title: Llama antibodies against a lactococcal protein located at the tip of the phage tail prevent phage infection.
abstract: Bacteriophage p2 belongs to the most prevalent lactococcal phage group (936) responsible for considerable losses in industrial production of cheese. Immunization of a llama with bacteriophage p2 led to higher titers of neutralizing heavy-chain antibodies (i.e., devoid of light chains) than of the classical type of immunoglobulins. A panel of p2-specific single-domain antibody fragments was obtained using phage display technology, from which a group of potent neutralizing antibodies were identified. The antigen bound by these antibodies was identified as a protein with a molecular mass of 30 kDa, homologous to open reading frame 18 (ORF18) of phage sk1, another 936-like phage for which the complete genomic sequence is available. By the use of immunoelectron microscopy, the protein is located at the tip of the tail of the phage particle. The addition of purified ORF18 protein to a bacterial culture suppressed phage infection. This result and the inhibition of cell lysis by anti-ORF18 protein antibodies support the conclusion that the ORF18 protein plays a crucial role in the interaction of bacteriophage p2 with the surface receptors of Lactococcus lactis.
authors.affiliation: Department of Biotechnology, Unilever Research Vlaardingen, 3133 AT Vlaardingen, Biotechnology Application Centre, 1411 GP Naarden, The Netherlands. hans.dehaard@ablynx.com
authors.forename: Hans J W
authors.initials: HJ
authors.lastname: De Haard
authors.forename: Sandra
authors.initials: S
authors.lastname: Bezemer
authors.forename: Aat M
authors.initials: AM
authors.lastname: Ledeboer
authors.forename: Wally H
authors.initials: WH
authors.lastname: Müller
authors.forename: Piet J
authors.initials: PJ
authors.lastname: Boender
authors.forename: Sylvain
authors.initials: S
authors.lastname: Moineau
authors.forename: Marie-Cecile
authors.initials: MC
authors.lastname: Coppelmans
authors.forename: Arie J
authors.initials: AJ
authors.lastname: Verkleij
authors.forename: Leon G J
authors.initials: LG
authors.lastname: Frenken
authors.forename: C Theo
authors.initials: CT
authors.lastname: Verrips
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000494:pharmacology*; D000918:Antibody Specificity; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D001433:Bacteriolysis / Q000276:immunology; D017901:Bacteriophage P2 / Q000276:immunology* / Q000648:ultrastructure; D002161:Camelids, New World; D005524:Food Technology / Q000379:methods; D007143:Immunoglobulin Heavy Chains / Q000494:pharmacology; D013294:Lactococcus lactis / Q000737:chemistry / Q000821:virology*; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009500:Neutralization Tests; D016366:Open Reading Frames; D011991:Receptors, Virus / Q000235:genetics / Q000276:immunology*; D016415:Sequence Alignment; D014764:Viral Proteins / Q000276:immunology; D014779:Virus Replication / Q000276:immunology
chemical_list: D000906:Antibodies; D001426:Bacterial Proteins; D007143:Immunoglobulin Heavy Chains; D011991:Receptors, Virus; D014764:Viral Proteins