Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 1996
Publication Date: N/A
Interpretive Summary: Barley yellow dwarf is the most economically damaging viral disease of cereal crops. The disease is caused by a group of related luteoviruses collectively known as barley yellow dwarf virus (BYDV) which are efficiently transmitted by aphids in nature. Currently there are no methods to effectively control this disease. The objective of this work was to in- vestigate the specific interactions of virus with the salivary glands of aphids. We have previously shown that virus must specifically associate with 2 salivary gland membranes, 1 surrounding each cell of the salivary gland & the other surrounding the entire gland. We have now shown that the membrane surrounding the entire salivary gland is differentially able to bind & filter various isolates of BYDV. The membrane is negatively charged, a property which may confer additional selectivity. It is also impermeable to particles the size of viruses, so that the virus must induce some type of conformational change in the structure that would allow the relatively large virus particle to move across the membrane. An understanding of the physical and chemical properties and the limitations of the salivary gland membranes is necessary to fully understand how luteoviruses are transmitted by their insect vectors. Since other economically important plant and animal viruses may use similar mechanisms for transmission, the luteovirus-aphid experimental system can serve as an important model system in developing novel strategies for interfering with insect-transmitted pathogenic viruses.
This research investigates the physical properties of the accessory salivary gland basement membrane and its role in the regulation of BYDV transmission. Several species of aphids, both vectors and nonvectors, were injected with two different strains of BYDV. The ability of the virus to associate with and penetrate the ASG basement membrane was examined ultramicroscopically. In addition, ferritin and colloidal gold were used t examine the effect of size and charge on the ability of these tracers to associate with and penetrate the basement membrane. Both tracers associated nonspecifically and were able to penetrate basement membranes of several tissue types. Cationized ferritin tended to aggregate along the outer edge of basement membranes and at the openings of membrane invaginations on the plasmalemma of the ASG suggesting that these sites were negatively charged. Anionic 7-14 nm and 20 nm gold was able to penetrate all basement membranes sexamined but 30 nm gold was excluded. Cationic 20nm gold attached to ASG basement membranes, but did not penetrate. Purified preparations of BYDV strains were able to associae with and penetrate the ASG basement membrane of efficient aphid vectors both in vivo and in vitro using dissected salivary glands. Two distinct mechanisms operated to prevent or reduce the transmission of BYDV strains in nonvectors or inefficient vectors; 1) the degree that virus was able to attach to the ASG basement membrane and 2) the degree the virus was able to penetrate through the basement membrane.