title: N-Glycans on the Rift Valley Fever Virus Envelope Glycoproteins Gn and Gc Redundantly Support Viral Infection via DC-SIGN.
abstract: Rift Valley fever is a mosquito-transmitted, zoonotic disease that infects humans and ruminants. Dendritic cell specific intercellular adhesion molecule 3 (ICAM-3) grabbing non-integrin (DC-SIGN) acts as a receptor for members of the phlebovirus genus. The Rift Valley fever virus (RVFV) glycoproteins (Gn/Gc) encode five putative N-glycan sequons (asparagine (N)-any amino acid (X)-serine (S)/threonine (T)) at positions: N438 (Gn), and N794, N829, N1035, and N1077 (Gc). The N-glycosylation profile and significance in viral infection via DC-SIGN have not been elucidated. Gc N-glycosylation was first evaluated by using Gc asparagine (N) to glutamine (Q) mutants. Subsequently, we generated a series of recombinant RVFV MP-12 strain mutants, which encode N-to-Q mutations, and the infectivity of each mutant in Jurkat cells stably expressing DC-SIGN was evaluated. Results showed that Gc N794, N1035, and N1077 were N-glycosylated but N829 was not. Gc N1077 was heterogeneously N-glycosylated. RVFV Gc made two distinct N-glycoforms: "Gc-large" and "Gc-small", and N1077 was responsible for "Gc-large" band. RVFV showed increased infection of cells expressing DC-SIGN compared to cells lacking DC-SIGN. Infection via DC-SIGN was increased in the presence of either Gn N438 or Gc N1077. Our study showed that N-glycans on the Gc and Gn surface glycoproteins redundantly support RVFV infection via DC-SIGN.
authors.affiliation: Department of Pathology, The University of Texas Medical Branch, Galveston, TX 77555, USA. inphoeni@utmb.edu.
authors.forename: Inaia
authors.initials: I
authors.lastname: Phoenix
authors.affiliation: Department of Pathology, The University of Texas Medical Branch, Galveston, TX 77555, USA. shnishiy@utmb.edu.
authors.forename: Shoko
authors.initials: S
authors.lastname: Nishiyama
authors.affiliation: Department of Pathology, The University of Texas Medical Branch, Galveston, TX 77555, USA. nalokuga@utmb.edu.
authors.forename: Nandadeva
authors.initials: N
authors.lastname: Lokugamage
authors.affiliation: Department of Pathology, The University of Texas Medical Branch, Galveston, TX 77555, USA. tehill@utmb.edu.
authors.forename: Terence E
authors.initials: TE
authors.lastname: Hill
authors.affiliation: Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, TX 77555, USA. mbhuante@utmb.edu.
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Huante
authors.affiliation: Department of Pathology, The University of Texas Medical Branch, Galveston, TX 77555, USA. olga.slack@novartis.com.
authors.forename: Olga A L
authors.initials: OA
authors.lastname: Slack
authors.affiliation: Department of Microbiology and Immunology, The University of Texas Medical Branch, Galveston, TX 77555, USA. vhcarpio@utmb.edu.
authors.forename: Victor H
authors.initials: VH
authors.lastname: Carpio
authors.affiliation: Department of Pathology, The University of Texas Medical Branch, Galveston, TX 77555, USA. anfreibe@utmb.edu.|The Sealy Center for Vaccine Development, The University of Texas Medical Branch, Galveston, TX 77555, USA. anfreibe@utmb.edu.|The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch, Galveston, TX 77555, USA. anfreibe@utmb.edu.|Galveston National Laboratory, The University of Texas Medical Branch, Galveston, TX 77555, USA. anfreibe@utmb.edu.
authors.forename: Alexander N
authors.initials: AN
authors.lastname: Freiberg
authors.affiliation: Department of Pathology, The University of Texas Medical Branch, Galveston, TX 77555, USA. teikegam@utmb.edu.|The Sealy Center for Vaccine Development, The University of Texas Medical Branch, Galveston, TX 77555, USA. teikegam@utmb.edu.|The Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch, Galveston, TX 77555, USA. teikegam@utmb.edu.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Ikegami
mesh_terms: D019943:Amino Acid Substitution; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D037181:Lectins, C-Type / Q000378:metabolism*; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011991:Receptors, Virus / Q000378:metabolism*; D012296:Rift Valley fever virus / Q000235:genetics / Q000502:physiology*; D015678:Viral Structural Proteins / Q000235:genetics / Q000378:metabolism*; D053585:Virus Attachment; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin
chemical_list: D015815:Cell Adhesion Molecules; D006023:Glycoproteins; D037181:Lectins, C-Type; D050505:Mutant Proteins; D011134:Polysaccharides; D011956:Receptors, Cell Surface; D011991:Receptors, Virus; D015678:Viral Structural Proteins; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin
keywords: DC-SIGN; Gc; Gn; L-SIGN; N-glycosylation; Rift Valley fever virus; sequon