Differential immune responses to Borrelia burgdorferi in European wild rodent species influence spirochete transmission to Ixodes ricinus L. (Acari: Ixodidae)

Abstract

Immune responses to Borrelia burgdorferi and their influence on spirochete transmission to Ixodes ricinus were analyzed in the natural European reservoir hosts; i.e., the mouse species Apodemus flavicoUis (yellownecked mouse) and Apodemus sylvaticus (wood mouse) and the vole species Ckthrionomys glareolus (bank vole), and, in addition, in the laboratory mouse strain NMRI. Naive and preimmunized rodents were infected either by artificially infected I. ricinus larvae or by intradermal injection of spirochetes. Independent of the species, all animals developed antibodies to various spirochetal antigens. However, antibodies to the outer surface proteins A (OspA) and B (OspB) were not found in recipients infected via ticks. Rodents of the genus Apodemus and of the NMRI strain showed higher levels of B. burgdorfiei-specific antibodies than those of the species C. glareolus. The rate of spirochete transmission to noninfected ticks correlated with both the quality and quantity of spirochete-specific antibodies generated in the various species: high levels of spirochete-specific immunoglobulins correlated with low transmission rates. Furthermore, lower transmission rates were observed with rodents expressing antibodies to OspA and OspB (i.e., intradermally infected or immunized) than with those lacking these specificities (i.e., infected via ticks). The study provides evidence that transmission of B.

Infection intensity and infectivity of the tick‐borne pathogen Borrelia afzelii

“…Hence, it seems likely that the difference in bacterial load is mainly a result of that bank voles are less resistant rather than that they are infected by more virulent strains than yellow-necked mice. This interpretation is supported by the finding that yellow-necked mice mount stronger antibody responses to Borrelia than bank voles (Kurtenbach et al, 1994).…”

Ecological factors influencing small mammal infection by Anaplasma phagocytophilum and Borrelia burgdorferi s.l. in agricultural and forest landscapes

“…Yet, our results can be explained, for A. phagocytophilum, by a longer infection period in bank voles than in wood mice, and, for B. burgdorferi s.l., by a higher bacterial load in bank voles than in wood mice associated to a stronger immune response of wood mice to the spirochetes (Kurtenbach et al, 1994;Bown et al, 2003). Results from a study of the while-footed mouse (Peromyscus leucopus) and prairie vole (Microtus ochrogaster) which showed that species with higher tick burden were more capable of overcoming bacterial infection, presumably because of an evolutionary trade-off (Rynkiewicz et al, 2013).…”

Few vertebrate species dominate the Borrelia burgdorferi s.l. life cycle

“…Host species differ in their ability to infect I. ricinus larvae with different genospecies of B. burgdorferi. For example, B. afzelii is mainly transmitted by small mammals, while B. garinii is mainly transmitted by birds (Hanincova et al 2003a(Hanincova et al , 2003b, and even within genospecies, different host species differ in their ability to transmit B. burgdorferi (Kurtenbach et al 1994). Both the number of ticks a host can feed and the transmission of B. burgdorferi could be linked to general host characteristics, such as host body mass, which is related to both immunological and behavioral responses (Carbone et al 2005, Lee 2006, Previtali et al 2012, and could therefore influence both tick burden and reservoir competence for B. burgdorferi (Marsot et al 2012, Huang et al 2013, , Barbour et al 2015.…”