Monthly fluctuation of parasitism by adult Ixodes keiransi ticks in dogs from Yucatán, Mexico.

The monthly fluctuation of adult Ixodes keiransi in dogs from two cattle farms in southeastern Mexico was determined. In ranch 1 (R1), 6-7 mixed breed dogs from six months to five years of age; while in ranch 2 (R2), 7-8 mixed breed dogs from one to four years of age, were followed. All dogs were monthly inspected for tick infestation through one year. The abundance of dogs infested with ticks was estimated for each month. Tick specimens were taxonomically identified as I. keiransi using morphological features. In R1 the dogs were inspected 60 times and in R2 90 times. The overall proportion of dogs infested by ticks through the year was 75% (60/80) in R1 and 67% (67/90) in R2. The higher abundance of adult I. keiransi parasitizing dogs was from July to December with maximum peaks from September to November. In April, May and June, no ticks were observed on dogs from both ranches. Tick abundance fluctuation showed a concordant pattern with rainfall but with a delay because de maximum peak of I. keiransi abundance was almost two months after the greatest rainfall peak. It is concluded that, in some conditions, the adult I. keiransi in southeastern Mexico presents high-infested rates on dogs and a maximum abundance from September to November. The I. keiransi abundance fluctuation showed a concordant pattern with rainfall.

Topical permethrin may increase blacklegged tick (Ixodes scapularis) repellency but is associated with cutaneous irritation in horses.

OBJECTIVE: To evaluate the safety of repeated applications of permethrin concentrations (0% control, 1.5%, 5%, and 10%) to the necks and faces of horses and assess the efficacy and longevity of permethrin as an equine tick repellent. ANIMALS: 5 healthy adult Quarter Horses. PROCEDURES: Each treatment was applied to the neck of each horse (0.01 m2) 4 times a day, for up to 10 days. An 8-mm biopsy was taken to evaluate postexposure dermal responses. Any treatments that were not withdrawn were applied to a quadrant of the horse's face 4 times a day, for up to 5 days. For tick bioassays, a treatment was applied to 1 leg of a horse and 5 female blacklegged ticks (Ixodes scapularis) were evaluated as "repelled" or "not repelled" by the treatment. The bioassays were repeated up to 5 days, but treatment application took place only on the first day of the experiment. RESULTS: Histological results of neck biopsies indicated that more repeated exposures or higher concentrations resulted in more dermal damage. Tick bioassays showed that 5% and 10% permethrin had the greatest efficacy and longevity as a tick repellent, but the differences in tick repellency were not significant overall. CLINICAL RELEVANCE: While there was a nonsignificant trend of higher permethrin concentrations repelling more ticks with longer-lasting residual repellent effects, higher concentrations also produced greater skin damage after repeated exposures. These opposing findings emphasize the need for better tick prevention and control methods that balance safety and efficacy for the equine community.

Free-living hard ticks (Ixodida: Ixodidae) from three different natural environments of Costa Rica.

This paper presents data on free-living ticks collected by flagging and using CO2 traps in three natural areas in Costa Rica: Carara National Park (CNP), Palo Verde National Park (PVNP), and a Private Forest Reserve in Sarapiquí (SPR). Data were analyzed calculating aspects of alpha diversity (species richness, entropy; dominance index, and evenness); and for beta diversity, compositional similarity between communities of ticks was also calculated. We collected 12,795 ticks belonging to 10 species: Amblyomma coelebs, Amblyomma dissimile, Amblyomma mixtum, Amblyomma naponense, Amblyomma cf. oblongoguttatum, Amblyomma cf. parvum, Amblyomma sabanerae, Amblyomma tapirellum, Haemaphysalis juxtakochi and Ixodes affinis. The number of species and individuals varied between sites: 5970 ticks were collected in CNP, 4443 in PVNP, and 2382 in SPR. Amblyomma cf. oblongoguttatum and A. cf. parvum were collected at all three sites, but A. mixtum was the most abundant species, even though it was not collected in SPR. Values of alpha diversity were calculated for CNP and SPR, while diversity in PVNP was the lowest of the three locations. Evenness was highest in SPR and lowest in CNP. The only community that presented dominance was PVNP. Beta diversity showed low similarity between the three locations with the lowest being CNP and SPR. For the three localities, estimates of the number of tick species based on presence/absence data was higher using flagging than CO2; and considering the stage of the ticks collected. More larvae were captured using CO2 traps than by flagging, while flagging was better for collecting adults. To our knowledge this is the first study in Costa Rica that compares these two sampling methods in three different environmental areas.

