Microbial Communities in North American Ixodid Ticks of Veterinary and Medical Importance

Abstract

Interest in microbial communities, or microbiota, of blood-feeding arthropods such as ticks (order Parasitiformes, suborder Ixodida) is increasing. Studies on tick microorganisms historically emphasized pathogens of high medical or veterinary importance. Current techniques allow for simultaneous detection of pathogens of interest, non-pathogenic symbionts, like Coxiella-LE and Francisella-LE, and microorganisms of unknown pathogenic potential. While each generation of ticks begins with a maternally acquired repertoire of microorganisms, microhabitats off and on vertebrate hosts can alter the microbiome during the life cycle. Further, blood-feeding may allow for horizontal exchange of various pathogenic microbiota that may or may not also be capable of vertical transmission. Thus, the tick microbiome may be in constant flux. The geographical spread of tick vector populations has resulted in a broader appreciation of tick-borne diseases and tick-associated microorganisms. Over the last decade, next-generation sequencing technology targeting the 16S rRNA gene led to documented snapshots of bacterial communities among life stages of laboratory and field-collected ticks, ticks in various feeding states, and tick tissues. Characterizing tick bacterial communities at population and individual tissue levels may lead to identification of markers for pathogen maintenance, and thus, indicators of disease “potential” rather than disease state. Defining the role of microbiota within the tick may lead to novel control measures targeting tick-bacterial interactions. Here, we review our current understanding of microbial communities for some vectors in the family Ixodidae (hard ticks) in North America, and interpret published findings for audiences in veterinary and medical fields with an appreciation of tick-borne disease.

Endosymbionts carried by ticks feeding on dogs in Spain

“…Although the number of pools were low, our results corroborate that R. monacensis, a Rickettsia of the spotted fever group, could be associated with I. ricinus (Duron et al, 2015;Papa et al, 2017;Perlman et al, 2006). As previously reported, there is the possibility that this endosymbiont could also be acquired when the tick feeds on the mammalian host (Varela-Stokes et al, 2017). Therefore, the question about if it is a symbiotic organism intrinsically associated with the tick, and necessary of the metabolic functions of the arthropod, still remains.…”

“…Rickettsia sibirica mongolitimonae has been mainly reported in Hyalomma spp. ticks (Taylor et al, 2012;Varela-Stokes et al, 2017;Wang and Chandler, 2016). However, other data support the hypothesis that this Rickettsia circulates in Rhipicephalus spp.…”

Comparative analysis of microbial community in the whole body and midgut from fully engorged and unfed female adult Melophagus ovinus

“…The bacterial community of insect vectors is easily affected by blood‐feeding behaviour that may cause the bacterial diversity of vectors to increase or decrease (Wang et al ., ; Nayduch et al ., ; Kelly et al ., ; Varela‐Stokes et al ., ; Telleria et al ., ). In the present study, whole‐body samples from newly hatched and unfed adult female M. ovinus showed the highest bacterial diversity.…”

“…Blood feeding stimulated proliferation and diversification of bacterial populations colonizing the gut of female midges (Nayduch et al ., ). Host blood meal and the process of imbibing blood also induced physiological changes in ticks that appeared to affect the tick microbiome (Varela‐Stokes et al ., ). Although the microbial community of the midgut from fully engorged male and female M. ovinus have been studied in the past, the present study aimed to confirm whether blood‐feeding behaviour could change or affect the microbial community of midgut of M. ovinus .…”

RNA Viruses of Amblyomma variegatum and Rhipicephalus microplus and Cattle Susceptibility in the French Antilles

“…[17,23]. Bio-ecological parameters may influence virome diversity, such as the tick life cycle or host range [24,[61][62][63][64]. For example, although both tick species are mainly found feeding on ruminants in tropical areas, Amblyomma variegatum and Rhipicephalus microplus present different life cycle strategies.…”