title: Characterization of the Neospora caninum NcROP40 and NcROP2Fam-1 rhoptry proteins during the tachyzoite lytic cycle.
abstract: Virulence factors from the ROP2-family have been extensively studied in Toxoplasma gondii, but in the closely related Neospora caninum only NcROP2Fam-1 has been partially characterized to date. NcROP40 is a member of this family and was found to be more abundantly expressed in virulent isolates. Both NcROP2Fam-1 and NcROP40 were evaluated as vaccine candidates and exerted a synergistic effect in terms of protection against vertical transmission in mouse models, which suggests that they may be relevant for parasite pathogenicity. NcROP40 is localized in the rhoptry bulbs of tachyzoites and bradyzoites, but in contrast to NcROP2Fam-1, the protein does not associate with the parasitophorous vacuole membrane due to the lack of arginine-rich amphipathic helix in its sequence. Similarly to NcROP2Fam-1, NcROP40 mRNA levels are highly increased during tachyzoite egress and invasion. However, NcROP40 up-regulation does not appear to be linked to the mechanisms triggering egress. In contrast to NcROP2Fam-1, phosphorylation of NcROP40 was not observed during egress. Besides, NcROP40 secretion into the host cell was not successfully detected by immunofluorescence techniques. These findings indicate that NcROP40 and NcROP2Fam-1 carry out different functions, and highlight the need to elucidate the role of NcROP40 within the lytic cycle and to explain its relative abundance in tachyzoites.
authors.affiliation: SALUVET,Animal Health Department,Faculty of Veterinary Sciences,Complutense University of Madrid,Ciudad Universitaria s/n,28040-Madrid,Spain.
authors.forename: Iván
authors.identifier: http://orcid.org/0000-0001-8454-5654
authors.initials: I
authors.lastname: Pastor-Fernández
authors.affiliation: SALUVET,Animal Health Department,Faculty of Veterinary Sciences,Complutense University of Madrid,Ciudad Universitaria s/n,28040-Madrid,Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Regidor-Cerrillo
authors.affiliation: SALUVET,Animal Health Department,Faculty of Veterinary Sciences,Complutense University of Madrid,Ciudad Universitaria s/n,28040-Madrid,Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Jiménez-Ruiz
authors.affiliation: SALUVET,Animal Health Department,Faculty of Veterinary Sciences,Complutense University of Madrid,Ciudad Universitaria s/n,28040-Madrid,Spain.
authors.forename: Gema
authors.initials: G
authors.lastname: Álvarez-García
authors.affiliation: SALUVET,Animal Health Department,Faculty of Veterinary Sciences,Complutense University of Madrid,Ciudad Universitaria s/n,28040-Madrid,Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Marugán-Hernández
authors.affiliation: Institute of Parasitology,Vetsuisse Faculty,University of Berne,Länggass-Strasse 122,CH-3012 Berne,Switzerland.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hemphill
authors.affiliation: SALUVET,Animal Health Department,Faculty of Veterinary Sciences,Complutense University of Madrid,Ciudad Universitaria s/n,28040-Madrid,Spain.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Ortega-Mora
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005786:Gene Expression Regulation; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D018688:Neospora / Q000235:genetics* / Q000502:physiology / Q000648:ultrastructure; D010766:Phosphorylation; D021381:Protein Transport; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015854:Up-Regulation
chemical_list: D008565:Membrane Proteins; D015800:Protozoan Proteins; C090555:ROP 2 protein, Toxoplasma gondii; D011994:Recombinant Proteins
keywords: NcROP2Fam-1; NcROP40; Neospora caninum; characterization; immunolocalization; in silico analysis; lytic cycle of tachyzoites; mRNA expression profile; protein phosphorylation; secretion assays