MECHANISMS OF ARTHROPOD TRANSMISSION OF PLANT AND ANIMAL VIRUSES

Authors: Gray, Stewart; BANERJEE, N - CORNELL UNIVERSITY

Submitted to: Microbiology and Molecular Biology Reviews
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: A majority of the plant-infecting viruses and many of the animal-infecting viruses are dependent upon insect vectors for transmission between hosts and/or as alternative hosts. The viruses have evolved very specific associations with their vectors and we are beginning to understand the underlying mechanisms that regulate the virus transmission process. A majority of plant viruses are carried on the cuticle lining of a vector's mouthparts or foregut. This may at first appear to be a simple mechanical contamination, but it is now known to be a biologically complex interaction between specific virus proteins and, as of yet, unidentified vector cuticle-associated compounds. Numerous other plant viruses and a majority of animal viruses are carried internally in the body of the vector. These viruses have evolved very specific mechanisms to be transported through multiple vector tissues and to evade vector defenses. In response, vector species have evolved so that not all individuals within a species are susceptible to virus infection or can serve as a competent vector. Not only are the virus components of the transmission process being identified, but the genetic and physiological components of the vectors which determine their ability to be used successfully by the virus are being elucidated. The mechanisms of arthropod-virus associations are many and complex, but common themes are beginning to emerge which may allow the development of novel strategies to ultimately control the disease epidemics caused by the arthropod-borne viruses.

Technical Abstract: A majority of plant- and animal-infecting viruses are transmitted between hosts by insect or tick vectors. A majority of the viruses also kill or severely damage their primary plant or animal host, therefore the vector not only allows the virus to spread to multiple hosts, but insures the virus survival by moving it out of a dying host. Most vectors have specialized mouthparts that allow them to pierce the skin of the plant or animal and feed on the sap or blood. Viruses live within cells, but are freely transported around the host in the blood or sap and this allows the virus to be picked up by vectors as they feed. The scientific community is only recently beginning to understand the relationships and mechanisms that allow viruses to be transmitted by insects. Rarely have the scientists working on plant virus transmission interacted with those working on animal virus transmission mainly due to the major differences in the experimental systems. However, both plant and animal systems have different advantages that have led to important discoveries in one system that are not possible in the other, and visa versa. This manuscript reviews the progress that has been made in understanding the transmission of plant viruses and relates the findings to progress that has been made with animal virus transmission. Interestingly there are many common themes that are being to emerge and should allow more open and active communication and collaboration among plant virologists, animal virologists and medical entomologists. Several paradigms that link animal and plant virus transmission are developed and the central dogma developed decades ago and followed today is challenged.