjugates sialyllactose (9 mM) and 20 µg colominic acid, fetuin and glycophorin (Sigma), as well as the lectins Triticum vulgaris agglutinin (wheat germ agglutinin, WGA), Maackia amurensis (MAA) agglutinin, Sambucus nigra (SNA) agglutinin, Tetragonolobus purpureus agglutinin (APL) and concanavalin A (ConA) (100 µg ml1; Sigma).
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
ERAV.393/76 binds to and infects a range of cell types
Vero cells were chosen as the cell line for this study as they are routinely utilized in our laboratory for the replication of ERAV isolates, as described by Li et al. (1997). The binding of ERAV.393/76 virions to a range of cell lines was examined and the results are shown in Table 1
. EFK and mouse fibroblast (McCoy) cells bound ERAV.393/76 to high levels, whereas MDBK and baby hamster kidney (BHK-21) cells showed little or no significant binding. The capacity of each of these cell lines to support replication of ERAV.393/76 was also assessed. As shown in Table 1
, the level of ERAV.393/76 binding to these cells generally correlated with the relative infectivity of the virus in the different cell types. In particular, EFK, McCoy, RK-13 and Crandell feline kidney (CRFK) cells bound virus to high levels and produced high virus yields (
107 TCID50 ml1). MDBK and BHK-21 cells showed little or no binding of virus, producing yields of
101·8 TCID50 ml1. Of the cells tested, ovine fetal kidney (OFK) cells showed the least correlation between binding and infectivity, with ERAV.393/76 binding OFK cells to levels comparable with Vero cells, but not supporting replication of virus to titres of >101·8 TCID50 ml1. The inability of ERAV.393/76 to infect these cells, as well as MDBK and BHK-21 cells, was confirmed by immunofluorescence (data not shown).
Protein is a component of the receptor required for ERAV.393/76 binding
To assess the role of cell-surface proteins in ERAV binding, cells were treated with a range of proteases. Pre-treatment of Vero cells with the proteases trypsin, proteinase K, dispase or factor X reduced ERAV.393/76 binding in a dose-dependent manner (Fig. 2). At the concentrations used, these proteases did not significantly affect the viability of cells, as assessed by eosin exclusion. Factor X and trypsin in particular, which both cleave peptide bonds at the carboxylic side of arginine, both reduced binding at relatively low concentrations. Over five separate experiments, 2 µg factor X decreased binding by 4858 %, while 50 µg trypsin reduced binding by 5265 %. These results suggested that the ERAV.393/76 receptor on Vero cells contains a protein component.
|
|
|
The involvement of sialic acid residues in ERAV.393/76 binding was further investigated using sialic acid-specific lectins. Vero cells were pre-incubated with 100 µg of different lectins ml1 prior to incubation with biotin-labelled virus. In three separate experiments, WGA and MAA lectins, which have an affinity for N-acetylneuraminic acid (NeuAc), N-acetylglucosamine (GlcNAc), (GlcNAc)n and NeuAc2,3-Gal/GalNAc side chains, respectively, inhibited ERAV.393/76 binding by 6672 % and 6070 %, respectively (Fig. 5
). SNA lectin, which has an affinity for NeuAc
2,6-Gal/GalNAc side chains, inhibited binding by 2030 %. Given the relative binding specificities of these lectins, these results suggested that ERAV shows a strong preference for binding to sialic acids with an
2,3 linkage to the underlying sugar chains. The lectins ConA and APL (with affinities for
-mannose and
-glucose, and NeuAc
2-6Gal/GalNAc side chains, respectively) were also tested. ConA and APL reduced ERAV binding by 7090 % and 1013 %, respectively, suggesting that terminal mannose residues of a glycan branched chain or mannose residues within the branched sialylated structure are also involved in ERAV binding. The reduction in binding produced by the lectins WGA, MAA and SNA was dose dependent (data not shown). There was no evidence that these three lectins or ConA caused cell agglutination, as determined by light microscopy and by the forward- and side-scatter profiles of these cells when examined by flow cytometry.
