title: Antiviral drug valacyclovir treatment combined with a clean feeding system enhances the suppression of salivary gland hypertrophy in laboratory colonies of Glossina pallidipes.
abstract: BACKGROUND
  Hytrosaviridae cause salivary gland hypertrophy (SGH) syndrome in some infected tsetse flies (Diptera: Glossinidae). Infected male and female G. pallidipes with SGH have a reduced fecundity and fertility. Due to the deleterious impact of the virus on G. pallidipes colonies, adding the antiviral drug valacyclovir to the blood diet and changing the feeding regime to a clean feeding system (each fly receives for each feeding a fresh clean blood meal) have been investigated to develop virus management strategies. Although both approaches used alone successfully reduced the virus load and the SGH prevalence in small experimental groups, considerable time was needed to obtain the desired SGH reduction and both systems were only demonstrated with colonies that had a low initial virus prevalence (SGH ≤ 10%). As problems with SGH are often only recognized once the incidence is already high, it was necessary to demonstrate that this combination would also work for high prevalence colonies.
  
  
  RESULTS
  Combining both methods at colony level successfully suppressed the SGH in G. pallidipes colonies that had a high initial virus prevalence (average SGH of 24%). Six months after starting the combined treatment SGH symptoms were eliminated from the treated colony, in contrast to 28 months required to obtain the same results using clean feeding alone and 21 months using antiviral drug alone.
  
  
  CONCLUSIONS
  Combining valacyclovir treatment with the clean feeding system provides faster control of SGH in tsetse than either method alone and is effective even when the initial SGH prevalence is high.
authors.affiliation: Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, International Atomic Energy Agency, Wagramer Straße 5, A-1400 Vienna, Austria. a.m.m.abd-alla@iaea.org.
authors.forename: Adly Mm
authors.initials: AM
authors.lastname: Abd-Alla
authors.forename: Carmen
authors.initials: C
authors.lastname: Marin
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Parker
authors.forename: Marc Jb
authors.initials: MJ
authors.lastname: Vreysen
mesh_terms: D000212:Acyclovir / Q000031:analogs & derivatives* / Q000494:pharmacology; D000822:Animal Husbandry; D000818:Animals; D005260:Female; D054884:Host-Pathogen Interactions / Q000187:drug effects; D007304:Insect Viruses / Q000187:drug effects / Q000502:physiology*; D008297:Male; D012469:Salivary Glands / Q000821:virology*; D014370:Tsetse Flies / Q000821:virology*; D000077483:Valacyclovir; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D014633:Valine; D000077483:Valacyclovir; D000212:Acyclovir