title: [Quantitative study on synergistic effect of radix astragali A6 and acyclovir against herpes simplex virus type I by polymerase chain reaction].
abstract: OBJECTIVE
  To evaluate the synergistic effect of Radix Astragali A6(A6) and acyclovir (ACV) in antagonizing herpes simplex virus type I (HSV1).
  
  
  METHODS
  The synergistic effect was measured by competitive polymerase chain reaction (PCR) and compared with that measured by traditional cytopathic effect (CPE) inhibition method.
  
  
  RESULTS
  The minimum inhibition concentration of A6, ACV and A6 + ACV measured by PCR was 1.88 mg/ml, 3.37 micrograms/ml and 0.47 mg/ml + 0.84 microgram/ml respectively, while measured by CPE, it was 6.25 mg/ml, 50 micrograms/ml and 0.94 mg/ml + 12.5 micrograms/ml respectively. The fractional inhibitory combined indexes were all less than 0.5, which is an indication of obvious co-synergistic effect.
  
  
  CONCLUSIONS
  The quantitative PCR is an effective method of screening antiviral drugs. The inhibitory action of A6 and ACV on HSV1 revealed mainly at the replicative stage of viral proliferation cycle.
authors.affiliation: Department of Immunology, Guiyang Medical College, Guiyang 550004.
authors.forename: L
authors.initials: L
authors.lastname: Zuo
authors.forename: H
authors.initials: H
authors.lastname: Guo
mesh_terms: D000212:Acyclovir / Q000494:pharmacology*; D000998:Antiviral Agents / Q000494:pharmacology*; D004357:Drug Synergism; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D014645:Herpesvirus 3, Human / Q000187:drug effects* / Q000302:isolation & purification; D016133:Polymerase Chain Reaction
chemical_list: D000998:Antiviral Agents; D004365:Drugs, Chinese Herbal; D000212:Acyclovir