Replication of Flock House Virus in Three Genera of Medically Important Insects

• Published in: Journal of medical entomology Vol. 44; no. 1; pp. 102 - 110
• Main Authors: Dasgupta, R, Free, H.M, Zietlow, S.L, Paskewitz, S.M, Aksoy, S, Shi, L, Fuchs, J, Hu, C, Christensen, B.M
• Format: Journal Article
• Language: English
• Published: England 2007
• Subjects: Animals; Anopheles gambiae; Anopheles stephensi; Cell Line; disseminated infection; dose response; Flock house virus; Glossina morsitans morsitans; host range; insect vectors; Insect Vectors - virology; insect viruses; Insecta - virology; mortality; Nodaviridae - growth & development; Rhodnius prolixus; Species Specificity; Survival Analysis; Time Factors; tissue distribution; virus replication; Virus Replication - physiology
• ISSN: 0022-2585; 1938-2928
• DOI: 10.1603/0022-2585%282007%2944%5B102%3AROFHVI%5D2.0.CO%3B2

Flock House Virus (family Nodaviridae, genus Alphanodavirus, FHV) was originally isolated from grass grubs Costelytra zealandica (White) (Coleoptera: Scarabaeidae) in New Zealand and belongs to a family of divided genome, plus-sense RNA insect viruses. FHV replicates in insects, a nematode, plants, and yeast. We previously reported replication of FHV in four genera of mosquitoes and expression of green fluorescent protein in Aedes aegypti (L.) produced by an FHV-based vector. We report here that FHV multiplies vigorously in vivo in the malaria vectors Anopheles gambiae Giles and An. stephensi Liston and in vitro in a cell line derived from An. gambiae. In addition, FHV multiplies extensively in two other medically important insects, the tsetse fly, Glossina morsitans morsitans Westwood, and the reduviid bug Rhodnius prolixus Stal, extending its host range to four orders of insects (Coleoptera, Lepidoptera, Diptera, and Hemiptera). The virus disseminates in all the major tissues of the insects studied. Anopheles and Glossina show mortality when FHV is injected at a dose above 10⁴ plaque-forming units (pfu) or the virus accumulates to titer above 10⁸ pfu. A lower dose (10³ pfu) promotes more extensive virus multiplication and reduces mortality to <10%. No adverse effects are observed in Ae. aegypti, Culex pipiens pipiens L., and Armigeres subalbatus (Coquillett), when injected with a dose of up to 10⁷ pfu. Mosquitoes orally fed with FHV exhibited slower virus growth rate with lower mortality. Our results indicate that FHV has uniquely broad insect host range and that the virus can be used to study virus host interactions in a variety of medically important insects.