RA92A recombinant protein as immunogen to protect cattle against tick challenge in Brazil and Uganda

Rodrigo Casquero Cunha,Claire Julie Akwongo,Kokas Ikwap,Emukule Samuel,Nanteza Ann,Renato Andreotti,Fábio Pereira Leivas Leite,Francisco Denis Souza Santos,Margaret Saimo-Kahwa,Marcos Valério Garcia

doi:10.14393/bj-v37n0a2021-49905

Rodrigo Casquero Cunha, Claire Julie Akwongo + Show 8 more

Open Access

https://doi.org/10.14393/bj-v37n0a2021-49905

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Abstract

In this study, the recombinant gut protein rRa92A produced in Pichia pastoris yeast cells was used to immunize cattle in two experiments, one in Brazil and the other in Uganda. In both experiments, the animals were intramuscularly (IM) injected with 200 µg of recombinant protein in Brazil on days 0, 30 and 51 and in Uganda on days 0, 30. Blood samples for sera separation were collected from different days in both experiments. These samples were analyzed by ELISAs. In Brazil, ticks collected from the animals during the experimental period were analyzed for biological parameters. At Uganda, blood was collected to assess blood parameters, clinical signs were recorded and adult tick (Rhipicephalus appendiculatus) counts were performed. All animals of the vaccinated groups were shown to produce antibodies, and it was not possible to detect an effect on Rhipicephalus microplus. All the clinical parameters were considered within the normal ranges for both the experimental and control groups in Uganda. Antibody absorbance was elevated after each immunization and remained high until the end of the experiments, remaining low in the control animals. The results of stall test carried out in Brazil using R. microplus tick showed efficacy of 21.95%. The rRa92A immunization trial experiments in Uganda showing a decrease of 55.2% in the number of engorged adult ticks, which was statistically significant (p<0.05). Assessment of the immunogenicity of Ra92A produced in the P. pastoris expression system in bovines is reported for the first time, and the protein acted as a concealed antigen.

Highlights

Ticks are obligate ecto-parasites that transmit pathogens causing diseases that result in significant economic losses to livestock farmers in Brazil reaching an economic loss around US$3,23 billion in Brazilian cattle herds (Grisi et al 2014), which are estimated at 17 billion of dollars globally per year (Graham and Hourrigan 1977; Playford et al 2005).RA92A recombinant protein as immunogen to protect cattle against tick challenge in Brazil and UgandaThe tick affect bovine by the effects on weight loss, damage to the hides and skin, and a drop in milk yield (Pegram et al 1989) and cattle population are at risk of acquiring TBDs (Anon 1997)
There are two different homologues in ticks, Ra85A and Ra92A, and when both variants are present, one of them is transcriptionally dominant (Kamau et al 2010). One variant of this protein, Ra92A, was explored as an anti-tick vaccine in cattle in this experimental study for its efficacy against ticks. This protein was used as imunogen in a stall test in Brazil to test its immunogenic potential in bovines and its efficacy against R. microplus, and after, it was used to immunize cattle breeds mainly kept under intensive management for beef and local cattle under free range management in Uganda under parallel arrangement confirm its efficacy to control R. appendiculatus infestation
Vaccine formulations with Ra92A induced an immune response, which was confirmed by Western blot analysis and enzyme linked immunosorbent assay (ELISA)

Summary

Introduction

Ticks are obligate ecto-parasites that transmit pathogens causing diseases that result in significant economic losses to livestock farmers in Brazil reaching an economic loss around US$3,23 billion in Brazilian cattle herds (Grisi et al 2014), which are estimated at 17 billion of dollars globally per year (Graham and Hourrigan 1977; Playford et al 2005).RA92A recombinant protein as immunogen to protect cattle against tick challenge in Brazil and UgandaThe tick affect bovine by the effects on weight loss, damage to the hides and skin, and a drop in milk yield (Pegram et al 1989) and cattle population are at risk of acquiring TBDs (Anon 1997). There are two different homologues in ticks, Ra85A and Ra92A, and when both variants are present, one of them is transcriptionally dominant (Kamau et al 2010) One variant of this protein, Ra92A, was explored as an anti-tick vaccine in cattle in this experimental study for its efficacy against ticks. This protein was used as imunogen in a stall test in Brazil to test its immunogenic potential in bovines and its efficacy against R. microplus, and after, it was used to immunize cattle breeds mainly kept under intensive management for beef and local cattle under free range management in Uganda under parallel arrangement confirm its efficacy to control R. appendiculatus infestation

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