Progress in development of vaccine against Hyalomma anatolicum anatolicum—Indian scenario

Biological Control of Hyalomma Ticks in Cattle by Fungal Isolates

Ticks pose a major threat to cattle health and production in Pakistan because they transmit pathogens of diseases like Babesiosis and Theileriosis. Hyalomma spp., found across Africa, Asia, and Europe, are especially problematic. This study explored biocontrol of Hyalomma spp. using spore-free fungal culture filtrates collected from dairy farm soil in Kohat, Pakistan. Three fungal species of the genera Alternaria, Aspergillus, and Penicillium were isolated, and their filtrates were tested against tick adults and larvae. Filtrate concentrations were prepared at different strengths. Data were taken after the exposure of adults and larvae ticks to various concentrations of the fungal filtrates. Results indicated that at 100% concentration, all fungal filtrates induced 100% mortality in adults and larvae. Decreasing filtrate concentration lowered tick mortality. The lowest concentration caused the least mortality. The effect was time- and dose-dependent. In conclusion, spore-free fungal culture filtrates can provide biocontrol of Hyalomma spp. in a time- and concentration-dependent manner. Further research should explore the active compounds causing mortality and optimal application methods. The process outlined here provides a natural biocontrol alternative to chemical pesticides to reduce tick infestations and associated cattle diseases in Pakistan.

An insight into the ecobiology, vector significance and control of Hyalomma ticks (Acari: Ixodidae): A review

Ticks (Acari:Ixodoidea) are important ectoparasites infesting livestock and human populations around the globe. Ticks can cause damage directly by affecting the site of infestation, or indirectly as vectors of a wide range of protozoa, bacteria and viruses which ultimately lead to lowered productivity of livestock populations. Hyalomma is a genus of hard ticks, having more than 30 species well-adapted to hot, humid and cold climates. Habitat diversity, vector ability, and emerging problem of acaricidal resistance in enzootic regions typify this genus in various countries around the world. This paper reviews the epidemiology, associated risk factors (temperature, climate, age, sex, breed etc.), vector role, vector-pathogen association, and reported control strategies of genus Hyalomma. The various proteins in saliva of Hyalomma secreted into the blood stream of host and the prolonged attachment are responsible for the successful engorgement of female ticks in spite of host immune defense system. The various immunological approaches that have been tried by researchers in order to cause tick rejection are also discussed. In addition, the novel biological control approaches involving the use of entomo-pathogenic nematodes and Bacillus thuringiensis (B. thuringiensis) serovar thuringiensis H14; an endotoxin, for their acaricidal effect on different species and life cycle stages of Hyalomma are also presented.

Identification of candidate transmission-blocking antigen genes in Theileria annulata and related vector-borne apicomplexan parasites

Background

Vector-borne apicomplexan parasites are a major cause of mortality and morbidity to humans and livestock globally. The most important disease syndromes caused by these parasites are malaria, babesiosis and theileriosis. Strategies for control often target parasite stages in the mammalian host that cause disease, but this can result in reservoir infections that promote pathogen transmission and generate economic loss. Optimal control strategies should protect against clinical disease, block transmission and be applicable across related genera of parasites. We have used bioinformatics and transcriptomics to screen for transmission-blocking candidate antigens in the tick-borne apicomplexan parasite, Theileria annulata.

Results

A number of candidate antigen genes were identified which encoded amino acid domains that are conserved across vector-borne Apicomplexa (Babesia, Plasmodium and Theileria), including the Pfs48/45 6-cys domain and a novel cysteine-rich domain. Expression profiling confirmed that selected candidate genes are expressed by life cycle stages within infected ticks. Additionally, putative B cell epitopes were identified in the T. annulata gene sequences encoding the 6-cys and cysteine rich domains, in a gene encoding a putative papain-family cysteine peptidase, with similarity to the Plasmodium SERA family, and the gene encoding the T. annulata major merozoite/piroplasm surface antigen, Tams1.

Conclusions

Candidate genes were identified that encode proteins with similarity to known transmission blocking candidates in related parasites, while one is a novel candidate conserved across vector-borne apicomplexans and has a potential role in the sexual phase of the life cycle. The results indicate that a ‘One Health’ approach could be utilised to develop a transmission-blocking strategy effective against vector-borne apicomplexan parasites of animals and humans.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3788-1) contains supplementary material, which is available to authorized users.

