Anaplasma marginale major surface protein 1a directs cell surface display of tick BM95 immunogenic peptides on Escherichia coli

An insight into control strategies against bovine tropical tick (Rhipicephalus microplus) in context to acaricide resistance

The monoxenous Ixodid tick Rhipicephalus microplus is an economically important pest infesting cattle populations worldwide. Apart from being a vector of various diseases, they cause substantial production losses. The control against this tick is mostly through chemical acaricides, which have been undermined by problems of resistance as well as toxic residues in the environment and living beings. In spite of the development of two commercial vaccines against the tick way back in the 1990s, the anticipated results were not recorded in field conditions. The search for vaccine antigens has led to the identification of subolesin, serpins, lipocains and proteoses showing protective immune response. The efficacy of these candidate antigens is mostly assessed by the mortality of adult and larval stages and effect on reproductive performance. Similarly, the use of plant extracts, nano encapsulation of plant extracts and entomopathogenic fungi have been widely subjected to in vitro and in vivo trials to offer a cost-effective and green solution to tick infestation. In recent years, the use of modern technologies like RNA interference, in silico docking and CRISPR technology have accelerated the identification of potent antigens and active fractions of plant extracts. Integrated tick management is a good option for the eradication of R. microplus. However, the integration of chemical and non-chemical control strategies still remains a challenge. The present review article is focused on the ongoing and emerging control strategies against the tick that will help researchers evolve a sustainable solution against R. microplus infestation.

Escherichia coli Surface Display: Advances and Applications in Biocatalysis

Escherichia coli surface display technology, which facilitates the stable display of target peptides and proteins on the bacterial surface through fusion with anchor proteins, has become a potent and versatile tool in biotechnology and biomedicine. The E. coli surface display strategy presents a unique alternative to classic intracellular and extracellular expression systems, facilitating the anchorage of target peptides and proteins on the cell surface for functional execution. This distinctive attribute also introduces a novel paradigm in the realm of biocatalysis, harnessing cells with surface-displayed enzymes to catalyze the conversion of substrates. This strategy effectively eliminates the requirement for enzyme purification, overcomes the limitations related to substrate transmembrane transport, improves enzyme activity and stability, and greatly reduces the cost of downstream product purification, thus making it widely used in biocatalysis. Here, we review recent advances in various surface display systems and surface display technology for biocatalytic applications. Additionally, we discuss the current limitations of this technology and several promising alternative display methods.

A Quantum Vaccinomics Approach for the Design and Production of MSP4 Chimeric Antigen for the Control of Anaplasma phagocytophilum Infections

Anaplasma phagocytophilum Major surface protein 4 (MSP4) plays a role during infection and multiplication in host neutrophils and tick vector cells. Recently, vaccination trials with the A. phagocytophilum antigen MSP4 in sheep showed only partial protection against pathogen infection. However, in rabbits immunized with MSP4, this recombinant antigen was protective. Differences between rabbit and sheep antibody responses are probably associated with the recognition of non-protective epitopes by IgG of immunized lambs. To address this question, we applied quantum vaccinomics to identify and characterize MSP4 protective epitopes by a microarray epitope mapping using sera from vaccinated rabbits and sheep. The identified candidate protective epitopes or immunological quantum were used for the design and production of a chimeric protective antigen. Inhibition assays of A. phagocytophilum infection in human HL60 and Ixodes scapularis tick ISE6 cells evidenced protection by IgG from sheep and rabbits immunized with the chimeric antigen. These results supported that the design of new chimeric candidate protective antigens using quantum vaccinomics to improve the protective capacity of antigens in multiple hosts.

Changes in Serum Biomarkers of Oxidative Stress in Cattle Vaccinated with Tick Recombinant Antigens: A Pilot Study

