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Published on: October 11, 2022
Propagation dynamics of Anaplasma marginale in a Brazilian tick cell line (RBME-6) derived from Rhipicephalus
Gustavo Seron Sanches1, Ana Carolina Castro-Santiago1,2, Ricardo Bassini-Silva1,3
1Universidade Estadual Paulista - UNESP, Faculdade de Ciências Agrárias e Veterinárias - FCAV, Departamento de Patologia, Reprodução e Saúde Única, Vector-Borne Bioagents Laboratory - VBBL, Jaboticabal, SP, Brasil.
Abstract:
Anaplasma marginale is an obligate intraerythrocytic alpha-proteobacterium that causes bovine anaplasmosis, which is responsible for economic losses in the livestock industry worldwide. Although the mechanism of A. marginale infection in tick cell lines has been extensively studied, replication dynamics have not been investigated so far. This study presents the replication kinetics of A. marginale in the RBME-6 tick cell line derived from Rhipicephalus microplus over time. Cell cultures were infected with corpuscles of A. marginale isolated from bovine blood. The replication curve was generated by the number of copies of the msp1β gene obtained by reverse-transcription quantitative PCR (RT-qPCR) using complementary DNA (cDNA) synthesized from RNA. An initial lag phase and an exponential replication phase were recorded. A subsequent death phase was observed, with rapidly decreasing numbers of A. marginale msp1β copies. The surviving population of A. marginale entered a long-term stationary phase from 13 dpi until 29 dpi. Light microscopy was used to monitor the infection in the cells. The propagation kinetics of A. marginale in RBME-6 cells were shown to be essential for guiding future studies aimed at unraveling the crosstalk between this bacterium and its biological tick vector.
Insights
This study reveals the replication dynamics of Anaplasma marginale in tick cells, identifying distinct lag, exponential, death, and stationary phases. Understanding these bovine anaplasmosis dynamics is crucial for vector-host research.
Area of Science:
- Veterinary Microbiology
- Tick-borne Diseases
- Bacterial Pathogenesis
Background:
- Anaplasma marginale causes bovine anaplasmosis, leading to significant global livestock economic losses.
- While A. marginale infection in tick cell lines is studied, its replication dynamics remain largely uninvestigated.
Purpose of the Study:
- To investigate the replication kinetics of Anaplasma marginale within the RBME-6 tick cell line.
- To establish a timeline of bacterial proliferation and survival in a tick cell model.
Main Methods:
- Infection of RBME-6 tick cells with Anaplasma marginale from bovine blood.
- Quantification of A. marginale msp1β gene copies using RT-qPCR on synthesized cDNA.
- Monitoring of infection progression via light microscopy.
Main Results:
- Identified distinct replication phases: initial lag, exponential growth, followed by a death phase.
- Observed a long-term stationary phase for surviving A. marginale from 13 to 29 days post-infection.
- Characterized the temporal propagation of A. marginale within the tick cell line.
Conclusions:
- The study elucidates the replication kinetics of Anaplasma marginale in the RBME-6 tick cell line.
- These findings provide a crucial framework for future research into the bacterium-tick interactions.
- Understanding these dynamics aids in developing strategies against bovine anaplasmosis.