Diversity of Rickettsia in ticks collected from wild animals in Panama.

This paper presents new data about Rickettsia species detected in ticks collected from wild animals, using 16S rRNA, gltA and ompA. Rickettsia DNA was found in 66 of 101 ticks. Using EZ BioCloud libraries were produced reads that identified Rickettsia aeschlimannii, and Illumina BaseSpace produced reads of Rickettsia rickettsii group, Rickettsia bellii group, and unclassified Rickettsia. Using gltA and ompA gene-specific primers, R. aeschlimannii could not be confirmed, but detection of Rickettsia amblyommatis was achieved in Amblyomma auricularium, Amblyomma geayi, Amblyomma mixtum, and Amblyomma pacae; R. bellii from Amblyomma dissimile, "Candidatus Rickettsia colombianensi" from A. dissimile, Rickettsia spp. closely related to R. raoultii from A. geayi, Rickettsia tamurae from A. dissimile, and Rickettsia endosymbionts of Ixodes from Ixodes affinis. There were no databases available specifically for 16S rRNA of Neotropical Rickettsia, highlighting the need to use species primers over only 16S rRNA primers to achieve more accurate interpretations and identifications. These findings increase the number of Rickettsia species detected in Panama and highlight the need to establish isolates to further characterize the nature of Rickettsia in the area.

Life cycle of Ixodes schulzei (Acari: Ixodidae) in the laboratory, and demonstration of reproduction by parthenogenesis.

Ixodes schulzei is an ixodid tick that parasitizes Cricetidae rodents, chiefly the South American water rat, Nectomys squamipes, in Brazil and Argentina. In the present study, we evaluated the life cycle of I. schulzei by exposing larvae and nymphs to feed on two rodent species, N. squamipes and Calomys callosus (large vesper mouse),while adult ticks were exposed to feed on N. squamipes. Off-host developmental periods were observed in an incubator at 27 °C, 95% relative humidity, and 0:24 (light:dark) regimen. Larvae and nymphs successfully fed on either C. callosus or N. squamipes. Mean larval and nymphal feeding periods were 8.8 and 8.7 days on N. squamipes and 8.5 and 9.7 days on C. callosus. The majority of engorged larvae (79.0-80.8%) and nymphs (67.0-86.0%) successfully molted to nymphs and adults, respectively. Mean premolt periods were 11.5-11.7 days for engorged larvae and 22.5-23.7 days for engorged nymphs. Only adult females emerged from engorged nymphs, regardless of host species, i.e., none of 120 engorged nymphs molted to male. Around 18% of the unfed females presented teratologies compatible with the metagynander type of gynandromorphism. Ixodes schulzei adult females successfully fed (mean feeding period, 9.4 days), oviposited, and presented high reproductive performance (high engorged weight, egg mass weight, and % egg mass hatching), in the absence of male ticks. Our results showed that I. schulzei successfully reproduces by parthenogenesis, and corroborate field data that indicate N. squamipes as the most important host for this tick species. The male of I. schulzei remains unknown.

Free-living ticks (Acari: Ixodidae) in the Iguaçu National Park, Brazil: Temporal dynamics and questing behavior on vegetation.

