Abstract:Studies in the biology, ecology and behaviour of R. appendiculatus in Zambia have shown considerable variation within and between populations often associated with their geographical origin. We studied variation in the mitochondrial COI (mtCOI) gene of adult R. appendiculatus ticks originating from the Eastern and Southern provinces of Zambia. Rhipicephalus appendiculatus ticks from the two provinces were placed into two groups on the mtCOI sequence data tree. One group comprised all haplotypes of specimens fr… Show more
“…One sub-haplogroup (sub-haplogroup II) contained Kenyan haplotypes only ( n = 5), another (sub-haplogroup I-B) comprised nine Kenyan haplotypes and one from Rwanda, while the third (sub-haplogroup I-A) was made up of five haplotypes from Kenya, two from Rwanda and four from Zambia’s eastern province. This result suggests higher variation in R. appendiculatus , especially in haplogroup A, and a higher degree of phylogenetic complexity in this haplogroup not revealed in the studies of Mtambo et al [ 17 , 18 ]. Fig.…”
Section: Resultsmentioning
confidence: 61%
“…The utility of COI as a phylogenetic marker for ticks has been demonstrated previously [ 55 – 58 ]. It has also been used previously to show R. appendiculatus speciation [ 17 , 18 , 59 ] and the current study found the variation in the COI to be adequate for phylogeny reconstruction and associated analyses using R. appendiculatus samples from Kenya.…”
BackgroundThe ixodid tick Rhipicephalus appendiculatus transmits the apicomplexan protozoan parasite Theileria parva, which causes East coast fever (ECF), the most economically important cattle disease in eastern and southern Africa. Recent analysis of micro- and minisatellite markers showed an absence of geographical and host-associated genetic sub-structuring amongst field populations of R. appendiculatus in Kenya. To assess further the phylogenetic relationships between field and laboratory R. appendiculatus tick isolates, this study examined sequence variations at two mitochondrial genes, cytochrome c oxidase subunit I (COI) and 12S ribosomal RNA (rRNA), and the nuclear encoded ribosomal internal transcribed spacer 2 (ITS2) of the rRNA gene, respectively.ResultsThe analysis of 332 COI sequences revealed 30 polymorphic sites, which defined 28 haplotypes that were separated into two distinct haplogroups (A and B). Inclusion of previously published haplotypes in our analysis revealed a high degree of phylogenetic complexity never reported before in haplogroup A. Neither haplogroup however, showed any clustering pattern related to either the geographical sampling location, the type of tick sampled (laboratory stocks vs field populations) or the mammalian host species. This finding was supported by the results obtained from the analysis of 12S rDNA sequences. Analysis of molecular variance (AMOVA) indicated that 90.8 % of the total genetic variation was explained by the two haplogroups, providing further support for their genetic divergence. These results were, however, not replicated by the nuclear transcribed ITS2 sequences likely because of recombination between the nuclear genomes maintaining a high level of genetic sequence conservation.ConclusionsCOI and 12S rDNA are better markers than ITS2 for studying intraspecific diversity. Based on these genes, two major genetic groups of R. appendiculatus that have gone through a demographic expansion exist in Kenya. The two groups show no phylogeographic structure or correlation with the type of host species from which the ticks were collected, nor to the evolutionary and breeding history of the species. The two lineages may have a wide geographic distribution range in eastern and southern Africa. The findings of this study may have implications for the spread and control of R. appendiculatus, and indirectly, on the transmission dynamics of ECF.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1631-1) contains supplementary material, which is available to authorized users.
