Until recently the only biomedical use of erythrocytes was in transfusion medicine to restore a normal oxygen delivery. The development of a technology that permits one to open and reseal erythrocytes has dramatically changed this perspective. Currently, a number of teams have shown that engineered erythrocytes can behave as circulating bioreactors for the degradation of toxic metabolites or the inactivation of xenobiotics, as drug delivery systems, as carriers of antigens of vaccinal interest, and in many others biomedical applications. The technology of opening and resealing the erythrocytes has also been used successfully to investigate several basic aspects of erythrocyte metabolism, survival, pathology, etc. Thus, researchers in this field have an extraordinary opportunity to specifically modify the erythrocytes by the introduction of enzymes that generate new metabolic abilities, antibodies that inactivate single metabolic steps, or metabolites that can influence oxygen delivery and/or other cell properties. Furthermore, the pharmacokinetics of any drug can be potentially manipulated by using the erythrocytes as a delivery system. This book, The Use of Resealed Erythrocytes, is based on the fourth meeting of the "International Society for the Use of Resealed Erythrocytes as Carriers and Bioreactors" (I. S. U. R. E. ), held in Urbino, Italy, in 1991, and examines the most recent applications and developments of this technology.

We open Volume 7 with a series of four chapters on plant virus transmission by insects. In Chapter 1, Karen Gibb and John Randles present preliminary information about an association between the plant bug Cyrtopeitis nicotianae (Heteroptera: Miridae) and velvet tobacco mottle virus (VTMo V): the only reported instance of mirid transmission of a known virus. Mirids could be considered as likely vectors of plant viruses because they are phytophagous, possess a piercing-sucking-feeding apparatus, have winged adults, and are cosmopolitan pests of a wide range of crops. Surprisingly, however, there are only three plant viruses purportedly transmitted by heteropterous vectors, compared with the nearly 250 by homopterous ones. To what extent these figures reflect actual differences in the abilities of members of the two suborders to transmit plant pathogens remains to be determined. Compared with the Homop tera, the Heteroptera have been ignored by researchers as potential vectors of plant viruses. The authors are quick to point out that additional studies are needed before generalizations can be made about virus-mirid-plant interactions and that virus transmission by mirids is not easily characterized using the conventional transmission criteria and terminology established for such homopterous vectors as aphids and leafhoppers. Transmission of VTMoV by C. nicotianae appears to have characteristics in common with both nonpersistent noncirculative and circulative (persistent) transmission."