Immunogenic potential of the recombinant Rhipicephalus microplus aquaporin protein against the tick Rhipicephalus sanguineus Latreille, 1806 in domestic dogs

Authors: EVORA, PATRICIA - Faculdade De Ciências Agrárias E Veterinárias De Jaboticabal-Unesp; SANCHEZ, GUSTAVO - Faculdade De Ciências Agrárias E Veterinárias De Jaboticabal-Unesp; Guerrero, Felicito; Perez De Leon, Adalberto - Beto; BECHARA, GERVASIO - Faculdade De Ciências Agrárias E Veterinárias De Jaboticabal-Unesp

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2014
Publication Date: N/A
Citation: N/A

Interpretive Summary: Aquaporins regulate water transport through cell membranes enclosing the cells of higher organisms. As ticks ingest large volumes of host blood in relation to their size, they are required to concentrate blood components and have efficient water transport mechanisms that incorporate aquaporins. This study aimed to evaluate the potential of a recombinant Rhipicephalus microplus aquaporin protein (Antigen 1) as an anti-tick vaccine. The evaluation was done in domestic dogs using a vaccination protocol with three vaccinations, followed by a challenge with a tick infestation using a Brazilian laboratory strain of the tick brown dog tick, Rhipicephalus sanguineus. Dogs were distributed into two experimental groups of five animals each: Group 1 dogs received three intramuscular vaccinations with 1 mL of 100 micrograms of Antigen 1 and Montanide adjuvant at three weeks intervals; Group 2 control group dogs were vaccinated three times with an equal volume of vaccine containing the Montanide adjuvant only. Tick challenge infestation was performed 21 days after the third immunization. R. sanguineus biological parameter data was collected from each tick life stage, nymph, larvae, and adult. ELISA was used to monitor Antigen 1 immunogenicity through determination of Antigen 1 antibody amounts in blood serum samples obtained from vaccinated dogs. Comparisons between Group 1 and Group 2 were done to determine efficacy of the vaccine against R. sanguineus. Immunized dogs developed effective antibodies against Antigen 1. After challenge infestation, although larvae from Group 1 had 8.7% longer engorgement period than larvae from Group 2 controls, the Group 1 larvae weighed 7.2% less than Group 2 control larvae. Moreover, nymphs from Group 1 demonstrated significant differences compared to nymphs from Group 2 controls, weighing 3.6% less and having a 4.5% lower engorgement period. Finally, though the mean engorged female weight in both groups was not different statistically, females from Group 1 showed 12% reduction in their engorgement periods when compared to the females from Group 2 controls. Results point out that Antigen 1 had good immunogenicity but low potential as an anti-tick vaccine against R. sanguineus infestations in domestic dogs.

Technical Abstract: Aquaporins regulate water transport through the highly hydrophobic lipid bilayer of cell membranes. As ticks ingest large volumes of host blood in relation to their size, they are required to concentrate blood components and have efficient water transport mechanisms. This study aimed to evaluate the immunogenic potential of a recombinant Rhipicephalus microplus aquaporin protein (Antigen 1) in domestic dogs using a vaccination protocol followed by challenge infestation with a Brazilian stock of the tick Rhipicephalus sanguineus. Dogs were distributed into two experimental groups of five animals each: G1) three intramuscular vaccinations with 1 mL of 100 µg of Antigen 1 plus Montanide at three weeks interval; G2) control group vaccinated three times with an equal volume of Montanide only. Tick challenge infestation was performed 21 days after the third immunization. R. sanguineus biological parameter data was collected from each tick life stage. ELISA was used to monitor Antigen 1 antibody titers in dog sera. Comparisons between G1 and G2 were done to determine efficacy of the vaccine against R. sanguineus. Immunized dogs developed effective antibodies against Antigen 1. After challenge infestation, although larvae from G1 had 8.7% longer engorgement period than larvae from G2, the G1 larvae weighed 7.2% less than G2 larvae. Moreover, nymphs from G1 demonstrated significant differences compared to nymphs from G2, weighing 3.6% less and having a 4.5% lower engorgement period. Finally, though the mean engorged female weight in both groups was not different statistically, females from G1 showed 12% reduction in their engorgement periods when compared to the females from G2. Results point out that Antigen 1 had good immunogenicity but low potential as an anti-tick vaccine against R. sanguineus infestations in domestic dogs.