B.F. Stone

Tick/host interactions forIxodes holocyclus: Role, effects, biosynthesis and nature of its toxic and allergenic oral secretions

The Australian paralysis tickIxodes holocyclus occurs along the eastern coast of Australia. Its interaction with a wide variety of hosts causes a serious toxicosis (tick paralysis) in domestic pets and livestock (occasionally in wildlife and humans) as well as hypersensitivity reactions in humans. Tick paralysis in animals is usually fatal in the absence of speedy antitoxin treatment and human hypersensitivity may result in life-threatening anaphylaxis. The protection of such hosts against toxic or allergic effects by vaccination or desensitisation respectively has been the objective of most of our recent research.The role, biosynthesis and nature of the paralysing toxin (holocyclotoxin) and of the allergens is gradually being elucidated. In this review, some emphasis has been placed on recent research on the interactions of humans with this tick and on the partial characterisation of the allergens.

Artificial feeding of the Australian paralysis tick, Ixodes holocyclus and collection of paralysing toxin

Abstract Unfed or partially-fed female Australian paralysis ticks Ixodes holocyclus have been successfully attached to a silicone rubber membrane and fed on the tissue culture medium TC199 plus additives. Weight gains were well below those expected for ticks feeding on a host but toxin was secreted into the medium and was recovered by ultrafiltration and gel chromatography. The artificially-feeding ticks repeatedly sucked and salivated with a behavioural pattern similar to that of naturally-feeding ticks. The methods of inducing feeding, the monitoring of feeding patterns and the separation of toxin are described. In some experiments the yield of soluble toxin by this method compared favourably with that obtained by extraction of salivary glands but overall the yield was lower.

Vector competence of the Australian paralysis tick, Ixodes holocyclus, for the lyme disease spirochete Borrelia burgdorferi

Clinical and serologic evidence of Lyme disease in Australia, including the typical rash, erythema migrans, has been reported. The vector tick transmitting Borrelia burgdorferi in Australia, however, has not been determined. The Australian paralysis tick, Ixodes holocyclus, is a logical candidate vector of the Lyme disease spirochete in Australia; therefore, we tested the ability of I. holocyclus to acquire and maintain a North American isolate of B. burgdorferi. Larval I. holocyclus ingested spirochetes, but none of 84 derived nymphs were infected. These experiments should be repeated with Australian strains of spirochetes.

Developmental changes in morphology and toxin content of the salivary gland of the australian paralysis tick Ixodes holocyclus

Abstract Binnington K.C. and Stone B.F. 1981. Developmental changes in morphology and toxin content of the salivary gland of the Australian paralysis tick Ixodes holocyclus.International Journal for Parasitology11: 343–351. Histological study of the salivary gland of female I. holocyclus has shown that 2 of the 4 cell types present are richest in granules in the unfed stage but have discharged these granules after an attachment period of 24 h. The presence of a toxin in homogenates of salivary glands from unfed females and its absence after 24 h of attachment may be associated with the loss of granules from these 2 cell types shortly after attachment. Another cell type shows a gradual increase in granule content throughout feeding and a fourth, a peak in granule content after an attachment period of 120 h. The latter cell type may produce the paralysing toxin since ticks do not paralyse the host until they have fed for about this time and homogenised glands are most toxic at 120–144 h.

Aggregation pheromones in 2 Australian hard ticks, Ixodes holocyclus and Aponomma concolor

The presence of an aggregation pheromone has been demonstrated for the first time in indigenous Australian ticks. Filter paper discs exposed to either Australian paralysis ticks Ixodes holocyclus or echidna ticks Aponomma concolor showed inter-sex or intra-sex attraction for ticks of their own species. Nymphal exuviae of Ap. concolor were highly attractive to adult ticks. Discs were significantly attractive to I. holocyclus at distances up to 80 cm.

Norepinephrine as principal catecholamine in a specific neurone of an invertebrate (Boophilus microplus: Acarina)

Norepinephrine has been identified as the principal catecholamine in individual neurons of the synganglion of an arthropod, the cattle tickBoophilus microplus. This suggests that norepinephrine may have a hitherto unsuspected major physiological role in at least one group of invertebrates.