“…One sub-haplogroup (sub-haplogroup II) contained Kenyan haplotypes only ( n = 5), another (sub-haplogroup I-B) comprised nine Kenyan haplotypes and one from Rwanda, while the third (sub-haplogroup I-A) was made up of five haplotypes from Kenya, two from Rwanda and four from Zambia’s eastern province. This result suggests higher variation in R. appendiculatus , especially in haplogroup A, and a higher degree of phylogenetic complexity in this haplogroup not revealed in the studies of Mtambo et al [ 17 , 18 ]. Fig.…”
Section: Resultsmentioning
confidence: 61%
“…The utility of COI as a phylogenetic marker for ticks has been demonstrated previously [ 55 – 58 ]. It has also been used previously to show R. appendiculatus speciation [ 17 , 18 , 59 ] and the current study found the variation in the COI to be adequate for phylogeny reconstruction and associated analyses using R. appendiculatus samples from Kenya.…”
BackgroundThe ixodid tick Rhipicephalus appendiculatus transmits the apicomplexan protozoan parasite Theileria parva, which causes East coast fever (ECF), the most economically important cattle disease in eastern and southern Africa. Recent analysis of micro- and minisatellite markers showed an absence of geographical and host-associated genetic sub-structuring amongst field populations of R. appendiculatus in Kenya. To assess further the phylogenetic relationships between field and laboratory R. appendiculatus tick isolates, this study examined sequence variations at two mitochondrial genes, cytochrome c oxidase subunit I (COI) and 12S ribosomal RNA (rRNA), and the nuclear encoded ribosomal internal transcribed spacer 2 (ITS2) of the rRNA gene, respectively.ResultsThe analysis of 332 COI sequences revealed 30 polymorphic sites, which defined 28 haplotypes that were separated into two distinct haplogroups (A and B). Inclusion of previously published haplotypes in our analysis revealed a high degree of phylogenetic complexity never reported before in haplogroup A. Neither haplogroup however, showed any clustering pattern related to either the geographical sampling location, the type of tick sampled (laboratory stocks vs field populations) or the mammalian host species. This finding was supported by the results obtained from the analysis of 12S rDNA sequences. Analysis of molecular variance (AMOVA) indicated that 90.8 % of the total genetic variation was explained by the two haplogroups, providing further support for their genetic divergence. These results were, however, not replicated by the nuclear transcribed ITS2 sequences likely because of recombination between the nuclear genomes maintaining a high level of genetic sequence conservation.ConclusionsCOI and 12S rDNA are better markers than ITS2 for studying intraspecific diversity. Based on these genes, two major genetic groups of R. appendiculatus that have gone through a demographic expansion exist in Kenya. The two groups show no phylogeographic structure or correlation with the type of host species from which the ticks were collected, nor to the evolutionary and breeding history of the species. The two lineages may have a wide geographic distribution range in eastern and southern Africa. The findings of this study may have implications for the spread and control of R. appendiculatus, and indirectly, on the transmission dynamics of ECF.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1631-1) contains supplementary material, which is available to authorized users.
“…a group found in Southern and Eastern Africa (Southern stock, distributed in South Africa, Southern Zambia and Zimbabwe) and a second group distributed mainly in Eastern Africa (Eastern stock, found in parts of Burundi, Kenya, Tanzania and Uganda). Both stocks display major morphological, ecological and epidemiological differences [7]. Ticks from the southern stock are larger, display a unimodal phenology and obligatory diapause while ticks from the Eastern stock are smaller than their southern stock counterparts, display a bimodal phenology and require a photoperiod induction for diapause.…”
Section: Discussionmentioning
confidence: 99%
“…In addition to morphological identification of collected samples, we conducted molecular investigations to assess the intra-specific genetic diversity of the Comorian populations of R. appendiculatus . Indeed, former studies have shown that this species may be separated in two genetically distinct cytoplasmic lineages with marked different ecology and distribution [7-10]. Phylogenetic investigations were thus carried out on R. appendiculatus to identify their lineage and origin.…”
BackgroundUnion of the Comoros suffered a severe East Coast Fever epidemic in 2004. Rhipicephalus appendiculatus was probably involved in pathogen transmission as this competent tick species, although previously absent from Comoros, was sampled on 4 animals on one geographical site during the epidemic. We carried out an entomological survey on all three islands of Union of the Comoros to establish cattle tick species distribution with a special emphasis on R. appendiculatus. We investigated R. appendiculatus intraspecific diversity as this species has been previously shown to be split off into two main cytoplasmic lineages with different ecology, physiology and vectorial competence. This survey also included sampling of live cattle imported from Tanzania to investigate the possibility of tick introduction through animal trade.ResultsOur data show that Comoros cattle are infested with Amblyomma variegatum, Rhipicephalus microplus and R. appendiculatus. This latter species has established throughout Grande Comore but is absent from Anjouan and Moheli. Interestingly, 43 out of the 47 sequenced R. appendiculatus ticks belong to one single highly competent lineage while ticks from the other lineage where only found on imported cattle or on cattle parked at the vicinity of the harbor. At last, 2 ticks identified as R. evertsi, a species so far virtually absent on Comoros, were sampled on imported cattle.ConclusionsThis survey shows that importation of live cattle is clearly a source of vector introduction in Comoros. The wide distribution of one highly competent R. appendiculatus lineage on Grande Comore, together with the absence of this species on the two neighbouring islands is in accordance with the rapid and disastrous spread of East Coast Fever epidemics on Grande Comore Island only. Whether the other R. appendiculatus lineage as well as R. evertsi species will succeed in establishing permanently on Grande Comore needs to be monitored.
“…Presumably, C. variipennis populations in this area are not efÞcient vectors. Using the mitochondrial COI gene, Mtambo et al (2007) discovered signiÞcant genetic variation between Rhipicephalus appendiculatus populations in the eastern and southern provinces of Zambia where this vector transmits Theileria parva (Katete), the causative agent for East Coast fever in cattle. In addition, Tempia (1997) found higher infection rates for T. parva in R. appendiculatus adults in the Eastern province than the Southern province, which lends support to the significant regional differences in the epidemiology of East Coast fever (Speybroeck et al 2004, Billiouw 2005.…”
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