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Uncharacterized Bacilliform Viruses 



These viruses caused striking symptoms in their hosts. 

 Chlorotic and necrotic fleck lesions occurred on Cymbidium 

 leaves (Fig. 23), while necrotic and ringspot lesions occurred 

 on Brassia leaves (Fig. 24). Nuclear, but not cytoplasmic 

 inclusions were observed in mesophyll and phloem tissues of 

 plants infected with bacilliform viruses. Those in Brassia 

 were relatively large and solitary (Fig. 25b), whereas those 

 found in the Cymbidium specimens were smaller, and usually 

 there was more than one inclusion within each nucleus (Fig. 

 26). The 0/G stain combination readily stained these 

 inclusions (Fig. 27). With Azure A, however, penetration was 

 facilitated considerably by pretreatment of tissues in 1% 

 Triton X-100 for 10 minutes and heating at 60 C for 10 minutes 

 during staining. Without these treatments, the nuclear 

 inclusions did not stain well (Fig. 25a). Thin sections for 

 both isolates revealed rhabdovirus particles. These nuclear 

 inclusions are composed of virus particles and granular 

 materials (Fig. 28). Particles ca . 45 nm in diameter occurred 

 in aggregates within the nucleus and in the cytoplasm. Those 

 in the cytoplasm were sometimes arranged in a "spokewheel-like" 

 fashion, like those described previously for Dendrobium leaf 

 spot, orchid fleck, and Phalaenopsis chlorotic spot viruses 

 (Lesemann and Begtrup, 1971; Petzold, 1971; Lesemann and 



