Equine infectious anemia virus entry occurs through clathrin-mediated endocytosis.
Entry of wild-type lentivirus equine infectious anemia virus (EIAV) into cells requires a low-pH step. This low-pH constraint implicates endocytosis in EIAV entry. To identify the endocytic pathway involved in EIAV entry, we examined the entry requirements for EIAV into two different cells: equine dermal (ED) cells and primary equine endothelial cells. We investigated the entry mechanism of several strains of EIAV and found that both macrophage-tropic and tissue culture-adapted strains utilize clathrin-coated pits for entry. In contrast, a superinfecting strain of EIAV, EIAV(vMA-1c), utilizes two mechanisms of entry. In cells such as ED cells that EIAV(vMA-1c) is able to superinfect, viral entry is pH independent and appears to be mediated by plasma membrane fusion, whereas in cells where no detectable superinfection occurs, EIAV(vMA-1c) entry that is low-pH dependent occurs through clathrin-coated pits in a manner similar to wild-type virus. Regardless of the mechanism of entry being utilized, the internalization kinetics of EIAV is rapid with 50% of cell-associated virions internalizing within 60 to 90 min. Cathepsin inhibitors did not prevent EIAV entry, suggesting that the low-pH step required by wild-type EIAV is not required to activate cellular cathepsins.
Department of Microbiology, University of Iowa, Iowa City, Iowa 52242, USA.
Melinda A
MA
Brindley
Wendy
W
Maury
D000199:Actins / Q000378:metabolism; D000818:Animals; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism*; D022163:Clathrin-Coated Vesicles / Q000821:virology*; D034284:Dynamin I / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D004860:Infectious Anemia Virus, Equine / Q000502:physiology*; D008561:Membrane Fusion; D021962:Membrane Microdomains / Q000821:virology; D011480:Protease Inhibitors / Q000494:pharmacology; D053586:Virus Internalization / Q000187:drug effects
D000199:Actins; D002966:Clathrin; D011480:Protease Inhibitors; D002784:Cholesterol; D002403:Cathepsins; D034284:Dynamin I