Replication kinetics of Rickettsia raoultii in tick cell lines
Document Type
Article
Publication Date
7-1-2021
Abstract
Rickettsia raoultii is one of the causative agents of tick-borne lymphadenopathy in humans. This bacterium was previously isolated and propagated in tick cell lines; however, the growth characteristics have not been investigated. Here, we present the replication kinetics of R. raoultii in cell lines derived from different tick genera (BME/CTVM23, RSE/PILS35, and IDE8). Tick cell cultures were infected in duplicate with cryopreserved R. raoultii prepared from homologous cell lines. By 12-14 days post infection, 100% of the cells were infected, as visualized in Giemsa-stained cytocentrifuge smears. R. raoultii growth curves, determined by rickettsiae-specific gltA qPCR, exhibited lag, exponential, stationary and death phases. Exponential phases of 4-12 days and generation times of 0.9-2.6 days were observed. R. raoultii in BME/CTVM23 and RSE/PILS35 cultures showed, respectively, 39.5- and 37.1-fold increases compared to the inoculum. In contrast, multiplication of R. raoultii in the IDE8 cultures was 110.1-fold greater than the inoculum with a 7-day stationary phase. These findings suggest variation in the growth kinetics of R. raoultii in the different tick cell lines tested, amongst which IDE8 cells could tolerate the highest levels of R. raoultii replication. Further studies of R. raoultii are needed for a better understanding of its persistence within tick populations.
Keywords
Vector-borne disease, Rickettsia raoultii, Infectious disease, Tick cell line
Divisions
tidrec
Funders
Newton-Ungku Omar Fund partnership (332192305),UK Department of Business, Energy and Industrial Strategy (BEIS),UK Department of Business, Energy and Industrial Strategy,Malaysian Industry-Government Group for High Technology (MIGHT),Ministry of Education, Malaysia (MO002-2019),Universiti Malaya, Malaysia (RU008-2018),Universiti Malaya, Malaysia (UM.00000188/HGA.GV),UK Research & Innovation (UKRI) Biotechnology and Biological Sciences Research Council (BBSRC) (BB/P024270/1),UK Research & Innovation (UKRI) Biotechnology and Biological Sciences Research Council (BBSRC) (BB/P024378/1)
Publication Title
Microorganisms
Volume
9
Issue
7
Publisher
MDPI
Publisher Location
ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND