Analysis of Amblyomma sculptum haplotypes in an area endemic for Brazilian spotted fever

Abstract

Amblyomma sculptum (Ixodida: Ixodidae) Berlese, 1888, a member of the Amblyomma cajennense complex, is the major vector of Brazilian spotted fever (BSF) in southeastern Brazil. In this study, the genetic diversity of A. sculptum populations in the state of Rio de Janeiro (RJ), Brazil, was investigated because genetic variability in tick populations may be related to vector competence. Samples of A. sculptum from 19 municipalities in 7 regions of RJ were subjected to DNA extraction, amplification and sequencing of D-loop, cytochrome oxidase II and 12S rDNA mitochondrial genes. These sequences were used to map the genetic diversity of this tick. Amblyomma sculptum populations are genetically diverse in RJ, especially in the South Centre and Highland regions. Few unique haplotypes were observed in all populations, and the majority of genetic variation found was among ticks within each population. Phylogenetic reconstruction reinforced the assumption that all the haplotypes identified in RJ belong to A. sculptum. However, some RJ haplotypes are closer to A. sculptum from Argentina than to A. sculptum from elsewhere in Brazil. In RJ, A. sculptum has high genetic diversity, although little genetic differentiation. Observations also indicated a high level of gene flow among the studied populations and no evidence of population structure according to region in RJ.

Ultrastructural Morphology and Molecular Analyses of Tropical and Temperate “Species” of Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) in Brazil

“…The final number of processed ticks was 11 from RN, 10 from RO, 10 from RR, 14 from PR, and 23 from RS. Polymerase chain reaction (PCR) was executed according to the methodology proposed by Bitencourth et al (2016) , using the GeneAmp PCR System 9700 (Applied Biosystems, CA). The primers used were T1B and T2A for 12S rDNA (≈360 bp; Beati and Keirans 2001 ) and D-loop 3-1x and D-loop 4-1x, for D-loop rDNA (≈440 bp; Burkman 2009 ).…”

Comparative population genetic structure of two ixodid tick species (Ixodes ovatusandHaemaphysalis flava) in Niigata Prefecture, Japan

“…These results from the unbiased estimator allowing a negative FST when the sample size is small. 311 (Bitencourth et al, 2016;Vial et al, 2006;Weir and Cockerham, 1984) . It can also be noted that 312 we found significant pairwise FST values in 2 sampling location in H. flava cox1 sequences probably 313 due to the fact that both locations have only one tick sample.…”

“…These results from the unbiased estimator allowing a negative FST when the sample size is small. (Bitencourth et al, 2016;Vial et al, 2006;Weir and Cockerham, 1984) .…”

“…We found three groups (China 1, Japan, and China 2) and two slightly divergent cox1 haplotypes (Hap 60 and 59) in the Japan group of I. ovatus in Niigata. Considering two or more cryptic species can be concealed in one morphologically described species (Bitencourth et al, 2016), the occurrence of the three groups and the divergent haplotypes suggests that I. ovatus may be a species complex. It can be inferred that China 1 and China 2 might have a longer evolutionary time as compared to Japan.…”

Amblyomma aureolatum Genetic Diversity and Population Dynamics Are Not Related to Spotted Fever Epidemiological Scenarios in Brazil

“…In all samples, DNA was extracted using the saturated sodium chloride solution protocol [25]. For A. aureolatum population analysis, a set of mitochondrial gene fragments (12S rDNA [26], D-loop [27], and COII [11]) was amplified by a polymerase chain reaction (PCR) following previously established protocols [11].…”