AUTHOR=Ma Hejia , Ai Jingkai , Kang Ming , Li Jixu , Sun Yali 

TITLE=The life cycle of Dermacentor nuttalli from the Qinghai-Tibetan Plateau under laboratory conditions and detection of spotted fever group Rickettsia spp.

JOURNAL=Frontiers in Veterinary Science

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2023.1126266

DOI=10.3389/fvets.2023.1126266

ISSN=2297-1769

ABSTRACT=<p><italic>Dermacentor nuttalli</italic> has been a focus of study because tick-borne pathogens have been widely identified in this tick from northern and southwestern China. The aim of this study was to characterize the life cycle of <italic>D. nuttalli</italic> under laboratory conditions and to detect spotted fever group (SFG) <italic>Rickettsia</italic> in the midgut and salivary glands of both field-collected and first laboratory generation adults. <italic>D. nuttalli</italic> ticks were collected in the field on the Qinghai-Tibetan Plateau from March to April 2021 and their life cycle was studied under laboratory conditions. Tick identify was molecularly confirmed, and SFG <italic>Rickettsia</italic> were detected in the midgut and salivary glands of males and females by PCR targeting different rickettsial genes. The results showed that the life cycle of <italic>D. nuttalli</italic> under laboratory conditions was completed in an average of 86.1 days. High positivity of <italic>Rickettsia</italic> spp. was detected in the midgut and salivary glands of both males (92.0%) and females (93.0%) of field-collected <italic>D. nuttalli</italic> ticks. However, a relatively lower positivity (4.0–6.0%) was detected in first laboratory generation adults. Furthermore, sequencing analysis showed that the <italic>Rickettsia</italic> sequences obtained in this study shared 98.6 to 100% nucleotide identity with <italic>Rickettsia slovaca</italic> and <italic>Rickettsia raoultii</italic> isolated from <italic>Dermacentor</italic> spp. in China. Phylogenetic analysis of <italic>Rickettsia</italic> spp. based on the <italic>gltA, ompA, ompB</italic> and <italic>sca4</italic> genes revealed that the <italic>Rickettsia</italic> sequences obtained could be classified as belonging to <italic>R. slovaca</italic> and <italic>R. raoultii</italic> clades. This study described for the first time the life cycle of <italic>D. nuttalli</italic> from the Qinghai-Tibetan Plateau under laboratory conditions. Two species of SFG <italic>Rickettsia</italic> were detected in the midgut and salivary glands of males and females in both field-collected and first laboratory-generation adults of <italic>D. nuttalli</italic>. Our study provides new insights into pathogen detection in ticks in the Qinghai-Tibet Plateau, and the relationships among hosts, ticks, and pathogens.</p>