Molecular characterization of Echinococcus granulosus isolates from Bulgarian human cystic echinococcosis patients

Abstract

Although cystic echinococcosis (CE) is highly endemic in Bulgaria, there is still scarce information about species and/or genotypes of the Echinococcus granulosus complex that infect humans. Our study tackled the genetic diversity of E. granulosus complex in a cohort of 30 Bulgarian CE patients. Ten animal E. granulosus isolates from neighboring Greece were additionally included. Specimens were comparatively analyzed for partial sequences of five mitochondrial (mt) (cox I, nad I, rrnS, rrnL, and atp6) and three nuclear (nc) genes (act II, hbx 2, and ef-1α) using a PCR-sequencing approach. All 30 Bulgarian isolates were identified as E. granulosus sensu stricto (s.s.) and were showing identical sequences for each of the three examined partial nc gene markers. Based upon concatenated sequences from partial mtDNA markers, we detected 10 haplotypes: 6 haplotypes (H1-H6) clustering with E. granulosus s.s. (G1) and 4 haplotypes (H9-H13) grouping with E. granulosus s.s. (G3), with H1 and H10 being the most frequent in Bulgarian patients. The haplotypes H1, H4, and H11 were also present in Greek hydatid cyst samples of animal origin. In conclusion, E. granulosus s.s. (G1 and G3 genotypes) is the only causative agent found so far to cause human CE in Bulgaria. However, further studies including larger sample sizes and other additional geographic regions in Bulgaria will have to be performed to confirm our results.

Genetic survey of alveolar and cystic echinococcoses in Romania: first molecular evidence of Echinococcus multilocularis in humans in the country

“…This genetic form was found in sheep, cattle and pig in the country, whereas the present fi nding provides the fi rst report of G3 in humans from Romania. High rates of G3 infections within E. granulosus s.s. were recently recorded also in neighboring Serbia (40 %, 18 of 40 isolates) and Bulgaria (46.7 %, 14 of 30 isolates) (Debeljak et al, 2016;Marinova et al, 2017). Interestingly, in two of the four human samples E. canadensis G7 was diagnosed as CE causative agent.…”

Molecular Characterization of Echinococcus granulosus sensu lato from Humans in Slovenia

“…Although formerly known as the “buffalo strain”, E. granulosus s.s. G3 has a wide range of intermediate hosts and is now recognized to circulate in almost all continents [ 15 , 36 ]. It is significantly less prevalent worldwide than genotype G1 but was found to be associated with a high rate of human CE cases in Italy, Bulgaria, Pakistan, Iran and India [ 37 , 38 , 39 , 40 , 41 ]. Until recently, it was not possible to differentiate unambiguously between genotypes G1 and G3, so the real contribution of genotype G3 to the global burden of CE may have been underestimated.…”

“…Fragments of cytochrome c oxidase subunit 1, cox1 [ 38 ], NADH dehydrogenase subunit 1, nad1 [ 38 , 54 ], NADH dehydrogenase subunit 5, nad5 [ 55 ] and small ribosomal RNA, rrnS [ 55 , 56 ] mitochondrial genes were amplified by conventional PCR as described previously, using FastStart™ High Fidelity PCR System (Roche, Germany) reagents. The sequences of the primers are shown in Table 2 .…”

Genetic characterization ofEchinococcusisolates from various intermediate hosts in the Qinghai-Tibetan Plateau Area, China

“…The results presented in this report indicated that G1 was the most dominant distinct species of E. granulosus s. s. in the hydatid cyst samples from humans and animals in regions of the QTPA, China. The epidemiological data of this present study were in line with some previous molecular studies from China that had demonstrated G1 was the most common and dominant species of E. granulosus s. s. in humans, livestock and wild animals in China (Ma et al ., 2008, 2015; Yang et al ., 2009; Liu et al ., 2013; Yan et al ., 2013; Zhong et al ., 2014; Hu et al ., 2015), Turkey (Erdogan et al ., 2017), Iran (Farhadi et al ., 2015; Arbabi et al ., 2017), and Bulgaria (Marinova et al ., 2017). Likewise, many epidemiological studies conducted in the majority of regions of the world have also indicated E. granulosus s. s. G1 as the predominant species (Laurimae et al ., 2016; Roinioti et al ., 2016; Avila et al ., 2017; Debiaggi et al ., 2017; Ehsan et al ., 2017; Thapa et al ., 2017).…”

“…Genetic analysis employing mitochondrial genes ( cox 1, nad 1, cob and nad 5 gene) and ribosomal genes might reveal the biological relationships between Echinococcus spp. and strains (Marinova et al ., 2017; Kinkar et al ., 2018 a ). Mitochondrial DNA (mtDNA) is the most suitable genetic marker for the analysis of genetic diversity, genetic differentiation and evolution of species and is widely used in species classification (Umhang et al ., 2014).…”