title: In vitro inactivation of the rabies virus by ascorbic acid.
abstract: OBJECTIVE
  The current recommended inactivating agent for the rabies virus, beta propiolactone (BPL) is very expensive and potentially carcinogenic. There is a need to evaluate alternative chemicals, which will inactivate the virus without affecting its antigenicity. In this study the effect of ascorbic acid on the infectivity of the rabies virus has been investigated.
  
  
  METHODS
  Vero cell grown fixed rabies virus CVS strain was treated with 0.1 mg/ml, 0.5 mg/ml and 1mg/ml final concentrations of ascorbic acid and 5 microg/ml of copper sulfate and kept at 4 degrees C along with untreated virus material. Each aliquot was titrated after various intervals for viral infectivity using both mice inoculation and titration in vero cells. The antigenicity of the virus material was determined by antibody induction in mice and modified NIH tests in parallel with virus material inactivated with a 1:4000 concentration of BPL.
  
  
  RESULTS
  An optimal concentration of 0.5 mg/ml of ascorbic acid and 5 microg/ml of copper sulfate completely inactivated the virus after 72 hours. The inactivated virus retained good antigenicity and potency value, which was comparable with using BPL.
  
  
  CONCLUSIONS
  These findings suggest that ascorbic acid can be used as an inactivating agent for fixed rabies virus grown in cell culture particularly for the preparation of diagnostic reagents. Further studies are required to evaluate its effect on the cell associated virus, probable therapeutic potential and feasibility of replacing BPL in production of inactivated rabies vaccine.
authors.affiliation: Department of Neurovirology, National Institute of Mental Health and Neurosciences (NIMHANS), Post Box 2900, Hosur Road, Bangalore 560029, India. mshampur@hotmail.com
authors.forename: Shampur Narayan
authors.initials: SN
authors.lastname: Madhusudana
authors.forename: Ranjini
authors.initials: R
authors.lastname: Shamsundar
authors.forename: Saraswati
authors.initials: S
authors.lastname: Seetharaman
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001205:Ascorbic Acid / Q000494:pharmacology*; D001681:Biological Assay; D002522:Chlorocebus aethiops; D019327:Copper Sulfate / Q000494:pharmacology; D005260:Female; D051379:Mice; D011818:Rabies / Q000276:immunology / Q000517:prevention & control; D011819:Rabies Vaccines / Q000276:immunology; D011820:Rabies virus / Q000187:drug effects* / Q000276:immunology / Q000472:pathogenicity / Q000502:physiology*; D015164:Vaccines, Inactivated / Q000276:immunology; D014709:Vero Cells; D014775:Virus Activation / Q000187:drug effects; D014779:Virus Replication / Q000187:drug effects / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D011819:Rabies Vaccines; D015164:Vaccines, Inactivated; D019327:Copper Sulfate; D001205:Ascorbic Acid