Two field-collected tomato plants, with severe and mild tomato leaf curl disease symptoms, were shown to be infected with tomato leaf curl New Delhi virus. The plant with severe symptoms was shown to additionally contain tobacco leaf curl betasatellite (TobLCuB). Inoculation of Nicotiana benthamiana plants with the cloned components showed the severe symptoms to be due to the presence of TobLCuB. A shorter latent period was associated with the presence of TobLCuB except in the presence of the DNA-A and DNA-B components of the severe type. The DNA-B component from the mild type also reduced the latent period, more so than the DNA-B from the severe type, except in the interaction with the DNA-A from the mild type. These differences in the effects of the virus components from the two isolates may possibly be due to mutations in the DNA-B from the severe type. The results show that betasatellites can enhance the virulence of bipartite begomoviruses, even for isolates that induce quite mild symptoms.

两种严重和轻度番茄叶片卷曲疾病症状的田间番茄植株均被感染了番茄叶片卷曲的新德里病毒。显示出症状严重的植物还含有烟叶卷曲的β-卫星（TobLCuB）。接种本氏烟草具有克隆成分的植物显示出严重的症状是由于存在TobLCuB。除存在严重类型的DNA-A和DNA-B成分外，更短的潜伏期与TobLCuB的存在有关。除了与轻度型的DNA-A相互作用之外，轻度型的DNA-B组分也缩短了潜伏期，比重度型的DNA-B减少得更多。来自两个分离株的病毒组分的作用的这些差异可能是由于严重类型的DNA-B突变所致。结果表明，即使对于诱导出相当轻度症状的分离株，β卫星也可以增强二倍体Begomovirus病毒的毒力。