Analysis of the Microbial Community Structure of Ixodes persulcatus at Each Developmental Stage.

Ticks are the second most significant vector of pathogens worldwide. Ixodes persulcatus is one of the dominant tick species in Inner Mongolia that can carry and transmit various pathogenic microorganisms. However, only one specific pathogen has been detected in a particular developmental stage of I. persulcatus, moreover metagenomic analysis has been conducted only in the adult tick stage. In this study, we used I. persulcatus at different developmental stages (first-generation female adult ticks, eggs, larval ticks, engorged larval ticks, nymphal ticks, engorged nymphal ticks, and second-generation adult ticks) from Inner Mongolia as materials for nucleic acid extraction. Subsequently, we constructed Illumina PE250 and Illumina PE150 libraries and sequenced them on the Illumina NovaSeq 6000 platform. Finally, we used molecular biology software and sequence analysis platform to analyze microbial community structures. Illumina PE250 sequencing revealed that the seven developmental stages of I. persulcatus were annotated to 21 phyla, 43 classes, 104 orders, 188 families, 391 genera, and 556 species of bacteria. Among them, 4 phyla and 14 genera were present at all developmental stages, with Proteobacteria being the dominant phylum and Rickettsia spp. being the dominant genus. In addition, Rickettsia had the highest relative abundance in the seven developmental stages. All developmental stages were annotated to a certain abundance of Brucella spp. Illumina PE150 sequencing revealed that the three samples (X-I-YDCP: first-generation adult ticks; X-I-MIX: mixed samples of eggs, larval ticks, and nymphal ticks; X-I-EDCP: second-generation adult ticks) of I. persulcatus were annotated to six orders, 28 families, 72 genera, and 158 species of viruses, of which 46 genera and 80 species were found in all three sample species. To the best of our knowledge, this is the first study that comprehensively analyzed the microbial community composition of I. persulcatus at different developmental stages. Based on the study outcomes, certain abundance of Rickettsia japonica, bovine viral diarrhea virus, and African swine fever virus were annotated to I. persulcatus.