RESUMEN
The reactivity of sera collected from guinea pigs after three infestations with Amblyomma triste nymphs on histological sections of the same tick species was investigated through immunohistochemistry to identify potential target cells and tissues. Six guinea pigs were infested thrice, at 30 day intervals, with 30 nymphs of A. triste per animal per infestation. Blood samples were collected from the guinea pigs 15 days after each infestation for serum separation; normal serum was obtained before the first infestation as control. Unfed A. triste nymphs' histological sections were submitted to indirect immunohistochemistry technique by using normal or hyperimmune guinea pig serum as primary antibody and a goat IgG-alkaline phosphatase-APase conjugate as secondary antibody. A weak to moderate APase activity was observed in cells of salivary glands, midgut and haemolymph of unfed nymphs incubated with hyperimmune serum.
Asunto(s)
Ixodidae/fisiología , Infestaciones por Garrapatas/inmunología , Fosfatasa Alcalina , Animales , Antígenos , Cobayas , Inmunohistoquímica , Ninfa , Infestaciones por Garrapatas/sangreRESUMEN
Ticks deposit saliva at the site of their attachment to a host in order to inhibit haemostasis, inflammation and innate and adaptive immune responses. The anti-haemostatic properties of tick saliva have been described by many studies, but few show that tick infestations or its anti-haemostatic components exert systemic effects in vivo. In the present study, we extended these observations and show that, compared with normal skin, bovine hosts that are genetically susceptible to tick infestations present an increase in the clotting time of blood collected from the immediate vicinity of haemorrhagic feeding pools in skin infested with different developmental stages of Rhipicepahlus microplus; conversely, we determined that clotting time of tick-infested skin from genetically resistant bovines was shorter than that of normal skin. Coagulation and inflammation have many components in common and we determined that in resistant bovines, eosinophils and basophils, which are known to contain tissue factor, are recruited in greater numbers to the inflammatory site of tick bites than in susceptible hosts. Finally, we correlated the observed differences in clotting times with the expression profiles of transcripts for putative anti-haemostatic proteins in different developmental stages of R. microplus fed on genetically susceptible and resistant hosts: we determined that transcripts coding for proteins similar to these molecules are overrepresented in salivary glands from nymphs and males fed on susceptible bovines. Our data indicate that ticks are able to modulate their host's local haemostatic reactions. In the resistant phenotype, larger amounts of inflammatory cells are recruited and expression of anti-coagulant molecules is decreased tick salivary glands, features that can hamper the tick's blood meal.
Asunto(s)
Enfermedades de los Bovinos/sangre , Rhipicephalus/fisiología , Piel/parasitología , Infestaciones por Garrapatas/veterinaria , Análisis de Varianza , Animales , Bovinos , Enfermedades de los Bovinos/genética , Enfermedades de los Bovinos/parasitología , Enfermedades de los Bovinos/patología , Biología Computacional , ADN Complementario/química , Femenino , Perfilación de la Expresión Génica , Biblioteca de Genes , Interacciones Huésped-Parásitos , Inflamación/sangre , Inflamación/parasitología , Inflamación/veterinaria , Masculino , Metaloproteasas/antagonistas & inhibidores , Metaloproteasas/genética , ARN Mensajero/genética , ARN Mensajero/aislamiento & purificación , Rhipicephalus/genética , Glándulas Salivales/enzimología , Glándulas Salivales/fisiología , Proteínas y Péptidos Salivales/genética , Piel/irrigación sanguínea , Piel/patología , Infestaciones por Garrapatas/sangre , Infestaciones por Garrapatas/genética , Infestaciones por Garrapatas/patología , Tiempo de Coagulación de la Sangre TotalRESUMEN
Serum samples were collected from 582 horses from 40 stud farms in the State of São Paulo and tick (Acari: Ixodidae) infestations were evaluated on them. Serum samples were subjected to the complement fixation test (CFT) and a competitive inhibition ELISA (cELISA) for Babesia caballi and Theileria equi. Logistic regression analyses were performed to construct multivariate models that could explain the dependent variable (horses positive for B. caballi or T. equi) as a function of the independent variables (presence or abundance of each one of the tick species found on the farms). A higher overall prevalence of B. caballi (54.1%) than of T. equi (21.6%) was found by the two tests. The ticks Dermacentor nitens Neumann, 1897, Amblyomma cajennense (Fabricius, 1787) and Rhipicephalus (Boophilus) microplus (Canestrini, 1887) were present on horses on 38 (95%), 20 (50%), and 4 (10%) farms, respectively. Infestations by D. nitens were statistically associated with B. caballi-positive horses on the farms by either the CFT or cELISA. Infestations by A. cajennense were statistically associated with T. equi-positive horses on the farms by either CFT or cELISA.
