| dc.description.abstract | Rhipicephalus appendiculatus gut protein Ra86 (variants Ra85A and Ra92A)
and the salivary gland cement protein (Trp64) were expressed in the baculovirus-insect cell
system. The recombinant gut proteins expressed as soluble proteins and the recombinant cement
protein, as insoluble inclusion bodies, were used to immunize rabbits, which were then challenged
with larval, nymphal, and adult stages of R. appendiculatus ticks. High tick mortality
(23.3%) occurred on adult ticks that fed on rabbits vaccinated with the gut proteins, compared
with 1.9% mortality in ticks that fed on unvaccinated naïve control rabbits. The mean weight
of engorged female ticks was significantly reduced by 31.5% in rabbits vaccinated with the
Ra86 recombinant protein compared with controls, as was egg production. Marked effects on
these parameters were also observed in adult ticks as a result from vaccination using Trp64,
but these were not statistically significant. For both antigens, there was no demonstrable effect
on larval or nymphal ticks. This study demonstrates for the first time the protective efficacy of
a homolog of Boophilus microplus Bm86 in reducing tick infestation by the adult stage of the
three-host tick R. appendiculatus. The results demonstrate the potential of Ra86 for vaccine
development against this tick and for the control of East Coast fever. | en |
