Genetic characterization of the prion protein gene in camels (Camelus) with comments on the evolutionary history of prion disease in Cetartiodactyla.

Transmissible spongiform encephalopathies (TSEs) are a fatal neurogenerative disease that include Creutzfeldt-Jakob disease in humans, scrapie in sheep and goats, bovine spongiform encephalopathy (BSE), and several others as well as the recently described camel prion disease (CPD). CPD originally was documented in 3.1% of camels examined during an antemortem slaughterhouse inspection in the Ouargla region of Algeria. Of three individuals confirmed for CPD, two were sequenced for the exon 3 of the prion protein gene (PRNP) and were identical to sequences previously reported for Camelus dromedarius. Given that other TSEs, such as BSE, are known to be capable of cross-species transmission and that there is household consumption of meat and milk from Camelus, regulations to ensure camel and human health should be a One Health priority in exporting countries. Although the interspecies transmissibility of CPD currently is unknown, genotypic characterization of Camelus PRNP may be used for predictability of predisposition and potential susceptibility to CPD. Herein, eight breeds of dromedary camels from a previous genetic (mitochondrial DNA and microsatellites) and morphological study were genotyped for PRNP and compared to genotypes from CPD-positive Algerian camels. Sequence data from PRNP indicated that Ethiopian camels possessed 100% sequence identity to CPD-positive camels from Algeria. In addition, the camel PRNP genotype is unique compared to other members of the Orders Cetartiodactyla and Perissodactyla and provides an in-depth phylogenetic analysis of families within Cetartiodactyla and Perissodactyla that was used to infer the evolutionary history of the PRNP gene.

Morphometric and genetic variation in 8 breeds of Ethiopian camels (Camelus dromedarius).

Dromedary camels (Camelus dromedarius) are a domesticated and closely guarded economic staple of indigenous people located throughout Ethiopian territorial states. Seventeen morphometric variables were examined to determine intraspecific variation among 8 pastoralist-designated breeds of camels. Additionally, DNA sequences from mitochondrial cytochrome-b gene and genotyping of 6 nuclear microsatellite loci were examined to assess genetic diversity and phylogenetic relationship of Ethiopian camels. Examination of 525 individuals revealed significant morphometric differentiation in Afar as compared with the remaining 7 breeds. Analysis of cytochrome-b sequences failed to recover monophyletic groups associated with pastoralist-recognized breeds. Analysis of 6 microsatellite loci from 104 individuals depicted no resolution of distinct genetic lineages in accordance to geographical or designated breeds. Overall, separation of 2 ecotypes based on the morphometric data was supported; however, genetic analysis of cytochrome-b and microsatellite data failed to support any unique genetic lineage or statistically significant population structure.