The Host Cell Receptors for Measles Virus and Their Interaction with the Viral Hemagglutinin (H) Protein

Abstract

The hemagglutinin (H) protein of measles virus (MeV) interacts with a cellular receptor which constitutes the initial stage of infection. Binding of H to this host cell receptor subsequently triggers the F protein to activate fusion between virus and host plasma membranes. The search for MeV receptors began with vaccine/laboratory virus strains and evolved to more relevant receptors used by wild-type MeV. Vaccine or laboratory strains of measles virus have been adapted to grow in common cell lines such as Vero and HeLa cells, and were found to use membrane cofactor protein (CD46) as a receptor. CD46 is a regulator that normally prevents cells from complement-mediated self-destruction, and is found on the surface of all human cells, with the exception of erythrocytes. Mutations in the H protein, which occur during adaptation and allow the virus to use CD46 as a receptor, have been identified. Wild-type isolates of measles virus cannot use the CD46 receptor. However, both vaccine/laboratory and wild-type strains can use an immune cell receptor called signaling lymphocyte activation molecule family member 1 (SLAMF1; also called CD150) and a recently discovered epithelial receptor known as Nectin-4. SLAMF1 is found on activated B, T, dendritic, and monocyte cells, and is the initial target for infections by measles virus. Nectin-4 is an adherens junction protein found at the basal surfaces of many polarized epithelial cells, including those of the airways. It is also over-expressed on the apical and basal surfaces of many adenocarcinomas, and is a cancer marker for metastasis and tumor survival. Nectin-4 is a secondary exit receptor which allows measles virus to replicate and amplify in the airways, where the virus is expelled from the body in aerosol droplets. The amino acid residues of H protein that are involved in binding to each of the receptors have been identified through X-ray crystallography and site-specific mutagenesis. Recombinant measles "blind" to each of these receptors have been constructed, allowing the virus to selectively infect receptor specific cell lines. Finally, the observations that SLAMF1 is found on lymphomas and that Nectin-4 is expressed on the cell surfaces of many adenocarcinomas highlight the potential of measles virus for oncolytic therapy. Although CD46 is also upregulated on many tumors, it is less useful as a target for cancer therapy, since normal human cells express this protein on their surfaces.

Keywords: CD150; CD46; PVRL4; SLAM; SLAMF1; measles virus; membrane cofactor protein; nectin-4; polio virus receptor like protein 4; signaling lymphocyte activation molecule family member 1.

Figure 1

Structure of the head region from the hemagglutinin (H) protein of measles virus (MeV). (A) View from the top of the H protein showing the six β-sheet regions of the propeller-like structure; (B) View of the H protein from the side showing the dimer formed through two cysteine linkages in the stem region. Arrows indicate central head region; (C) Amino acid sequence of the H protein from the IC-323 strain of MeV. The N481 (red) residue is mutated to Y481 in vaccine/laboratory strains of MeV, enabling H protein to bind to the CD46 receptor. Panel A is adapted with permission from the Nature Publishing Group, Macmillan Publishers Ltd: Colf, L.M.; Juo, Z.S.; Garcia, K.C. Nat. Struct. Mol. Biol 2007, 14 1227–1228 [43]; Panel B is adapted from the American Society of Microbiology Journals: Rasbach, A.; Abel, T.; Münch, R.C.; Boller, K.; Schneider-Schaulies, J.; Buchholz, C.J. J. Virol. 2013, 87, 6246–6255 [47].

Figure 2

Chinese hamster ovary (CHO) and CHO-CD46 cells infected for 48 h with the Edmonston vaccine strain of MeV. The CD46 coding region (BC2 isoform) was expressed using a dihydrofolate reductase (DHFR) amplification vector under control of the cytomegalovirus (CMV) promoter. Four different cell lines (#8, #16, #27, #41) are shown at indicated magnifications (100×, 200×, or 400×) using Nomarsky optical microscopy. Cells were infected at a multiplicity of infection (m.o.i.) of 1. Syncitia/multinucleated cells were clearly apparent in the infected cells at 48 h post-infection.

