Circulative Transmission of Cileviruses in Brevipalpus Mites May Involve the Paracellular Movement of Virions

Abstract

Plant viruses transmitted by mites of the genus Brevipalpus are members of the genera Cilevirus, family Kitaviridae, or Dichorhavirus, family Rhabdoviridae. They produce non-systemic infections that typically display necrotic and/or chlorotic lesions around the inoculation loci. The cilevirus citrus leprosis virus C (CiLV-C) causes citrus leprosis, rated as one of the most destructive diseases affecting this crop in the Americas. CiLV-C is vectored in a persistent manner by the flat mite Brevipalpus yothersi. Upon the ingestion of viral particles with the content of the infected plant cell, virions must pass through the midgut epithelium and the anterior podocephalic gland of the mites. Following the duct from this gland, virions reach the salivary canal before their inoculation into a new plant cell through the stylet canal. It is still unclear whether CiLV-C multiplies in mite cells and what mechanisms contribute to its movement through mite tissues. In this study, based on direct observation of histological sections from viruliferous mites using the transmission electron microscope, we posit the hypothesis of the paracellular movement of CiLV-C in mites which may involve the manipulation of septate junctions. We detail the presence of viral particles aligned in the intercellular spaces between cells and the gastrovascular system of Brevipalpus mites. Accordingly, we propose putative genes that could control either active or passive paracellular circulation of viral particles inside the mites.

Kitaviruses: A Window to Atypical Plant Viruses Causing Nonsystemic Diseases

“…Additionally, the assessments of the ratio p29sgRNA:RNA1 of CiLV-C in mites were markedly lower than those detected in plants (7). Based on these results, the hypothesis raised is that, although CiLV-C uses the paracellular route to cross the epithelial cell barrier moving from the midgut lumen up to the stylet channel (117), the virus can replicate in yet unidentified cells, in which the replication occurs at a low rate.…”

“…These particles may appear aligned up to 10 µm long in the intercellular spaces, and the rows are frequently interrupted by septate junctions. Longer acquisition time seems to lead to higher viral loads in mites, but neither recognizable viral particles nor viroplasms could ever be observed inside cells (43,117).…”

Gama de hospedeiros naturais e experimentais de >i<Passion fruit green spot vírus>/i< e interações com o vetor >i<Brevipalpus yothersi>/i<

“…A internalização neste caso ocorreria a nível de intestino médio, mediada pela liberação de uma proteína com a função de abrir temporariamente as junções septadas do epitélio intestinal, como ocorre com a zonulina no intestino humano (STURGEON; FASANO, 2012;FASANO, 2016), permitindo a passagem dos vírions via paracelular (Figura 15). A via paracelular parece ser a utilizada pelos cilevirus para sua circulação no vetor (KITAJIMA; TASSI et al, 2022) A presença de receptores no intestino do vetor e a manipulação das junções septadas em ácaros Brevipalpus spp. necessita de maiores estudos para confirmação da hipótese aqui levantada, podendo também fornecer maiores informações que auxiliarão na compreensão da especificidade ácaro/vírus.…”