Characterization of the Bacterial Communities of Life Stages of Free Living Lone Star Ticks (Amblyomma americanum)

Abstract

The lone star tick (Amblyomma americanum) is an abundant and aggressive biter of humans, domestic animals, and wildlife in the southeastern-central USA and an important vector of several known and suspected zoonotic bacterial pathogens. However, the biological drivers of bacterial community variation in this tick are still poorly defined. Knowing the community context in which tick-borne bacterial pathogens exist and evolve is required to fully understand the ecology and immunobiology of the ticks and to design effective public health and veterinary interventions. We performed a metagenomic survey of the bacterial communities of questing A. americanum and tested 131 individuals (66 nymphs, 24 males, and 41 females) from five sites in three states. Pyrosequencing was performed with barcoded eubacterial primers targeting variable 16S rRNA gene regions 5–3. The bacterial communities were dominated by Rickettsia (likely R. amblyommii) and an obligate Coxiella symbiont, together accounting for 6.7–100% of sequences per tick. DNAs from Midichloria, Borrelia, Wolbachia, Ehrlichia, Pseudomonas, or unidentified Bacillales, Enterobacteriaceae, or Rhizobiales groups were also detected frequently. Wolbachia and Midichloria significantly co-occurred in Georgia (p<0.00001), but not in other states. The significance of the Midichloria-Wolbachia co-occurrence is unknown. Among ticks collected in Georgia, nymphs differed from adults in both the composition (p = 0.002) and structure (p = 0.002) of their bacterial communities. Adults differed only in their community structure (p = 0.002) with males containing more Rickettsia and females containing more Coxiella. Comparisons among adult ticks collected in New York and North Carolina supported the findings from the Georgia collection despite differences in geography, collection date, and sample handling, implying that the differences detected are consistent attributes. The data also suggest that some members of the bacterial community change during the tick life cycle and that some sex-specific attributes may be detectable in nymphs.

Effects of temperature on bacterial microbiome composition in Ixodes scapularis ticks

“…In addition, they carry numerous endosymbionts and commensals, which may provide nutrient supplements to the tick and also affect vector competence (reviewed in (Narasimhan & Fikrig, ; Bonnet et al., ; Clay & Fuqua, )). Studies have reported that the tick microbial community is variable depending on several factors such as source of host blood meal (Rynkiewicz, Hemmerich, Rusch, Fuqua, & Clay, ), feeding status (Menchaca et al., ; Swei & Kwan, ; Zhang et al., ), tick species, life stage, gender, and geographical origin (Carpi et al., ; Van Treuren et al., ; Williams‐Newkirk, Rowe, Mixson‐Hayden, & Dasch, ). However, very few studies have focused on the tick microbiome differences based on environmental conditions such as seasons of collection (Lalzar, Harrus, Mumcuoglu, & Gottlieb, ) or the immediate environment (Menchaca et al., ).…”

Tick microbiome and pathogen acquisition altered by host blood meal

“…But it remains unclear what factors drive natural variation of the tick microbiome and whether such variation would affect pathogen transmission in the wild and therefore regulate disease risk. Prior field studies have identified microbiome differences by tick species (Hawlena et al, 2013), sex (Williams-Newkirk et al, 2014;Zhang et al, 2014) and region (Carpi et al, 2011;van Treuren et al, 2015) but have not found correlations with host blood or the immediate environment (Hawlena et al, 2013;Rynkiewicz et al, 2015).…”

De novo sequencing, assembly and analysis of salivary gland transcriptome of Haemaphysalis flava and identification of sialoprotein genes

“…To date, in order to identify protein families and dis-70 cover novel target antigen, salivary gland (SG) transcriptomes from 71 several ticks species have been described (Chmelar et al, 2008;72 Aljamali et al, 2009a;Francischetti et al, 2011). 73 Among the various transcriptome studies, next generation Williams-Newkirk et al, 2012;Hue et al, 2013;Kaewkong et al, 81 2014; Budachetri et al, 2014;Carpi et al, 2011) and parasitic 82 communities (Bonnet et al, 2014) associated with ticks. Until 83 now, transcriptomic analyses of SG of only a few ticks (Karim 84 et al, 2011;Schwarz et al, 2013Schwarz et al, , 2014 have been performed using 85 RNA-Seq technique, but H. flava SG transcriptome has not been 86 explored.…”