|
Inhibitors of ERAV.393/76 binding also reduce infectivity
The attachment of virus to the cell surface may result in specific uptake by the cell as the first step of infection or may result in trafficking to a dead-end pathway where no virus progeny are made. To investigate whether the specific inhibition of ERAV binding to Vero cells resulted in a reduction in virus infectivity, compounds known to reduce virus binding to cells were tested for their ability to reduce virus infectivity. Monolayers of Vero cells were pre-treated with ConA, WGA, MAA, SNA, APL, CP neuraminidase, NaIO4 or tunicamycin prior to infection. Virus infection was detected by immunofluorescence after 24 h. All treatments reduced the infectivity of ERAV.393/76 in Vero cells at levels comparable with the reduction in ERAV.393/76 binding (Table 2), with both ConA and NaIO4 treatments reducing infectivity by 80 %, and MAA and neuraminidase by 50 %. APL had no significant effect on infectivity. PDMP and heparin treatments had no effect on infectivity (Table 2
). Lectins, enzymes, glycosaminoglycans and other ligands used in the biochemical characterization of both binding and infectivity of ERAV.393/76 to Vero cells did not modify the measured pH of the medium or the viability of the cells (as assessed by eosin exclusion), which argues for a specific effect of these compounds in reducing the binding to and infection of Vero cells by ERAV.393/76.
|
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Sialic acid moieties are acylated derivatives of neuraminic acid (5-amino-3,5-dideoxy-D-glycero-D-galactononulosonic acid) and are frequently found on glycoproteins or glycolipids, usually at the free terminus of short, often branched oligosaccharide chains (Burness, 1981; Alberts et al., 1989
). Several picornaviruses use sialic acid for binding to the surfaces of susceptible cells, including bovine enterovirus, HRV-87 and persistent strains of Theiler's murine encephalomyelitis virus (Zhou et al., 1997
; Evans & Almond, 1998
; Alexander & Dimmock, 2002
; Jnaoui et al., 2002
). An early study by Lonberg-Holm & Philipson (1974)
also indicated that ERAV may interact with cell-surface receptors containing sialic acid, since pre-treatment of HeLa cells with neuraminidase prevented the binding of radiolabelled ERAV but not the binding of HRVs and poliovirus.
Sialic acid molecules gain diversity in their structure by variation in the type of sialic acid (usually NeuAc or GlcNAc) or by the type of linkage of the sialic acid to the underlying sugar chain. The ability of both WGA and MAA, but not SNA, lectins to inhibit ERAV binding significantly suggests that ERAV has a preference for binding to sialic acid with an 2,3 linkage to the underlying sugar residues. Both CP and VC neuraminidases have a preference for NeuAc sialic acids over GlcNAc sialic acids. Taken together, these results suggest that ERAV.393/76 shows a preference for binding to NeuAc sialic acid with an
2,3 linkage to the underlying sugar residues. ConA, a lectin that binds to terminal mannose residues of a glycan branched chain or mannose residues within the branched sialylated structure (Varki et al., 1999
), also strongly inhibited binding of ERAV to Vero cells. This suggests that either mannose or glucose residues also participate directly in receptor binding, or that ConA sterically inhibits binding of virus to cells by binding mannose residues proximal to sialic acid side chains on the glycan.
It has been suggested that non-enveloped viruses require a specific protein entry receptor for internalization into the cell (Reddi & Lipton, 2002). While the concentration of tunicamycin used in this study may have affected the glycosylation of both proteins and lipids (Ogawa et al., 1998
), the inability of PDMP to reduce binding to cells suggests that ERAV is binding to sialic acid on the surface of N-linked glycoproteins. The reduction in binding demonstrated after protease treatment of cells supports this notion.