Asunto(s)
Babesiosis/veterinaria , Enfermedades de los Caballos/epidemiología , Enfermedades de los Caballos/parasitología , Infestaciones por Garrapatas/veterinaria , Animales , Antígenos de Protozoos/sangre , Babesiosis/sangre , Babesiosis/complicaciones , Babesiosis/epidemiología , Brasil , Enfermedades de los Caballos/sangre , Caballos , Prevalencia , Theileria/inmunología , Infestaciones por Garrapatas/sangre , Infestaciones por Garrapatas/complicaciones , Infestaciones por Garrapatas/epidemiologíaRESUMEN
Serum samples were collected from 582 horses from 40 stud farms in the State of São Paulo and tick (Acari: Ixodidae) infestations were evaluated on them. Serum samples were subjected to the complement fixation test (CFT) and a competitive inhibition ELISA (cELISA) for Babesia caballi and Theileria equi. Logistic regression analyses were performed to construct multivariate models that could explain the dependent variable (horses positive for B. caballi or T. equi) as a function of the independent variables (presence or abundance of each one of the tick species found on the farms). A higher overall prevalence of B. caballi (54.1 percent) than of T. equi (21.6 percent) was found by the two tests. The ticks Dermacentor nitens Neumann, 1897, Amblyomma cajennense (Fabricius, 1787) and Rhipicephalus (Boophilus) microplus (Canestrini, 1887) were present on horses on 38 (95 percent), 20 (50 percent), and 4 (10 percent) farms, respectively. Infestations by D. nitens were statistically associated with B. caballi-positive horses on the farms by either the CFT or cELISA. Infestations by A. cajennense were statistically associated with T. equi-positive horses on the farms by either CFT or cELISA.
Amostras de soro sanguineo foram coletadas de 582 equinos de 40 haras no estado de São Paulo, onde as infestações por carrapatos foram avaliadas nos animais. Os soros foram testados por reação de fixação do complemento (RFC) e ELISA competitivo por inibição (cELISA) com antígenos de Babesia caballi e Theileria equi. Análises de regressão logística foram realizadas para construir modelos multivariados que pudessem explicar as variáveis dependentes (equinos positivos para B. caballi ou T. equi) em função de variáveis independentes (presença e abundância de cada uma das espécies de carrapatos encontradas nos equinos dos haras). Em geral, os dois testes sorológicos indicaram uma prevalência maior para B. caballi (54,1 por cento) do que para T. equi (21,6 por cento). Os carrapatos Dermacentor nitens Neumann, 1897, Amblyomma cajennense (Fabricius, 1787) e Rhipicephalus (Boophilus) microplus (Canestrini, 1887) estiveram presentes em equinos de 38 (95 por cento), 20 (50 por cento) e 4 (10 por cento) haras, respectivamente. As infestações por D. nitens estiveram estatisticamente associadas com equinos positivos para B. caballi tanto pela RFC como pelo cELISA. As infestações por A. cajennense estiveram estatisticamente associadas com equinos soropositivos para T. equi, tanto pela RFC como pelo cELISA.
Asunto(s)
Animales , Babesiosis/veterinaria , Enfermedades de los Caballos/epidemiología , Enfermedades de los Caballos/parasitología , Infestaciones por Garrapatas/veterinaria , Antígenos de Protozoos/sangre , Brasil , Babesiosis/sangre , Babesiosis/complicaciones , Babesiosis/epidemiología , Caballos , Enfermedades de los Caballos/sangre , Prevalencia , Theileria/inmunología , Infestaciones por Garrapatas/sangre , Infestaciones por Garrapatas/complicaciones , Infestaciones por Garrapatas/epidemiologíaRESUMEN
The tick Rhipicephalus (Boophilus) microplus is a hematophagous ectoparasite that causes considerable economic losses to cattle breeding. Although R. microplus saliva contains several molecules that interfere with the blood coagulation process, so far the systemic alterations in the host hemostatic system have not been described. This study aims to determine if R. microplus infestation induces any disturbance to the host's hemostatic system. To address these questions, six calves were experimentally infested with 20,000 R. microplus larvae and their blood was collected before and 7, 14 and 21 days post-infestation. Collagen and ADP-induced platelet aggregation as well as coagulation (activated partial thromboplastin time and prothrombin time) decreased in infested bovines. Platelet blood count and fibrinogen increased during the course of infestation, probably as a compensatory response. These alterations may play a role in host health status, and show that the host cannot fully counteract the tick anti-hemostatic mechanisms.