Detection of Malathion Resistance in Hyalomma anatolicum anatolicum from Bathinda District, Punjab

Objective:

The resistance status against malathion in Hyalomma anatolicum anatolicum ticks collected from Bathinda district, Punjab, was evaluated by adult immersion test (AIT).

Materials and Methods:

Technical grade malathion was used for conduction of AIT with 2 min immersion time protocol. The regression graph of probit mortality of ticks was plotted against log values of increasing concentrations of malathion and was utilized for the determination of slope of mortality, LC₅₀, LC_{95 (}95% confidence interval [CI]) and resistance factor (RF). The reproductive parameters of treated ticks viz. egg mass weight, reproductive index (RI), and percentage inhibition of oviposition (% IO) were also studied.

Results:

The increasing concentration of malathion showed an upward trend in per cent tick mortality. The slope of mortality (95% CI) was 2.489 ± 0.719 (2.489 ± 0.719) and value of goodness of fit (R²) was 0.799. The LC_{50 (}95% CI) and LC_{95 (}95% CI) values were recorded as 9099.2 (8378.6–9881.7) and 41,511.3 (35,060.2–49,149.4) ppm, respectively, with RF as 16.60 indicating level II resistance status. A negative dose-dependent slope of egg mass weight (−91.79 ± 25.15 [−171.8 to −11.76]) was recorded as the survived ticks laid significantly (P = 0.0355) fewer eggs. The mean RI of treated ticks decreased with increasing concentrations of drug and the slope (95% CI) was −0.293 ± 0.059 (−0.482 to −0.105). Further, a dose-dependent significant increase (P = 0.0157) in the mean % IO was recorded in treated ticks.

Conclusions:

The results of the current study would be useful in the formulation and implementation of effective tick strategies in the region.

Detection of acaricidal resistance in Hyalomma anatolicum anatolicum from Banaskantha district, Gujarat

The resistance status in Hyalomma anatolicum anatolicum collected from Banaskantha district, Gujarat (India) was estimated by larval packet test (LPT) with different concentrations of amitraz (125, 250, 500, 750 and 1,000 ppm) and cypermethrin (100, 200, 300, 400 and 500 ppm). The regression graphs of mean mortality of larvae ticks were plotted against values of progressively increasing concentrations of amitraz and cypermethrin for the estimation of LC95 values and were determined as 1,529.39 and 351.84 ppm, respectively. Further a resistance of level I was determined against cypermethrin whereas, a comparatively higher resistance level (II) was recorded against amitraz. The current study appears to be the pioneer report of amitraz and cypermethrin resistance in H. a. anatolicum from the Gujarat state, India.

Tick-borne diseases of bovines in Pakistan: major scope for future research and improved control

Ticks and tick-borne diseases (TBDs) affect the productivity of bovines in tropical and subtropical regions of the world, leading to a significant adverse impact on the livelihoods of resource-poor farming communities. Globally, four main TBDs, namely anaplasmosis, babesiosis, theileriosis, and cowdriosis (heartwater) affect bovines, and the former three are of major economic importance in bovines in Pakistan. Given that the livestock sector has become an integral part of Pakistan’s economy and a large number of dairy cattle are being imported into the country, in order to meet an increasing demand of milk and milk products, it is timely to review current status of bovine TBDs in Pakistan and to identify gaps in the knowledge of TBDs and their control. Although there has been a recent increase in the number of studies of TBDs in this country, information on their prevalence, distribution, tick vectors, and control is limited. This article provides a brief background on key bovine TBDs and ticks and reviews the current status of bovine TBDs in Pakistan to identify gaps in knowledge and understanding of these diseases, propose areas for future research and draw attention to the need for improved tools for the diagnosis and control of TBDs in this country.

