Lettuce infectious yellows virus: in vitro acquisition analysis using partially purified virions and the whitefly Bemisia tabaci.

Abstract

Virions of lettuce infectious yellows virus (LIYV ; genus Crinivirus) were purified from LIYV-infected plants and their protein composition was analysed by SDS-PAGE and immunoblotting. Virion preparations contained the major capsid protein (CP), but the minor capsid protein (CPm), p59 and the HSP70 homologue were also identified by immunoblot analysis. Immunogold labelling analysis showed that CP constituted the majority of the LIYV virion capsid, but CPm was also part of the capsid and localized to one end of the virion, similar to the polar morphology seen for viruses in the genus Closterovirus. p59 and the HSP70 homologue were not detected on virions by immunogold labelling, but were always detected in virion preparations by immunoblot analysis. Purified LIYV virions were used for in vitro acquisition analysis with Bemisia tabaci whiteflies and were efficiently transmitted to plants. Infectivity neutralization analyses were done using antisera to the LIYV-encoded CP, CPm, p59 and HSP70 homologue. Only antiserum to the CPm effectively neutralized LIYV transmission by B. tabaci. These data suggest that the LIYV-B. tabaci transmission determinants are associated with purified virions, and that the LIYV virion structural protein CPm is involved in transmission by B. tabaci.

Helical capsids of plant viruses: architecture with structural lability

“…The main virion part (approximately 95 % of its length) is made of the CP, while the remaining segment, which is located at the virion end encapsidating the 5¢-terminal region of genomic RNA, is formed by the CPm (Agranovsky et al, 1995;Peremyslov et al, 2004;Satyanarayana et al, 2004). Additionally, the CPm-formed region of BYV virions contains three other viral proteins, namely an Hsp70 homologue (Hsp70h), a p64 protein with a CP-like structural domain in its C-terminal region and p20 (Kiss et al, 2013;Napuli et al, 2000Napuli et al, , 2003Tian et al, 1999). The latter is dispensable for virion formation and virus cell-to-cell movement, but is essential for the viral systemic transport through the plant vascular system (Prokhnevsky et al, 2002).…”

Whitefly-transmitted criniviruses of cucurbits: current status and future prospects

“…The CP encapsidates and protects the RNA from cellular degradation. The CPm is a whitefly-transmission determinant needed for plant-to-plant transmission for LIYV [16,79,81]. CPm constitutes an integral part of the tail protein complex, whereby CPm binds to the anterior foregut of whitefly epithelial cells [79].…”

Complex molecular architecture of beet yellows virus particles

“…In contrast, p20 is dispensable for virion assembly and cell-to-cell movement, but is necessary for BYV transport through the plant vascular system (18). A CPm, Hsp70h, and p64 ortholog were also found in the virions of lettuce infectious yellows virus (25) and were implicated in assembly of citrus tristeza virus (26). Both these viruses belong to the family Closteroviridae and are distantly related to BYV.…”