Vaccination against ectoparasites

Abstract

Ectoparasites of livestock are of great economic and social importance but their effective control remains difficult. The feasibility of vaccination as a novel control measure was established over a decade ago with the commercial release of a recombinant vaccine against the cattle tick Boophilus microplus. Since then, research has continued on ticks and other ectoparasites. While some ectoparasite species will undoubtedly be refractory to immunological control, for others there has been a steady accumulation of knowledge of partially protective antigens, now accelerating through the application of genomic technologies. Nevertheless, progress towards usable, commercially available vaccines has been limited by a number of factors. The number of highly effective antigens is still very small. Although some classes of antigen have been investigated in more detail than others, we have no systematic knowledge of what distinguishes an effective antigen. Much hope has been placed on the potential of multi-antigen mixtures to deliver the efficacy required of a successful vaccine but with little experimental evidence. The application of current knowledge across parasite and host species needs to be explored but little has been done. In most cases, the path to commercial delivery is uncertain. Although many constraints and challenges remain, the need for vaccines and our capacity to develop them can only increase.

Effect of vaccination with a recombinant metalloprotease from Haemaphysalis longicornis

“…Intensive efforts to develop an anti-tick vaccine against the cattle tick Rhipicephalus (B.) microplus have resulted in the commercialization of the first antiarthropod vaccine in Australia (Willadsen et al 1995;Willadsen 2004Willadsen , 2006. Despite the discovery of an anti-R. microplus vaccine in 1986 and of its commercial introduction in 1994, an alternative and more effective anti-tick vaccine for R. microplus and other tick species has not yet been made available.…”

Parasite Vaccines: Recent Progress in, and Problems Associated with their Development

“…The maintenance of natural immunity is often dependent on repeated infection, may be stage-specific and will be dependent on different antibody classes and T-cell responses. Despite it being almost 30 years since the technology to produce recombinant proteins became available, recombinant proteins with the required efficacy are rare, spectacular exceptions being vaccine developments in ticks and cestodes, these developments constituting land mark achievements [23,24].…”

“…Gut membrane proteins have been effectively employed as vaccine antigens against cattle ticks [23] and H. contortus [38,44] and are offering promise as vaccine components against hookworms. Haemoglobin digestion is thought to be facilitated by a multi-enzyme cascade in blood-feeding parasites [45,69] and some of the enzymes involved in this process have been identified in hookworms and Haemonchus with many commonalities evident between the two and also when compared to the fluke and malaria parasites.…”

“…The reader is directed to accounts of this process in the livestock sector with vaccines against Boophilus microplus [23] and vaccines against cestodes [24]. Hotez et al [125] listed a number of obstacles which would need to be addressed before a hookworm vaccine could become a reality.…”

Localization and function ofRhipicephalus (Boophilus) microplusvitellin-degrading cysteine endopeptidase

“…The tick Rhipicephalus (Boophilus) microplus infests cattle in many tropical and subtropical regions and causes economic losses by direct parasitism and by transmission of several pathogenic microorganisms (Willadsen, 2006). Tick control methods are based on the application of chemical acaricides, which induce selection of drug-resistant populations and present potential food and environmental contamination risks (Willadsen, 2004).…”