title: Differential sensitivity of viruses to the antiviral activity of Shiga toxin 1 A subunit.
abstract: The non-toxic enzymic A subunit of Shiga toxin 1 (StxA1) reduces expression and replication of the bovine retroviruses, bovine leukemia virus and bovine immunodeficiency virus (BIV). Here, the impact of StxA1 on representative positive and negative stranded RNA viruses was compared. BIV and equine infectious anemia virus were sensitive to picomolar concentrations of StxA1 while poliovirus, rhinovirus, and vesicular stomatitis virus were only marginally sensitive to nanomolar concentrations of toxin. Thus, the length of the reproductive cycle and/or other factors, but not viral encapsulation may play a role in determining sensitivity to StxA1. The effects of StxA1 at concentrations from 0.01 to 10 microg/ml on the most sensitive virus (BIV-infected cultures of fetal bovine lung cells) were analyzed by electron microscopy 48 h post challenge. Cells treated with 0.1 microg StxA1/ml or higher toxin concentrations were similar in appearance and showed progressively fewer viral factories with increasing toxin concentration. However, cells treated with 0.01 microg/ml StxA1 had a radically different appearance, exhibiting smooth cell membranes and high vacuolization. These results showed that complex retroviruses were more sensitive to StxA1 than single-stranded RNA viruses and that StxA1 interfered with retroviral replication in a concentration-dependent manner.
authors.affiliation: Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID 83844-3052, USA.
authors.forename: Witold A
authors.initials: WA
authors.lastname: Ferens
authors.forename: Mandi
authors.initials: M
authors.lastname: Halver
authors.forename: Kurt E
authors.initials: KE
authors.lastname: Gustin
authors.forename: Troy
authors.initials: T
authors.lastname: Ott
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Hovde
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D016087:Immunodeficiency Virus, Bovine / Q000187:drug effects / Q000502:physiology; D008826:Microbial Sensitivity Tests; D022622:Shiga Toxin 1 / Q000737:chemistry / Q000494:pharmacology*; D014721:Vesicular stomatitis Indiana virus / Q000187:drug effects / Q000502:physiology; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D000998:Antiviral Agents; D022622:Shiga Toxin 1