Replication-competent, oncolytic herpes simplex virus type 1 mutants induce a bystander effect following ganciclovir treatment.
Cells expressing herpes simplex virus (HSV) thymidine kinase (tk) are killed by ganciclovir (GCV). Adjacent cells without HSV-tk also die, a phenomenon known as the 'bystander effect'. However, there is no evidence that replication-competent HSV induces a bystander effect in the presence of GCV. Therefore, we investigated the bystander effect in HEp-2 cells infected with replication-competent, oncolytic HSV-1 mutants, hrR3 and HF10. In cells infected at a multiplicity of infection (MOI) of 3, GCV did not induce apoptosis. At low MOIs of 0.3 and 0.03, however, a number of adjacent, uninfected cells apoptosed following GCV treatment. Irrespective of GCV treatment, HEp-2 cells expressed minimal levels of connexin 43 (Cx43). However, Cx43 expression was enhanced by GCV in response to infection with HF10 at an MOI of 0.3, but not at an MOI of 3. Expression of other proteins involved in gap junctions, including Cx26 and Cx40, was not augmented under these conditions. The PKA and PI3K signal transduction pathways are likely involved in enhanced Cx43 expression as inhibitors of these pathways prevented Cx43 upregulation. These results suggest that infection with replication-competent HSV-1 induces the bystander effect in cells treated with GCV because of efficient intercellular transport of active GCV through abundant gap junctions.
Department of Virology, Nagoya University Graduate School of Medicine, Tsuruma, Nagoya 466-8550, Japan.
Chenhong
C
Luo
Isamu
I
Mori
Fumi
F
Goshima
Yoko
Y
Ushijima
Akihiro
A
Nawa
Hiroshi
H
Kimura
Yukihiro
Y
Nishiyama
D000212:Acyclovir / Q000494:pharmacology; D000818:Animals; D000998:Antiviral Agents / Q000633:toxicity*; D017209:Apoptosis; D024201:Bystander Effect; D002277:Carcinoma / Q000628:therapy; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D000072259:Connexin 26; D018031:Connexin 43 / Q000378:metabolism; D017630:Connexins; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D015774:Ganciclovir / Q000633:toxicity*; D018259:Herpesvirus 1, Human / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D006801:Humans; D009154:Mutation; D050130:Oncolytic Virotherapy; D050504:Oncolytic Viruses / Q000235:genetics*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D013937:Thymidine Kinase / Q000235:genetics; D014162:Transfection; D014709:Vero Cells; D014779:Virus Replication / Q000235:genetics
D000212:Acyclovir; D000998:Antiviral Agents; D000072259:Connexin 26; D018031:Connexin 43; D017630:Connexins; D017868:Cyclic AMP-Dependent Protein Kinases; D015774:Ganciclovir; D019869:Phosphatidylinositol 3-Kinases; D013937:Thymidine Kinase; C000607042:GJB2 protein, human