Canine distemper viruses expressing a hemagglutinin without N-glycans lose virulence but retain immunosuppression.
Paramyxovirus glycoproteins are posttranslationally modified by the addition of N-linked glycans, which are often necessary for correct folding, processing, and cell surface expression. To establish the contribution of N glycosylation to morbillivirus attachment (H) protein function and overall virulence, we first determined the use of the potential N-glycosylation sites in the canine distemper virus (CDV) H proteins. Biochemical characterization revealed that the three sites conserved in all strains were N glycosylated, whereas only two of the up to five additional sites present in wild-type strains are used. A wild-type virus with an H protein reproducing the vaccine strain N-glycosylation pattern remained lethal in ferrets but with a prolonged course of disease. In contrast, introduction of the vaccine H protein in the wild-type context resulted in complete attenuation. To further characterize the role of N glycosylation in CDV pathogenesis, the N-glycosylation sites of wild-type H proteins were successively deleted, including a nonstandard site, to ultimately generate a nonglycosylated H protein. Despite reduced expression levels, this protein remained fully functional. Recombinant viruses expressing N-glycan-deficient H proteins no longer caused disease, even though their immunosuppressive capacities were retained, indicating that reduced N glycosylation contributes to attenuation without affecting immunosuppression.
Sawatsky
Bevan
B
INRS-Institut Armand-Frappier, University of Quebec, Laval, Quebec H7V 1B7, Canada.
von Messling
Veronika
V
D000818:Animals; D002522:Chlorocebus aethiops; D004216:Distemper / Q000276:immunology / Q000503:physiopathology / Q000821:virology; D004217:Distemper Virus, Canine / Q000276:immunology / Q000472:pathogenicity; D004285:Dogs; D005289:Ferrets / Q000276:immunology / Q000821:virology; D006031:Glycosylation; D006389:Hemagglutinins, Viral / Q000737:chemistry* / Q000276:immunology; D006801:Humans; D007165:Immunosuppression Therapy; D008297:Male; D011134:Polysaccharides / Q000276:immunology*; D014709:Vero Cells
D006389:Hemagglutinins, Viral; D011134:Polysaccharides