The ubiquitous nature of sialic acid on the surface of cells is consistent with the ability of ERAV to bind to and infect a range of cell types from a range of host species. However, the effects on ERAV.393/76 binding when a range of cells was treated with WGA, MAA and SNA lectins and neuraminidase were variable. This might occur as a result of variation in the types of sialic acid presented on the different cells, where stronger binding of ERAV to a particular sialic acid may be more difficult to inhibit with these lectins. Allaway & Burness (1987) demonstrated that treatment of the sialylated glycoprotein glycophorin with neuraminidase prevented it binding to encephalomyocarditis virusSepharose columns, indicating a requirement for sialic acid for receptor activity. However, sialoglycoconjugates such as fetuin, which binds to specific sialic acids, were unable to bind the virus. This indicates that the presence of sialic acid alone on a molecule is insufficient to result in binding and that other features of the molecule must be important. Glycophorin was the strongest inhibitor of binding, reducing binding by 35 %, and this glycoconjugate is known to contain a mixture of sialic acid molecules. While the substrate specificity of neuraminidases and lectins may cleave and bind to a relatively broad range of sialic acid moieties, the sialic acid molecules presented on individual glycoconjugates may be more limited and as such may not contain exactly the right conformation required for ERAV binding.
The process resulting in infection of a cell by a virus is complex. Binding of virus to more than one surface molecule has been demonstrated for several viruses. In a recent biochemical study of rotavirus receptors, it was shown that at least three cell-surface molecules were involved in the early steps of the interaction of rotaviruses with MA104 cells (Guerrero et al., 2000). For other viruses such as adenovirus 9 (Ad9) and Ad19, it is known that binding to a cell does not necessarily lead to infection (Arnberg et al., 2000
). Interestingly, inhibitors that prevented ERAV.393/76 binding to sialylated molecules on the surface of Vero cells reduced the infection of Vero cells by ERAV.393/76 to levels comparable with their effect on ERAV.393/76 binding. However, none of the treatments resulted in complete inhibition of binding or infection, which suggests that another molecule(s) may be involved in the binding and infection of Vero cells by ERAV. The existence of a second receptor for ERAV, in addition to sialic acid, could provide an alternative explanation for the reduction in binding of ERAV after protease treatment of cells.
The results presented in this study provide preliminary data on the types of receptor molecules that may be involved in ERAV.393/76 binding and infection of cells, and indicate that ERAV may utilize more than one receptor molecule. Further studies are required to elucidate the nature and involvement of these receptor molecules in more detail.
![]() |
ACKNOWLEDGEMENTS |
---|
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Alexander, D. A. & Dimmock, K. (2002). Sialic acid functions in enterovirus 70 binding and infection. J Virol 76, 1126511272.
Allaway, G. P. & Burness, A. T. H. (1987). Analysis of the bond between encephalomyocarditis virus and its human erythrocyte receptor by affinity chromatography on virussepharose columns. J Gen Virol 68, 18491856.[Abstract]
Arnberg, N., Edlund, K., Kidd, A. H. & Wadell, G. (2000). Adenovirus type 37 uses sialic acid as a cellular receptor. J Virol 74, 4248.
Baranowski, E., Sevilla, N., Verdaguer, N., Ruiz-Jarabo, C. M., Beck, E. & Domingo, E. (1998). Multiple virulence determinants of foot-and-mouth disease virus in cell culture. J Virol 72, 63626372.
Baxt, B. & Mason, P. W. (1995). Foot-and-mouth disease virus undergoes restricted replication in macrophage cell cultures following Fc receptor-mediated adsorption. Virology 207, 503509.[CrossRef][Medline]
Berinstein, A., Roivainen, M., Hovi, T., Mason, P. W. & Baxt, B. (1995). Antibodies to the vitronectin receptor (integrin V
3) inhibit binding and infection of foot-and-mouth disease virus to cultured cells. J Virol 69, 26642666.[Abstract]
Burness, A. T. H. (1981). Glycophorin and sialylated components as receptors for viruses. In Virus Receptors, Part 2: Animal Viruses, pp. 6584. Edited by K. Lonberg-Holm & L. Philipson. London: Chapman & Hall.
