title: A Vaccine Approach for the Prevention of Infections by Multidrug-resistant Enterococcus faecium.
abstract: The incidence of multidrug-resistant Enterococcus faecium hospital infections has been steadily increasing. With the goal of discovering new vaccine antigens, we systematically fractionated and purified four distinct surface carbohydrates from E. faecium endocarditis isolate Tx16, shown previously to be resistant to phagocytosis in the presence of human serum. The two most abundant polysaccharides consist of novel branched heteroglycan repeating units that include signature sugars altruronic acid and legionaminic acid, respectively. A minor high molecular weight polysaccharide component was recognized as the fructose homopolymer levan, and a glucosylated lipoteichoic acid (LTA) was identified in a micellar fraction. The polysaccharides were conjugated to the CRM197 carrier protein, and the resulting glycoconjugates were used to immunize rabbits. Rabbit immune sera were evaluated for their ability to kill Tx16 in opsonophagocytic assays and in a mouse passive protection infection model. Although antibodies raised against levan failed to mediate opsonophagocytic killing, the other glycoconjugates induced effective opsonic antibodies, with the altruronic acid-containing polysaccharide antisera showing the greatest opsonophagocytic assay activity. Antibodies directed against either novel heteroglycan or the LTA reduced bacterial load in mouse liver or kidney tissue. To assess antigen prevalence, we screened a diverse collection of blood isolates (n = 101) with antibodies to the polysaccharides. LTA was detected on the surface of 80% of the strains, and antigens recognized by antibodies to the two major heteroglycans were co-expressed on 63% of these clinical isolates. Collectively, these results represent the first steps toward identifying components of a glycoconjugate vaccine to prevent E. faecium infection.
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654.
authors.forename: Srinivas
authors.initials: S
authors.lastname: Kodali
authors.affiliation: the National Research Council, Ottawa, Ontario K1A 0R6, Canada.
authors.forename: Evgeny
authors.initials: E
authors.lastname: Vinogradov
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654.
authors.forename: Fiona
authors.initials: F
authors.lastname: Lin
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654.
authors.forename: Nancy
authors.initials: N
authors.lastname: Khoury
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654.
authors.forename: Li
authors.initials: L
authors.lastname: Hao
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654.
authors.forename: Vilo
authors.initials: V
authors.lastname: Pavliak
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654.
authors.forename: C Hal
authors.initials: CH
authors.lastname: Jones
authors.affiliation: the Division of Infectious Diseases, Department of Medicine, University Hospital, Hugstetter Strasse 55, 79106 Freiburg, Germany, and.
authors.forename: Diana
authors.initials: D
authors.lastname: Laverde
authors.affiliation: the Division of Infectious Diseases, Department of Medicine, University Hospital, Hugstetter Strasse 55, 79106 Freiburg, Germany, and the Department of Pediatrics, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Lindwurmstrasse 4, 80338 Munich, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Huebner
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654.
authors.forename: Kathrin U
authors.initials: KU
authors.lastname: Jansen
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654.
authors.forename: Annaliesa S
authors.initials: AS
authors.lastname: Anderson
authors.affiliation: From Pfizer Vaccine Research and Early Development, Pearl River, New York 10654, robert.donald@pfizer.com.
authors.forename: Robert G K
authors.initials: RG
authors.lastname: Donald
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D000907:Antibodies, Bacterial / Q000096:biosynthesis* / Q000097:blood; D000942:Antigens, Bacterial / Q000737:chemistry* / Q000276:immunology; D058491:Bacterial Load / Q000187:drug effects; D001426:Bacterial Proteins / Q000737:chemistry / Q000276:immunology; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D002240:Carbohydrate Sequence; D004195:Disease Models, Animal; D024901:Drug Resistance, Multiple, Bacterial; D016984:Enterococcus faecium / Q000737:chemistry / Q000276:immunology*; D005260:Female; D005630:Fructans / Q000737:chemistry / Q000276:immunology; D016908:Gram-Positive Bacterial Infections / Q000097:blood / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D006801:Humans; D007106:Immune Sera / Q000737:chemistry; D008070:Lipopolysaccharides / Q000737:chemistry / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D009895:Opsonin Proteins / Q000737:chemistry / Q000276:immunology; D011817:Rabbits; D012794:Sialic Acids / Q000737:chemistry / Q000276:immunology; D013682:Teichoic Acids / Q000737:chemistry / Q000276:immunology; D014574:Uronic Acids / Q000737:chemistry / Q000276:immunology; D018074:Vaccines, Conjugate
chemical_list: C110570:5,7-diacetamido-8-O-acetyl-3,5,7,9-tetradeoxy-glycero-talo-nonulosonic acid; D000900:Anti-Bacterial Agents; D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001428:Bacterial Vaccines; D005630:Fructans; D007106:Immune Sera; D008070:Lipopolysaccharides; D009895:Opsonin Proteins; D012794:Sialic Acids; D013682:Teichoic Acids; D014574:Uronic Acids; D018074:Vaccines, Conjugate; C028581:CRM197 (non-toxic variant of diphtheria toxin); C009900:lipoteichoic acid; C102528:altruronic acid; C072599:levan
keywords: Enterococcus; antigen; carbohydrate structure; teichoic acid; vaccine