Esterase and glutathione S-transferase levels associated with synthetic pyrethroid resistance in Hyalomma anatolicum and Rhipicephalus microplus ticks from Punjab, India

Larval packet test was used for assessment of resistance status against cypermethrin and deltamethrin in Hyalomma anatolicum and Rhipicephalus microplus from various districts of Punjab (India). Among the various field isolates of H. anatolicum susceptible status was recorded against cypermethrin in all isolates, whereas against deltamethrin resistance status (level I-III) was recorded. In R. microplus lower resistance levels (I-II) were recorded against cypermethrin in comparison to deltamethrin (level I-IV). Quantitative analysis of general esterase activity revealed a range of 4.21 ± 0.46 to 6.05 ± 0.55 and 2.23 ± 0.23 to 2.66 ± 0.24 µmol/min/mg protein for α- and β-esterase activity, respectively, in different field isolates of H. anatolicum and the increase in comparison to susceptible was not significant (P > 0.05). In contrast to H. anatolicum, the α- and β-esterase activity in all field isolates (except Jalandhar) of R. microplus was higher (range of 3.89 ± 0.26 to 10.85 ± 0.47 and 1.75 ± 0.08 to 5.87 ± 0.29 µmol/min/mg protein, respectively) (P < 0.001). The glutathione-S-transferase (GST) activity in field isolates of H. anatolicum and R. microplus was in the range of 0.01 ± 0.001 to 0.03 ± 0.001 and 0.02 ± 0.0003 to 0.03 ± 0.001 mM/mg/min. The enzyme ratios (α-and β-esterase and GST) and RR95 against deltamethrin of H. anatolicum isolates were correlated (P < 0.05), whereas in R. microplus only α-and β-esterase and RR50 against deltamethrin were correlated (P < 0.05).

Laboratory assessment of acaricidal activity of Cymbopogon winterianus, Vitex negundo and Withania somnifera extracts against deltamethrin resistant Hyalomma anatolicum

Larval packet test was used for detection of resistance levels against cypermethrin and deltamethrin, the most commonly used synthetic pyrethroids, in the multi-host tick Hyalomma anatolicum collected from district Moga, Punjab (India). Results indicated the presence of level I resistance against deltamethrin (RF = 2.81), whereas the tick isolate was susceptible to cypermethrin (RF = 0.2). The aqueous and ethanolic extracts of leaves of Cymbopogon winterianus, Vitex negundo and Withania somnifera along with roots of Vitex negundo were assessed for their acaricidal activity against the larvae of deltamethrin resistant H. anatolicum. The efficacy was assessed by measuring per cent larval mortality and determination of LC50 values. The various ethanolic extracts produced a concentration dependent increase in larval tick mortality, whereas the aqueous extracts exhibited a much lower mortality. The highest mortality (93.7 ± 0.66 %) was observed at the 5.0 % concentration of ethanolic extract of leaves of C. winterianus and the lowest LC50 value (0.011 %) was recorded for ethanolic extracts of leaves of V. negundo. The results indicated that these plant extracts have potential to be developed as herbal acaricides.

Tick vaccines and the control of tick-borne pathogens

Ticks are obligate hematophagous ectoparasites that transmit a wide variety of pathogens to humans and animals. The incidence of tick-borne diseases has increased worldwide in both humans and domestic animals over the past years resulting in greater interest in the study of tick-host-pathogen interactions. Advances in vector and pathogen genomics and proteomics have moved forward our knowledge of the vector-pathogen interactions that take place during the colonization and transmission of arthropod-borne microbes. Tick-borne pathogens adapt from the vector to the mammalian host by differential gene expression thus modulating host processes. In recent years, studies have shown that targeting tick proteins by vaccination can not only reduce tick feeding and reproduction, but also the infection and transmission of pathogens from the tick to the vertebrate host. In this article, we review the tick-protective antigens that have been identified for the formulation of tick vaccines and the effect of these vaccines on the control of tick-borne pathogens.

Expression of recombinant HAO3 from an Iranian isolate of Hyalomma anatolicum anatolicum in Pichia pastoris and evaluation of its antigenicity

Hyalomma anatolicum anatolicum tick is considered as one of the main problem of ruminants' productivity in endemic countries such as parts of Africa, the Middle East and India. The disease is economically important and hence, its control and eradication is a priority. This problem reinforces the need for alternative approach like vaccine to control tick infestations instead of continuous application of acaricide which led to the natural selection of the acaricide-resistant ticks. Therefore, the present study provided evidence for the construction of transformant containing the chromosomally integrated multi-copy expression cassettes of HAO3, its successful and efficient expression in Pichia pastoris yeast and purification of the secreted protein by ultrafiltration (UF) system in a high level yield and purity. The result of antigenicity assay for the rHAO3 protein pointed well toward its capability for the elicitation of antibody response in immunized rabbits. Interestingly, the results indicated that the expressed HAO3 protein reacted well with mid gut antigen (MGAg) and rBm86 (Gavac) antisera in ELISA and western blot assays making it evident that the epitopes present in expressed protein are well recognized by the antibodies against MGAg and rBm86 proteins. Moreover, the presence of cross-reactive epitopes between rHAO3 protein with its native antigen from mid gut cells was also determined.