Evans, D. J. & Almond, J. W. (1998). Cell receptors for picornaviruses as determinants of cell tropism and pathogenesis. Trends Microbiol 6, 198202.[CrossRef][Medline]
Greve, J. M., Davis, G., Meyer, A. M., Forte, C. P., Yost, S. C., Marlor, C. W., Kamarck, M. E. & McClelland, A. (1989). The major human rhinovirus receptor is ICAM-1. Cell 56, 839847.[Medline]
Guerrero, C. A., Zarate, S., Corkidi, G., Lopez, S. & Arias, C. F. (2000). Biochemical characterization of rotavirus receptors in MA104 cells. J Virol 74, 93629371.
Hartley, C. A., Ficorilli, N., Dynon, K., Drummer, H. E., Huang, J. & Studdert, M. J. (2001). Equine rhinitis A virus: structural proteins and immune response. J Gen Virol 82, 17251728.
Inghirami, G., Nakamura, M., Balow, J. E., Notkins, A. L. & Casali, P. (1988). Model for studying virus attachment: identification and quantitation of EpsteinBarr virus-binding cells by using biotinylated virus in flow cytometry. J Virol 62, 24532463.[Medline]
Jackson, T., Ellard, F. M., Ghazaleh, R. A., Brookes, S. M., Blakemore, W. E., Corteyn, A. H., Stuart, D. I., Newman, J. W. & King, A. M. (1996). Efficient infection of cells in culture by type O foot-and-mouth disease virus requires binding to cell surface heparan sulfate. J Virol 70, 52825287.[Abstract]
Jackson, T., Blakemore, W., Newman, J. W. I., Knowles, N. J., Mould, A. P., Humphries, M. J. & King, A. M. Q. (2000). Foot-and-mouth disease virus is a ligand for the high-affinity binding conformation of integrin 5
1: influence of the leucine residue within the RGDL motif on selectivity of integrin binding. J Gen Virol 81, 13831391.
Jackson, T., Mould, A. P., Sheppard, D. & King, A. M. Q. (2002). Integrin v
1 is a receptor for foot-and-mouth disease virus. J Virol 76, 935941.
Jnaoui, K., Minet, M. & Michiels, T. (2002). Mutations that affect the tropism of DA and GDVII strains of Theiler's virus in vitro influence sialic acid binding and pathogenicity. J Virol 76, 81388147.
Li, F., Browning, G. F., Studdert, M. J. & Crabb, B. S. (1996). Equine rhinovirus 1 is more closely related to foot-and-mouth disease virus than to other picornaviruses. Proc Natl Acad Sci U S A 93, 990995.
Li, F., Drummer, H. E., Ficorilli, N., Studdert, M. J. & Crabb, B. S. (1997). Identification of noncytopathic equine rhinovirus 1 as a cause of acute febrile respiratory disease in horses. J Clin Microbiol 35, 937943.[Abstract]
Lonberg-Holm, K. & Philipson, L. (1974). Irreversible inhibition of receptors. In Early Interaction between Animal Viruses and Cells. Monographs in Virology, 9th edn, pp. 3437. Edited by J. L. Melnick. Houston, TX: S. Karger.
Luo, M., Rossmann, M. G. & Palmenberg, A. C. (1997). The structure of Theiler's virus complexed with its receptor. Exp Prog Rep 7, 5760.
Marlovits, T. C., Abrahamsberg, C. & Blass, D. (1998). Very-low-density lipoprotein receptor fragment shed from HeLa cells inhibits human rhinovirus infection. J Virol 72, 1024610250.
Martinez-Barragan, J. J. & Angel, R. M. (2001). Identification of a putative coreceptor on Vero cells that participates in dengue 4 virus infection. J Virol 75, 78187827.
McCollum, W. H. & Timoney, P. J. (1992). Studies on the seroprevalence and frequency of equine rhinovirus-I and -II infection in normal horse urine. In Equine Infectious Diseases, pp. 8387. Cambridge: R & W Publications.
Newcombe, N. G., Andersson, P., Johansson, E. S., Au, G. G., Lindberg, A. M., Barry, R. D. & Shafren, D. R. (2003). Cellularreceptor interactions of C-cluster human group A coxsackieviruses. J Gen Virol 84, 30413050.