Asunto(s)
Enfermedades de los Bovinos/sangre , Enfermedades de los Bovinos/parasitología , Hemostasis/fisiología , Rhipicephalus/crecimiento & desarrollo , Infestaciones por Garrapatas/sangre , Infestaciones por Garrapatas/veterinaria , Animales , Bovinos , Femenino , Fibrinógeno/análisis , Tiempo de Tromboplastina Parcial/veterinaria , Agregación Plaquetaria/fisiología , Recuento de Plaquetas/veterinaria , Tiempo de Protrombina/veterinaria , Infestaciones por Garrapatas/parasitologíaRESUMEN
Enzyme-linked immunosorbent assay (ELISA) and Western blot were used to investigate the pattern of antibody responses of six bovines infested twelve times with Rhipicephalus (Boophilus) microplus (Canestrini, 1887) (Acari: Ixodidae) (six heavy infestations followed by six light infestations) against salivary gland, gut and larvae extracts. During heavy infestations, bovine IgG levels were shown to be higher, and a decrease in the number and weight of ticks that completed the parasitic cycle was observed. The pattern changed starting from the seventh infestation, showing a decrease in IgG levels. An initial increase followed by a significant decrease in the proportion of ticks that completed the parasitic cycle was also observed from the seventh infestation. The number of molecules recognized by Western blot was higher from sera collected following heavy infestations than after light infestations, although a great variation in the profiles detected could be seen when the bovines were compared. These results indicate that IgG responses to different tick antigens may not be generally associated with bovine resistance, and that infestation levels modulate the magnitude of humoral responses and possibly the immune mechanisms in the natural acquisition of tick resistance.
Asunto(s)
Enfermedades de los Bovinos/inmunología , Inmunoglobulina G/sangre , Rhipicephalus/inmunología , Infestaciones por Garrapatas/veterinaria , Animales , Animales Salvajes , Western Blotting/métodos , Western Blotting/veterinaria , Bovinos , Enfermedades de los Bovinos/sangre , Enfermedades de los Bovinos/parasitología , Ensayo de Inmunoadsorción Enzimática/métodos , Ensayo de Inmunoadsorción Enzimática/veterinaria , Sueros Inmunes/inmunología , Masculino , Distribución Aleatoria , Rhipicephalus/química , Infestaciones por Garrapatas/sangre , Infestaciones por Garrapatas/inmunología , Infestaciones por Garrapatas/parasitología , Factores de TiempoRESUMEN
The dog is considered to be the natural host of Rhipicephalus sanguineus and is unable to develop appreciable resistance even after repeated feedings. The guinea pig develops strong resistance after one infestation with adult ticks. Antibody (IgG) titres against tick salivary gland antigens (SGAs) and blood leukocyte numbers in dogs and guinea pigs undergoing experimental R. sanguineus tick infestations were measured to detect a possible correlation with susceptibility or resistance of hosts. Since infested dogs develop an immediate hypersensitivity reaction to R. sanguineus antigens, total and anti-R. sanguineus SGA IgE levels were also measured in this host species. IgG and IgE antibody levels were determined by an enzyme-linked immunosorbent assay (ELISA) along three consecutive infestations of both hosts. Most dogs and guinea pigs displayed low IgG levels against R. sanguineus SGAs, though marked differences in individual response were observed. Although dog's total serum IgE levels increased significantly after infestations, no change in the amount of anti-salivary gland IgE was detected. Total and differential blood cell counts were determined in dogs and guinea pigs during primary and secondary infestation. In dogs, a tertiary infestation and a subsequent higher infestation level were also evaluated. Infested dogs did not display any alteration in blood leukocyte counts throughout the experiment. Guinea pigs, on the other hand, developed a significant basophilia during primary infestation which increased further during secondary infestation. These data reveal similarities and differences in the reactions of resistant and non-resistant hosts to ticks. They contribute for the understanding of such host-parasite relationships and will hopefully aid in the development of immune control of ticks.