Pea seed-borne mosaic virus (PSbMV) RNA replication in pea cotyledonary tissues was restricted largely to a zone of cells close to the infection front. In situ hybridization probes representing nine genes from two pathways of metabolism failed to detect RNA transcripts within this zone, although transcripts were found in similar amounts in tissues on either side of the zone. Thus, in common with some animal viruses, PSbMV transiently suppresses the expression of host genes. Host protein accumulation was also affected. These observations provide insights into virus-plant interactions and symptom expression.