A sorghum virus isolate collected in an experimental crop at Maracay,
Aragua State, was mechanically inoculated to some differential hosts f
or identification. The virus infected sorghum (Sorghum bicolor), maize
(Zea mays), and johnsongrass (Sorghum halepense), but it didn't infec
t oats (Avena sativa), barley (Hordeum vulgare), wheat (Triticum aesti
vum), or sugarcane (Saccharum officinarum) cvs CP-31294 and CP-31588.
The thermal inactivation point of the virus was 55-60 degrees C, the d
ilution end point was 10(-3)-10(-4), and the longevity in vitro was 1-
2 days at 23 degrees C. The virus was transmitted from sorghum to sorg
hum in the non-persistent manner by Rhopalosiphum maidis, but it was n
ot transmitted through sorghum seed. The virus was purified by a proto
col that featured clarification with 5% chloroform, precipitating with
4% polyethylene glycol in 0.3 M NaCl, and centrifugation in 10-40% su
crose density gradients. Yield of 10.20 Mg/g of infected corn leaves w
ere obtained. The A260/A280 ratio were 1.28. The virus particles appea
red as flexuous rods with a mean of 726.80 nm. In agar double-diffusio
n tests the viral isolate reacted positively with maize dwarf mosaic v
irus strain A (MDMV-A) antiserum, but it didn't react with MDMV-B anti
serum. On the basis of these criterions, the sorghum virus isolate cor
responds to MDMV-A. This is the first report of this strain in Venezue
la.