Silencing of genes involved in Anaplasma marginale-tick interactions affects the pathogen developmental cycle in Dermacentor variabilis

Abstract

Background: The cattle pathogen, Anaplasma marginale, undergoes a developmental cycle in ticks that begins in gut cells. Transmission to cattle occurs from salivary glands during a second tick feeding. At each site of development two forms of A. marginale (reticulated and dense) occur within a parasitophorous vacuole in the host cell cytoplasm. However, the role of tick genes in pathogen development is unknown. Four genes, found in previous studies to be differentially expressed in Dermacentor variabilis ticks in response to infection with A. marginale, were silenced by RNA interference (RNAi) to determine the effect of silencing on the A. marginale developmental cycle. These four genes encoded for putative glutathione S-transferase (GST), salivary selenoprotein M (SelM), H+ transporting lysosomal vacuolar proton pump (vATPase) and subolesin.

RNA Interference – A Powerful Functional Analysis Tool for Studying Tick Biology and its Control

“…In conclusion, the authors suggested that RNAi may be used to massively produce sterile ticks (SAT) that may be released in the field. Releasing subolesinsilenced ticks may also aid in the control of A. marginale, since it has been reported that subolesin knockdown reduced the infection level of this pathogen [141][142][143]. Introducing dsRNA to eggs through electroporation described above may be a more convenient way of producing knockdowned ticks.…”

“…Several proteins have been studied through RNAi to determine their importance in the development cycle of different pathogens. The knockdown of subolesin [142,156], GST, vATPase, and selenoprotein M [142] in D. variabilis, and putative von Willebrand factor, flagelliform silk protein and subolesin in R. (B.)…”

In vitro cultivation of Anaplasma marginale and A. phagocytophilum in tick cell lines: a review

“…In addition, in vitro cultivation of A. marginale in tick cells has been used in comparative studies with infected bovine erythrocytes for differential bacterial gene transcriptional analyses and expression profile of outer membrane proteins to search for potential A. marginale vaccine candidates GARCIA-GARCIA et al, 2004;NOH et al, 2006), and in RNA interference approaches for functional studies to discover genes/proteins that are differentially expressed in tick cells in response to infection with A. marginale (DE LA FUENTE et al, 2007;KOCAN et al, 2009). These studies indicate that A. marginale affects the expression of tick genes important for tick survival and pathogen multiplication; thus, a molecular mechanism occurs by which tick cell gene expression mediates the development of the pathogen through ticks.…”

Efeitos da infecção por Rickettsia rickettsii sobre o perfil de expressão gênica do carrapato vetor Amblyomma cajennense.

“…Dentre os métodos disponíveis, o RNA de interferência (RNAi) é um dos mais utilizados, inclusive em carrapatos (Aljamali et al, 2002;de la Fuente et al, 2005de la Fuente et al, , 2007aKocan et al, 2008Kocan et al, , 2009Kocan et al, , 2011Nijhof et al, 2007). A utilização da técnica de RNAi in vivo permite elucidar mecanismos fisiológicos de genes específicos e propiciam a descoberta rápida de alvos para vacinas contra carrapatos.…”

“…Também foi relatado que o silenciamento da GST, da V-ATPase, da selenoproteína M e da subolesina apresentou efeitos nas colônias de A. marginale, promovendo mudança no padrão das formas densas e reticuladas das colônias, podendo afetar sua multiplicação no intestino e/ou glândulas salivares do carrapato D. variabilis (Kocan et al, 2009). Recentemente, a subolesina foi apontada como um novo candidato a antígeno protetor contra carrapatos (Almazán et al, 2003;de la Fuente et al, 2011 (Pinter et al, 2002).…”