title: Enhancement of the Musca domestica hytrosavirus infection with orally delivered reducing agents.
abstract: House flies (Musca domestica L.) throughout the world are infected with the salivary gland hypertrophy virus MdSGHV (Hytrosaviridae). Although the primary route of infection is thought to be via ingestion, flies that are old enough to feed normally are resistant to infection per os, suggesting that the peritrophic matrix (PM) is a barrier to virus transmission. Histological examination of the peritrophic matrix of healthy flies revealed a multilaminate structure produced by midgut cells located near the proventriculus. SEM revealed the PM to form a confluent sheet surrounding the food bolus with pores/openings less than 10nm in diameter. TEM revealed the PM to be multilayered, varying in width from 350 to 900 nm, and generally thinner in male than in female flies. When flies were fed on the reducing agents dithiothetriol (DTT) or tris (2-caboxyethyl)phosphine hydrochloride (TCEP) for 48 h before per os exposure to the virus, infection rates increased 10- to 20-fold compared with flies that did not receive the reducing agent treatments. PM's from flies treated with DTT and TCEP displayed varying degrees of disruption, particularly in the outer layer, and lacked the electron-dense inner layer facing the ectoperitrophic space. Both drugs were somewhat toxic to the flies, resulting in>40% mortality at doses greater than 10mM (DTT) or 5 mM (TCEP). DTT increased male fly susceptibility (55.1% infected) more than that of females (7.8%), whereas TCEP increased susceptibility of females (42.9%) more than that of males (26.2%). The cause for the sex differences in response to oral exposure the reducing agents is unclear. Exposing flies to food treated with virus and the reducing agents at the same time, rather than pretreating flies with the drugs, had no effect on susceptibility to the virus. Presumably, the reducing agent disrupted the enveloped virus and acted as a viricidal agent. In summary, it is proposed that the reducing agents influence integrity of the PM barrier and increase the susceptibility of flies to infection by MdSGHV.
authors.affiliation: Entomology and Nematology Department, University of Florida, 970 Natural Area Drive, Gainesville, FL 32611, USA.
authors.forename: D
authors.initials: D
authors.lastname: Boucias
authors.affiliation: Entomology and Nematology Department, University of Florida, 970 Natural Area Drive, Gainesville, FL 32611, USA.
authors.forename: J
authors.initials: J
authors.lastname: Baniszewski
authors.affiliation: BioNet-Asia Co., Ltd., Hi-Tech Industrial Estate, 81 Moo 1, Baan-Lane, Bang Pa-In, Ayutthaya 13160, Thailand.
authors.forename: P
authors.initials: P
authors.lastname: Prompiboon
authors.affiliation: Entomology and Nematology Department, University of Florida, 970 Natural Area Drive, Gainesville, FL 32611, USA.
authors.forename: V
authors.initials: V
authors.lastname: Lietze
authors.affiliation: Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS, 1600 SW 23[rd] Drive, Gainesville, FL 32608, USA.
authors.forename: C
authors.initials: C
authors.lastname: Geden
mesh_terms: D000818:Animals; D005260:Female; D006793:Houseflies / Q000187:drug effects / Q000648:ultrastructure / Q000821:virology*; D007304:Insect Viruses / Q000472:pathogenicity*; D008297:Male; D010720:Phosphines / Q000494:pharmacology; D012737:Sex Factors
chemical_list: D010720:Phosphines; C080938:tris(2-carboxyethyl)phosphine
keywords: Dithiothetriol; Hytrosavirudae; Midgut barrier; Musca domestica; Peritrophic matrix; Tris (2-caboxyethyl)phosphine hydrochloride