The dynamics of the microbiome in Ixodidae are shaped by tick ontogeny and pathogens in Sarawak, Malaysian Borneo

Tick-borne diseases have recently been considered a potential emerging public health threat in Malaysia; however, fundamental studies into tick-borne pathogens and microbiome appear limited. In this study, ticks collected from two primary forests and an oil palm plantation in Sarawak, Malaysian Borneo, were used for the microbiome analysis using Next-generation sequencing (NGS). The species of main symbionts and potential pathogens detected in NGS were further characterized in conventional PCRs. We managed to collect six tick species of three genera from the sampling consisting of different developmental stages and statuses of Ixodes granulatus, Haemaphysalis hystricis, Haemaphysalis shimoga, Dermacentor compactus, Dermacentor steini, and Dermacentor atrosignatus were included in the study. Our findings revealed that microbial variations were significant between tick species, with genus Dermacentor showing the highest microbial diversity and H. shimoga having the significant difference in microbial composition than other tick species. Potential factors contributing to the variations included blood meal feeding and the presence of a single symbiont in high abundance. Comparative analyses of H. shimoga ticks revealed the ontogenetic variations and identification of main symbionts in different developmental stages. Finally, we observed significant differences in microbial composition between Borrelia-positive and negative I. granulatus ticks. This study provides first insights into the tick microbiome and pathogenic and potentially pathogenic bacteria circulating in different tick species, such as Rickettsia heilongjiangensis, Ehrlichia sp., Anaplasma sp., and Bartonella spp. in Sarawak. Furthermore, Coxiella and Francisella-like symbionts were identified from H. shimoga and D. steini, respectively. More studies are required to unravel the factors associated with the variations observed in this study.