Figure 3

Alignment of CD46 proteins derived from complementary DNAs (cDNAs) prepared from the lymphocytes of humans, Old World, and New World monkeys. CD46 molecules from New World monkeys contain a deletion of the short consensus repeat 1 (SCR1) domain due to alternative messenger RNA (mRNA) splicing. Shaded residues indicate amino acids that differ from the human sequence. Baboons (Papio anubis, Papio hamadryas), macaques (rhesus monkey, cynomolgus monkey), African green monkey (Cercopithecus aethiops), marmosets (Callithrix jaccus, Callimico goeldii, Saguinus oedipus), saki (Pithecia pithecia), owl monkey (Aotidae aotus), squirrel monkey (Saimiri sciureus). Reprinted with permission from the American Society of Microbiology Journals: Hsu, E.C.; Dörig, R.E., Sarangi, F.; Marcil, A; Iorio, C.; Richardson, C.D. J. Virol. 1997, 71, 6144–6154 [58].

Figure 4

Interaction of CD46 with H dimer from the vaccine strain of MeV. (A) Schematic of membrane cofactor protein (MCP) or CD46. Protein is comprised of four short conserved regions (SCR1-SCR4), the Ser/Thr/Pro (STP) domain, transmembrane region, and two alternatively spliced cytoplasmic tails. MeV binds to SCR1 and SCR2 and complement components C3b, and C4b bind to SCR3 and SCR4. Sugars in SCR2 are important for MeV binding; (B) Structure of SCR1 and SCR2 domains of CD46 bound to H protein dimer head region. Adapted by permission from the Nature Publishing Group, Macmillan Publishers Ltd.: Santiago, C.; Celma, M.L.; Stehle, T.; Casasnovas, J.M. Nat. Struct. Mol. Biol. 2010, 17, 124–129 [73].

Figure 5

Wild type MeV can infect Vero cells that express human and marmoset SLAMF1 but not mouse SLAMF1. (A) Alignment of protein sequences of signaling lymphocyte activation molecule family member 1 (SLAMF1) from human (AAH12602.1), marmoset (XP_002760222), and mouse (AA17100.1) homologues. Shaded residues indicate amino acids that differ from the human sequence. Shaded residues indicate amino acids that differ from the human sequence. There is a high level of conservation between human and marmoset SLAMF1 sequences; (B) Vero-SLAMF1 cells can be infected with wild-type IC-323 strain of MeV that expresses the enhanced green fluorescent protein (eGFP) reporter gene. Cells were infected with virus at an m.o.i. of 5 for a period of 60 h. Syncytia were visible as early as 18 h.

Figure 6

Structure of the head region from the H protein of MeV bound to the V region of SLAMF1. (A) Schematic of SLAMF1 showing the V and C2 regions of the extracellular domain, the membrane spanning region, and the intracellular region containing phosphotyrosine regions. Either of two cytoplasmic tails (1 or 2) may be present depending upon alternate splicing; (B) V region of SLAMF1 binding to β5 and β6 sheet regions from the head of the H protein viewed from the top; (C) Side view of V region of SLAMF1 binding to heads of the H dimer proteins; (D) V regions of four SLAMF1 molecules binding to the tetrameric H proteins. Panels B, C, and D adapted by permission from the Nature Publishing Group, Macmillan Publishers Ltd.: Hashiguchi, T.; Ose, T., Kubota, M.; Maita, N.; Kamishikiryo, J.; Maenaka, K.; Yanagi, Y. Nat. Struct. Mol. Biol. 2011, 18, 135–141 [102].

Figure 7

Infection of lymphocytes and spleen from human SLAMF1 transgenic mouse in Stat1(-/-) background with wtMeV expressing eGFP reporter protein. (A) T and B cells from infected mice express eGFP reporter protein; (B) Spleens from infected SLAMF1 transgenic mice in a Stat1(-/-) background are highly enlarged. Reprinted with permission from the Proc. Natl. Acad. Sci. U.S.A.: Welstead, G.G.; Iorio, C.; Draker, R.; Bayani, J.; Squire, J.; Vongpunsawad, S.; Cattaneo, R.; Richardson, C.D. Proc. Natl. Acad. Sci. USA 2005, 102, 16415–16420 [108].

