The development of a qPCR assay to detect tick (Ixodida) DNA and its implementation for the study of tick-borne pathogen transmission

Polymerase chain reaction (PCR) analysis is regularly used to detect pathogens within arthropod vectors, but has also been applied to investigate vector DNA. This study details a novel highly sensitive quantitative PCR (qPCR) which detects and quantifies DNA from Ixodes ricinus, the European vector of Anaplasma phagocytophilum. By pairing this with a qPCR to detect A. phagocytophilum, valid comparisons of pathogen load can be made between different sized tick-tissue samples. These qPCRs were validated in I. ricinus that were fed A. phagocytophilum-infected blood using an artificial membrane feeder. Pathogens were detected in the tick haemolymph within 36 h, indicating that successful infection had taken place. This study illustrates the application of vector-targeted qPCRs to confirm and validate pathogen load in samples as part of investigations of vector–pathogen interactions.