Lack of acquired resistance in dogs to successive infestations of Rhipicephalus sanguineus ticks from Brazil and Argentina

Abstract

Comparative studies between brown dog tick Rhipicephalus sanguineus populations from Brazil (Jaboticabal, São Paulo) and Argentina (Rafaela, Santa Fé) showed significant biological, morphological and genetic differences between them. This work aimed to study, in a comparative way, the acquisition of resistance in domestic dogs to R. sanguineus from Jaboticabal and Rafaela, after successive and controlled infestations. Ticks were kept in a BOD incubator under controlled conditions (27 °C, 80 % relative humidity, 12-h photoperiod). Ten dogs, Dachshund breed, males and females, 6 months old, short- or long-haired, without prior contact with ticks, were used as hosts. They were distributed into two experimental groups composed of five animals each: G1 infested with ten adult couples of R. sanguineus (Jaboticabal) per animal, and G2 infested with ten adult couples of R. sanguineus (Rafaela) per animal. Ticks' biological parameters and titration of antibodies from the dogs' sera by ELISA test were used for comparison between the strains. Results of the biological parameters showed that the dogs did not acquire immunity to either of the R. sanguineus strains after repeated infestations. The ELISA test showed low antibody titers in sera of dogs from G2, in successive infestations, and higher antibody responses post second and third infestations in G1. It also demonstrated cross-reactivity between sera of dogs infested with R. sanguineus (Jaboticabal) and antigens from R. sanguineus (Rafaela) and vice versa. We conclude that Dachshund dogs did not develop resistance against neither Jaboticabal nor Rafaela strains of R. sanguineus.

Rickettsial antibodies andRickettsia belliidetection in lagomorphs and their ectoparasites in Northern Baja California, Mexico

“…Body mass in this case is likely to be, at least partially, a proxy for age, and younger, and therefore smaller, animals may be susceptible to higher tick burdens due to lack of acquired immunity (Njau et al 1988) or behaviors favoring parasite acquisition. Immunity to ticks following infestation is dependent on both host and tick species (Évora et al 2015). However, the significant inverse relationship between rabbit size and burdens of H. leporispalustris and D. parumapertus suggests that younger, smaller animals may play a disproportionate role in supporting tick populations and tick-borne pathogens.…”

Ticks and antibodies: May parasite density and tick evasion influence the outcomes following immunization protocols?

“…Regarding specifically to the anti-tick immunological control perspective, antibody levels against a defined antigen like the midgut protein Bm86 are correlated with protection in commercial vaccines against R. microplus (Willadsen et al, 1989;de la Fuente et al, 2020), although this is not universally true to explain protection against ticks following artificial immunizations (Knorr et al, 2018). Also, higher levels of antibodies against tick components following infestations may not be correlated with increased resistance (Kashino et al, 2005;Cruz et al, 2008;Piper et al, 2009;Leal et al, 2013;Évora et al, 2015;Leal et al, 2018) and, surprisingly, artificial immunization with tick antigens may instead enhance tick infestations (Almazán et al, 2020). Therefore, some controversy still populates the evaluation of the roles performed by antibody responses in tick-mammalian host relationships and we intend to briefly review some of these points in the following sections, with a special focus on the R. microplus-bovine relationship and the immunization attempts that have been developed.…”