The passage of Potato leafroll virus through Myzus persicae gut membrane regulates transmission efficiency

Potato leafroll virus (PLRV) is transmitted by aphids in a persistent manne r. Although virus circulation within the aphid leading to transmission has been well characterized, the mechanisms involved in virus recognition at ap hid membranes are still poorly understood. One isolate in our collection (P LRV-14.2) has been shown to be non- or only poorly transmitted by some clon es of aphids belonging to the Myzus persicae complex. To determine where th e transmission process was blocked within the aphid, three virus transmissi on procedures were used. PLRV-14.2 could not be transmitted, or was only ve ry poorly transmitted, after acquisition from infected plants or from purif ied preparations. In contrast, it could be transmitted with more than 70% e fficiency when microinjected, Therefore, it is concluded that the gut membr ane was a barrier regulating passage of PLRV particles from the gut lumen i nto the haemocoel of M. persicae. Comparison of coat protein (CP) and readt hrough protein (RTP) sequences between poorly and readily transmissible iso lates showed that PLRV-14.2 differed from other PLRV isolates by amino acid changes in both of these proteins. It is hypothesized that at least some o f the changes found in CP and/or RTP reduced virus recognition by aphid gut receptors, resulting in reduced acquisition and subsequent transmission of PLRV-14.2.