The protection or inhibitory mechanism is believed
to occur as the satellite replication overtakes the viral replication, thus blocking
accumulation and symptom expression of
the virus (8). The efficacy of this virussatellite RNA preinoculation technology
has been compared with conventional
cross-protection (14). Conventional crossprotection was found to be essentially ineffective against challenge by CMV containing a necrogenic CARNA 5 (6; M. S.
Montasser, unpublished data); however, it
has been shown to be effective against
satellite RNA-free CMV strains (2) but not
as effective against a very severe satellite
RNA-free strain as is protection by CMV +
satellite RNA (14).
In our previous field trials with tomato,
protection was maintained when the challenge virus was introduced mechanically or
by aphids (14), and under natural infection
conditions (5). This augurs well for the
future of this technique, at least for tomatoes and severe strains of necrotic satellite
RNA-containing CMV under conditions
where epidemics are frequent, or where
CMV infections are endemic.
We report here the feasibility of using
viral satellite RNA to protect pepper and
melon plants in the field. This work presents the effect of satellite RNA vaccination on preventing disease and preserving
fruit yield in melon and pepper growing
under simulated aphid infestation conditions in the field.