The mature avian leukosis virus subgroup A envelope glycoprotein is metastable, and refolding induced by the synergistic effects of receptor binding and low pH is coupled to infection.
The spring-loaded model stipulates that influenza virus infection is coupled to the transition of the virus hemagglutinin (HA) from a metastable conformation to a highly stable conformation at low pH. The properties of retrovirus envelope glycoproteins indicate that infection is coupled to an analogous conformational change. As a test of this hypothesis, the requirements for avian leukosis virus A (ALV-A) infection were examined. These studies indicate that, like HA, the conformation of the mature ALV-A envelope glycoprotein is metastable and that infection is linked to refolding at low pH. However, unlike HA, low-pH activation is only observed after priming by receptor. Therefore, ALV-A infection is dependent on the synergistic effects of receptor binding and low pH, suggesting that receptor binding superimposes an additional constraint on activation of ALV-A fusion that proceeds by a mechanism comparable to that of influenza virus.
Smith
Jason G
JG
Department of Medicine. Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
Mothes
Walther
W
Blacklow
Stephen C
SC
Cunningham
James M
JM
D000818:Animals; D001354:Avian Leukosis Virus / Q000472:pathogenicity*; D030161:Avian Proteins; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008561:Membrane Fusion; D011487:Protein Conformation; D017510:Protein Folding; D011991:Receptors, Virus / Q000378:metabolism*; D012995:Solubility; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000378:metabolism
D030161:Avian Proteins; D011991:Receptors, Virus; C062390:Rous sarcoma virus envelope protein gp37; C088745:Tva receptor; D014759:Viral Envelope Proteins