Characterisation and serology of virus‐like particles associated with faba bean necrotic yellows

Abstract

A disease showing chlorosis, leaf rolling and stunting in Vicia faba and other legumes was observed in West Asia and North Africa during 1987-1988. The putative causal agent could not be transmitted mechanically, but could be transmitted by aphids, most efficiently by Acyrthosiphon pisum, in the persistent manner. Further studies revealed isometric virus-like particles (VLPs) closely associated with the disease, although their infectivity could not be demonstrated by membrane feeding. These particles, measuring c. 18 nm in diameter and containing a capsid protein of about 22 kDa and ssDNA of about 1 kb, are hereafter designated faba bean necrotic yellows virus (FBNYV). A high proportion of circular nucleic acid molecules of about 0.9 kb were visualised by electron microscopy. Hybridisation analysis of cloned viral DNA suggests that the circular genome is larger than 1 kb and consists of several components of similar size. An antiserum produced against FBNYV was used in ELISA, immunoelectron microscopy (IEM) and Western blot experiments for virus detection in aphids and field samples and for serological comparison with other viruses. Weak heterologous reactions between FBNYV and subterranean clover stunt virus (SCSV) were detected in IEM, but could not be confirmed in ELISA or Western blots. No serological relationship to banana bunchy top virus (BBTV) was detected. Using a direct tissue blot immunoassay (TBIA), FBNYV was detected in vascular tissue of infected faba bean leaves and stems.

Incidence and transmission of Faba bean necrotic yellows virus (FBNYV) in Spain

“…The virus has a multipartite genome consisting of several circular ssDNA components that are similar in size (about 1 kb) and individually encapsidated in small isometric particles about 18 nm in diameter (Katul et al, 1993). The main host is the faba bean (Vicia faba L.).…”

Advances in Small Isometric Multicomponent ssDNA Viruses Infecting Plants

“…Isometric virus of 18 nm containing circular ssDNA as genome of 1.0 kb was observed in faba bean affected with necrotic yellows and the virus was named as FBNYV [44]. By host range, transmission and serology, the virus was similar to SCSV and MDV.…”

“…Recently, MDV has been recorded in China [49]. FBNYV occurs in many Arab countries of West Asia, North and East Africa and Europe (Syria, Jordan, Ethiopia, Egypt, Algeria, Morocco, Sudan, Azerbaijan, Tunisia and Spain) [20, 21, 44,48,54,[56][57][58][59]72]. FBNSV has been recently reported from Ethiopia [25] and Morocco [1], and PNYDV from Germany [26].…”

“…Faba bean (Vicia faba) is an important crop affected by the disease. In addition, several cool season (Lens culinaris, Cicer arietinum and Pisum sativum) and summer season legumes (Phaseolus vulgaris and Vigna unguiculata) are also affected by the disease [20,44,54,58]. The disease (Fig.…”

“…The causal virus of some of these diseases like bunchy top of banana and dwarfing/ stunting of milk vetch and subterranean clover was misunderstood as luteovirus [63,71,81]. During late 1980s and early 1990s, when virus purification was successful from several of these diseases, association of smallest isometric virus of 17-20 nm was evident [13,40,44,73,103]. Subsequently, during 1993-1995, genome sequencing and molecular characterisation revealed that these viruses contained multiple components of single stranded circular DNA (ssDNA) each about 1.0 kb in size.…”