Basic knowledge of species, ecological preferences and behavior of ticks in preserved rainforests are scanty. We herein describe species richness, seasonal activity, altitude influence and questing height of ticks along 3375 m of animal trails within the largest remain of inland Atlantic rainforest in Brazil, the Iguaçu National Park (INP). Altogether, 2954 ticks from nine tick species were collected; Amblyomma brasiliense Aragão (49.09% of the specimens), Amblyomma coelebs Neumann (29.08%), Amblyomma incisum Neumann (12.49%), Haemaphysalis juxtakochi Cooley (5.21%), Amblyomma ovale Koch (2.64%), Amblyomma longirostre Koch (0.20%), Ixodes fuscipes Fonseca (0.17%), Ixodes loricatus Neumann (0.07%) and Amblyomma dubitatum Neumann (0.03%) (Ixodida: Ixodidae). There was an evident seasonal influence on tick host-questing activity, with each tick stage prevailing in a season before the following one, and a general trend of one tick generation per year. Adult tick questing height mode on vegetation showed a correspondence between tick species and preferred host size and height. Adult ticks quested higher than immatures, but several larval clusters were found high enough to seek for large-sized hosts as well. Nymphal and adult tick questing height increased significantly at higher altitudes within the park. Amblyomma incisum and A. coelebs were more abundant at higher and lower altitudes, respectively. The knowledge on tick species richness, ecological preferences and behavior herein obtained provides baseline information to understand tick-borne disease epidemiology occurring at landscapes under a strong anthropogenic impact.

Description of a new species of Ixodes (Acari: Ixodidae) and first report of Ixodes lasallei and Ixodes bocatorensis in Brazil.

In a recent study, we relegated the taxon Ixodes aragaoi Fonseca, 1935 to a junior synonym of Ixodes fuscipes Koch, 1844, and reinstated Ixodes spinosusNeumann, 1899 (a former synonym of I. fuscipes) to a valid species. We examined all lots of ticks formerly identified as I. fuscipes or I. aragaoi in three tick collections of Brazil. Through morphological analysis, some of the examined specimens could not be assigned to either I. fuscipes or I. spinosus based on the examination of the type specimens of these two species. Herein, we report these ticks to represent three different species: Ixodes catarinensis n. sp. Onofrio & Labruna, Ixodes lasalleiMéndez Arocha and Ortiz, 1958, and Ixodes bocatorensisApanaskevich and Bermúdez, 2017. The latter two species are reported for the first time in Brazil. Phylogenetic analysis inferred from the tick 16S rRNA gene partial sequences corroborated our morphological analysis, indicating that I. spinosus, I. lasallei, I. bocatorensis, and I. catarinensis n. sp. form a natural group of neotropical ticks. With the present study, the number of Ixodes species in Brazil increases from 9 to 12. We propose a new identification key for females and males of Ixodes species currently recognized in Brazil.

Ticks as potential vectors of Mycobacterium leprae: Use of tick cell lines to culture the bacilli and generate transgenic strains.

Leprosy is an infectious disease caused by Mycobacterium leprae and frequently resulting in irreversible deformities and disabilities. Ticks play an important role in infectious disease transmission due to their low host specificity, worldwide distribution, and the biological ability to support transovarial transmission of a wide spectrum of pathogens, including viruses, bacteria and protozoa. To investigate a possible role for ticks as vectors of leprosy, we assessed transovarial transmission of M. leprae in artificially-fed adult female Amblyomma sculptum ticks, and infection and growth of M. leprae in tick cell lines. Our results revealed M. leprae RNA and antigens persisting in the midgut and present in the ovaries of adult female A. sculptum at least 2 days after oral infection, and present in their progeny (eggs and larvae), which demonstrates the occurrence of transovarial transmission of this pathogen. Infected tick larvae were able to inoculate viable bacilli during blood-feeding on a rabbit. Moreover, following inoculation with M. leprae, the Ixodes scapularis embryo-derived tick cell line IDE8 supported a detectable increase in the number of bacilli for at least 20 days, presenting a doubling time of approximately 12 days. As far as we know, this is the first in vitro cellular system able to promote growth of M. leprae. Finally, we successfully transformed a clinical M. leprae isolate by inserting the reporter plasmid pCHERRY3; transformed bacteria infected and grew in IDE8 cells over a 2-month period. Taken together, our data not only support the hypothesis that ticks may have the potential to act as a reservoir and/or vector of leprosy, but also suggest the feasibility of technological development of tick cell lines as a tool for large-scale production of M. leprae bacteria, as well as describing for the first time a method for their transformation.

