Effects of anisotonic exposure on duck hepatitis B virus replication.
In cultured hepatocytes from in vivo duck hepatitis B virus-infected ducks the effect of medium osmolarity on viral replication was studied. A 10-day exposure to hypotonic media (277 mOsm/L due to removal of 26 mmol/L NaCl) lowered the duck hepatitis B virus DNA content of cells and of the medium by about 50%, whereas hyperosmotic exposure (421 mOsm/L by addition of 46 mmol/L NaCl) increased it about four-fold compared with normotonic standard incubation medium (329 mOsm/L). The tissue levels of viral RNA transcripts increased during the 10 days of hypertonic exposure but decreased only slightly after hypoosmotic treatment. Western-blot analysis for the production of viral pre-S/S proteins revealed a marked stimulation of viral protein synthesis in hypertonic media, whereas hypotonic exposure inhibited it. Conversely, total cellular protein synthesis as assessed from [3H]leucine incorporation into acid-precipitable material decreased during hyperosmotic exposure but increased during hypoosmotic exposure. We noted a comparable increase of duck hepatitis B virus DNA when raffinose (80 mmol/L) was added to hypotonic or normotonic media, without change in the NaCl concentrations. This suggests that the effects of anisotonicity on viral replication were not due to alterations of Na+ or Cl- activity in the incubation media, but might reflect changes of cellular volume. The effects of anisotonicity on viral replication were only seen after exposure of more than 8 hr of the cells to anisotonicity. The findings suggest that the cellular volume is an important determinant for duck hepatitis B virus replication, yet the underlying molecular mechanisms remain elusive.
Medizinische Universitätsklinik, Freiburg, Germany.
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Offensperger
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Offensperger
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Stoll
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Gerok
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Häussinger
D000818:Animals; D015153:Blotting, Western; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D003470:Culture Media; D004261:DNA Replication / Q000187:drug effects; D004279:DNA, Viral / Q000096:biosynthesis; D004372:Ducks; D015611:Hepatitis B Virus, Duck / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D008099:Liver / Q000382:microbiology* / Q000473:pathology; D009994:Osmolar Concentration; D012367:RNA, Viral / Q000096:biosynthesis; D012965:Sodium Chloride / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014764:Viral Proteins / Q000096:biosynthesis; D014779:Virus Replication / Q000187:drug effects*
D003470:Culture Media; D004279:DNA, Viral; D012367:RNA, Viral; D014764:Viral Proteins; D012965:Sodium Chloride