Filamentous viral ribonucleoproteins (RNPs) 12 to 16 nm in diameter and 100
to 1,260 nm in length, and characteristic of the genus Tenuivirus, were de
tected by transmission electron microscopy in purified extracts of needles
collected from two mature, asymptomatic black spruce (Picea mariana) trees
in New York, but not in extracts of needles from nursery seedlings. Purifie
d RNPs from one tree had a buoyant density in CsCl = 1.39 g/cm(3) and an A(
260/280) = 1.436. Four ssRNA segments of 1.3, 2.1, 2.3, and 3.5 kb, but not
the 8- to 9-kb fragment characteristic of most tenuiviruses, were detected
in purified RNA extracts. Amplification products of the expected size were
observed when RNA extracts from the two spruce trees and Maize stripe tenu
ivirus (MStpV), but not from tobacco, Chenopodium quinoa, or spruce seedlin
gs were subjected to reverse transcription-polymerase chain reaction (RT-PC
R) using primers to the p3 open reading frame (ORF) of MStpV vRNA 3. Howeve
r, only MStpV amplified when primers to the nucleocapsid ORF (pc3 ORF on vc
RNA 3) were used. Similarly, only MStpY amplified by immunocapture polymera
se chain reaction (PCR) using antiserum to MStpV and primers to the p3 ORE
Sequence comparisons suggest that two distinct tenuiviruses occur in black
spruce, one more closely related to MStpV than the other. One of these tenu
iviruses was detected in one of 10 additional black spruce trees tested, bu
t not in trees of six other coniferous species sampled in the Adirondack Mo
untains of New York.