Host-parasite association between Didelphis albiventris (Didelphimorphia: Didelphidae) and Ixodes loricatus (Acari: Ixodidae) in their southern ranges.

The parasitism of Ixodes loricatus Neumann on white-eared opposum, Didelphis albiventris Lund, was analysed in the southern ranges of both. In central Argentina, 118 wild opossums were captured from 2005 to 2012. Adults of I. loricatus were collected (prevalence = 66.1%, mean = 7.03, median = 4), but no immature stage. Tick infestation was not affected by sex (p = 0.27) or age (p = 0.37) of hosts. In line with previous studies about seasonality of larvae and nymphs of I. loricatus, adult tick infestation showed no seasonal trend. This lack of seasonal pattern of infestation for all parasitic stages of I. loricatus may indicate a life cycle governed by nidicolous behaviour, in such a way that this habit would contribute to minimize the influence of external environmental variables. The tick sex ratio was female biased, with two females per one male (p = 0.002). The absence of I. loricatus immatures on D. albiventris suggests that in the study region there is clear segregation of immatures in rodents and adults in marsupials.

Ticks as potential vectors of Mycobacterium leprae: use of tick cell lines to culture the bacilli and generate transgenic strains

Leprosy is an infectious disease caused by Mycobacterium leprae and frequently resulting in irreversible deformities and disabilities. Ticks play an important role in infectious disease transmission due to their low host specificity, worldwide distribution, and the biological ability to support transovarial transmission of a wide spectrum of pathogens, including viruses, bacteria and protozoa. To investigate a possible role for ticks as vectors of leprosy, we assessed transovarial transmission of M. leprae in artificially-fed adult female Amblyomma sculptum ticks, and infection and growth of M. leprae in tick cell lines. Our results revealed M. leprae RNA and antigens persisting in the midgut and present in the ovaries of adult female A. sculptum at least 2 days after oral infection, and present in their progeny (eggs and larvae), which demonstrates the occurrence of transovarial transmission of this pathogen. Infected tick larvae were able to inoculate viable bacilli during blood-feeding on a rabbit. Moreover, following inoculation with M. leprae, the Ixodes scapularis embryo-derived tick cell line IDE8 supported a detectable increase in the number of bacilli for at least 20 days, presenting a doubling time of approximately 12 days. As far as we know, this is the first in vitro cellular system able to promote growth of M. leprae. Finally, we successfully transformed a clinical M. leprae isolate by inserting the reporter plasmid pCHERRY3; transformed bacteria infected and grew in IDE8 cells over a 2-month period. Taken together, our data not only support the hypothesis that ticks may have the potential to act as a reservoir and/or vector of leprosy, but also suggest the feasibility of technological development of tick cell lines as a tool for large-scale production of M. leprae bacteria, as well as describing for the first time a method for their transformation.

Infection with Borrelia chilensis in Ixodes stilesi ticks collected from Pudu puda deer.

Lyme borreliosis is a vector-borne zoonosis caused by Borrelia burgdorferi sensu lato species complex spirochetes, which are maintained in transmission cycles among vertebrates and Ixodes ticks. Recently, a new genospecies within this complex, Borrelia chilensis, was described in Ixodes stilesi collected from the environment and from rodents in Chile. This tick also infests the native Southern pudu deer (Pudu puda). The objectives of this study were to investigate the prevalence, intensity of infestation, and aggregation of hard ticks on this deer species, and to determine the presence of borrelial pathogens in the ticks. Sixty-six deer were examined over a two-year period. A total of 179 ticks of two species, I. stilesi and Ixodes taglei, were collected. Of those, 100 were adults, 78 were nymphs, and one was a larva. Ixodes stilesi was the most prevalent tick (47%) and was highly aggregated (D=0.77) on the deer. Deer body weight was positively associated with tick burden. Borrelia spirochetes were detected in two (6.45%) of the examined I. stilesi ticks. Phylogenetic analyses of 16S and flaB gene sequences positioned these samples in the same clade with Borrelia chilensis VA1 previously described from Chile. These findings suggest that I. stilesi may play a role in the local persistence of B. chilensis. Further studies are required to fully understand the mechanisms of natural transmission of B. chilensis and the risk of infection in humans.