Ogawa, M., Yamaguchi, T., Setiyono, A., Ho, T., Matsuda, H., Furusawa, S., Fukushi, H. & Hirai, K. (1998). Some characteristics of a cellular receptor for virulent infectious bursal disease virus by using flow cytometry. Arch Virol 143, 23272341.[CrossRef][Medline]
Plummer, G. (1962). An equine respiratory virus with enterovirus properties. Nature 195, 519520.[Medline]
Plummer, G. (1963). An equine respiratory enterovirus: some biological and physical properties. Arch Gesamte Virusforsch 12, 694700.[Medline]
Reddi, H. V. & Lipton, H. L. (2002). Heparan sulfate mediates infection of high-neurovirulence Theiler's viruses. J Virol 76, 84008407.
Rieder, E., Berinstein, A., Baxt, B., Kang, A. & Mason, P. W. (1996). Propagation of an attenuated virus by design: engineering a novel receptor for a noninfectious foot-and-mouth disease virus. Proc Natl Acad Sci U S A 93, 1042810433.
Roivainen, M., Piirainen, L., Hovi, T., Virtanen, I., Riikonen, T., Heino, J. & Hyypia, T. (1994). Entry of coxsackievirus A9 into host cells specific interactions with v
3 integrin, the vitronectin receptor. Virology 203, 357365.[CrossRef][Medline]
Rossmann, M. G., He, Y. & Kuhn, R. J. (2002). Picornavirusreceptor interactions. Trends Microbiol 10, 324331.[CrossRef][Medline]
Staunton, D. E., Merluzzi, V. J., Rothlein, R., Barton, R., Marlin, S. D. & Springer, T. A. (1989). A cell adhesion molecule, ICAM-1, is the major surface receptor for rhinoviruses. Cell 56, 849853.[Medline]
Studdert, M. J. & Gleeson, L. J. (1978). Isolation and characterisation of an equine rhinovirus. Zentralbl Veterinarmed B 25, 225237.[Medline]
Tomassini, J. E., Graham, D., DeWitt, C. M., Lineberger, D. W., Rodkey, J. A. & Colonno, R. J. (1989). cDNA cloning reveals that the major group rhinovirus receptor on HeLa cells is intercellular adhesion molecule 1. Proc Natl Acad Sci U S A 86, 49074911.[Abstract]
Varki, A., Cummings, R., Esko, J., Freeze, H., Hart, G. & Marth, J. (1999). Essentials of Glycobiology. Edited by A. Varki, R. Cummings, J. Esko, H. Freeze, G. Hart & J. Marth. La Jolla, CA: CSHL Press.
Warner, S., Hartley, C. A., Stevenson, R. A., Ficorilli, N., Varrasso, A., Studdert, M. J. & Crabb, B. S. (2001). Evidence that equine rhinitis A virus is a target of neutralising antibodies and participates directly in receptor binding. J Virol 75, 92749281.
Wasserman, K., Subklewe, M., Pothoff, G., Banik, N. & Schell-Frederick, E. (1994). Expression of surface markers on alveolar macrophages from symptomatic patients with HIV infection as detected by flow cytometry. Chest 105, 13241334.[Abstract]
Woodward, M. P., Young, W. W. & Bloodgood, R. A. (1985). Detection of monoclonal antibodies specific for carbohydrate epitopes using periodate oxidation. J Immunol Methods 78, 143153.[CrossRef][Medline]
Xiao, C., Bator, C. M., Bowman, V. D. & 8 other authors (2001). Interaction of coxsackievirus A21 with its cellular receptor, ICAM-1. J Virol 75, 24442451.
Zhou, L., Lin, X., Green, T. J., Lipton, H. L. & Luo, M. (1997). Role of sialyloligosaccharide binding in Theiler's virus persistence. J Virol 71, 97019712.[Abstract]
Received 20 April 2004;
accepted 28 May 2004.
HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
INT J SYST EVOL MICROBIOL | MICROBIOLOGY | J GEN VIROL |
J MED MICROBIOL | ALL SGM JOURNALS |