Bacteria of the genera Ehrlichia and Rickettsia in ticks of the family Ixodidae with medical importance in Argentina

Wild birds as hosts of ticks (Acari: Ixodidae) and Anaplasmataceae (Rickettsiales) in the Atlantic rainforest ecoregion, Argentina

This study aimed to assess the presence of Anaplasma, Ehrlichia and Rickettsia species infecting wild birds and their associated ticks in two localities: Moconá Provincial Park (MPP) and Piñalito Provincial Park (PPP), within the Atlantic rainforest ecoregion of Argentina. A total of 142 birds were captured representing 34 species, 28 genera, 15 families and five orders. Ticks were collected from 33 of these birds, comprising 19 species, 14 genera and one order. A total of 59 ticks were collected and identified as Amblyomma calcaratum (13 larvae and four nymphs), Amblyomma longirostre (31 larvae and four nymphs), Amblyomma ovale (one larva and one nymph) and Haemaphysalis leporispalustris (five larvae). All samples were screened for detection of Anaplasma, Ehrlichia and Rickettsia DNA by polymerase chain reaction (PCR) assay. Four bird species tested positive for Anaplasmataceae, with three closely related to Anaplasma and Ehrlichia species previously reported in A. calcaratum adults from a site 15 km away from MPP. The fourth Anaplasmataceae agent was phylogenetically related to Ehrlichia strains reported in Amblyomma triste from the Delta and Parana Islands ecoregion. Additionally, two Rickettsia species were detected and molecularly identified within ticks collected from birds: Rickettsia amblyommatis in A. longirostre larvae and Rickettsia rhipicephali in H. leporispalustris larvae. These findings suggest that birds may play a significant role in the spread of ticks and their associated tick-borne pathogens across diverse biomes.

Molecular characterization of Amblyomma geoemydae using CO1 mitochondrial gene to validate phenotypic taxonomical evaluation

Animal ectoparasites are linked to the spread of serious medical and veterinary important pathogens. Our research intends to close the knowledge gap concerning the numerous ectoparasites that inhabit animals in Wayanad. Ectoparasites in animals brought to the veterinary dispensaries in Wayanad were retrieved and identified morphologically and molecularly. Using a high-quality stereomicroscope, the taxonomic features of the four following species were examined and identified: Haemaphysalis bispinosa, Rhipicephalus annulatus, R. microplus, and Amblyomma geoemydae. The important disease vector A. geoemydae was reported for the first time in Kerala. The important phenotypic characters of the highlighted species A. geoemydae are the edge of the basis capituli is circular without cornua, and the hypostomal dental formula is 2/2. The taxonomically identified four species were subjected to CO1 gene sequence analysis. The evolutionary relationship was inspected through the neighbour-joining method, and the phylogenetic tree was built through the Maximum Likelihood method. The present study has also estimated the diversity index of R. microplus, R. annulatus, H. bispinosa, and A. geoemydae. Among them, R. microplus 0.36638 have reported with the maximum diversity index score. The significance of the study is the presence of Lyme disease vector A. geoemydae, in the Wayanad District of Kerala, and it is the first report of the species from where an outbreak of Lyme disease occurred in 2013.

Molecular Detection of Candidatus Rickettsia andeanae and Ehrlichia sp. in Amblyomma pseudoconcolor Aragão, 1908 (Acari: Ixodidae) from the Argentinian Patagonia

This study presents the molecular detection of Candidatus Rickettsia andeanae and Ehrlichia sp. in Amblyomma pseudoconcolor Aragão, 1908 (Acari: Ixodidae) collected on a large hairy armadillo (Chaetophractus villosus (Desmarest, 1804)). On 12 October 2020, a specimen of C. villosus was found dead on the road in Río Negro province, Argentina. Molecular detection of Rickettsia and Ehrlichia agents was performed amplifying the gltA and 16S rRNA gene, respectively. One tick, determined morphologically and genetically as A. pseudoconcolor, was collected on C. villosus. The rickettsial agent detected in A. pseudoconcolor was identified as Candidatus Rickettsia andeanae. The Ehrlichia sp. strain showed high sequence similarity to different uncultured Ehrlichia sp. detected in horses, capybaras and Ixodes ornithorhynchi from Nicaragua, Brazil and Australia, respectively. The results of this study and previous findings suggest that A. pseudoconcolor may be a potential vector of some Rickettsia and Ehrlichia bacteria of unknown pathogenicity.

Rickettsia spp., Ehrlichia sp. and Candidatus Midichloria sp. associated to ticks from a protected urban area in Buenos Aires City (Argentina)

The aim of this study was to determine the infection with Rickettsiales in ticks and birds from the main protected urban area of Buenos Aires City (Argentina). One Amblyomma aureolatum (0.2%) and one Ixodes auritulus (0.1%) were positive by PCR targeting Rickettsia 23S-5S rRNA intergenic spacer. Phylogenetic analysis shows to findings in A. aureolatum are closely to Rickettsia bellii and for I. auritulus are related to 'Candidatus Rickettsia mendelii'. One I. auritulus (0.1%) and three A. aureolatum (0.6%) were positive by PCR for a fragment of the 16S rRNA gene of the Anaplasmataceae family. The sequences obtained from A. aureolatum were phylogenetically related to Midichloriaceae endosymbionts. The sequence from I. auritulus s.l. had 100% identity with Ehrlichia sp. Magellanica from Chile and two genotypes of Ehrlichia sp. from Uruguay. The results of our study show that Rickettsia and Ehrlichia are present in ticks in the main protected urban area of Buenos Aires City.