Ecology of the interaction between Ixodes loricatus (Acari: Ixodidae) and Akodon azarae (Rodentia: Criceridae).

The present study explores associations of different factors (i.e. host parameters, presence of other ectoparasites and [mainly biotic] environmental factors) with burdens of Ixodes loricatus immature stages in one of its main hosts in Argentina, the rodent Akodon azarae. For 2 years, rodents were trapped and sampled monthly at 16 points located in four different sites in the Parana River Delta region. Data were analysed with generalized linear mixed models with a negative binomial response (counts of larvae or nymphs). The independent variables assessed were (a) environmental: trapping year, presence of cattle, type of vegetation, rodent abundance; (b) host parameters: body length, sex, body condition, blood cell counts, natural antibody titers and (c) co-infestation with other ectoparasites. Two-way interaction terms deemed a priori as relevant were also included in the analysis. Most of the associations investigated were found significant, but in general, the direction and magnitude of the associations were context-dependent. An exception was the presence of cattle, which was consistently negatively associated with both larvae and nymphs independently of all other variables considered and had the strongest effect on tick burdens. Mites, fleas and Amblyomma triste were also significantly associated (mostly positively) with larval and nymph burdens, and in many cases, they influenced associations with environmental or host factors. Our findings strongly support that raising cattle may have a substantial impact on the dynamics of I. loricatus and that interactions within the ectoparasite community may be an important-but generally ignored-driver of tick dynamics.

Rhipicephalus microplus and Ixodes ovatus cystatins in tick blood digestion and evasion of host immune response.

BACKGROUND: Cystatins are a group of cysteine protease inhibitors responsible for physiological proteolysis regulation and present in a wide range of organisms. Studies about this class of inhibitors in parasites have contributed to clarify their roles in important physiological processes, like blood digestion and modulation of host immune response during blood feeding. Thus, cystatins are a subject of research on the development of new parasite control methods. Additionally, the characterization of proteins shared by different parasite species represents a valuable strategy to find potential targets in multi-species control methods. However, cystatin functions in ticks remain undetermined, especially in Rhipicephalus microplus and Ixodes ovatus, two species that affect livestock and human health, respectively. METHODS: Here we report the inhibitory profile of two R. microplus (BrBmcys2b and BrBmcys2c) and one I. ovatus (JpIocys2a) cystatins to commercial cathepsins B, C, and L. The presence of native cystatins in R. microplus tissues was analyzed using sera against recombinant BrBmcys2b and BrBmcys2c. Also, a peptide from JpIocys2a was synthesized for rabbit immunization, and this serum was used to analyze the cross antigenicity between R. microplus and I. ovatus cystatins. RESULTS: Enzymatic inhibition profile of tick cystatins shows a distinct modulation for cathepsins related to tick blood digestion and evasion of host immune response. Furthermore, BrBmcys2b was detected in saliva and different tissues along tick stages, while BrBmcys2c was detected mainly in gut from partially engorged R. microplus females, demonstrating a distinct pattern of cystatin expression, secretion and traffic between tick tissues. Moreover, phylogenetic analysis suggests that JpIocys2a belongs to the group of tick gut secreted cystatins. Finally, cross-antigenicity assays revealed that antibodies against the JpIocys2a peptide recognize native and recombinant R. microplus cystatins. CONCLUSION: The presence of these proteins in different tissues and their ability to differentially inhibit cathepsins suggest distinct roles for JpIocys2a, BrBmcys2b, and BrBmcys2c in blood digestion, egg and larvae development, and modulation of host immune response in tick physiology. The cross-antigenicity between native and recombinant cystatins supports further experiments using JpIocys2a, BrBmcys2b, and BrBmcys2c as vaccine antigens.

Implications of climate change on the distribution of the tick vector Ixodes scapularis and risk for Lyme disease in the Texas-Mexico transboundary region.

