Tick Research at ILRIRichard Bishop

8 International Congress on Ticks and Tick-Borne Pathogens (TTP8) and 12 Biennial Conference, South Africa, 24-29 August 2014

ILRI Tick Unit WorkshopICTTD Cape Town 2014

• How Does ILRI Reintegrate into the Global Tick Research Arena?

• How can we better utilise the ILRI Tick unit -Collaborative projects?

•

ILRI Tick Unit- Tick Species

• Ixodid ticks (9 species)• Rhipicephalus appendiculatus: 9 stocks

Vector of ECF- differences in vector competence for Theileria parva

• R. zambeziensis, R.evertsi, R.pulchellus• Amblyomma variegatum• A.gemma• Hyalomma anatolicum• Boophilus (Rhipicephalus) decoloratus• B.(Rhipicephalus) microplus

Tick Unit facilities and expertise

• Capacity for 16 cattle experiments for evaluation of vaccines or acaricides

• Rabbit room with capacity for 48 rabbits• Salivary gland and other tissue

dissection• RNAi equipment • Manager- with an agenda to develop s

bew scientific activities-Naftaly Githaka

Laboratory Capacity

• Advanced Molecular biology infrastructure

• Next Generation sequencing

- 454 titanium

- Illumina Mi Seq

Library preparation specialist:

Bioinformatics Cluster

Systems Administrator

TickGard (based on recombinant BM86 gut glycoprotein) from Rhipicephalus (Boophilus) microplus

The First Commercial ‘Anti-Parasite’ Vaccine

• BM86 protects against Boophilus (Rhipicephalus ) decoloratus but not R. appendiculatus

• Homologues cloned from R. decoloratus and R. appendiculatus-

• In three host tick R. appendiculatus moulting from nymph to adults was affected

• Protection does not correlate with sequence identity- Better efficacy with heterologus challenge

• Conserved epitopes identified-Pepscan Hylomma-Rhipicephalus- Boophilus

BM86 and homologues

ILRI-Evaluation of Unconventional tick vaccine candidates in cattle

• Cement proteins• RIM 36-Immunodominant in cattle- no protection • Trp64-from IxodesPat Nuttall group protects against

human encephalitis virus- no protection in cattle• Histamine Binding (Lipocalin fold) protein-ambiguous

results

Genomics and Functional genomics for novel vaccine candidates

• Salivary gland EST databases developed in collaboration with TIGR

• Amblyomma variegatum• R.appendiculatus-infected versus uninfected-

Many differences (7000+) low abundance• Suppression subtractive approach to look for

transcripts up-regulated in infected salivary glands

Tick Genomics

• Genome organisation.• Many Transposons• Novel SINE element

• Allelic exclusion of very distinct RA86 variants in R. appendulatus lab stock

• Development of microsatellite markers for R. appendiculatus laboratory and field populations

A Wider Research Agenda

• Recent Review of ILRI tick unit by Peter Willadsen-Ex CSIRO-recommended inclusion of novel activities in additional tick species

• Activities related to direct tick control- Evaluating vaccines and acaricides-Group 1

• Tick-pathogen interaction research-Group2 • Measuring tick burdens and impact –Group 3 Special focus on B. (R) microplus in Africa

ECF recombinant vaccine support

• Sporozoite production• Tick challenge model-All current work is based on ITM (live

sporozoite and drug administration model)• Investigate mechanisms of immunity from tick-delivered T. parva• Tick-sporozoite antigen combination vaccines• Complexity of challenge scenario-taxonomy of ticks using new

techniques and monitoring pathogen loads

• Irradiated sporozoite vaccine• Plasmodium-Malaria analogy• Not fully researched for T. parva• Interest from Sanaria• Simplify composition of current vaccine.

ITM improvement irradiated sporozoite vaccine

Improved tick control

• Novel acaricide evaluation:

- Sigma-Genosys acaricide trial

New Vaccines-• FER2 evaluation as a vaccine candidate in cattle for

b. microplus• Participation in wider evaluation of novel candidates

from reverse vaccinology

Acaricide Resistance Monitoring

• In Collaboration with Ministries of Livestock• Not Well researched in Africa• Start in East Africa

Theileria parva

Arthropod vector

Vertebrate host

Tick-Host-Pathogen interface

(i)

(iii)

(ii)

Pathogen-vectorPathogen has to overcome tick ‘barriers’:1. Gut Invasion2. Tick immune system3 Salivary gland maturation

Tick- vertebrate hostProlonged attachment by Ixodid tick:Tick injects a cocktail of peptides and lipids Tissue cement to enhance feeding Inflammatory responsesImmunomodulationHaemostatic responses

Pathogen-HostInfection of vertebrate hostRole of tick salivary gland factors?Parasite evasion of vertebrate host

responses

ILRI Nascent Activities for tick/pathogen interaction

• Two R. appendiculatus genetically related stocks that differ in vector competence for T. parva

• Metagenomics- Novel viral pathogen discovery-Access to African tick species

Livestock Tick distribution and Impact

• Special focus on Boophilus (Rhipicephalus) in an African context- This tick is spreading rapidly in South, East and West Africa

• Test for acaricide resistance not well monitored in Africa

• What is the direct impact of ticks on livestock production including milk?

Tick Challenge Model

• Efficacy of anti-pathogen or anti-vector antigens in the field is difficult to test using a needle challenge in the laboratory

• Needle challenge is a MODEL SYSTEM• Therefore an experimental tick challenge system run in

parallel will be very valuable • Baseline data on tick challenge has been generated at

ILRI using a selected low abundance line-designed to be more comparable to field challenge

R. appendiculatus salivary gland EST Data from T.parva infected and

uninfected females

• 18,000+ total sequences RA sequences. 7359 unique-Generated in collaboration with TIGR.

• No Major clusters qualitatively different between T. parva infected and uninfected salivary glands

ILRI research-Combination sporozoite-tick salivary gland

• T.parva p67 sporozoite antigen better in the laboratory than the field

• Combine with salivary gland antigens • Antibody responses can be induced against

seven distinct recombinant antigens P67, and six salivary gland components

The presentation has a Creative Commons licence. You are free to re-use or distribute this work, provided credit is given to ILRI.

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