Lizard Feeding Enhancesixodes Pacificusvector Competency

AbstractA vector’s susceptibility and ability to transmit a pathogen— termed vector competency—determines disease outcomes, yet the ecological factors influencing tick vector competency remain largely unknown.Ixodes pacificus, the vector ofBorrelia burgdorferi(Bb) in the western U.S., feeds on rodents, birds, and lizards. While rodents and birds are reservoirs forBband infect juvenile ticks, lizards areBb-refractory. DespiteI. pacificusfeeding on a range of hosts, it is undetermined how larval host bloodmeal identity affects future nymphal vector competency. We experimentally evaluate the influence of larval host bloodmeal onBbacquisition by nymphalI. pacificus. LarvalI. pacificuswere fed on either lizards or mice and after molting, nymphs were fed onBb-infected mice. We found that lizard-fed larvae were significantly more likely to become infected withBbduring their next bloodmeal than mouse-fed larvae. We also conducted the first RNA-seq analysis on whole-bodiedI. pacificusand found significant upregulation of antioxidants and antimicrobial peptides in the lizard-fed group. Our results indicate that the lizard bloodmeal significantly alters vector competency and gene regulation in ticks, highlighting the importance of host bloodmeal identity in disease transmission and upends prior notions about the role of lizards in Lyme disease transmission.