State of the art on the agent of citrus psorosis disease Milne R.G. in

Milne R.G.

in

Martelli G.P. (ed.), D' Onghia A.M. (ed.).

Proceedings of the Mediterranean network on certification of citrus. 1995-1997 Bari : CIHEAM

Options Méditerranéennes : Série B. Etudes et Recherches; n. 21 1998

pages 99-105

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--- To cite th is article / Pou r citer cet article

--- Milne R.G. State of th e art on th e agen t of citru s psorosis disease. In : Martelli G.P. (ed.), D 'Onghia A.M. (ed.). Proceedings of the Mediterranean network on certification of citrus. 1995-1997.

Bari : CIHEAM, 1998. p. 99-105 (Options Méditerranéennes : Série B. Etudes et Recherches; n. 21) ---

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G.

dì Fìtovirologia Applicata, Torino -

-

Symptoms can include and the best isolate is known as

the name

to avoid confusion with diseases of is a

multicomponent with a coat of 48-50 The f i e kinky

filaments of lengths and about 3 nm with the ends joined to of the

Two with some have

and tulip mild mottle mosaic of 43 and 46

A new the The of

and also some of of

of and the nucleocapsid components of in the family

which includes the the of and

sizes of about 31 and 29 diagnostics,

sequences of an isolate of been with the use of based

on them. A using a also and is

being employed to detect in some in

words: diagnosis

-

Les particules du genre ‘ophiovirus’ et quelques-unes de leurs propriétés moléculaires ressemblent à celles des tenuivirus (virus à localisation phloémique des céréales) et des similitudes avec les composantes nucléocapsidiques des virus de la famille des bunyaviridae qui incluent les tospovirus. Toutefois, les protéines capsidiques des tenuivirus et des tospovirus ont

Options Méditerranéennes, Série B /n021, - of on Certification of Citrus

100 G.

une taille respective de 31 et ce qui concerne le diagnostic, il a été rapporté l‘obtention des séquences partielles d‘un isolat de et leur utilisation pour la mise au point d‘amorces pour la un test utilisant un antisérum polyclonal a été décrit et cette technique est actuellement employée pour détecter la psorose dans des vergers d’agrumes et des pépinières dans le sud de

clés: agrumes, ophiovirus, diagnostic

one the disease known as

damaging in of the including the the basin; it has been

studied by symptomatology, use of

mechanical to species such as Chenopodium quinoa this

of the in the

of the sequencing of the

nucleic acid. This especially is the subject of my

a note As well as the classical that gave to the name

flecks and also be in the leaves of infected and

the name some isolates, e.g.

Gamsey & 1980). now seems that usually caused by the same et al., 1993; 1993) but a single name this has not yet been

officially the name be used; the

“associated” is still advisable because in only one case

to fulfilling postulates been made (Gamsey & The postulates, as adapted to

isolation of the in that such a

can be inoculated back into the symptoms,

and enabling of the once These tests the

in low and the plant, which is not easy to inoculate successfully

A decisive advance in the et al. (1988a,

They to it and published evidence that the

of a novel filamentous type, coming in at least two length classes. They showed that density infectivity in C. quinoa was maximized by combining top and bottom

and that a 48 was associated with the

followed (da et al., 1991, 1992; et al., 1991, 1993; et al., 1991a,b, 1992; Navas-Castillo, 1991; Navas Castillo & 1993, 1995; Navas-Castillo et al., 1991, 1993)

on isolates Spain, the

of to the isolate, associated with these symptoms. was

that a capsid of 48-50 and that the nucleic acid of the was

The nm wide

and 300-500 nm in length. The that the of a novel

type with no immediate affinities, since of at least 12-13

nm, and did The this single

of et al., 1993).

all this time, the in the by staining it with the

in the so-called positive-stain mode, in which the the stain.

The next of my the positive staining and negative

staining, so will make a small to explain these.

the to (UA) as a stain

in the positive-stain mode, UA stains nucleic acid little to the negative-stain mode, UA stains the

only, thus causing the the whole shape of

the becomes outlined in detail, including nucleic lipid if

Thus example, with a such as the nucleocapsid of influenza about 5 % nucleic acid and 95 % Compans et al. (1972) noted that

seen in negative stain, in positive stain as thin

and ill-defined shadows - if 5 % of the

So to do with influenza? The is that the of in

themselves nucleocapsids in basic to those of

except they Thus negative staining fine detail in the

than does positive staining; in fact it of the

and hence its has been aided by the

in of but in

et al., 1997) and the finding in Japan of in tulip (tulip

mild mottle et al., of

42 and 46 not the 48-50 of of the

in et al. et al. (1996).