Tick vaccination is an environmentally friendly alternative for tick control, pathogen infection, and transmission. Tick vaccine protection is sometimes incomplete, which may be due to problems in the stability, conformation, and activity of antibodies. This might be related to oxidative stress, but more studies are needed about the possible relationships between oxidative stress and immune function. The objective of this study was to evaluate and compare various serum biomarkers of antioxidant response and oxidative damage in cattle vaccinated with two recombinant antigens, the chimera of Subolesin- BM95 (homologue antigen of BM86)-MSP1a and BM86, and a control consisting in the adjuvant of the vaccines. Cupric reducing antioxidant capacity (CUPRAC), ferric reducing ability of the plasma (FRAP), trolox equivalent antioxidant capacity (TEAC), total thiol concentrations, and uric acid were evaluated in serum to determine the antioxidant response. To evaluate oxidative status, ferrous oxidation-xylenol orange (FOX), total oxidant status (TOS), advanced oxidation protein products (AOPP) and hydrogen peroxide (H₂O₂) concentrations in serum were determined. In addition, correlations between biomarkers of oxidative stress and antibody titers were evaluated. A significant decrease in all antioxidant biomarkers, with exception of thiol, and also a decrease in the oxidant markers TOS, AOPP and H₂O₂ was observed in cattle vaccinated with BM86, that also showed the highest antibody titers response whereas no significant differences in any of the biomarkers were detected in the Subolesin-Bm95-MSP1a and control groups. In addition, the dynamics of Cuprac and H₂O₂ with time showed significant differences between the groups. Although this is a pilot study and the results should be interpreted with caution and corroborated by studies involving a large number of animals, our results indicate that, in our experimental conditions, those vaccines able to induce a lower oxidative stress produce a higher concentration of antigen-specific antibodies. Overall, the results of the study provided information on the behavior of different biomarkers related to antioxidant defense, and the oxidative damage in cattle in response to vaccination.

Tick and Host Derived Compounds Detected in the Cement Complex Substance

Ticks are obligate hematophagous arthropods and vectors of pathogens affecting human and animal health worldwide. Cement is a complex protein polymerization substance secreted by ticks with antimicrobial properties and a possible role in host attachment, sealing the feeding lesion, facilitating feeding and pathogen transmission, and protection from host immune and inflammatory responses. The biochemical properties of tick cement during feeding have not been fully characterized. In this study, we characterized the proteome of Rhipicephalus microplus salivary glands (sialome) and cement (cementome) together with their physicochemical properties at different adult female parasitic stages. The results showed the combination of tick and host derived proteins and other biomolecules such as α-Gal in cement composition, which varied during the feeding process. We propose that these compounds may synergize in cement formation, solidification and maintenance to facilitate attachment, feeding, interference with host immune response and detachment. These results advanced our knowledge of the complex tick cement composition and suggested that tick and host derived compounds modulate cement properties throughout tick feeding.

Bacterial membranes enhance the immunogenicity and protective capacity of the surface exposed tick Subolesin-Anaplasma marginale MSP1a chimeric antigen

Ticks are vectors of diseases that affect humans and animals worldwide. Tick vaccines have been proposed as a cost-effective and environmentally sound alternative for tick control. Recently, the Rhipicephalus microplus Subolesin (SUB)-Anaplasma marginale MSP1a chimeric antigen was produced in Escherichia coli as membrane-bound and exposed protein and used to protect vaccinated cattle against tick infestations. In this research, lipidomics and proteomics characterization of the E. coli membrane-bound SUB-MSP1a antigen showed the presence of components with potential adjuvant effect. Furthermore, vaccination with membrane-free SUB-MSP1a and bacterial membranes containing SUB-MSP1a showed that bacterial membranes enhance the immunogenicity of the SUB-MSP1a antigen in animal models. R. microplus female ticks were capillary-fed with sera from pigs orally immunized with membrane-free SUB, membrane bound SUB-MSP1a and saline control. Ticks ingested antibodies added to the blood meal and the effect of these antibodies on reduction of tick weight was shown for membrane bound SUB-MSP1a but not SUB when compared to control. Using the simple and cost-effective process developed for the purification of membrane-bound SUB-MSP1a, endotoxin levels were within limits accepted for recombinant vaccines. These results provide further support for the development of tick vaccines using E. coli membranes exposing chimeric antigens such as SUB-MSP1a.

Control of tick infestations and pathogen prevalence in cattle and sheep farms vaccinated with the recombinant Subolesin-Major Surface Protein 1a chimeric antigen

BACKGROUND

Despite the use of chemical acaricides, tick infestations continue to affect animal health and production worldwide. Tick vaccines have been proposed as a cost-effective and environmentally friendly alternative for tick control. Vaccination with the candidate tick protective antigen, Subolesin (SUB), has been shown experimentally to be effective in controlling vector infestations and pathogen infection. Furthermore, Escherichia coli membranes containing the chimeric antigen composed of SUB fused to Anaplasma marginale Major Surface Protein 1a (MSP1a) (SUB-MSP1a) were produced using a simple low-cost process and proved to be effective for the control of cattle tick, Rhipicephalus (Boophilus) microplus and R. annulatus infestations in pen trials. In this research, field trials were conducted to characterize the effect of vaccination with SUB-MSP1a on tick infestations and the prevalence of tick-borne pathogens in a randomized controlled prospective study.

