Rice Reoviruses in Insect Vectors

Abstract

Rice reoviruses, transmitted by leafhopper or planthopper vectors in a persistent propagative manner, seriously threaten the stability of rice production in Asia. Understanding the mechanisms that enable viral transmission by insect vectors is a key to controlling these viral diseases. This review describes current understanding of replication cycles of rice reoviruses in vector cell lines, transmission barriers, and molecular determinants of vector competence and persistent infection. Despite recent breakthroughs, such as the discoveries of actin-based tubule motility exploited by viruses to overcome transmission barriers and mutually beneficial relationships between viruses and bacterial symbionts, there are still many gaps in our knowledge of transmission mechanisms. Advances in genome sequencing, reverse genetics systems, and molecular technologies will help to address these problems. Investigating the multiple interaction systems among the virus, insect vector, insect symbiont, and plant during natural infection in the field is a central topic for future research on rice reoviruses.

Understanding the immune system architecture and transcriptome responses to southern rice black-streaked dwarf virus in Sogatella furcifera

“…The RNAi pathway is the classical antiviral immune pathway and is able to effectively modulate the replication of persistent propagative transmitted viruses37. Among all 27 genes of the RNAi pathway identified in WBPH, 15 were identified as MIEGs showing enhanced expression as the viral titer increased, among the NVF, MVT, and HVT groups (Fig.…”

“…Vector competence is the inherent ability of a vector to acquire, circulate, replicate, and transmit a virus to a host37383940. Naturally, the SRBSDV virus could be detected in 25–83% of individuals in a WBPH population, referred to as virus carriers6841, but the underlying mechanism determining viral titers in vivo is not well characterized.…”

Tubules of plant reoviruses exploit tropomodulin to regulate actin-based tubule motility in insect vector

“…Plant reoviruses encode a non-structural protein which assembles into tubules by self-interaction, for example, southern rice black-streaked dwarf virus (SRBSDV) from the genus Fijivirus encodes the protein P7-1, rice dwarf virus (RDV) and rice gall dwarf virus (RGDV) of the genus Phytoreovirus encodes Pns10 and Pns11, respectively1234. These tubules approximately 85 nm in diameter, regularly fix the viral particles on the inner surface, and exploit the actin-based tubule motility (ABTM) to positively facilitate viral spread in insect vectors45.…”

“…These tubules approximately 85 nm in diameter, regularly fix the viral particles on the inner surface, and exploit the actin-based tubule motility (ABTM) to positively facilitate viral spread in insect vectors45. Studies on infected cultured cells of insect vectors show that the virions-packaging tubules, which are propelled by the power from the ABTM, insert the actin-based filopodia and extend into the neighboring insect cells for viral cell-to-cell dissemination123.…”

“…Studies on infected cultured cells of insect vectors show that the virions-packaging tubules, which are propelled by the power from the ABTM, insert the actin-based filopodia and extend into the neighboring insect cells for viral cell-to-cell dissemination123. In alimentary canal of the insect vectors, the growing tubules take advantage of ABTM to pass through actin-based microvilli of the epithelium into the lumen, or cross the basal lamina from the initially infected epithelium, or traverse the tight junctions between epithelial cells for facilitating viral intercellular spread146. The tubules further move along the actin-based visceral muscles of the whole intestine for viral lateral spread in the aid of ABTM146.…”