Boophilus microplus : Cellular Responses to Larval Attachment and Their Relationship to Host Resistance

Abstract

The histology of early feeding lesions of the cattle tick B. microp/us has been studied using 32p labelled larvae to standardize the duration of attachment. Critical studies were made on 3-h lesions in six separate experiments on different groups of British breed animals. Each group consisted of three animals-one previously unexposed to ticks, one of high resistance and one of low resistance.The degree of mast cell disruption, eosinophil concentration and degranulation, and the extent of epidermal vesiculation were all significantly greater at the site of attachment on highly resistant hosts. In previously unexposed animals there was no mobilization of eosinophils nor mast cell breakdown and no epidermal vesiculation.Possible immune mechanisms producing mast cell disruption and the infiltration and concentration of eosinophils are suggested, and the effect of eosinophil degranulation on larval attachment and feeding is discussed.

Rhipicephalus (Boophilus) microplus: Clotting time in tick-infested skin varies according to local inflammation and gene expression patterns in tick salivary glands

“…3). Our findings are in accordance with those of Schleger et al (1976) that show that the numbers of eosinophils present in lesions correlate with the degree of resistance of bovines to R. microplus . However, breeds of B. indicus , as well as basophils, were not studied in that work.…”

The role of saliva in tick feeding

“…Soft ticks also induce a strong eosinophil response in guinea pigs [160]. Other species, such as cattle [161], bovines [162], rabbits [142], dogs [163], mice [164], and even capybaras [165] present similar eosinophil infiltration in the attachment site upon repeated hard-tick infestation. An anti-eosinophil serum conferred only a partial lack of resistence in tick-sensitized guinea pigs [166].…”

Modulation of host immunity by tick saliva

“…Repeated exposure to both soft and hard tick species raised eosinophil levels at the feeding site in many host species including cattle [115, 116], dogs [117], guinea pigs [118, 119], rabbits [86], mice [88], woolless lambs [120], rats [36], capybaras [121], and even anteaters and armadillos [122]. The relationship between eosinophil number and tick resistance is not clear.…”