BACKGROUND: Disease risk maps are important tools that help ascertain the likelihood of exposure to specific infectious agents. Understanding how climate change may affect the suitability of habitats for ticks will improve the accuracy of risk maps of tick-borne pathogen transmission in humans and domestic animal populations. Lyme disease (LD) is the most prevalent arthropod borne disease in the US and Europe. The bacterium Borrelia burgdorferi causes LD and it is transmitted to humans and other mammalian hosts through the bite of infected Ixodes ticks. LD risk maps in the transboundary region between the U.S. and Mexico are lacking. Moreover, none of the published studies that evaluated the effect of climate change in the spatial and temporal distribution of I. scapularis have focused on this region. METHODS: The area of study included Texas and a portion of northeast Mexico. This area is referred herein as the Texas-Mexico transboundary region. Tick samples were obtained from various vertebrate hosts in the region under study. Ticks identified as I. scapularis were processed to obtain DNA and to determine if they were infected with B. burgdorferi using PCR. A maximum entropy approach (MAXENT) was used to forecast the present and future (2050) distribution of B. burgdorferi-infected I. scapularis in the Texas-Mexico transboundary region by correlating geographic data with climatic variables. RESULTS: Of the 1235 tick samples collected, 109 were identified as I. scapularis. Infection with B. burgdorferi was detected in 45% of the I. scapularis ticks collected. The model presented here indicates a wide distribution for I. scapularis, with higher probability of occurrence along the Gulf of Mexico coast. Results of the modeling approach applied predict that habitat suitable for the distribution of I. scapularis in the Texas-Mexico transboundary region will remain relatively stable until 2050. CONCLUSIONS: The Texas-Mexico transboundary region appears to be part of a continuum in the pathogenic landscape of LD. Forecasting based on climate trends provides a tool to adapt strategies in the near future to mitigate the impact of LD related to its distribution and risk for transmission to human populations in the Mexico-US transboundary region.

Borrelia chilensis, a new member of the Borrelia burgdorferi sensu lato complex that extends the range of this genospecies in the Southern Hemisphere.

Borrelia burgdorferi sensu lato (s.l.), transmitted by Ixodes spp. ticks, is the causative agent of Lyme disease. Although Ixodes spp. ticks are distributed in both Northern and Southern Hemispheres, evidence for the presence of B. burgdorferi s.l. in South America apart from Uruguay is lacking. We now report the presence of culturable spirochetes with flat-wave morphology and borrelial DNA in endemic Ixodes stilesi ticks collected in Chile from environmental vegetation and long-tailed rice rats (Oligoryzomys longicaudatus). Cultured spirochetes and borrelial DNA in ticks were characterized by multilocus sequence typing and by sequencing five other loci (16S and 23S ribosomal genes, 5S-23S intergenic spacer, flaB, ospC). Phylogenetic analysis placed this spirochete as a new genospecies within the Lyme borreliosis group. Its plasmid profile determined by polymerase chain reaction and pulsed-field gel electrophoresis differed from that of B. burgdorferi B31A3. We propose naming this new South American member of the Lyme borreliosis group B. chilensis VA1 in honor of its country of origin.

Host range and geographical distribution of Ixodes sigelos (Acari: Ixodidae).

Larvae, nymphs and females of Ixodes sigelos Keirans, Clifford and Corwin (Ixodidae) were collected in 13 localities of the Patagonian region of Argentina parasitizing eight species of sigmodontine rodents. We report for the first time adults of I. sigelos for Argentina. Besides, we extend the southern limit of its geographical distribution, and six species of sigmodontines are added as new host species of I. sigelos (Phyllotis xanthopygus, Euneomys chinchilloides, Calomys musculinus, Reithrodon auritus, Loxodontomys micropus and Eligmodontia morgani). The presence of larvae, nymphs and females on sigmodontines, as well as more than 50% of the individuals engorged, indicate that I. sigelos can develop the complete parasitic phase of its life cycle on these small mammals. The geographical distribution of I. sigelos is restricted to the biogeographical Andean Region in Argentina and Chile.