Molecular detection of rickettsial bacteria in ticks of the genus Ixodes from the Southern Cone of America

To obtain information about rickettsial bacteria in ticks of the genus Ixodes from Argentina and Uruguay, specimens of I. fuscipes (previously named as I. aragaoi), Ixodes pararicinus, Ixodes sp. cf. I. affinis, and Ixodes sp. were tested targeting the rickettsial gltA and ompA genes. Rickettsial bacteria was detected in all of these species. Rickettsia found in Ixodes sp. is closely related to Ca. Rickettsia mendelii, which was previously detected in I. ricinus of the Czech Republic and later in I. brunneus from the USA. Phylogenetic analyses of the Rickettsia strains found in I. fuscipes, I. pararicinus, and Ixodes sp. cf. I. affinis showed that these strains form a clade together with R. buchneri detected in I. scapularis from the USA, which is closely related to R. monacensis from Europe. Rickettsia buchneri, R. cooleyi and the Rickettsia detected in I. fuscipes, I. pararicinus, and Ixodes sp. cf. I. affinis clustered together in a clade well supported, which suggest that they are different strains of R. buchneri. The phylogenetic analysis shows that Ixodes ticks that are closely related in evolutionary terms (i.e. Ixodes species from the I. ricinus complex, I. brunneus-Ixodes sp.) share closely related rickettsial strains. The results of this study show that rickettsial bacteria are present in Ixodes ticks from Argentina and describe the first detection of Ca. R. mendelii in South America.

Molecular survey of Rickettsia spp. in the Neotropical deer tick Haemaphysalis juxtakochi from Brazilian Pampa

Spotted fever (SF) is a tick-borne disease associated with Rickettsia spp.. In the Pampa biome, Southern Brazil, cases of SF seem to be strongly linked with the practice of hunting wild animals. An investigation of rickettsiae in tick species found on wild animals could provide more information regarding the rickettsiosis enzootic cycle. The aim of this study is to describe the results of a molecular survey of Rickettsia spp. in the Neotropical deer tick, Haemaphysalis juxtakochi Cooley, 1946 (Acari: Ixodidae), from the Brazilian Pampa. Ticks were obtained from 14 road-killed gray brocket deer, Mazama gouazoubira (Artiodactyla: Cervidae), found in nine different municipalities of Rio Grande do Sul state, Southern Brazil. Ticks were processed individually to obtain genomic DNA, and then Rickettsia spp. was investigated using a set of PCR reactions that amplified the rickettsial fragments of the gltA, ompA, and htrA genes. Of the 24 tick samples tested, DNA of Rickettsia parkeri sensu stricto (s.s.) was found in 11 H. juxtakochi specimens collected in two different areas of the Brazilian Pampa. This is the first report of R. parkeri s.s. (the main agent associated with SF in the Uruguayan, Argentinian, and Brazilian Pampa) in H. juxtakochi ticks. These findings indicate that R. parkeri s.s. may be much more common and widely distributed in the Pampa biome than previously assumed. Moreover, H. juxtakochi ticks and gray brocket deer could participate in the potential spillover of R. parkeri s.s. from endemic to non-endemic areas in the South American Pampa.

Relative transcription of autophagy-related genes in Amblyomma sculptum and Rhipicephalus microplus ticks

Ticks endure stressful off-host periods and perform as vectors of a diversity of infectious agents, thus engaging pathways that expectedly demand for autophagy. Little is known of ticks' autophagy, a conserved eukaryotic machinery assisting in homeostasis processes that also participates in tissue-dependent metabolic functions. Here, the autophagy-related ATG4 (autophagin-1), ATG6 (beclin-1) and ATG8 (LC3) mRNAs from the human diseases vector Amblyomma sculptum and the cattle-tick Rhipicephalus microplus were identified. Comparative qPCR quantifications evidenced different transcriptional status for the ATG genes in the salivary glands (SG), ovaries and intestines of actively feeding ticks. These ATGs had increased relative transcription under nutrient-deprivation, as determined by validation tests with R. microplus embryo-derivative cells BME26 and A. sculptum SG explants incubations in HBSS. Starvation lead to 4-31.8× and ~ 60-500× increments on the ATGs mRNA loads in BME26 and A. sculptum SG explants, respectively. PI3K inhibitor 3MA treatment also affected ATGs expression in BME26. Some ATGs were more transcribed in the SGs than in the ovaries of cattle-ticks. Amblyomma sculptum/R. microplus interspecific comparisons showed that ATG4 and ATG6 were 0.18× less expressed in A. sculptum SGs, but ~ 10-100× more expressed in their ovaries when compared to R. microplus organs. ATG4 and ATG8a transcript loads were ~ 120× and ~ 40× higher, respectively, in A. sculptum intestines when compared to cattle-ticks of similar weight category. ATGs expression in A. sculptum intestines increased with tick weight, indicating Atgs contribution to intracellular blood digestion. Possible roles of the autophagy machinery and their organ-specific expression profile on vector biology are discussed.