Protection against heartwater by DNA immunisation with four Ehrlichia ruminantium open reading frames

Pretorius, Ashley; Collins, Nicola E.; Steyn, H.C.; Strijp, F. Van; Kleef, Mirinda Van; Allsopp, B. A.

doi:10.1016/j.vaccine.2006.11.061

Cited by 27 publications

(33 citation statements)

References 35 publications

(44 reference statements)

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“…Disappointingly, when the vaccine was tested in the field against a natural heartwaterinfected tick challenge, levels of protection only reached 20%. In further trials, it was found that each of the four genes provided levels of protection similar to that obtained with the four-gene cocktail, but the protection against field challenge remained poor (81). Heterologous prime-boosting was tried in an attempt to improve the field protection rate.…”

Section: Recombinant Vaccine Developmentmentioning

confidence: 99%

Heartwater – Ehrlichia ruminantium infection

Allsopp¹

2015

Rev. Sci. Tech. OIE

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SummaryHeartwater is a notifiable disease that is listed by the World Organisation for Animal Health. It is caused by Ehrlichia ruminantium, an obligately intracellular Gramnegative bacterium in the order Rickettsiales and the family Anaplasmataceae. The disease is borne by ticks in the genus Amblyomma and causes heartwater, or cowdriosis, in wild and domestic ruminants, primarily in Africa, but also in parts of the Caribbean. The disease was recognised in South Africa in the 19th Century and determined to be tick borne in 1900, while the organism was identified in 1925 and first cultured in vitro in 1985. This latter achievement boosted research into the disease at a time when biology was moving into the molecular genetic age. Over the last 20 years, there have been significant improvements in our understanding of E. ruminantium, yielding major advances in diagnosis, epidemiology, genetic characterisation, phylogeny, immunology, and vaccine development. The organism is genetically highly variable; this has important implications for future control measures, and is making it difficult to develop an effective vaccine for protection against tick challenge. Research is continuing into three different types of vaccine, inactivated, attenuated, and recombinant, and the current state of development of each is discussed. KeywordsAmblyomma hebraeum -Amblyomma variegatum -Attenuated vaccine -ControlCowdriosis -Diagnosis -Economic importance -Ehrlichia ruminantium -Heartwater -Inactivated vaccine -Occurrence -Recombinant vaccine -Tick-borne disease.Rev. Sci. Tech. Off. Int. Epiz., 2015, 34 (2), 557-568 AetiologyHeartwater is listed by the World Organisation of Animal Health as a notifiable disease (1). It was known in South Africa for nearly 90 years before the causative organism was identified in 1925 as a rickettsia, originally named Rickettsia ruminantium (2, 3). The name was later changed to Cowdria ruminantium (4), from which arose the term 'cowdriosis'. Molecular phylogenetic studies of the Rickettsiales in the 1990s uncovered the real evolutionary relationships within the order and the organism was reclassified as Ehrlichia ruminantium in the family Anaplasmataceae (5). Ehrlichia ruminantium, which is transmitted by Amblyomma ticks, is obligately intracellular, infects cattle, sheep, goats and some wild ruminants, and is frequently fatal. A comprehensive account of the history and biology of E. ruminantium can be found elsewhere (6). Economic and social importanceHeartwater is a serious economic problem wherever it occurs, in an enormous area covering most of sub-Saharan Africa, its offshore islands, and several islands in the Caribbean. The disease generally prevents livestock farmers from upgrading their herds to modern high-yielding breeds, as these are more susceptible to infection than traditional stock breeds, which often have a measure of resistance (7). Since heartwater is so common in the endemic areas of Africa, farmers are usually unwilling or unable to pay for definitive diagnoses, so it is difficul...

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Section: Recombinant Vaccine Developmentmentioning

confidence: 99%

Heartwater – Ehrlichia ruminantium infection

Allsopp¹

2015

Rev. Sci. Tech. OIE

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“…These ORFs are known to provide protective immunity against a heartwater needle challenge in sheep (Pretorius et al, 2007(Pretorius et al, , 2008. To achieve this, we developed a microencapsulation method that is capable of fast initial release of pDNA followed by a Fig.…”

Section: Discussionmentioning

confidence: 99%

“…This underlines the need for an improved vaccine, preferably one which does not require cold storage as with the blood vaccine used in the infection and treatment method. A DNA vaccine consisting of a cocktail of 4 1H12 open reading frames (ORFs) has been found to protect sheep against a homologous needle challenge using either 3 DNA inoculations (Pretorius et al, 2007) or alternatively, a DNA prime-recombinant (r)1H12 protein boost vaccination strat-egy (Pretorius et al, 2008). This approach was, however, not fully successful in the field.…”

Section: Introductionmentioning

confidence: 99%

Preparation and in vitro characterisation of Ehrlichia ruminantium plasmid DNA and proteins encapsulated into and DNA adsorbed onto biodegradable microparticles

Tshikhudo

Pretorius

Putterill

et al. 2010

Ticks and Tick-borne Diseases

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“…Ten to twelve month old Merino sheep were purchased from heartwater free areas of South Africa and tested negative for E. ruminantium using the pCS20 real-time PCR assay (Steyn et al, 2008 Pretorius et al, 2007. Gene gun inoculations were done using the OPgun™ (Brayton et al, 1997).…”

Section: Immunisation and Challenge Of Sheepmentioning

confidence: 99%

“…To determine the severity of the infection, clinical signs were scored using a reaction index (RI) as described previously (Pretorius et al, 2007).…”

Section: Immunisation and Challenge Of Sheepmentioning

confidence: 99%

In vitro and in vivo evaluation of five low molecular weight proteins of Ehrlichia ruminantium as potential vaccine components

Sebatjane

Pretorius

Liebenberg

et al. 2010

Veterinary Immunology and Immunopathology

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Protection against heartwater by DNA immunisation with four Ehrlichia ruminantium open reading frames

Abstract: We have reported previously that a recombinant DNA vaccine consisting of four

Cited by 27 publications

References 35 publications

Heartwater – Ehrlichia ruminantium infection

Heartwater – Ehrlichia ruminantium infection

Preparation and in vitro characterisation of Ehrlichia ruminantium plasmid DNA and proteins encapsulated into and DNA adsorbed onto biodegradable microparticles

In vitro and in vivo evaluation of five low molecular weight proteins of Ehrlichia ruminantium as potential vaccine components

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