The effects of bovine tick resistance on the susceptibility of Hyalomma anatolicum anatolicum to infection with Theileria annulata (Ankara)

The mRNA expression of immune-related genes in crossbred and Tharparkar cattle in response to in vitro infection with Theileria annulata

Tropical theileriosis is a major protozoan disease of cattle and is associated with high rates of morbidity and mortality. Indigenous cattle (Bos indicus) are less affected by this disease than exotic and crossbred cattle. Genetic basis of resistance to tropical theileriosis in indigenous cattle is not well studied. Recent reports suggest that number of immune response genes expressed differentially in exotic and indigenous breeds play an important role in breed specific resistance to tropical theileriosis. Such studies comparing expression of these genes in crossbred cattle and indigenous cattle are lacking. The present study compares the mRNA expression of immune-related genes in response to Theileria annulata infection in indigenous and crossbred cattle. Peripheral blood mononuclear cells (PBMCs) were isolated from blood samples of indigenous (Tharparkar) and crossbred (HF/BS/Jersey × Hariana) cattle and challenged with prepared ground-up tick supernatant carrying Theileria annulata sporozoites in vitro. qPCR was employed to measure relative mRNA expression of toll-like receptor 10 (TLR10), signal-regulatory protein alpha (SIRPA), MHC class II DQα (BoLA-DQA), musculoaponeurotic fibrosarcoma (MAF) and prion protein (PRNP) genes in infected and control PBMCs from crossbred and indigenous cattle. On the basis of comparative fold change analysis, significant up-regulation in SIRPA, PRNP and MHC DQα genes and significant down-regulation in TLR10, cMAF and MAFB genes in crossbreds as compared to indigenous cattle was observed. Results of the present study suggest that breed specific differential expression of the genes under study may contribute to the breed specific resistance to Theileria annulata infection in indigenous cattle compared to crossbred cattle.

Vaccine potential of recombinant antigens of Theileria annulata and Hyalomma anatolicum anatolicum against vector and parasite

In an attempt to develop vaccine against Hyalomma anatolicum anatolicum and Theileria annulata, three antigens were expressed in prokaryotic expression system and protective potentiality of the antigens was evaluated in cross bred calves. Two groups (grs. 1 and 4) of male cross-bred (Bos indicus × Bos taurus) calves were immunized with rHaa86, a Bm86 ortholog of H. a. anatolicum, while one group of calves (gr. 2) were immunized with cocktails of two antigens viz., surface antigens of T. annulata (rSPAG1, rTaSP). One group each was kept as negative controls (grs. 3 and 5). The animals of groups 1, 2 and 3 were challenged with T. annulata infected H. a. anatolicum adults while the animals of groups 1, 3, 4 and 5 were challenged with uninfected adult ticks. A significantly high (p<0.05) antibody responses to all the three antigens were detected in immunized calves, but the immune response was comparatively higher with rHaa86 followed by rTaSP and rSPAG1. Upon challenge with T. annulata infected ticks, animals of all groups showed symptoms of the disease but there was 50% survival of calves of group 1 while all non immunized control calves (group 3) and rSPAG1+rTaSP immunized calves died. The rHaa86 antigen was found efficacious to protect calves against more than 71.4-75.5% of the challenge infestation. The experiment has given a significant clue towards the development of rHaa86 based vaccine against both H. a. anatolicum and T. annulata.

Immunization of cattle with nymphal Hyalomma anatolicum anatolicum extracts: effects on tick biology

Antigens derived from partially engorged nymphs of Hyalomma anatolicum anatolicum were used in immunizing crossbred (Bos indicus x Bos taurus) cattle against larval, nymphal and adult H. a. anatolicum and H. dromedarii. The cattle were either infected with Theileria annulata at low parasitaemia or were uninfected. Whole nymphal extract (WNE), nymphal membrane antigens (NMA) and nymphal soluble antigens (NSA) were used for immunization. The group immunized with WNE showed significant and better rejection of H. a. anatolicum ticks as compared to calves immunized with either NMA or NSA. The moulting rates of both engorged larvae and nymphs remained unaffected. Nymphs which engorged on the immunized calves were fully susceptible to infection by T. annulata as indicated by the intensity and abundance of Theileria infections in the resulting adult ticks from immunized and unimmunized Theileria infected cattle. These ticks also transmitted fatal theileriosis to susceptible calves.

Sustainable tick and tickborne disease control in livestock improvement in developing countries

Tick and tickborne disease (TTBD) control is a major component of animal health programmes protecting livestock, thereby enhancing global food security. The present methods for TTBD control are reviewed and an integrated use of the tools is recommended with a broader view of how to link TTBD control to the control of other parasitic diseases. The work of FAO in this field is presented and it is advocated that, although there are still areas that need further investigation, a stage has been reached where robust integrated TTBD control schemes, based on ecological and epidemiological knowledge of ticks and their associated diseases, can be promoted and implemented. Major challenges are the implementation of these policies in the field through the continuation of the present on-going programme in Africa and support to Latin America and Asia. The importance of involving all parties, governments, international and private organisations and the agrochemical industry in developing sustainable, cost-efficient control programmes is stressed and a global strategy is proposed. The main thrust should now be to convince policy makers on the adoption of the strategies and veterinarians and farmers on their implementation.

Prevalence of Theileria in the tick Hyalomma detritum detritum in the Doukkala region, Morocco

The overall prevalence of Theileria species, mainly, if not exclusively, T.annulata, in 901 Hyalomma detritum detritum collected from cattle in the Doukkala region of Morocco over a period of 2 years was 21.5%. The quantity of infection (number of sporoblasts per infected tick) followed the negative binomial distribution with between one and 250 sporoblasts per infected tick. Infected ticks were found in eight of fourteen areas examined whilst T.annulata was present in all fourteen. There were significant differences in both the prevalence and the quantity of infection between ticks collected from different farms, and between nymphs collected in the autumn from these farms, and moulted in the laboratory, and adults collected in the following summer. The prevalence, but not the quantity, of infection was higher in female than in male ticks. No correlations were established between infection of engorged nymphs and the breed, sex and Theileria piroplasm parasitaemia of the host animal. However, calves infected a greater proportion of nymphs than adult cattle and the heavier the infestation of nymphs on an animal, up to a plateau, the higher the prevalence of infection in those nymphs. There were no differences in infection between ticks moulted at 24 degrees C and 37 degrees C, after the engorged nymphs had been stored at 18 degrees C to simulate over-wintering.