However , the capsid protein is required for systemic infection .
Formation of virions is not always necessary for localized spread of the virus into neighboring plant cells , because ribonucleoprotein particles containing viral genetic material can spread to immediate neighbors through plasmodesmata .
The capsid protein is required for systemic infection .
Formation of virions is not always necessary for localized spread of the virus into neighboring plant cells , because ribonucleoprotein particles containing viral genetic material can spread to immediate neighbors through plasmodesmata .