The main isolate the USA, Spain and

in “top”

“bottom”

in 50 p1 of %

of the few

with 1 % following

102 G.

negative stain, the come in at least two size classes, small and levels of complexity became The

shaped, out to be composed of two closely twined filaments, each about 3 nm in These filaments in one continuous looping back on itself at each end.

that if an elastic band a closed loop of is twisted and then allowed to take its own shape, it can assume the of the seen in the complete with a sinuous wave

along the length of the Thus we think that the the is in some

way coiled.

these in fact composed of a should

sometimes be fact the of in the in open

though the in outline but highly kinked looped, again

suggesting a of that in the of

in the open but that as time passed, they tended to collapse into the

Available of Japan show top and bottom both in the open

of seen in open in dilute

8 containing the but can be to the duplex

in 6 et al., 1997). These images have

of the of

somewhat in with those of colleagues, some specific questions as well as ones. example, and associates did not the open

positive staining, these visible, having low

addition, incubation of the on

but in this was because, as noted by

us, long incubation allowed a of the open to collapse into the

easily detected duplex

What can the new of the of suggest about the of

this plant and it is likely that

out to a genus, and we have the name such a genus

et al., 1994). The name is the “ophis”, a snake, in the

of the While the name has it is based on a

misconception of the of the to Spiroplasma

cifri, the name of the agent of disease, and to the name used a genus of

it is that such as have

closely those of the in being in at least two size classes, and in

both open and dimensions and physical

et al., et al., et al.,

1994a). the to be closely the

of that also includes the

et al., 1995). The out of a study of

is that the will in time be as a genus within the

on advanced, it is known in

that the is found in

is found with the

The is that vivo the is

of vitro, the of opposite

1994).

We have noted that the of it is that the

the nucleocapsids of the also the basically

of

the 5’ and 3’ ends of each et al., et‘al., 1995). Such

could the the of its the

sequence data not yet available is so.

What implications of all

have insect at least in which they multiply. This suggests that

also be found to have in no case has such

The above will help to fits into the

that the The

how to detect the to the amount of also

beginning to go beyond the biological indexing et al.

sequences the that allow the

to be the

enough to be used in this is, by it

of isolates the Spain and

the basis field in the of as also

the meeting in Adana, 1996.

104 G.

Compans, Content, J. and of the of influenza

J. Virol., 10, pp. 795-800.

J.V, (1991). of isolates of

and agents of Disease 75, pp. 613-616.

da J.V., and (1992). detection of

using 12'h Conf. 432-434.'

J.V., Lee, L.W. and Nguyen, (1988a).

of a associated with 78, pp. 1298-1301.

L.W. and Nguyen, (1988b). Two components

associated with Con. Spain, pp. 340-342.

Lee, G.A. and J.V. (1991). of

C o n . pp. 386-390.

Lee, and (1993). A new of

associated with and 12th C o n . pp. 428-429.

and (1985). Atlas of Vol. 2.

O. and A.N. (1991a). is caused by a

in Virology 142, pp. 303-311.

O. and A.N. (1991b). disease agent behaves as a

two component In C o n . 337-344.

and O. (1992). associated and

belong to a new 12*h Conf. of pp. 430-431.

O. and (1994). The closely and

of novel filamentous J. Gen. Virol. 75, pp. 3585-3590.

Sanchez de la N., Luisoni, E., and

O. (1997). of using and

46 (6), pp. 830-836.

and L.W. (1980). of isolates

and 8'" Conf. pp. 174-179.

and L.W. (1988). Local lesion isolate of induces scaling. loth Col$ Spain, pp. 334-339.

Zubay, G. (1961). staining of nucleic acid-containing Biophys. Biochem. Cytol. 11, pp. 273-296.

T. and (1989). of J. Gen.

Virol. 70, pp. 3465-3468.

(1993). of in Diagnosis Virus Diseases, eds

pp 215-251.'

E. and O. of

diagnosis and taxonomy. 13'" Conf.

China, pp. 189-197.

T., Yamamoto, T. and Natsuaki, T. (1995). of

associated with tulip mild mottle mosaic. Ann. Soc. Jpn. 61, pp. 578-581.

F.A., Fauquet, S.A., A.W., and

(1995). taxonomy. Committee on Taxonomy of

Arch. Virol. Suppl. 10.

Navas-Castillo, J. (1991). de las de los y ensayos de de

asociados. Thesis, of Valencia, Spain.

Navas-Castillo, J. and (1993). of isolates in Spain.

42, pp. 347-357.

Navas-Castillo, J. and (1995). Filamentous

of size associated with and diseases. J. 101, pp. 343-

348.

Navas-Castillo, J., J.F., and de A. (1991).

of a of in in Spain. Conf.

pp. 345-351.

Navas-Castillo, J., (1993). of a associated

with a Spanish isolate of 42, pp. 339-346.

and A.L. (1994). biology of a of plant

J. Gen. pp. 467-475.

C.N. (1993). - a 12th Conf. pp. 139-154.

S . , Suzuki, Y., Goto, Y. and (1994a). Effects of salts on activity

and of filamentous of Ann. Soc. Jpn. 60, pp.

555-562.

S . , Takahashi, Sano, Y., Shimizu, T. and A. (1994b). Nucleotide sequence of

genome segment of of the J. Gen. Virol. 75,

pp. 3569-3579.

Accotto, Luisoni, V. and Lisa, V. (1997).

of a new with a divided genome and

Arch. Virol. 142, pp. 2131-2146.