Host-Specific Expression of Tick Salivary Genes
Updated: Jan 30, 2019
Findings provide new insight into vector-host interactions and offer a functional paradigm to better understand the phenomenon of acquired tick-resistance
New findings out of Yale University provide insight into the differences in hosts and their specific immune responses to repeated tick bites, with implications for understanding the process of becoming tick-resistant. Laboratory models in hosts like guinea pigs develop a strong immune response to tick salivary proteins and reject ticks upon repeated tick infestations. Anecdotal and scientific evidence suggests that humans that get bit frequently might also develop resistance to ticks. However, Mus musculus or the typical house mouse as the laboratory model of the natural host, does not develop this type of resistance to repeated tick bites. Understanding these interactions and the phenomena of tick resistance can help advance the effort to develop vaccines and treatment strategies for major tick-borne infections and curtail the spread of disease.
Ixodes scapularis or black-legged ticks carry several pathogens including Borrelia burgdorferi, the agent of Lyme disease. Nymphal and larval stages, and the pathogens transmitted by these ticks, are maintained in a zoonotic cycle by rodent reservoir hosts, predominantly Peromyscus leucopus or the white-footed mouse. Humans are not reservoir hosts; however, accidental encounters of infected ticks with humans lead to the transmission of Borrelia and the contraction of Lyme disease. The incidence of this disease is only growing, with over 300,000 new cases each year in the U.S. according to the Centers for Disease Control and Prevention. Even this number is felt to be drastically under-reported, making Lyme disease and other tick-borne infections a major public health issue.
Addressing the dichotomy in vector-host interaction, Dr. Erol Fikrig of Yale University presents data that suggest that the salivary transcriptome and proteome composition is different in mouse and guinea pig-fed black-legged ticks, and that these differences might contribute to differences in host immune responses. These findings reveal a new insight into vector-host interactions and offer a functional paradigm to better understand the phenomenon of acquired tick-resistance.
The paper entitled, Host-specific expression of Ixodes scapularis salivary genes, is published in the Journal of Ticks and Tick-borne Diseases.