Selection and partial characterization of dengue 2 virus mutants that induce fusion at elevated pH.
Two types of dengue (DEN) 2 virus mutants were selected either by repeated exposure to acidic pH (acid mutant, AM), or by the addition of ammonium chloride to Aedes albopictus C6/36 cells prior to and during viral infection (fusion mutant, FM). Both mutants grew more slowly than the parent strain and induced smaller plaques in Vero cells. The 50% fusion from within index for both mutants occurred at least 0.65 pH units higher than with the wild-type DEN virus. A single amino acid substitution (Asn-153 to Asp) was found in the envelope (E)-glycoprotein of the AM virus. Three amino acid substitutions were detected on the E-glycoprotein of the FM virus: Ile-6 to Met, Asn-134 to Ser, and Asn-153 to Tyr. No mutations were found in the precursor to the membrane protein, prM. The DEN virus E-glycoprotein has two potential glycosylation sites: Asn-67 and Asn-153. The loss of the potential glycosylation site at Asn-153 or the change in the chemical characteristics resultant from the amino acid substitutions in both mutants implicates these regions of the E-glycoprotein in virus-mediated membrane fusion.
Guirakhoo
F
F
Division of Vector-Borne Infectious Diseases, Centers for Disease Control, Fort Collins, Colorado 80522.
Hunt
A R
AR
Lewis
J G
JG
Roehrig
J T
JT
D000143:Acids / Q000494:pharmacology; D000330:Aedes; D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D002459:Cell Fusion; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003716:Dengue Virus / Q000235:genetics* / Q000254:growth & development*; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000166:cytology; D016296:Mutagenesis; D014759:Viral Envelope Proteins / Q000235:genetics*; D014760:Viral Fusion Proteins / Q000235:genetics*; D014779:Virus Replication
D000143:Acids; C051821:E-glycoprotein, Dengue virus type 2; D014759:Viral Envelope Proteins; D014760:Viral Fusion Proteins; D000643:Ammonium Chloride