Hd86, the Bm86 tick protein ortholog in Hyalomma scupense (syn. H. detritum): expression in Pichia pastoris and analysis of nucleotides and amino acids sequences variations prior to vaccination trials

The genus Hyalomma includes the most frequent tick species infesting livestock in North Africa, one of these species, Hyalomma scupense (syn. H. detritum) is particularly important due to its role in the transmission of tropical theileriosis to cattle (Theileria annulata infection). We have cloned and characterized the orthologs of the Bm86 gene from H. scupense strains collected over Tunisia in 2006 and 2009. The recombinant protein rHd86 was expressed in Pichia pastoris for vaccination purpose using a transcript from the 2006 strain. The rHd86 was then purified from the yeast culture supernatant by a filtration and a size exclusion process. It was recognized by specific anti-Bm86 antisera. An important extent of inter-specific diversity ranging from 35 to 40% was recorded between Hd86 and Bm86/Bm95 proteins whilst a very limited level of intra-specific diversity (1.7%) occurred between the Hd86 vaccine candidate protein and its homologues from H. scupense strains collected in 2009. These results emphasise the need for assessing the efficacy against H. scupense and others important cattle Hyalomma species in Tunisia of our Hd86 vaccine candidate alongside with a Bm86 vaccine.

Immunoaffinity chromatographic analysis for purification of specific diagnostic antigens of Paramphistomum epiclitum

Polypeptide profile of somatic antigen of Paramphistomum epiclitum (PSAg) and Gastrothylax crumenifer (GSAg) was studied by SDS-PAGE. PSAg and GSAg showed 14 and 19 polypeptides in the range of 14.9-95.5 and 13.7-129.6 kDa with six common polypeptides of mol wt 16.8, 21.8, 23.7, 35.5, 43.4 and 70.8 kDa. P. epiclitum experimentally infected sheep sera were used for identification of specific immuno-dominant peptide in the range of 37-40 kDa against P. epiclitum by western blotting. Hyperimmune sera (HIS) was raised in rabbit against the identified polypeptide, IgG was separated from HIS and an immunoaffinity column was constructed with a binding percentage of 83.74 of IgG with CNBr activated Sepharose 4B. Purification of somatic antigen (PSAg) was done with immunoaffinity chromatography and 37-40 kDa protein antigen was isolated in pure form with recovery percentage of 2.97%. This purified fraction of somatic antigen can be used as a candidate antigen for development of serological assay for early diagnosis of paramphistomosis among livestock.

Vaccine Efficacy of Bm86 Ortholog of H. a. anatolicum, rHaa86 Expressed in Prokaryotic Expression System

The use of tick vaccine in controlling ticks and tick borne diseases has been proved effective in integrated tick management format. For the control of H. a. anatolicum, Bm86 ortholog of H. a. anatolicum was cloned and expressed as fusion protein in E. coli as E. coli-pETHaa86. The molecular weight of the rHaa86 was 97 kDa with a 19 kDa fusion tag of thioredoxin protein. The expressed protein was characterized immunologically and vaccine efficacy was evaluated. After 120 hours of challenge, only 26% tick could successfully fed on immunized animals. Besides significant reduction in feeding percentages, a significant reduction of 49.6 mg; P < .01 in the weight of fed females in comparison to the females fed on control animals was recorded. Following oviposition, a significant reduction of 68.1 mg; P < .05 in the egg masses of ticks fed on immunized animals in comparison to the ticks fed on control animals was noted. The reduction of number of females, mean weight of eggs, adult females and efficacy of immunogen were 73.8%, 31.3%, 15.8%, and 82.3%, respectively. The results indicated the possibility of development of rHaa86 based vaccine as a component of integrated control of tick species.