Isolation of infective tomato bushy stunt virus after passage through the human alimentary tract

Abstract

Research on plant virus vectors has shown that almost all types of organisms feeding on or parasitizing infected plants, including sucking and biting insects, mites, nematodes and chytrid fungi, can act as specific vectors. Surprisingly, however, natural vectors have not been found for some of the most infectious of the plant viruses such as tomato bushy stunt virus (TBSV) and tobacco mosaic virus (TMV). Here we report that when purified TBSV was consumed by human volunteers, it subsequently occurred in their faeces and could be detected by mechanical inoculation of faecal extracts to the leaves of an indicator plant (Chenopodium quinoa) in which the virus causes countable, discrete lesions. Thus, the virus remained stable on passage through the alimentary tract. The significance of man as a carrier, able to disseminate the virus widely within the environment, is discussed in relation to the epidemiology of the disease. To our knowledge, this is the first demonstration of an ‘alimentary-resistant’ plant virus.