Figure 8

Small airway epithelial cells (SAECs) grown in 2% fetal calf serum can be infected with wild-type IC-323 measles virus in the absence of SLAMF1, and independently of CD46 receptor. Neutralizing antibodies against CD46 and SLAMF1 receptors have no effect upon infections of SAEC’s with Edmonston vaccine or wild type IC-323 measles virus (indicated by the arrow). Antibodies against CD46 inhibit infections of HeLa cells by the Edmonston vaccine MeV and antibodies against SLAMF1 block infections of Vero-SLAM cells with wild type IC-323 MeV. Reprinted by the author from PLoS Pathogens under the Creative Commons Attribution agreement from: Noyce, R.S.; Bondre, D.G.; Ha, M.N.; Lin, L.T.; Sisson, G.; Tsao, M.S.; Richardson, C.D. PLoS Pathog. 2011, 7, e1002240 [133].

Figure 9

Microarray analysis reveals that Nectin-4 is a receptor for wild type MeV. (A) Comparative microarray analysis of mRNAs from permissive versus non-permissive cancer cell lines and SAECs grown in the presence or absence of 2% fetal calf serum revealed 11 candidate cellular receptors; (B) COS-1 monkey kidney cells were transfected with expression plasmids encoding PVRL4 (Nectin-4), CD150 (SLAMF1), solute carrier family 6 member 14 (SLC6A14), six transmembrane epithelial antigen of prostate 4 (STEAP4), transmembrane serine protease 11E (TMPRSS11E), mucin 1 (MUC1), erb-b2 receptor tyrosine kinase 3 (ERBB3), and mucin 20 (MUC20) genes. After 36 h, cells were infected with wild type IC-323 MeV expressing the eGFP reporter protein. Only PVRL4 (Nectin-4) and CD150 (SLAMF1) expression supported wtMeV infection of the COS-1 host cells. Fluorescence micrographs were taken at 36 h post-infection; (C) COS-1 cells were transfected with expression plasmids encoding PVRL4 (Nectin-4), poliovirus receptor (PVR), PVRL1 (Nectin-1), PVRL2 (Nectin-2), and PVRL3 (Nectin-3). Only PVRL4 (Nectin-4) expression supported wtMeV infection. Reprinted by the author from PLoS Pathogens under the Creative Commons Attribution agreement from: Noyce, R.S.; Bondre, D.G.; Ha, M.N.; Lin, L.T.; Sisson, G.; Tsao, M.S.; Richardson, C.D. PLoS Pathog. 2011, 7, e1002240 [133].

Figure 10

Structure of the head region from the H protein of MeV bound to the V region of Nectin-4. (A) Schematic of Nectin-4 showing the V and two C2 regions of the extracellular domain, the membrane spanning region, and the intracellular cytoplasmic tail; (B) Structure derived by X-ray crystallography showing heads of the H protein dimer interacting with the V regions of Nectin-4; (C) Structure of the head from β4 and β5 regions of monomeric H protein interacting with of the V domain of Nectin-4 (Nectin-4v). Adapted by permission from the Nature Publishing Group, Macmillan Publishers Ltd.: Zhang, X.; Lu, G.; Qi, J.; Li, Y.; He, Y.; Xu, X.; Shi, J.; Zhang, C.W.; Yan, J.; Gao, G.F. Nat. Struct. Mol. Biol. 2013, 20, 67–72 [151].

Figure 11

Summary of the principal residues contained in the β4, β5, and β6 regions in the head of the H protein involved in binding to its receptors. (A) CD46; (B) Nectin-4; and (C) SLAMF1/SLAM cellular receptors. Amino acid residues involved in binding to CD46 are shown in red, those binding to Nectin-4 in yellow, and those interacting with SLAMF1/SLAM in blue; (D) Overview of receptor binding residues in H protein. Overlapping interacting H residues (F483, Y541, Y543) for CD46 and Nectin-4 are shown in orange. Reprinted with permission from the American Society of Microbiology Journals: Mateo, M.; Navaratnarajah, C.K.; Syed, S.; Cattaneo, R. J. Virol. 2013, 87, 9208–9216 [152].