METHODS

Two cattle and two sheep farms with similar geographical locations and production characteristics were randomly assigned to control and vaccinated groups. Ticks were collected, counted, weighed and classified and the prevalence of tick-borne pathogens at the DNA and serological levels were followed for one year prior to and 9 months after vaccination.

RESULTS

Both cattle and sheep developed antibodies against SUB in response to vaccination. The main effect of the vaccine in cattle was the 8-fold reduction in the percent of infested animals while vaccination in sheep reduced tick infestations by 63%. Female tick weight was 32-55% lower in ticks collected from both vaccinated cattle and sheep when compared to controls. The seroprevalence of Babesia bigemina was lower by 30% in vaccinated cattle, suggesting a possible role for the vaccine in decreasing the prevalence of this tick-borne pathogen. The effect of the vaccine in reducing the frequency of one A. marginale msp4 genotype probably reflected the reduction in the prevalence of a tick-transmitted strain as a result of the reduction in the percent of tick-infested cattle.

CONCLUSIONS

These data provide evidence of the dual effect of a SUB-based vaccine for controlling tick infestations and pathogen infection/transmission and provide additional support for the use of the SUB-MSP1a vaccine for tick control in cattle and sheep.

Oral vaccination with vaccinia virus expressing the tick antigen subolesin inhibits tick feeding and transmission of Borrelia burgdorferi

Immunization with the Ixodes scapularis protein, subolesin, has previously been shown to protect hosts against tick infestation and to decrease acquisition of Anaplsma marginale and Babesia bigemina. Here we report the efficacy of subolesin, a conserved tick protein that can act as a regulator of gene expression, expressed from vaccinia virus for use as an orally delivered reservoir - targeted vaccine for prevention of tick infestation and acquisition/transmission of Borrelia burgdorferi to its tick and mouse hosts. We cloned subolesin into vaccinia virus and showed that it is expressed from mammalian cells infected with the recombinant virus in vitro. We then vaccinated mice by oral gavage. A single dose of the vaccine was sufficient for mice to generate antibody response to subolesin. Vaccination with the subolesin expressing vaccinia virus inhibited tick infestation by 52% compared to control vaccination with vaccinia virus and reduced uptake of B. burgdorferi among the surviving ticks that fed to repletion by 34%. There was a reduction in transmission of B. burgdorferi to uninfected vaccinated mice of 40% compared to controls. These results suggest that subolesin has potential as a component of a reservoir targeted vaccine to decrease B. burgdorferi, Babesia and Anaplasma species infections in their natural hosts.

Protective efficacy of bacterial membranes containing surface-exposed BM95 antigenic peptides for the control of cattle tick infestations

The Rhipicephalus (Boophilus) microplus BM86 and BM95 glycoproteins are homologous proteins that protect cattle against tick infestations. In this study, we demonstrated that the recombinant chimeric protein comprising tick BM95 immunogenic peptides fused to the A. marginale MSP1a N-terminal region for presentation on the Escherichia coli membrane was protective against R. microplus infestations in rabbits. This system provides a novel and simple approach for the production of tick protective antigens by surface display of antigenic protein chimera on live E. coli and suggests the possibility of using recombinant bacterial membrane fractions for vaccination against cattle tick infestations.

Evaluation of baits for oral vaccination of European wild boar piglets

The objective of this study was to develop and evaluate new baits for the oral delivery of vaccine preparations to 2-4 month-old wild boar piglets. Baits were prepared using a matrix composed of wild boar feed, wheat flour, paraffin, sacarose and cinnamon-truffle powder attractant with polyethylene capsules dipped into the matrix to introduce vaccine formulation. Physical stability studies demonstrated that baits were stable for at least three days at temperatures as high as 42 degrees C. Recombinant Escherichia coli expressing the membrane-displayed BM95-MSP1a fusion protein were used to test bacterial viability in the baits and the antibody response in orally immunized wild boar. The E. coli viability was not significantly affected after bait incubation at 25 and 37 degrees C for 96h. Bait acceptance studies using artificial feeders in the field showed that baits were accepted by 2-3month-old animals, the preferred age for vaccination. Orally immunized wild boar piglets excreted recombinant E. coli in the feces and developed antibody titers to recombinant BM95-MSP1a protein, thus confirming that vaccine composition was released and reached the wild boar gastrointestinal track. The results of these experiments support the use of these baits for oral delivery of vaccine formulations to 2-4month-old wild boar piglets.