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

Abstract

Potato leafroll virus (PLRV) is transmitted by aphids in a persistent manner. Although virus circulation within the aphid leading to transmission has been well characterized, the mechanisms involved in virus recognition at aphid membranes are still poorly understood. One isolate in our collection (PLRV-14.2) has been shown to be non-or only poorly transmitted by some clones of aphids belonging to the Myzus persicae complex. To determine where the transmission process was blocked within the aphid, three virus transmission procedures were used. PLRV-14.2 could not be transmitted, or was only very poorly transmitted, after acquisition from infected plants or from purified preparations. In contrast, it could be transmitted with more than 70 % efficiency when microinjected. Therefore, it is concluded that the gut membrane was a barrier regulating passage of PLRV particles from the gut lumen into the haemocoel of M. persicae. Comparison of coat protein (CP) and readthrough protein (RTP) sequences between poorly and readily transmissible isolates 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 of 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.

A selective barrier in the midgut epithelial cell membrane of the nonvector whitefly Trialeurodes vaporariorum to Tomato yellow leaf curl virus uptake

“…The gut epithelial membrane was shown to not be selective for the transport of luteoviruses, because both vector and nonvector aphids can acquire the viruses in their cells. It has also been shown that amino acid changes in the coat and read-through proteins of Potato leafroll virus reduce virus recognition by putative gut receptors in an aphids vector, resulting in reduced transmission of the mutated virus (Rouzé-Jouan et al 2001). These studies indicate that virus recognition mediated by a putative gut receptor must occur before transcytosis of the virion at the gut epithelial cell membrane.…”

Intra-specific variation and inheritance of BYDV-PAV transmission in the aphid Sitobion avenae

“…In the aphid, the virus must cross from the hindgut into the hemocoel, then survive in the hemocoel, join the salivary glands and penetrate into the accessory salivary glands to be egested: thus, it is likely that several barriers and therefore several genetic loci are responsible for vector competence. In some cases (Potato leafroll virus, PLRV transmitted by M. persicae), gut membrane seems to regulate transmission efficiency (Rouze´-Jouan et al, 2001). For our S. avenae clones, it was shown (Papura, 2001) that the RNA of PAV4 could be detected by RT-PCR in the hemolymph of a PEV as well as of a HEV clone (Sa (self.Sa5)52 and Sa (self.Sa5)28), suggesting that viruses are acquired similarly by the two clones and that the molecular determinants of transmission may be situated in the hemolymph and/or in the salivary glands.…”

Role of Pea Enation Mosaic Virus Coat Protein in the Host Plant and Aphid Vector

“…The α-helical conformation of the motif requiring few specific aa is essential for RNA recognition, transactivation [45,46], and packaging [43]. Several authors observed similar effects of mutations in the R domain of PLRV CP, but transmission by aphids was not totally abolished [22,47]. Crystal structures of tomato bushy stunt virus, [33], and virions belonging to the Sobemovirus genus (e.g., RGMoV [48]; SeMV [49]), which are closely related to Enamovirus , reveal that viral RNA interacts with the flexibly-linked arms of the R-domain, which can be disordered in A/B subunits of the trimer.…”