Introduction:

Rhipicephalus microplus ticks are hematophagous ectoparasites that economically impact lifestock industry worldwide. Acaricides have been an effective control strategy, but generate resistance to chemical compounds and environmental pollution. An alternative to counteract the chemical adverse effects is the vaccination usage, which is effective, environmentally friendly and unexpensive. However, still anti-tick vaccines present variable efficacy due to possible differences in aminoacid sequences within tick antigens from geografically distinct isolates. The aim of this work was to analyze the variability of two vaccine antigens: BmVDAC (Voltage Dependent Anion Channel) and Subolesin from R. microplus isolates from different states of Mexico.

Methods:

Two proteins were selected based on its efficacy as protective antigens: BmVDAC and Subolesin. R. microplus ticks was collected from different states of Mexico. Isolation of both DNA and RNA was performed to amplify bmvdac and subolesin respectively. Predicted amino acid sequences were obtained. A BLAST analysis was carried out to confirm the identity within sequences and determine similarity by an alignment using Clustal Omega. Finally, to determine the phylogenetic relationship of each isolate an analysis by MEGAX64 software was performed.

Results:

For BmVDAC, an average percentage of 99.79% identity and similarity was observed within the different aminoacid sequences. In the isolates from Chiapas, Nayarit, Media Joya, Queretaro, Tamaulipas and Guerrero a similarity and identity percentage of 99.87% was observed. Jalisco, Tabasco and Sinaloa a similarity and identity percentage of 99.56% was presented. On average, a variability percentage of 0.21% was observed.

The Subolesin alignment with isolates from Yucatan, Nayarit, Queretaro, Chiapas, Sinaloa, Veracruz, Tamaulipas, and the reference Munoz strain, an identity average percentage of 99.87% and similarity percentage of 100% was observed in the aminoacid sequences. Seven from eight sequences presented identity percentage of 99.91% whereas for Nayarit the percentage was 99.39%. The average variability was 0.13%. Phylogenetic analysis did not show significant differences between sequences using the UPGMA method. Average percentage obtained by 10000 replicas by Bootstrap method for bmvdac and subolesin was up to 50%.

Discussion and conclusion.

This report represents the first research on the characterization of the variability for BmVDAC and Subolesin, two vaccine antigens against R. microplus isolates from different states of Mexico. Considering the low variability presented by the different R. microplus isolates sequences, we can conclude that BmVDAC and Subolesin are antigens that are conserved and can be considered as vaccine candidates. This information is relevant for antigen selection and vaccine design against R. microplus in Mexico.

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