Life cycle of Ixodes luciae (Acari: Ixodidae) in the laboratory.

The life cycle of Ixodes luciae was evaluated for five consecutive generations in the laboratory. Wild mice Calomys callosus and laboratory rats Rattus norvegicus were used as hosts for larvae and nymphs. For adult ticks, opossums Didelphis aurita were used as hosts. Off-host developmental periods were observed in an incubator at 27 degrees C and 95% RH. The life cycle of I. luciae lasted 95-97 days, excluding prefeeding periods. C. callosus, one of the natural host species for I. luciae immature stages, was shown to be much more suitable than the artificial host R. norvegicus. Significantly (P < 0.05), more larvae and nymphs successfully fed on C. callosus than on R. norvegicus. When tick-naïve C. callosus were exposed to three consecutive larval infestations at 24-day intervals, recovery of engorged larvae were greater in the second and third infestations, indicating that previous infestations did not induce acquired resistance to ticks. Larval feeding period typically varied from 5 to 10 days on R. norvegicus, but was significantly (P < 0.05), longer on C. callosus (range, 7-34 days). The majority (71.7%) of I. luciae adult females successfully fed and oviposited after exposed to D. aurita. Mean engorged weight (581.9 mg; range, 237.1-796.0 mg) of these females were much higher than those previously reported for other New World Ixodes species. Our results are in accordance to the current literature that appoints opossums Didelphidae and small rodents (e.g., C. callosus) natural hosts for I. luciae immature and adult stages, respectively.

Comparative immunogenicity of Haemaphysalis longicornis and Rhipicephalus (Boophilus) microplus calreticulins.

The ticks Rhipicephalus (Boophilus) microplus and Haemaphysalis longicornis are blood-sucking ectoparasites of bovines, causing serious damages to the livestock production. The main control method for these ticks is based on acaricides. However, the use of vaccines has been studied as a promising control strategy. Calreticulin (CRT) is a multifunctional, predominantly intracellular protein present in almost all cells of animals. The secretion of CRT during feeding might be linked to the modulation of the parasite-host interaction. In the present study, recombinant CRTs of R. microplus (rBmCRT) and H. longicornis (rHlCRT) were expressed in Escherichia coli and purified by ion exchange chromatography and used for the immunization of bovines and mouse. ELISA demonstrated that both rCRTs are recognized by the sera of immunized bovines. In silico, despite the difference in amino acid sequences, antigenic index analysis of HlCRT and BmCRT using the Jameson-Wolf algorithm indicated that both proteins were very similar in antigenicity index, although six different epitopes between the tick CRTs have been inferred. These data were corroborated by competitive ELISA analyses, which suggest the presence of different epitopes within the proteins. Western blot analyses showed that anti-rBmCRT and anti-rHlCRT bovine sera also recognized the native proteins in larvae extracts and, moreover, sera of bovines immunized with saliva and extract of salivary glands recognized both recombinant CRTs. Thus, mouse and bovine immune system recognized rCRTs, resulting in the production of antibodies with similar specificity for both recombinant proteins, although different epitopes could be distinguished between rBmCRT and rHlCRT.

Ocorrência de Ixodes loricatus Neumann, 1899 (Acari: Ixodidae) parasitando Didelphis albiventris (Lund, 1841), (Didelphimorphia: Didelphidae), em Campo Grande, MS / Occurrence of Ixodes loricatus Neumann, 1899 (Acari: Ixodidae) parasitizing Didelphis albiventris (Lund, 1841) (Didelphimorphia: Didelphidae) in Campo Grande , MS

Este é primeiro relato da ocorrência de Ixodes no Estado do Mato Grosso do Sul e primeiro caso identificado de Ixodes loricatus Neumann, 1899, parasitando Didelphis albiventris no município de Campo Grande, MS, Brasil.

This is first report of occurence of Ixodes in the State of Mato Grosso do Sul and first description of Ixodes loricatus Neumann, 1899, parasitizing Didelphis albiventris in Campo Grande, MS, Brazil.